C8051F350/1/2/3
C8051F350/1/2/3
8 k ISP Flash MCU Family
Analog Peripherals
- 24 or 16-Bit ADC
-
No missing codes
0.0015% nonlinearity
Programmable conversion rates up to 1 ksps
8-Input multiplexer
1x to 128x PGA
Built-in temperature sensor
instructions in 1 or 2 system clocks
- Up to 50 MIPS throughput
- Expanded interrupt handler
Memory
- 768 Bytes (256 + 512) On-Chip RAM
- 8 kB Flash; In-system programmable in 512-byte
Two 8-Bit Current Output DACs
Comparator
• Programmable hysteresis and response time
• Configurable as interrupt or reset source
• Low current (0.4 µA)
Sectors
On-chip Debug
- On-chip debug circuitry facilitates full speed, non-
intrusive in-system debug (No emulator required)
Provides breakpoints, single stepping,
inspect/modify memory and registers
Superior performance to emulation systems using
ICE-Chips, target pods, and sockets
Low Cost, Complete Development Kit
Supply Voltage 2.7 to 3.6 V
- Typical operating current:
5.8 mA @ 25 MHz;
11 µA @ 32 kHz
0.1 µA
capture/compare modules
Real time clock mode using PCA or timer and external clock source
Clock Sources
- Internal Oscillator: 24.5 MHz with ± 2% accuracy
supports UART operation
External Oscillator: Crystal, RC, C, or clock
(1 or 2 pin modes)
Clock multiplier to achieve 50 MHz internal clock
Can switch between clock sources on-the-fly
28-Pin QFN or 32-Pin LQFP Package
- 5 x 5 mm PCB footprint with 28-QFN
ANALOG
PERIPHERALS
8-bit
IDAC
24/16-bit
ADC
8-bit
IDAC
+
TEMP
SENSOR
-
-
- Typical stop mode current:
Temperature Range: –40 to +85 °C
A
M
U
X
Digital Peripherals
- 17 Port I/O; All 5 V tolerant with high sink current
- Enhanced UART, SMBus™, and SPI™ Serial Ports
- Four general purpose 16-bit counter/timers
- 16-bit programmable counter array (PCA) with three
VOLTAGE
COMPARATOR
DIGITAL I/O
UART
SMBus
SPI
PCA
Timer 0
Timer 1
Timer 2
Timer 3
CROSSBAR
•
•
•
•
•
•
High Speed 8051 µC Core
- Pipelined Instruction architecture; executes 70% of
Port 0
Port 1
P2.0
24.5 MHz PRECISION INTERNAL OSCILLATOR
WITH CLOCK MULTIPLIER
HIGH-SPEED CONTROLLER CORE
8 kB
ISP FLASH
FLEXIBLE
INTERRUPTS
Rev. 1.1 5/07
8051 CPU
(50 MIPS)
DEBUG
CIRCUITRY
768 B SRAM
POR
Copyright © 2007 by Silicon Laboratories
WDT
C8051F35x
C8051F350/1/2/3
NOTES:
2
Rev. 1.1
C8051F350/1/2/3
Table of Contents
1. System Overview.................................................................................................... 17
1.1. CIP-51™ Microcontroller................................................................................... 21
1.1.1. Fully 8051 Compatible Instruction Set...................................................... 21
1.1.2. Improved Throughput ............................................................................... 21
1.1.3. Additional Features .................................................................................. 21
1.2. On-Chip Debug Circuitry................................................................................... 22
1.3. On-Chip Memory............................................................................................... 23
1.4. 24 or 16-Bit Analog to Digital Converter (ADC0) .............................................. 24
1.5. Two 8-bit Current-Mode DACs.......................................................................... 25
1.6. Programmable Comparator .............................................................................. 26
1.7. Serial Ports ....................................................................................................... 26
1.8. Port Input/Output............................................................................................... 27
1.9. Programmable Counter Array ........................................................................... 28
2. Absolute Maximum Ratings .................................................................................. 29
3. Global DC Electrical Characteristics .................................................................... 30
4. Pinout and Package Definitions............................................................................ 31
5. 24 or 16-Bit Analog to Digital Converter (ADC0) ................................................. 41
5.1. Configuration..................................................................................................... 42
5.1.1. Voltage Reference Selection.................................................................... 42
5.1.2. Analog Inputs ........................................................................................... 42
5.1.3. Modulator Clock ....................................................................................... 43
5.1.4. Decimation Ratio ...................................................................................... 43
5.2. Calibrating the ADC .......................................................................................... 44
5.2.1. Internal Calibration ................................................................................... 44
5.2.2. System Calibration ................................................................................... 44
5.2.3. Calibration Coefficient Storage................................................................. 44
5.3. Performing Conversions ................................................................................... 46
5.3.1. Single Conversions .................................................................................. 46
5.3.2. Continuous Conversions .......................................................................... 46
5.3.3. ADC Output .............................................................................................. 46
5.3.4. Error Conditions ....................................................................................... 47
5.4. Offset DAC........................................................................................................ 47
5.5. Burnout Current Sources .................................................................................. 47
5.6. Analog Multiplexer ............................................................................................ 59
6. 8-Bit Current Mode DACS (IDA0 and IDA1).......................................................... 67
6.1. IDAC Output Scheduling................................................................................... 68
6.1.1. Update Output On-Demand ..................................................................... 68
6.1.2. Update Output Based on Timer Overflow ................................................ 68
6.1.3. Update Output Based on CNVSTR Edge................................................. 68
6.2. IDAC Output Mapping....................................................................................... 68
6.3. IDAC External Pin Connections ........................................................................ 71
7. Voltage Reference .................................................................................................. 73
8. Temperature Sensor............................................................................................... 77
Rev. 1.1
3
C8051F350/1/2/3
9. Comparator0 ........................................................................................................... 79
9.1. Comparator0 Inputs and Outputs...................................................................... 83
10. CIP-51 Microcontroller ........................................................................................... 87
10.1.Instruction Set................................................................................................... 89
10.1.1.Instruction and CPU Timing ..................................................................... 89
10.1.2.MOVX Instruction and Program Memory ................................................. 89
10.2.Register Descriptions ....................................................................................... 93
10.3.Power Management Modes.............................................................................. 96
10.3.1.Idle Mode ................................................................................................. 96
10.3.2.Stop Mode................................................................................................ 96
11. Memory Organization and SFRs ........................................................................... 99
11.1.Program Memory.............................................................................................. 99
11.2.Data Memory .................................................................................................. 100
11.3.General Purpose Registers ............................................................................ 100
11.4.Bit Addressable Locations .............................................................................. 100
11.5.Stack............................................................................................................... 100
11.6.Special Function Registers............................................................................. 101
12. Interrupt Handler .................................................................................................. 105
12.1.MCU Interrupt Sources and Vectors............................................................... 105
12.2.Interrupt Priorities ........................................................................................... 105
12.3.Interrupt Latency............................................................................................. 105
12.4.Interrupt Register Descriptions ....................................................................... 107
12.5.External Interrupts .......................................................................................... 111
13. Prefetch Engine .................................................................................................... 113
14. Reset Sources....................................................................................................... 115
14.1.Power-On Reset ............................................................................................. 116
14.2.Power-Fail Reset / VDD Monitor .................................................................... 117
14.3.External Reset ................................................................................................ 118
14.4.Missing Clock Detector Reset ........................................................................ 118
14.5.Comparator0 Reset ........................................................................................ 118
14.6.PCA Watchdog Timer Reset .......................................................................... 118
14.7.Flash Error Reset ........................................................................................... 118
14.8.Software Reset ............................................................................................... 118
15. Flash Memory ....................................................................................................... 121
15.1.Programming The Flash Memory ................................................................... 121
15.1.1.Flash Lock and Key Functions ............................................................... 121
15.1.2.Flash Erase Procedure .......................................................................... 121
15.1.3.Flash Write Procedure ........................................................................... 122
15.2.Non-volatile Data Storage .............................................................................. 123
15.3.Security Options ............................................................................................. 123
16. External RAM ........................................................................................................ 127
17. Oscillators ............................................................................................................. 129
17.1.Programmable Internal Oscillator ................................................................... 129
17.2.External Oscillator Drive Circuit...................................................................... 131
17.2.1.Clocking Timers Directly Through the External Oscillator...................... 131
4
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C8051F350/1/2/3
17.2.2.External Crystal Example....................................................................... 131
17.2.3.External RC Example............................................................................. 133
17.2.4.External Capacitor Example................................................................... 133
17.3.Clock Multiplier ............................................................................................... 135
17.4.System Clock Selection.................................................................................. 136
18. Port Input/Output.................................................................................................. 137
18.1.Priority Crossbar Decoder .............................................................................. 139
18.2.Port I/O Initialization ....................................................................................... 141
18.3.General Purpose Port I/O ............................................................................... 144
19. SMBus ................................................................................................................... 151
19.1.Supporting Documents ................................................................................... 152
19.2.SMBus Configuration...................................................................................... 152
19.3.SMBus Operation ........................................................................................... 152
19.3.1.Arbitration............................................................................................... 153
19.3.2.Clock Low Extension.............................................................................. 154
19.3.3.SCL Low Timeout................................................................................... 154
19.3.4.SCL High (SMBus Free) Timeout .......................................................... 154
19.4.Using the SMBus............................................................................................ 155
19.4.1.SMBus Configuration Register............................................................... 156
19.4.2.SMB0CN Control Register ..................................................................... 159
19.4.3.Data Register ......................................................................................... 162
19.5.SMBus Transfer Modes.................................................................................. 163
19.5.1.Master Transmitter Mode ....................................................................... 163
19.5.2.Master Receiver Mode ........................................................................... 164
19.5.3.Slave Receiver Mode ............................................................................. 165
19.5.4.Slave Transmitter Mode ......................................................................... 166
19.6.SMBus Status Decoding................................................................................. 167
20. UART0.................................................................................................................... 171
20.1.Enhanced Baud Rate Generation................................................................... 172
20.2.Operational Modes ......................................................................................... 173
20.2.1.8-Bit UART ............................................................................................. 173
20.2.2.9-Bit UART ............................................................................................. 174
20.3.Multiprocessor Communications .................................................................... 174
21. Serial Peripheral Interface (SPI0) ........................................................................ 181
21.1.Signal Descriptions......................................................................................... 182
21.1.1.Master Out, Slave In (MOSI).................................................................. 182
21.1.2.Master In, Slave Out (MISO).................................................................. 182
21.1.3.Serial Clock (SCK) ................................................................................. 182
21.1.4.Slave Select (NSS) ................................................................................ 182
21.2.SPI0 Master Mode Operation ......................................................................... 183
21.3.SPI0 Slave Mode Operation ........................................................................... 185
21.4.SPI0 Interrupt Sources ................................................................................... 185
21.5.Serial Clock Timing......................................................................................... 186
21.6.SPI Special Function Registers ...................................................................... 186
Rev. 1.1
5
C8051F350/1/2/3
22. Timers.................................................................................................................... 195
22.1.Timer 0 and Timer 1 ....................................................................................... 195
22.1.1.Mode 0: 13-bit Counter/Timer ................................................................ 195
22.1.2.Mode 1: 16-bit Counter/Timer ................................................................ 196
22.1.3.Mode 2: 8-bit Counter/Timer with Auto-Reload...................................... 197
22.1.4.Mode 3: Two 8-bit Counter/Timers (Timer 0 Only)................................. 198
22.2.Timer 2 .......................................................................................................... 203
22.2.1.16-bit Timer with Auto-Reload................................................................ 203
22.2.2.8-bit Timers with Auto-Reload................................................................ 204
22.3.Timer 3 .......................................................................................................... 207
22.3.1.16-bit Timer with Auto-Reload................................................................ 207
22.3.2.8-bit Timers with Auto-Reload................................................................ 208
23. Programmable Counter Array ............................................................................. 211
23.1.PCA Counter/Timer ........................................................................................ 212
23.2.Capture/Compare Modules ............................................................................ 213
23.2.1.Edge-triggered Capture Mode................................................................ 214
23.2.2.Software Timer (Compare) Mode........................................................... 215
23.2.3.High Speed Output Mode....................................................................... 216
23.2.4.Frequency Output Mode ........................................................................ 217
23.2.5.8-Bit Pulse Width Modulator Mode......................................................... 218
23.2.6.16-Bit Pulse Width Modulator Mode....................................................... 219
23.3.Watchdog Timer Mode ................................................................................... 220
23.3.1.Watchdog Timer Operation .................................................................... 220
23.3.2.Watchdog Timer Usage ......................................................................... 221
23.4.Register Descriptions for PCA........................................................................ 222
24. Revision Specific Behavior ................................................................................. 227
24.1.Revision Identification..................................................................................... 227
25. C2 Interface ........................................................................................................... 229
25.1.C2 Interface Registers.................................................................................... 229
25.2.C2 Pin Sharing ............................................................................................... 231
Document Change List............................................................................................. 232
Contact Information.................................................................................................. 234
6
Rev. 1.1
C8051F350/1/2/3
List of Figures
1. System Overview
Figure 1.1. C8051F350 Block Diagram .................................................................... 19
Figure 1.2. C8051F351 Block Diagram .................................................................... 19
Figure 1.3. C8051F352 Block Diagram .................................................................... 20
Figure 1.4. C8051F353 Block Diagram .................................................................... 20
Figure 1.5. Development/In-System Debug Diagram............................................... 22
Figure 1.6. Memory Map .......................................................................................... 23
Figure 1.7. ADC0 Block Diagram ............................................................................. 24
Figure 1.8. IDAC Block Diagram .............................................................................. 25
Figure 1.9. Comparator0 Block Diagram.................................................................. 26
Figure 1.10. Port I/O Functional Block Diagram ....................................................... 27
Figure 1.11. PCA Block Diagram.............................................................................. 28
2. Absolute Maximum Ratings
3. Global DC Electrical Characteristics
4. Pinout and Package Definitions
Figure 4.1. LQFP-32 Pinout Diagram (Top View) .................................................... 34
Figure 4.2. QFN-28 Pinout Diagram (Top View) ...................................................... 35
Figure 4.3. LQFP-32 Package Diagram ................................................................... 36
Figure 4.4. QFN-28 Package Drawing ..................................................................... 37
Figure 4.5. Typical QFN-28 Landing Diagram.......................................................... 38
Figure 4.6. Typical QFN-28 Solder Paste Diagram.................................................. 39
5. 24 or 16-Bit Analog to Digital Converter (ADC0)
Figure 5.1. ADC0 Block Diagram ............................................................................. 41
Figure 5.2. ADC0 Buffer Control .............................................................................. 43
Figure 5.3. ADC0 Offset Calibration Register Coding .............................................. 45
Figure 5.4. ADC0 Gain Calibration Register Coding ................................................ 45
Figure 5.5. ADC0 Multiplexer Connections .............................................................. 59
6. 8-Bit Current Mode DACS (IDA0 and IDA1)
Figure 6.1. IDAC Functional Block Diagram............................................................. 67
Figure 6.2. IDAC Data Word Mapping...................................................................... 68
Figure 6.3. IDAC Pin Connections ........................................................................... 71
7. Voltage Reference
Figure 7.1. Reference Circuitry Block Diagram ........................................................ 73
8. Temperature Sensor
Figure 8.1. Temperature Sensor Block Diagram...................................................... 77
Figure 8.2. Single Channel Transfer Function.......................................................... 78
Figure 8.3. Differential Transfer Function................................................................. 78
9. Comparator0
Figure 9.1. Comparator0 Functional Block Diagram ................................................ 79
Figure 9.2. Comparator Hysteresis Plot ................................................................... 80
Figure 9.3. Comparator Pin Connections ................................................................. 83
10. CIP-51 Microcontroller
Figure 10.1. CIP-51 Block Diagram.......................................................................... 87
Rev. 1.1
7
C8051F350/1/2/3
11. Memory Organization and SFRs
Figure 11.1. Memory Map ........................................................................................ 99
12. Interrupt Handler
13. Prefetch Engine
14. Reset Sources
Figure 14.1. Reset Sources.................................................................................... 115
Figure 14.2. Power-On and VDD Monitor Reset Timing ........................................ 116
15. Flash Memory
Figure 15.1. Flash Memory Map............................................................................. 123
16. External RAM
17. Oscillators
Figure 17.1. Oscillator Diagram.............................................................................. 129
Figure 17.2. 32.768 kHz External Crystal Example................................................ 132
18. Port Input/Output
Figure 18.1. Port I/O Functional Block Diagram ..................................................... 137
Figure 18.2. Port I/O Cell Block Diagram ............................................................... 138
Figure 18.3. Crossbar Priority Decoder with No Pins Skipped ............................... 139
Figure 18.4. Crossbar Priority Decoder with Crystal Pins Skipped ........................ 140
19. SMBus
Figure 19.1. SMBus Block Diagram ....................................................................... 151
Figure 19.2. Typical SMBus Configuration ............................................................. 152
Figure 19.3. SMBus Transaction ............................................................................ 153
Figure 19.4. Typical SMBus SCL Generation......................................................... 157
Figure 19.5. Typical Master Transmitter Sequence................................................ 163
Figure 19.6. Typical Master Receiver Sequence.................................................... 164
Figure 19.7. Typical Slave Receiver Sequence...................................................... 165
Figure 19.8. Typical Slave Transmitter Sequence.................................................. 166
20. UART0
Figure 20.1. UART0 Block Diagram ....................................................................... 171
Figure 20.2. UART0 Baud Rate Logic .................................................................... 172
Figure 20.3. UART Interconnect Diagram .............................................................. 173
Figure 20.4. 8-Bit UART Timing Diagram............................................................... 173
Figure 20.5. 9-Bit UART Timing Diagram............................................................... 174
Figure 20.6. UART Multi-Processor Mode Interconnect Diagram .......................... 175
21. Serial Peripheral Interface (SPI0)
Figure 21.1. SPI Block Diagram ............................................................................. 181
Figure 21.2. Multiple-Master Mode Connection Diagram ....................................... 184
Figure 21.3. 3-Wire Single Master and Slave Mode Connection Diagram ............. 184
Figure 21.4. 4-Wire Single Master and Slave Mode Connection Diagram ............. 184
Figure 21.5. Data/Clock Timing Relationship ......................................................... 186
Figure 21.6. SPI Master Timing (CKPHA = 0)........................................................ 191
Figure 21.7. SPI Master Timing (CKPHA = 1)........................................................ 191
Figure 21.8. SPI Slave Timing (CKPHA = 0).......................................................... 192
Figure 21.9. SPI Slave Timing (CKPHA = 1).......................................................... 192
8
Rev. 1.1
C8051F350/1/2/3
22. Timers
Figure 22.1. T0 Mode 0 Block Diagram.................................................................. 196
Figure 22.2. T0 Mode 2 Block Diagram.................................................................. 197
Figure 22.3. T0 Mode 3 Block Diagram.................................................................. 198
Figure 22.4. Timer 2 16-Bit Mode Block Diagram .................................................. 203
Figure 22.5. Timer 2 8-Bit Mode Block Diagram .................................................... 204
Figure 22.6. Timer 3 16-Bit Mode Block Diagram .................................................. 207
Figure 22.7. Timer 3 8-Bit Mode Block Diagram .................................................... 208
23. Programmable Counter Array
Figure 23.1. PCA Block Diagram............................................................................ 211
Figure 23.2. PCA Counter/Timer Block Diagram.................................................... 212
Figure 23.3. PCA Interrupt Block Diagram ............................................................. 213
Figure 23.4. PCA Capture Mode Diagram.............................................................. 214
Figure 23.5. PCA Software Timer Mode Diagram .................................................. 215
Figure 23.6. PCA High Speed Output Mode Diagram............................................ 216
Figure 23.7. PCA Frequency Output Mode ............................................................ 217
Figure 23.8. PCA 8-Bit PWM Mode Diagram ......................................................... 218
Figure 23.9. PCA 16-Bit PWM Mode...................................................................... 219
Figure 23.10. PCA Module 2 with Watchdog Timer Enabled ................................. 220
24. Revision Specific Behavior
Figure 24.1. Reading Package Marking ................................................................. 227
25. C2 Interface
Figure 25.1. Typical C2 Pin Sharing....................................................................... 231
Rev. 1.1
9
C8051F350/1/2/3
NOTES:
10
Rev. 1.1
C8051F350/1/2/3
List of Tables
1. System Overview
Table 1.1. Product Selection Guide ......................................................................... 18
2. Absolute Maximum Ratings
3. Global DC Electrical Characteristics
4. Pinout and Package Definitions
Table 4.1. Pin Definitions for the C8051F350/1/2/3 ................................................. 31
Table 4.2. LQFP-32 Package Dimensions .............................................................. 36
Table 4.3. QFN-28 Package Dimensions ................................................................ 37
5. 24 or 16-Bit Analog to Digital Converter (ADC0)
Table 5.1. ADC0 Unipolar Output Word Coding (AD0POL = 0) .............................. 47
Table 5.2. ADC0 Bipolar Output Word Coding (AD0POL = 1) ................................ 47
Table 5.3. ADC0 SINC3 Filter Typical RMS Noise (µV) .......................................... 62
Table 5.4. ADC0 SINC3 Filter Effective Resolution
in Unipolar Mode (bits) ......................................................................... 63
Table 5.5. ADC0 SINC3 Filter Flicker-Free (Noise-Free) Resolution
in Unipolar Mode (bits) ......................................................................... 63
Table 5.6. ADC0 Fast Filter Typical RMS Noise (µV) ............................................. 64
Table 5.7. ADC0 Fast Filter Effective Resolution1 in Unipolar Mode (bits) ............. 64
Table 5.8. ADC0 Fast Filter Flicker-Free (Noise-Free) Resolution
in Unipolar Mode (bits) ......................................................................... 65
6. 8-Bit Current Mode DACS (IDA0 and IDA1)
7. Voltage Reference
8. Temperature Sensor
9. Comparator0
10. CIP-51 Microcontroller
Table 10.1. CIP-51 Instruction Set Summary .......................................................... 89
11. Memory Organization and SFRs
Table 11.1. Special Function Register (SFR) Memory Map .................................. 101
Table 11.2. Special Function Registers ................................................................. 102
12. Interrupt Handler
Table 12.1. Interrupt Summary .............................................................................. 106
13. Prefetch Engine
14. Reset Sources
15. Flash Memory
16. External RAM
17. Oscillators
18. Port Input/Output
19. SMBus
Table 19.1. SMBus Clock Source Selection .......................................................... 156
Table 19.2. Minimum SDA Setup and Hold Times ................................................ 157
Table 19.3. Sources for Hardware Changes to SMB0CN ..................................... 161
Table 19.4. SMBus Status Decoding ..................................................................... 167
20. UART0
Rev. 1.1
11
C8051F350/1/2/3
Table 20.1. Timer Settings for Standard Baud Rates
Using the Internal Oscillator ............................................................... 178
Table 20.2. Timer Settings for Standard Baud Rates
Using an External 25.0 MHz Oscillator ............................................... 178
Table 20.3. Timer Settings for Standard Baud Rates
Using an External 22.1184 MHz Oscillator ......................................... 179
Table 20.4. Timer Settings for Standard Baud Rates
Using an External 18.432 MHz Oscillator ........................................... 179
Table 20.5. Timer Settings for Standard Baud Rates
Using an External 11.0592 MHz Oscillator ......................................... 180
Table 20.6. Timer Settings for Standard Baud Rates
Using an External 3.6864 MHz Oscillator ........................................... 180
21. Serial Peripheral Interface (SPI0)
Table 21.1. SPI Slave Timing Parameters ............................................................ 193
22. Timers
23. Programmable Counter Array
Table 23.1. PCA Timebase Input Options ............................................................. 212
Table 23.2. PCA0CPM Register Settings for PCA Capture/Compare Modules .... 213
Table 23.3. Watchdog Timer Timeout Intervals...................................................... 221
24. Revision Specific Behavior
25. C2 Interface
12
Rev. 1.1
C8051F350/1/2/3
List of Registers
SFR Definition 5.1. ADC0CN: ADC0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
SFR Definition 5.2. ADC0CF: ADC0 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
SFR Definition 5.3. ADC0MD: ADC0 Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
SFR Definition 5.4. ADC0CLK: ADC0 Modulator Clock Divisor . . . . . . . . . . . . . . . . . . 51
SFR Definition 5.5. ADC0DECH: ADC0 Decimation Ratio Register High Byte . . . . . . 51
SFR Definition 5.6. ADC0DECL: ADC0 Decimation Ratio Register Low Byte . . . . . . . 52
SFR Definition 5.7. ADC0DAC: ADC0 Offset DAC . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
SFR Definition 5.8. ADC0BUF: ADC0 Input Buffer Control . . . . . . . . . . . . . . . . . . . . . 53
SFR Definition 5.9. ADC0STA: ADC0 Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
SFR Definition 5.10. ADC0COH: ADC0 Offset Calibration Register High Byte . . . . . . 55
SFR Definition 5.11. ADC0COM: ADC0 Offset Calibration Register Middle Byte . . . . 55
SFR Definition 5.12. ADC0COL: ADC0 Offset Calibration Register Low Byte . . . . . . . 55
SFR Definition 5.13. ADC0CGH: ADC0 Gain Calibration Register High Byte . . . . . . . 56
SFR Definition 5.14. ADC0CGM: ADC0 Gain Calibration Register Middle Byte . . . . . 56
SFR Definition 5.15. ADC0CGL: ADC0 Gain Calibration Register Low Byte . . . . . . . . 56
SFR Definition 5.16. ADC0H: ADC0 Conversion Register (SINC3 Filter) High Byte . . 57
SFR Definition 5.17. ADC0M: ADC0 Conversion Register (SINC3 Filter) Middle Byte 57
SFR Definition 5.18. ADC0L: ADC0 Conversion Register (SINC3 Filter) Low Byte . . . 57
SFR Definition 5.19. ADC0FH: ADC0 Conversion Register (Fast Filter) High Byte . . . 58
SFR Definition 5.20. ADC0FM: ADC0 Conversion Register (Fast Filter) Middle Byte . 58
SFR Definition 5.21. ADC0FL: ADC0 Conversion Register (Fast Filter) Low Byte . . . . 58
SFR Definition 5.22. ADC0MUX: ADC0 Analog Multiplexer Control . . . . . . . . . . . . . . 60
SFR Definition 6.1. IDA0CN: IDA0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
SFR Definition 6.2. IDA0: IDA0 Data Word . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
SFR Definition 6.3. IDA1CN: IDA1 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
SFR Definition 6.4. IDA1: IDA1 Data Word . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
SFR Definition 7.1. REF0CN: Reference Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
SFR Definition 9.1. CPT0CN: Comparator0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
SFR Definition 9.2. CPT0MD: Comparator0 Mode Selection . . . . . . . . . . . . . . . . . . . . 82
SFR Definition 9.3. CPT0MX: Comparator0 MUX Selection . . . . . . . . . . . . . . . . . . . . 84
SFR Definition 10.1. SP: Stack Pointer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
SFR Definition 10.2. DPL: Data Pointer Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
SFR Definition 10.3. DPH: Data Pointer High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
SFR Definition 10.4. PSW: Program Status Word . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
SFR Definition 10.5. ACC: Accumulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
SFR Definition 10.6. B: B Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
SFR Definition 10.7. PCON: Power Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
SFR Definition 12.1. IE: Interrupt Enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
SFR Definition 12.2. IP: Interrupt Priority . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
SFR Definition 12.3. EIE1: Extended Interrupt Enable 1 . . . . . . . . . . . . . . . . . . . . . . 109
SFR Definition 12.4. EIP1: Extended Interrupt Priority 1 . . . . . . . . . . . . . . . . . . . . . . 110
SFR Definition 12.5. IT01CF: INT0/INT1 Configuration . . . . . . . . . . . . . . . . . . . . . . . 112
SFR Definition 13.1. PFE0CN: Prefetch Engine Control . . . . . . . . . . . . . . . . . . . . . . 113
Rev. 1.1
13
C8051F350/1/2/3
SFR Definition 14.1. VDM0CN: VDD Monitor Control . . . . . . . . . . . . . . . . . . . . . . . . 117
SFR Definition 14.2. RSTSRC: Reset Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
SFR Definition 15.1. PSCTL: Program Store R/W Control . . . . . . . . . . . . . . . . . . . . . 125
SFR Definition 15.2. FLKEY: Flash Lock and Key . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
SFR Definition 15.3. FLSCL: Flash Scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
SFR Definition 16.1. EMI0CN: External Memory Interface Control . . . . . . . . . . . . . . 127
SFR Definition 17.1. OSCICN: Internal Oscillator Control . . . . . . . . . . . . . . . . . . . . . 130
SFR Definition 17.2. OSCICL: Internal Oscillator Calibration . . . . . . . . . . . . . . . . . . . 130
SFR Definition 17.3. OSCXCN: External Oscillator Control . . . . . . . . . . . . . . . . . . . . 134
SFR Definition 17.4. CLKMUL: Clock Multiplier Control . . . . . . . . . . . . . . . . . . . . . . . 135
SFR Definition 17.5. CLKSEL: Clock Select . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
SFR Definition 18.1. XBR0: Port I/O Crossbar Register 0 . . . . . . . . . . . . . . . . . . . . . 142
SFR Definition 18.2. XBR1: Port I/O Crossbar Register 1 . . . . . . . . . . . . . . . . . . . . . 143
SFR Definition 18.3. P0: Port0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
SFR Definition 18.4. P0MDIN: Port0 Input Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
SFR Definition 18.5. P0MDOUT: Port0 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . . 146
SFR Definition 18.6. P0SKIP: Port0 Skip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
SFR Definition 18.7. P1: Port1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
SFR Definition 18.8. P1MDIN: Port1 Input Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
SFR Definition 18.9. P1MDOUT: Port1 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . . 148
SFR Definition 18.10. P1SKIP: Port1 Skip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
SFR Definition 18.11. P2: Port2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
SFR Definition 18.12. P2MDOUT: Port2 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . 149
SFR Definition 19.1. SMB0CF: SMBus Clock/Configuration . . . . . . . . . . . . . . . . . . . 158
SFR Definition 19.2. SMB0CN: SMBus Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
SFR Definition 19.3. SMB0DAT: SMBus Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
SFR Definition 20.1. SCON0: Serial Port 0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . 176
SFR Definition 20.2. SBUF0: Serial (UART0) Port Data Buffer . . . . . . . . . . . . . . . . . 177
SFR Definition 21.1. SPI0CFG: SPI0 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . 187
SFR Definition 21.2. SPI0CN: SPI0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188
SFR Definition 21.3. SPI0CKR: SPI0 Clock Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
SFR Definition 21.4. SPI0DAT: SPI0 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
SFR Definition 22.1. TCON: Timer Contro . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199
SFR Definition 22.2. TMOD: Timer Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200
SFR Definition 22.3. CKCON: Clock Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
SFR Definition 22.4. TL0: Timer 0 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202
SFR Definition 22.5. TL1: Timer 1 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202
SFR Definition 22.6. TH0: Timer 0 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202
SFR Definition 22.7. TH1: Timer 1 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202
SFR Definition 22.8. TMR2CN: Timer 2 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
SFR Definition 22.9. TMR2RLL: Timer 2 Reload Register Low Byte . . . . . . . . . . . . . 206
SFR Definition 22.10. TMR2RLH: Timer 2 Reload Register High Byte . . . . . . . . . . . 206
SFR Definition 22.11. TMR2L: Timer 2 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
SFR Definition 22.12. TMR2H Timer 2 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
SFR Definition 22.13. TMR3CN: Timer 3 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209
14
Rev. 1.1
C8051F350/1/2/3
SFR Definition 22.14. TMR3RLL: Timer 3 Reload Register Low Byte . . . . . . . . . . . . 210
SFR Definition 22.15. TMR3RLH: Timer 3 Reload Register High Byte . . . . . . . . . . . 210
SFR Definition 22.16. TMR3L: Timer 3 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210
SFR Definition 22.17. TMR3H Timer 3 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210
SFR Definition 23.1. PCA0CN: PCA Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222
SFR Definition 23.2. PCA0MD: PCA Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223
SFR Definition 23.3. PCA0CPMn: PCA Capture/Compare Mode . . . . . . . . . . . . . . . 224
SFR Definition 23.4. PCA0L: PCA Counter/Timer Low Byte . . . . . . . . . . . . . . . . . . . 225
SFR Definition 23.5. PCA0H: PCA Counter/Timer High Byte . . . . . . . . . . . . . . . . . . . 225
SFR Definition 23.6. PCA0CPLn: PCA Capture Module Low Byte . . . . . . . . . . . . . . . 226
SFR Definition 23.7. PCA0CPHn: PCA Capture Module High Byte . . . . . . . . . . . . . . 226
C2 Register Definition 25.1. C2ADD: C2 Address . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
C2 Register Definition 25.2. DEVICEID: C2 Device ID . . . . . . . . . . . . . . . . . . . . . . . . 229
C2 Register Definition 25.3. REVID: C2 Revision ID . . . . . . . . . . . . . . . . . . . . . . . . . 230
C2 Register Definition 25.4. FPCTL: C2 Flash Programming Control . . . . . . . . . . . . 230
C2 Register Definition 25.5. FPDAT: C2 Flash Programming Data . . . . . . . . . . . . . . 230
Rev. 1.1
15
C8051F350/1/2/3
NOTES:
16
Rev. 1.1
C8051F350/1/2/3
1.
System Overview
C8051F350/1/2/3 devices are fully integrated mixed-signal System-on-a-Chip MCUs. Highlighted features
are listed below. Refer to Table 1.1 for specific product feature selection.
•
•
•
•
•
•
•
•
•
•
•
•
•
High-speed pipelined 8051-compatible microcontroller core (up to 50 MIPS)
In-system, full-speed, non-intrusive debug interface (on-chip)
24 or 16-bit single-ended/differential ADC with analog multiplexer
Two 8-bit Current Output DACs
Precision programmable 24.5 MHz internal oscillator
8 kB of on-chip Flash memory
768 bytes of on-chip RAM
SMBus/I2C, Enhanced UART, and SPI serial interfaces implemented in hardware
Four general-purpose 16-bit timers
Programmable counter/timer array (PCA) with three capture/compare modules and watchdog timer
function
On-chip power-on reset, VDD monitor, and temperature sensor
On-chip voltage comparator
17 Port I/O (5 V tolerant)
With on-chip power-on reset, VDD monitor, watchdog timer, and clock oscillator, the C8051F350/1/2/3
devices are truly stand-alone System-on-a-Chip solutions. The Flash memory can be reprogrammed even
in-circuit, providing non-volatile data storage, and also allowing field upgrades of the 8051 firmware. User
software has complete control of all peripherals, and may individually shut down any or all peripherals for
power savings.
The on-chip Silicon Labs 2-Wire (C2) Development Interface allows non-intrusive (uses no on-chip
resources), full speed, in-circuit debugging using the production MCU installed in the final application. This
debug logic supports inspection and modification of memory and registers, setting breakpoints, single
stepping, run and halt commands. All analog and digital peripherals are fully functional while debugging
using C2. The two C2 interface pins can be shared with user functions, allowing in-system debugging without occupying package pins.
Each device is specified for 2.7 to 3.6 V operation over the industrial temperature range (–45 to +85 °C).
The Port I/O and /RST pins are tolerant of input signals up to 5 V. The C8051F350/1/2/3 are available in
28-pin QFN (also referred to as MLP or MLF) or 32-pin LQFP packaging, as shown in Figure 1.1 through
Figure 1.4.
Rev. 1.1
17
Clock Multiplier
SMBus/I2C
SPI
UART
Timers (16-bit)
Programmable Counter Array
Digital Port I/Os
24-bit ADC
16-bit ADC
Two 8-bit Current Output DACs
Internal Voltage Reference
Temperature Sensor
Analog Comparator
Lead-free (RoHS Compliant)
Package
C8051F350-GQ
50 8 kB 768 




4

17

—





LQFP-32
C8051F351-GM
50 8 kB 768 




4

17

—





QFN-28
C8051F352-GQ
50 8 kB 768 




4

17 —






LQFP-32
C8051F353-GM
50 8 kB 768 




4

17 —






QFN-28
18
RAM
Flash Memory
MIPS (Peak)
Calibrated Internal 24.5 MHz Oscillator
Ordering Part Number
C8051F350/1/2/3
Table 1.1. Product Selection Guide
Rev. 1.1
C8051F350/1/2/3
VDD
Digital Power
GND
AV+
Analog
Power
AGND
C2D
Debug HW
Reset
/RST/C2CK
BrownOut
POR
XTAL1
XTAL2
External
Oscillator
Circuit
System
Clock
24.5 MHz 2%
Internal
Oscillator
Clock
Multiplier
P0.0
8 kB
FLASH
8
0
5
1
256 byte
SRAM
Timer 0,
1, 2, 3
C
o SFR Bus
r
e
P0.3/XTAL2
D
r
v
UART
512 byte
XRAM
P0.1
P0.2/XTAL1
P
0
Port 0
Latch
X
B
A
R
3-Chnl
PCA/
WDT
SMBus
P0.4/TX
P0.5/RX
P0.6/CNVSTR
P0.7
CP0
+
CP0A
-
CP0+
CP0-
SPI Bus
VREF+
P1.0
VREF–
Port 1
Latch
VREF
P1.1
P1.2
P
1
AIN0
AIN1
AIN2
AIN3
A
M
U
X
AIN4
AIN5
+
Buffer
P1.5/CP0
P1.6/IDAC0
8-bit
IDAC0
24-bit
ADC0
PGA
+
P1.3
P1.4/CP0A
D
r
v
Offset
DAC
P1.7/IDAC1
8-bit
IDAC1
AIN6
AIN7
C2D
Temp
Sensor
Port 2
Latch
P2.0/C2D
Figure 1.1. C8051F350 Block Diagram
VDD
GND
AV+
Digital Power
Analog
Power
AGND
C2D
Debug HW
Reset
/RST/C2CK
POR
BrownOut
External
Oscillator
Circuit
XTAL1
XTAL2
System
Clock
24.5 MHz 2%
Internal
Oscillator
Clock
Multiplier
P0.0
P0.1
8 kB
FLASH
8
0
5
1
256 byte
SRAM
D
r
v
UART
512 byte
XRAM
Timer 0,
1, 2, 3
C
o SFR Bus
r
e
X
B
A
R
3-Chnl
PCA/
WDT
SMBus
SPI Bus
Offset
DAC
AIN4
AIN5
AIN6
AIN7
A
M
U
X
Buffer
+
+
PGA
+
CP0A
-
CP0-
P
1
P1.2/AIN6
P1.3/AIN7
D
r
v
P1.4/CP0A
P1.5/CP0
8-bit
IDAC0
24-bit
ADC0
CP0+
P1.0/AIN4
P1.1/AIN5
AIN0
AIN3
P0.7
CP0
Port 1
Latch
VREF
AIN1
AIN2
P0.5/RX
P0.6/CNVSTR
AIN4-7
VREF+
VREF–
P0.2/XTAL1
P0.3/XTAL2
P0.4/TX
P
0
Port 0
Latch
P1.6/IDAC0
P1.7/IDAC1
8-bit
IDAC1
C2D
Temp
Sensor
Port 2
Latch
P2.0/C2D
Figure 1.2. C8051F351 Block Diagram
Rev. 1.1
19
C8051F350/1/2/3
VDD
GND
AV+
AGND
Digital Power
Analog
Power
C2D
Debug HW
Reset
/RST/C2CK
POR
BrownOut
External
Oscillator
Circuit
XTAL1
XTAL2
System
Clock
24.5 MHz 2%
Internal
Oscillator
Clock
Multiplier
P0.0
8 kB
FLASH
8
0
5
1
256 byte
SRAM
512 byte
XRAM
C
o SFR Bus
r
e
P0.1
P0.2/XTAL1
P0.3/XTAL2
P
0
Port 0
Latch
D
r
v
UART
Timer 0,
1, 2, 3
X
B
A
R
3-Chnl
PCA/
WDT
SMBus
P0.4/TX
P0.5/RX
P0.6/CNVSTR
P0.7
CP0
+
CP0A
-
CP0+
CP0-
SPI Bus
VREF+
VREF–
P1.0
VREF
Port 1
Latch
P1.1
P1.2
P1.3
P1.4/CP0A
P
1
AIN0
AIN1
D
r
v
Offset
DAC
AIN2
AIN3
AIN4
A
M
U
X
AIN5
AIN6
AIN7
+
Buffer
P1.5/CP0
P1.6/IDAC0
P1.7/IDAC1
8-bit
IDAC0
16-bit
ADC0
PGA
+
8-bit
IDAC1
C2D
Temp
Sensor
Port 2
Latch
P2.0/C2D
Figure 1.3. C8051F352 Block Diagram
VDD
Digital Power
GND
AV+
AGND
Analog
Power
C2D
Debug HW
Reset
/RST/C2CK
POR
BrownOut
External
Oscillator
Circuit
XTAL1
XTAL2
System
Clock
x2
24.5 MHz 2%
Internal
Oscillator
P0.0
8 kB
FLASH
8
0
5
1
256 byte
SRAM
512 byte
XRAM
C
o SFR Bus
r
e
P0.1
P0.3/XTAL2
P0.4/TX
D
r
v
UART
Timer 0,
1, 2, 3
P0.5/RX
P0.6/CNVSTR
X
B
A
R
3-Chnl
PCA/
WDT
SMBus
SPI Bus
P0.7
CP0
+
CP0A
-
CP0+
CP0-
AIN4-7
VREF+
P1.0/AIN4
VREF–
VREF
Port 1
Latch
P1.1/AIN5
AIN0
AIN1
Offset
DAC
AIN2
AIN3
AIN4
AIN5
AIN6
AIN7
A
M
U
X
Buffer
+
+
PGA
P
1
P1.2/AIN6
D
r
v
P1.4/CP0A
8-bit
IDAC0
16-bit
ADC0
P1.3/AIN7
P1.5/CP0
P1.6/IDAC0
P1.7/IDAC1
8-bit
IDAC1
C2D
Temp
Sensor
Port 2
Latch
Figure 1.4. C8051F353 Block Diagram
20
P0.2/XTAL1
P
0
Port 0
Latch
Rev. 1.1
P2.0/C2D
C8051F350/1/2/3
1.1.
CIP-51™ Microcontroller
1.1.1. Fully 8051 Compatible Instruction Set
The C8051F35x devices use Silicon Labs’ proprietary CIP-51 microcontroller core. The CIP-51 is fully
compatible with the MCS-51™ instruction set. Standard 803x/805x assemblers and compilers can be used
to develop software. The C8051F35x family has a superset of all the peripherals included with a standard
8052.
1.1.2. Improved Throughput
The CIP-51 employs a pipelined architecture that greatly increases its instruction throughput over the standard 8051 architecture. In a standard 8051, all instructions except for MUL and DIV take 12 or 24 system
clock cycles to execute, and usually have a maximum system clock of 12 to 24 MHz. By contrast, the CIP51 core executes 70% of its instructions in one or two system clock cycles, with no instructions taking more
than eight system clock cycles.
With the CIP-51's system clock running at 50 MHz, it has a peak throughput of 50 MIPS. The CIP-51 has a
total of 109 instructions. The table below shows the total number of instructions that require each execution
time.
Clocks to Execute
1
2
2/3
3
3/4
4
4/5
5
8
Number of Instructions
26
50
5
14
7
3
1
2
1
1.1.3. Additional Features
The C8051F350/1/2/3 SoC family includes several key enhancements to the CIP-51 core and peripherals
to improve performance and ease of use in end applications.
An extended interrupt handler allows the numerous analog and digital peripherals to operate independently of the controller core and interrupt the controller only when necessary. By requiring less intervention from the microcontroller core, an interrupt-driven system is more efficient and allows for easier
implementation of multi-tasking, real-time systems.
Eight reset sources are available: power-on reset circuitry (POR), an on-chip VDD monitor, a Watchdog
Timer, a Missing Clock Detector, a voltage level detection from Comparator0, a forced software reset, an
external reset pin, and an illegal Flash access protection circuit. Each reset source except for the POR,
Reset Input Pin, or Flash error may be disabled by the user in software. The WDT may be permanently
enabled in software after a power-on reset during MCU initialization.
The internal oscillator is factory calibrated to 24.5 MHz ±2%. An external oscillator drive circuit is also
included, allowing an external crystal, ceramic resonator, capacitor, RC, or CMOS clock source to generate
the system clock. A clock multiplier allows for operation at up to 50 MHz. An external oscillator can also be
extremely useful in low power applications, allowing the MCU to run from a slow (power saving) source,
while periodically switching to the fast internal oscillator as needed.
Rev. 1.1
21
C8051F350/1/2/3
1.2.
On-Chip Debug Circuitry
The C8051F350/1/2/3 devices include on-chip Silicon Labs 2-Wire (C2) debug circuitry that provides nonintrusive, full speed, in-circuit debugging of the production part installed in the end application.
Silicon Labs' debugging system supports inspection and modification of memory and registers, breakpoints, and single stepping. No additional target RAM, program memory, timers, or communications channels are required. All the digital and analog peripherals are functional and work correctly while debugging.
All the peripherals (except for the ADC and SMBus) are stalled when the MCU is halted, during single
stepping, or at a breakpoint in order to keep them synchronized.
The C8051F350DK development kit provides all the hardware and software necessary to develop application code and perform in-circuit debugging with the C8051F35x MCUs. The kit includes software with a
developer's studio and debugger, a C2 debug adapter, a target application board with the associated MCU
installed, and the required cables and wall-mount power supply. The development kit requires a computer
with Windows 98 SE or later installed.
The Silicon Labs IDE interface is a vastly superior developing and debugging configuration, compared to
standard MCU emulators that use on-board "ICE Chips" and require the MCU in the application board to
be socketed. Silicon Labs' debug paradigm increases ease of use and preserves the performance of the
precision analog peripherals.
Silicon Labs Integrated
Development Environment
WINDOWS 98 SE or later
Debug
Adapter
C2 (x2), VDD, GND
VDD
TARGET PCB
GND
C8051F350
Figure 1.5. Development/In-System Debug Diagram
22
Rev. 1.1
C8051F350/1/2/3
1.3.
On-Chip Memory
The CIP-51 has a standard 8051 program and data address configuration. It includes 256 bytes of data
RAM, with the upper 128 bytes dual-mapped. Indirect addressing accesses the upper 128 bytes of general
purpose RAM, and direct addressing accesses the 128 byte SFR address space. The lower 128 bytes of
RAM are accessible via direct and indirect addressing. The first 32 bytes are addressable as four banks of
general purpose registers, and the next 16 bytes can be byte addressable or bit addressable.
Program memory consists of 8 kB bytes of Flash. This memory may be reprogrammed in-system in 512
byte sectors, and requires no special off-chip programming voltage.
DATA MEMORY (RAM)
INTERNAL DATA ADDRESS SPACE
PROGRAM/DATA MEMORY
(Flash)
0x1FFF
0x1E00
0xFF
RESERVED
0x1DFF
0x80
0x7F
Upper 128 RAM
(Indirect Addressing
Only)
(Direct and Indirect
Addressing)
8 kB Flash
(In-System
Programmable in 512
Byte Sectors)
0x30
0x2F
0x20
0x1F
0x00
Bit Addressable
Special Function
Register's
(Direct Addressing Only)
Lower 128 RAM
(Direct and Indirect
Addressing)
General Purpose
Registers
EXTERNAL DATA ADDRESS SPACE
0x0000
0xFFFF
Same 512 bytes as from
0x0000 to 0x01FF, wrapped
on 512-byte boundaries
0x0200
0x01FF
0x0000
XRAM - 512 Bytes
(accessable using MOVX
instruction)
Figure 1.6. Memory Map
Rev. 1.1
23
C8051F350/1/2/3
1.4.
24 or 16-Bit Analog to Digital Converter (ADC0)
The C8051F350/1/2/3 include a fully-differential, 24-bit (C8051F350/1) or 16-bit (C8051F352/3) SigmaDelta Analog to Digital Converter (ADC) with on-chip calibration capabiliites. Two separate decimation filters can be programmed for throughputs of up to 1 kHz. An internal 2.5 V reference is available, or a differential external reference can be used for ratiometric measurements. A Programmable Gain Amplifier
(PGA) is included, with eight gain settings up to 128x. An analog front-end multiplexer connects the differential inputs to eight external pins, the internal temperature sensor, or AGND. The on-chip input buffers
can be used to provide a high input impedance for direct connection to sensitive transducers. An 8-bit offset DAC allows for correction of large input offset voltages.
AV+
Internal
2.5V or
External
VREF
Burnout
Current
Sources
Eight
External
Inputs
Temperature
Sensor
AIN+
Σ
SINC3 Filter
PGA
AIN-
Modulator
Σ
Input
Buffers
AGND
Fast Filter
1x to 128x
8-Bit
Offset
DAC
Figure 1.7. ADC0 Block Diagram
24
Rev. 1.1
C8051F350/1/2/3
1.5.
Two 8-bit Current-Mode DACs
The C8051F350/1/2/3 devices include two 8-bit current-mode Digital-to-Analog Converters (IDACs). The
maximum current output of the IDACs can be adjusted for four different current settings; 0.25 mA, 0.5 mA,
1 mA, and 2 mA. A flexible output update mechanism allows for seamless full-scale changes, and supports
jitter-free updates for waveform generation. IDAC updates can be performed on-demand, scheduled on a
Timer overflow, or synchronized with an external signal. Figure 1.8 shows a block diagram of the IDAC circuitry.
8-bit Digital
Input
8
Latch
8
8-bit Digital
Input
8
Latch
Data Write
Timer 0
Timer 1
Timer 2
Timer 3
CNVSTR
8
IDA0
Current
Output
IDA1
Current
Output
Data Write
Timer 0
Timer 1
Timer 2
Timer 3
CNVSTR
Figure 1.8. IDAC Block Diagram
Rev. 1.1
25
C8051F350/1/2/3
1.6.
Programmable Comparator
C8051F350/1/2/3 devices include a software-configurable voltage comparator with an input multiplexer.
The Comparator offers programmable response time and hysteresis and two outputs that are optionally
available at the Port pins: a synchronous “latched” output (CP0), or an asynchronous “raw” output (CP0A).
Comparator interrupts may be generated on rising, falling, or both edges. When in IDLE mode, these interrupts may be used as a “wake-up” source for the processor. Comparator0 may also be configured as a
reset source. A block diagram of the Comparator is shown in Figure 1.9.
VDD
Port I/O
Pins
Multiplexer
Interrupt
Logic
+
D
-
SET
CLR
Q
Q
D
SET
CLR
Q
CP0
(synchronous output)
Q
(SYNCHRONIZER)
CP0A
(asynchronous output)
GND
Reset
Decision
Tree
Figure 1.9. Comparator0 Block Diagram
1.7.
Serial Ports
The C8051F350/1/2/3 Family includes an SMBus/I2C interface, a full-duplex UART with enhanced baud
rate configuration, and an Enhanced SPI interface. Each of the serial buses is fully implemented in hardware and makes extensive use of the CIP-51's interrupts, thus requiring very little CPU intervention.
26
Rev. 1.1
C8051F350/1/2/3
1.8.
Port Input/Output
C8051F350/1/2/3 devices include 17 I/O pins. Port pins are organized as two byte-wide ports and one 1-bit
port. The port pins behave like typical 8051 ports with a few enhancements. Each port pin can be configured as a digital or analog I/O pin. Pins selected as digital I/O can be configured for push-pull or open-drain
operation. The “weak pull-ups” that are fixed on typical 8051 devices may be globally disabled to save
power.
The Digital Crossbar allows mapping of internal digital system resources to port I/O pins. On-chip conter/timers, serial buses, hardware interrupts, and other digital signals can be configured to appear on the
port pins using the Crossbar control resgiters. This allows the user to select the exact mix of general-purpose port I/O, digital, and analog resources needed for the application.
XBR0, XBR1,
PnSKIP Registers
PnMDOUT,
PnMDIN Registers
Priority
Decoder
(Internal Digital Signals)
Highest
Priority
CP0
Outputs
2
Digital
Crossbar
4
SPI
SMBus
8
4
T0, T1
8
2
SYSCLK
PCA
Lowest
Priority
2
UART
P0
I/O
Cells
P0.0
P1
I/O
Cells
P1.0
P0.7
P1.7
2
(Port Latches)
8
P0
(P0.0-P0.7)
P1
(P1.0-P1.7)
8
P2
P2
I/O
Cell
(P2.0)
P2.0
Figure 1.10. Port I/O Functional Block Diagram
Rev. 1.1
27
C8051F350/1/2/3
1.9.
Programmable Counter Array
The Programmable Counter Array (PCA0) provides enhanced timer functionality while requiring less CPU
intervention than the standard 8051 counter/timers. The PCA consists of a dedicated 16-bit counter/timer
and three 16-bit capture/compare modules. The counter/timer is driven by a programmable timebase that
can select between six sources: system clock, system clock divided by four, system clock divided by
twelve, the external oscillator clock source divided by 8, Timer 0 overflow, or an external clock signal on the
External Clock nput (ECI) input pin.
Each capture/compare module may be configured to operate independently in one of six modes: EdgeTriggered Capture, Software Timer, High-Speed Output, Frequency Output, 8-Bit PWM, or 16-Bit PWM.
Additionally, PCA Module 2 may be used as a watchdog timer (WDT), and is enabled in this mode following a system reset. The PCA Capture/Compare Module I/O and the External Clock Input may be routed to
Port I/O using the digital crossbar.
SYSCLK/12
SYSCLK/4
Timer 0 Overflow
ECI
PCA
CLOCK
MUX
16-Bit Counter/Timer
SYSCLK
External Clock/8
Capture/Compare
Module 0
Capture/Compare
Module 1
Capture/Compare
Module 2 / WDT
Port I/O
Figure 1.11. PCA Block Diagram
28
Rev. 1.1
CEX2
CEX1
CEX0
ECI
Crossbar
C8051F350/1/2/3
2.
Absolute Maximum Ratings
Table 2.1. Absolute Maximum Ratings
Parameter
Min
Typ
Max
Units
Ambient temperature under bias
–55
—
125
°C
Storage Temperature
–65
—
150
°C
Voltage on AIN0.0–AIN0.7, VREF+, and VREF– with respect to
DGND
–0.3
—
VDD + 0.3
V
Voltage on any Port 0, 1, or 2 Pin or /RST with respect to DGND
–0.3
—
5.8
V
Voltage on VDD with respect to DGND
–0.3
—
4.2
V
Voltage on AV+ with respect to AGND
–0.3
—
4.2
V
Maximum output current sunk by any Port 0, 1, or 2 pin
—
—
100
mA
Maximum output current sunk by any other I/O pin
—
—
50
mA
Maximum output current sourced by any Port 0, 1, or 2 pin
—
—
100
mA
Maximum output current sourced by any other I/O pin
—
—
50
mA
Maximum Total current through VDD, AV+, DGND, and AGND
—
—
500
mA
Note: Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the device.
This is a stress rating only and functional operation of the devices at those or any other conditions above those
indicated in the operation listings of this specification is not implied. Exposure to maximum rating conditions for
extended periods may affect device reliability.
Rev. 1.1
29
C8051F350/1/2/3
3.
Global DC Electrical Characteristics
Table 3.1. Global DC Electrical Characteristics
–40 to +85 °C, 25 MHz System Clock unless otherwise specified.
Parameter
Analog Supply Voltage
Conditions
1
Min
Typ
Max
Units
2.7
3.0
3.6
V
Analog Supply Current
Internal REF, ADC, IDACs,
Comparators all active
—
0.75
1.3
mA
Analog Supply Current with analog
sub-systems inactive
Internal REF, ADC, IDACs,
Comparators all disabled,
oscillator disabled
—
<1
—
µA
Analog-to-Digital Supply Delta
(|VDD – AV+|)
—
—
0.5
V
Digital Supply Voltage
2.7
3.0
3.6
V
Digital Supply Current with CPU
active
VDD = 2.7 V; SYSCLK = 25 MHz
VDD = 2.7 V; SYSCLK = 50 MHz
VDD = 3.3 V; SYSCLK = 25 MHz
VDD = 3.3 V; SYSCLK = 50 MHz
—
—
—
—
9.9
17.8
13.6
24.9
11.3
20.0
15.5
27.1
mA
mA
mA
mA
Digital Supply Current with CPU
inactive (not accessing Flash)
VDD = 2.7 V; SYSCLK = 25 MHz
VDD = 2.7 V; SYSCLK = 50 MHz
VDD = 3.3 V; SYSCLK = 25 MHz
VDD = 3.3 V; SYSCLK = 50 MHz
—
—
—
—
5.7
11.1
7.5
15.0
6.6
12.7
8.5
16.5
mA
mA
mA
mA
Oscillator not running
—
< 0.1
—
µA
Digital Supply RAM Data Retention
Voltage
—
1.5
—
V
SYSCLK (System Clock) 2,3
0
—
50
MHz
–40
—
+85
°C
Digital Supply Current (shutdown)
Specified Operating Temperature
Range
Notes:
1. Analog Supply AV+ must be greater than 1 V for VDD monitor to operate.
2. SYSCLK is the internal device clock. For operational speeds in excess of 25 MHz, SYSCLK must be derived
from the internal clock multiplier.
3. SYSCLK must be at least 32 kHz to enable debugging.
30
Rev. 1.1
C8051F350/1/2/3
4.
Pinout and Package Definitions
Table 4.1. Pin Definitions for the C8051F350/1/2/3
Pin Numbers
Name
‘F350
‘F352
‘F351
‘F353
Type
Description
VDD
21
17
Power
Digital Supply Voltage. Must be tied to +2.7 V to +3.6 V
power.
DGND
22
18
Ground Digital Ground. Must be tied to Ground.
AV+
10
6
Power
AGND
9
5
Ground Analog Ground. Must be tied to Ground.
/RST
12
8
C2CK
P2.0/
11
7
C2D
Analog Supply Voltage. Must be tied to +2.7 V to +3.6 V
power.
D I/O
Device Reset. Open-drain output of internal POR or VDD
monitor. An external source can initiate a system reset by
driving this pin low for at least 15 µs. A 1kΩ pull-up to VDD is
recommended. See Reset Sources Section.
D I/O
Clock signal for the C2 Debug Interface.
D I/O
Port 2.0. See Port I/O Section for a complete description.
D I/O
Bi-directional data signal for the C2 Debug Interface.
P0.0
13
9
D I/O or Port 0.0. See Port I/O Section for a complete description.
A In
P0.1
14
10
D I/O or Port 0.1. See Port I/O Section for a complete description.
A In
P0.2/
15
11
D I/O or Port 0.2. See Port I/O Section for a complete description.
A In
XTAL1
P0.3/
16
12
XTAL2
A In
This pin is the external oscillator return for a crystal or resonator. See Oscillator Section.
D I/O
Port 0.3. See Port I/O Section for a complete description.
A I/O or This pin is the excitation driver for an external crystal or resD In
onator, or an external clock input for CMOS, capacitor, or
RC oscillator configurations. See Oscillator Section.
P0.4
17
13
D I/O or Port 0.4. See Port I/O Section for a complete description.
A In
P0.5
18
14
D I/O or Port 0.5. See Port I/O Section for a complete description.
A In
Rev. 1.1
31
C8051F350/1/2/3
Table 4.1. Pin Definitions for the C8051F350/1/2/3 (Continued)
Pin Numbers
Name
‘F350
‘F352
‘F351
‘F353
P0.6/
19
15
CNVSTR
Description
D I/O or Port 0.6. See Port I/O Section for a complete description.
A In
D In
External Convert Start Input for IDACs (See IDAC Section
for complete description).
P0.7
20
16
D I/O or Port 0.7. See Port I/O Section for a complete description.
A In
P1.0/
23
19
D I/O or Port 1.0. See Port I/O Section for a complete description.
A In
AIN0.4
P1.1/
A In
24
20
AIN0.5
P1.2/
25
21
P1.3/
22
AIN0.7
ADC0 Input Channel 5 (C8051F351/3 - See ADC0 Section
for complete description).
D I/O or Port 1.2. See Port I/O Section for a complete description.
A In
A In
26
ADC0 Input Channel 4 (C8051F351/3 - See ADC0 Section
for complete description).
D I/O or Port 1.1. See Port I/O Section for a complete description.
A In
A In
AIN0.6
ADC0 Input Channel 6 (C8051F351/3 - See ADC0 Section
for complete description).
D I/O or Port 1.3. See Port I/O Section for a complete description.
A In
A In
ADC0 Input Channel 7 (C8051F351/3 - See ADC0 Section
for complete description).
P1.4
27
23
D I/O or Port 1.4. See Port I/O Section for a complete description.
A In
P1.5
28
24
D I/O or Port 1.5. See Port I/O Section for a complete description.
A In
P1.6/
29
25
D I/O or Port 1.6. See Port I/O Section for a complete description.
A In
IDA0
P1.7/
IDA1
32
Type
A Out
30
26
IDAC0 Output (See IDAC Section for complete description).
D I/O or Port 1.7. See Port I/O Section for a complete description.
A In
A Out
IDAC1 Output (See IDAC Section for complete description).
Rev. 1.1
C8051F350/1/2/3
Table 4.1. Pin Definitions for the C8051F350/1/2/3 (Continued)
Pin Numbers
Name
‘F350
‘F352
‘F351
‘F353
Type
Description
AIN0.0
1
1
A In
ADC0 Input Channel 0 (See ADC0 Section for complete
description).
AIN0.1
2
2
A In
ADC0 Input Channel 1 (See ADC0 Section for complete
description).
AIN0.2
3
3
A In
ADC0 Input Channel 2(See ADC0 Section for complete
description).
AIN0.3
4
4
A In
ADC0 Input Channel 3 (See ADC0 Section for complete
description).
AIN0.4
5
—
A In
ADC0 Input Channel 4 (C8051F350/2 - See ADC0 Section
for complete description).
AIN0.5
6
—
A In
ADC0 Input Channel 5 (C8051F350/2 - See ADC0 Section
for complete description).
AIN0.6
7
—
A In
ADC0 Input Channel 6 (C8051F350/2 - See ADC0 Section
for complete description).
AIN0.7
8
—
A In
ADC0 Input Channel 7 (C8051F350/2 - See ADC0 Section
for complete description).
VREF+
31
27
A I/O
VREF Positive Voltage Pin (See VREF Section for complete
description).
VREF–
32
28
A I/O
VREF Negative Voltage Pin (See VREF Section for complete description).
Rev. 1.1
33
VREF-
VREF+
P1.7 / IDA1
P1.6 / IDA0
P1.5
P1.4
P1.3
P1.2
32
31
30
29
28
27
26
25
C8051F350/1/2/3
AIN0.0
1
24
P1.1
AIN0.1
2
23
P1.0
AIN0.2
3
22
DGND
AIN0.3
4
21
VDD
AIN0.4
5
20
P0.7
AIN0.5
6
19
P0.6
AIN0.6
7
18
P0.5
AIN0.7
8
17
P0.4
9
10
11
12
13
14
15
16
AGND
AV+
P2.0 / C2D
/RST / C2CK
P0.0
P0.1
P0.2 / XTAL1
P0.3 / XTAL2
C8051F350
C8051F352
Top View
Figure 4.1. LQFP-32 Pinout Diagram (Top View)
34
Rev. 1.1
VREF-
VREF+
P1.7 / IDA1
P1.6 / IDA0
P1.5
P1.4
P1.3 / AIN0.7
27
26
25
24
23
22
GND
28
C8051F350/1/2/3
AIN0.0
1
21
P1.2 / AIN0.6
AIN0.1
2
20
P1.1 / AIN0.5
AIN0.2
3
19
P1.0 / AIN0.4
AIN0.3
4
18
DGND
AGND
5
17
VDD
AV+
6
16
P0.7
15
P0.6
C8051F351
C8051F353
Top View
GND
8
9
10
11
12
13
14
P0.0
P0.1
P0.2 / XTAL1
P0.3 / XTAL2
P0.4
P0.5
7
/RST / C2CK
P2.0 / C2D
Figure 4.2. QFN-28 Pinout Diagram (Top View)
Rev. 1.1
35
C8051F350/1/2/3
Figure 4.3. LQFP-32 Package Diagram
Table 4.2. LQFP-32 Package Dimensions
A
A1
A2
b
c
D
D1
e
E
E1
L
36
MM
TYP
—
—
1.40
0.37
—
9.00
7.00
0.80
9.00
7.00
0.60
MIN
—
0.05
1.35
0.30
0.09
—
—
—
—
—
0.45
Rev. 1.1
MAX
1.60
0.15
1.45
0.45
0.20
—
—
—
—
—
0.75
C8051F350/1/2/3
Figure 4.4. QFN-28 Package Drawing
Table 4.3. QFN-28 Package Dimensions
MIN
MM
TYP
A
0.80
0.90
1.00
A1
0.03
0.07
0.11
A3
b
0.25 REF
0.18
D
D2
MAX
0.25
0.30
5.00 BSC.
2.90
3.15
e
0.50 BSC.
E
5.00 BSC.
3.35
E2
2.90
3.15
3.35
L
0.45
0.55
0.65
Rev. 1.1
37
C8051F350/1/2/3
Figure 4.5. Typical QFN-28 Landing Diagram
38
Rev. 1.1
C8051F350/1/2/3
Figure 4.6. Typical QFN-28 Solder Paste Diagram
Rev. 1.1
39
C8051F350/1/2/3
NOTES:
40
Rev. 1.1
C8051F350/1/2/3
5.
24 or 16-Bit Analog to Digital Converter (ADC0)
The C8051F350/1/2/3 include a fully-differential, 24-bit (C8051F350/1) or 16-bit (C8051F352/3) SigmaDelta Analog to Digital Converter (ADC) with on-chip calibration capabiliites. Two separate decimation filters can be programmed for throughputs of up to 1 kHz. An internal reference is available, or a differential
external reference can be used for ratiometric measurements. A Programmable Gain Amplifier (PGA) is
included, with eight gain settings up to 128x. The on-chip input buffers can be used to provide a high input
impedance for direct connection to sensitive transducers. An 8-bit offset DAC allows for correction of large
input offset voltages.
ADC0BUF
ADC0MD
ADC0STA
AD0VREF
AD0ISEL
ADC0CN
ADC0COH:M:L
Control and
Calibration
AV+
ADC0CGH:M:L
Voltage
Reference
AD0BCE
Σ
AIN+
Σ
AD0BCE
Input
Buffers
Fast Filter
ADC0FH:M:L
8-Bit
Offset
DAC
SYSCLK
AD0POL
AD0BCE
AD0GN2
AD0GN1
AD0GN0
ADC0DAC
÷
AGND
ADC0H:M:L
MDCLK
AIN-
SINC3 Filter
Modulator
PGA
ADC0CN
ADC0CLK
ADC0DECH:L
Figure 5.1. ADC0 Block Diagram
Rev. 1.1
41
C8051F350/1/2/3
5.1.
Configuration
ADC0 is enabled by setting the AD0EN bit in register ADC0MD (SFR Definition 5.3) to ‘1’. When the ADC
is disabled, it is placed in a low-power shutdown mode with all clocks turned off, to minimize unnecessary
power consumption. The ADC will retain all of its settings in shutdown mode, with the exception of the
AD0SM bits, which are reset to 000b (Idle Mode).
5.1.1. Voltage Reference Selection
The ADC’s voltage reference is selected using the AD0VREF bit in register ADC0CF (SFR Definition 5.2).
When set to ‘1’, the ADC uses an external voltage reference source. When cleared to ‘0’, the internal reference is used. A more detailed description of the voltage reference options can be found in Section
“7. Voltage Reference’ on page 73.
5.1.2. Analog Inputs
The ADC’s analog inputs are connected to external device pins or internal voltages as described in Section
“5.6. Analog Multiplexer’ on page 59. They can be configured as either single-ended (one independent
input measured with respect to AGND) or differential (two independent inputs measured with respect to
each other). For accurate measurements, the ADC inputs must remain within the input range specifications
found in Table 5.3. To prevent damage to the device, all external ADC inputs must also remain within the
Absolute Maximum ratings for the input pin, given in Table 2.1.
5.1.2.1. Programmable Gain Amplifier
A programmable gain amplifier (PGA) provides amplification settings of 1, 2, 4, 8, 16, 32, 64, and 128 for
the ADC inputs. The PGA gain setting is controlled by the AD0GN bits in register ADC0CN (SFR Definition
5.1).
5.1.2.2. Input Buffers
Independent input buffers are included for AIN+ and AIN–, as shown in Figure 5.2. Each input has a set of
two buffers that can be used to minimize the input current of the ADC for sensitive measurements. The
“low” input buffer can be used when the absolute pin input voltage is in the lower half of the supply range.
The “high” input buffer on each pin can be used when the absolute pin input voltage is in the upper half of
the supply range. See Table 5.3 for the input buffer range specifications. The input buffers can also be
bypassed, for a direct connection to the PGA inputs. The ADC input buffers are controlled with the
ADC0BUF register (SFR Definition 5.8).
42
Rev. 1.1
C8051F350/1/2/3
Bypass Buffer
High Buffer+
AIN+
Channel
To PGA
Low Buffer+
ADC0BUF
AD0BPHE
AD0BPLE
AD0BPS1
AD0BPS0
AD0BNHE
AD0BNLE
AD0BNS1
AD0BNS0
High Buffer-
AINChannel
To PGA
Low Buffer-
Bypass Buffer
Figure 5.2. ADC0 Buffer Control
5.1.3. Modulator Clock
The ADC0CLK register (SFR Definition 5.4) holds the Modulator Clock (MDCLK) divisor value. The modulator clock determines the switching frequency for the ADC sampling capacitors. Optimal performance will
be achieved when the MDCLK frequency is equal to 2.4576 MHz. The modulator samples the input at a
rate of MDCLK / 128.
5.1.4. Decimation Ratio
The decimation ratio of the ADC filters is selected by the DECI[10:0] bits in the ADC0DECH and ADC0DECL registers (SFR Definition 5.5 and SFR Definition 5.6, respectively). The decimation ratio is equal to
1 + DECI[10:0]. The decimation ratio determines how many modulator samples are used to generate a single output word. The ADC output word rate is equal to the modulator sampling rate divided by the decimation ratio. For more information on how the ADC output word rate is derived, see SFR Definition 5.4 and
SFR Definition 5.6. Higher decimation ratios will produce lower-noise results over a longer conversion
period. The minimum decimation ratio is 20. When using the fast filter output, the decimation ratio
must be set to a multiple of 8.
Rev. 1.1
43
C8051F350/1/2/3
5.2.
Calibrating the ADC
ADC0 can be calibrated in-system for both gain and offset, using internal or system calibration modes. To
ensure calibration accuracy, offset calibrations must be performed prior to gain calibrations. It is not necessary to perform both internal and system calibrations, as a system calibration will also compensate for any
internal error sources.
Offset calibration is a single-point measurement that sets which input voltage produces a zero at the ADC
output. When performing an offset calibration, any deviation from zero in the measurement is stored in the
offset register. The offset value is subtracted from all conversions as they take place.
Gain calibration is a two-point measurement that sets the slope of the ADC transfer function. When performed, a gain calibration takes only a single measurement, which is assumed to be the desired full-scale
value in the ADC transfer function. The offset calibration value is used as the other point in the gain calibration measurement, so that a gain factor can be calculated. After offset correction, conversions are multiplied by the gain factor.
Calibrations are initiated by writing the ADC System Mode bits (AD0SM) to one of the calibration options.
During a calibration, the AD0CBSY bit is set to ‘1’. Upon completion of a calibration the the AD0SM bits will
return to Idle mode, the AD0CBSY bit will be cleared to ‘0’, the AD0CALC bit will be set to ‘1’, and an ADC
interrupt will be generated. Calibration results are also written to the appropriate calibration registers when
the calibration is complete.
5.2.1. Internal Calibration
Internal calibration is performed without requiring a specific voltage on the ADC input pins. Internal calibrations can be performed in three different ways: offset only, gain only, or full (offset and gain). A full internal
calibration consists of an internal offset calibration followed by an internal gain calibration. If offset and gain
calibrations are performed independently, offset calibration must be performed prior to gain calibration.
During an internal offset calibration, the ADC inputs are connected internally to AGND. For an internal gain
calibration, the ADC inputs are connected internally to a full-scale Voltage that is equal to the selected Voltage reference divided by the PGA gain.
5.2.2. System Calibration
System calibration is performed using voltages which are applied to the ADC inputs. There are two system
calibration options: offset calibration and gain calibration. For accurate calibration results, offset calibration
must be performed prior to gain calibration. During a system offset calibration, the ADC inputs should be
connected to a “zero” value. During a system gain calibration, the ADC inputs should be connected to the
positive full-scale value for the current PGA gain setting.
5.2.3. Calibration Coefficient Storage
The calibration results for offset and gain are each 24-bits long. The calibration results are stored in SFRs
that are both readable and writeable from software. This enables factory calibrations, as well as manual
modification of the offset and gain parameters. The offset calibration results are stored as a two’s complement, 24-bit number in the ADC0COH, ADC0COM, and ADC0COL registers. The mapping of the offset
register is shown in Figure 5.3. The gain calibration results are stored as a fixed-point, 24-bit number in the
ADC0CGH, ADC0CGM, and ADC0CGL registers. The mapping of the gain register is shown in Figure 5.4.
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Rev. 1.1
C8051F350/1/2/3
The offset calibration value adjusts the zero point of the ADC’s transfer function. It is stored as a two’s
complement, 24-bit number. An offset calibration which results in a full-scale positive (0x7FFFFF) or fullscale negative (0x800000) result will cause an ADC error condition.
The Offset Calibration results are stored in registers ADC0COH, ADC0COM, and ADC0COL. The weighting of the bits in the offset register (in LSBs) are shown below:
24-bit ADC (C8051F350/1)
ADC0COM
ADC0COH
MSB 22
21
20
19
18
17
16
15
8
7
6
5
4
3
2
1
–223 222 221 220 219 218 217 216 215 214 213 212 211 210 29
8
7
6
5
4
3
2
1
20
1
LSB
20
12
11
10
2
2
2
2
16-bit ADC (C8051F352/3)
ADC0COM
ADC0COH
21
13
ADC0COL
9
MSB 22
14
2
2
2
2
LSB
ADC0COL
19
18
17
16
15
14
13
12
11
10
9
8
–215 214 213 212 211
210
29
28
27
26
25
24
23
22
21
20
7
6
5
4
3
2
2–1 2–2 2–3 2–4 2–5 2–6 2–7 2–8
Figure 5.3. ADC0 Offset Calibration Register Coding
The gain calibration value adjusts the slope of the ADC’s transfer function. The gain calibration regsiter
can range from 0 to 2 – 2–23. A gain calibration which results in either of these extremes will cause an
ADC error condition.
The Gain Calibration results are stored in registers ADC0CGH, ADC0CGM, and ADC0CGL, as follows:
ADC0CGH
MSB 22
20
21
20
19
ADC0CGM
18
17
16
15
14
13
12
11
10
ADC0CGL
9
8
7
6
5
4
3
2
1
LSB
2–1 2–2 2–3 2–4 2–5 2–6 2–7 2–8 2–9 2–10 2–11 2–12 2–13 2–14 2–15 2–16 2–17 2–18 2–19 2–20 2–21 2–22 2–23
Example Decoding for Gain Register setting of 0x940000 (10010100 00000000 00000000b):
Slope Adjustment = 20 + 2–3 + 2–5 = 1.0 + 0.125 + 0.03125 = 1.15625
Figure 5.4. ADC0 Gain Calibration Register Coding
Rev. 1.1
45
C8051F350/1/2/3
5.3.
Performing Conversions
The ADC offers two conversion modes: Single Conversion, and Continuous Conversion. In single conversion mode, a single conversion result is produced for each of the filters (SINC3 and Fast). In continuous
conversion mode, the ADC will perform back-to-back conversions until the ADC mode is changed. Procedures for single and continuous conversion modes are detailed in the sections below.
5.3.1. Single Conversions
A single conversion is initiated by writing the ADC System Mode bits (AD0SM) to the “Single Conversion”
option. Single conversion mode instructs the ADC to gather enough information to produce a result for the
filter that is selected by the AD0ISEL bit. During the conversion, the AD0BUSY flag will be set to ‘1’. The
Fast filter results will be available after one period of the ADC’s conversion cycle (determined by the modulator clock and the decimation ratio). The SINC3 filter results will be available after three periods of the
ADC’s conversion cycle. The AD0ISEL bit in register ADC0CF determines when the end-of-conversion
interrupt will occur, and return the ADC to Idle mode. If the AD0ISEL bit is set to ‘1’, the AD0INT bit will be
set to ‘1’ when the Fast filter results are available. If the AD0ISEL bit is cleared to ‘0’, the AD0INT bit will be
set to ‘1’ when the SINC3 filter results are available. The AD0SM bits will return to idle mode and the
AD0BUSY bit will be cleared to ‘0’ when the selected filter is finished. When using the SINC3 filter, a valid
result will also be output by the Fast filter. When using the Fast filter in single-conversion mode, the SINC3
filter results will not be accurate.
5.3.2. Continuous Conversions
Continuous conversions are initiated by writing the ADC System Mode bits (AD0SM) to the “Continuous
Conversion” option. In continous conversion mode, the ADC will start a new conversion as soon as each
conversion is completed. During the conversions, the AD0BUSY flag will be set to ‘1’. The Fast filter results
will be available after one period of the ADC’s conversion cycle, and on every conversion cycle thereafter
(determined by the modulator clock and the decimation ratio). The first SINC3 filter result will be available
after three periods of the ADC’s conversion cycle, and subsequent SINC3 conversion results will be available at the end of every conversion cycle thereafter. The AD0ISEL bit in register ADC0CF determines
when the end-of-conversion interrupts will occur. If the AD0ISEL bit is cleared to ‘0’, the AD0INT bit will be
set to ‘1’ when SINC3 filter results are available. If the AD0ISEL bit is set to ‘1’, the AD0INT bit will be set to
‘1’ when Fast filter results are available. Regardless of the setting of the AD0ISEL bit, both filters will
update their results registers when new results are available. To stop conversions and exit from continuous
conversion mode, the AD0SM bits should be written to Idle mode.
5.3.3. ADC Output
The ADC’s two filters each have their own output data registers. The SINC3 filter results are stored in the
ADC0H, ADC0M, and ADC0L registers, while the Fast filter results are stored in the ADC0FH, ADC0FM,
and ADC0FL registers. The ADC output can be configured for Unipolar or Bipolar mode using the AD0POL
bit in register ADC0CN. Decoding of the ADC output words are shown in Table 5.1 and Table 5.2. The
SINC3 filter uses information from the past three conversion cycles to produce an ADC output. The Fast filter uses information from only the current conversion cycle to produce an ADC output. The fast filter reacts
more quickly to changes on the analog input, while the SINC3 filter produces lower-noise results.
46
Rev. 1.1
C8051F350/1/2/3
Table 5.1. ADC0 Unipolar Output Word Coding (AD0POL = 0)
Input Voltage* (AIN+ – AIN–) 24-bit Output Word (C8051F350/1) 16-bit Output Word (C8051F352/3)
VREF – 1 LSB
0xFFFFFF
0xFFFF
VREF / 2
0x800000
0x8000
+1 LSB
0x000001
0x0001
0
0x000000
0x0000
*Note: Input Voltage is voltage at ADC inputs after amplification by the PGA.
Table 5.2. ADC0 Bipolar Output Word Coding (AD0POL = 1)
Input Voltage* (AIN+ – AIN–) 24-bit Output Word (C8051F350/1) 16-bit Output Word (C8051F352/3)
VREF – 1 LSB
0x7FFFFF
0x7FFF
VREF / 2
0x400000
0x4000
+1 LSB
0x000001
0x0001
0
0x000000
0x0000
–1 LSB
0xFFFFFF
0xFFFF
–VREF / 2
0xC00000
0xC000
–VREF
0x800000
0x8000
*Note: Input Voltage is voltage at ADC inputs after amplification by the PGA.
5.3.1. Error Conditions
Any errors during a conversion or calibration are indicated using bits in the ADC0STA register. The
AD0S3C flag will be set to ‘1’ if there is a SINC3 filter clip during the conversion. Likewise, the AD0FFC
flag will be set to ‘1’ if there is a Fast filter clip during the conversion. A filter clip occurs whenever an internal filter register overflows during a conversion. The AD0OVR flag will be set to ‘1’ if an ADC overrun condition occurs. An overrun occurs if the end of a conversion is reached while the AD0INT flag is still set to ‘1’
from the previous conversion. If the data registers have not been read, the new data values will be
updated, and the previous conversion will be lost. The general AD0ERR flag indicates that an AD0S3C,
AD0FFC, or AD0OVR error condition has occurred, or that a calibration resulted in a value that was
beyond the limits of the offset or gain register. The data output registers are updated at the end of every
conversion regardless of whether or not an error occurs.
5.4.
Offset DAC
An 8-bit offset DAC is included, which can be used for offset correction up to approximately ±1/2 of the
ADC’s input range on any PGA gain setting. The ADC0DAC register (SFR Definition 5.7) controls the offset DAC voltage. The register is decoded as a signed binary word. The MSB (bit 7) determines the sign of
the DAC magnitude (0 = positive, 1 = negative), and the remaining seven bits (bits 6–0) determine the
magnitude. Each LSB of the offset DAC is equivalent to approximately 0.4% of the ADC’s input span. A
write to the ADC0DAC register initiates a change on the offset DAC output.
5.5.
Burnout Current Sources
The burnout current sources can be used to detect an open circuit or short circuit at the ADC inputs. The
burnout current sources are enabled by setting the AD0BCE bit in register ADC0CN to ‘1’ (SFR Definition
5.1). The positive-channel burnout current source sources approximately 2 µA on AIN+, and the negativechannel burnout current sinks approximately 2 µA on AIN–. If an open circuit exists between AIN+ and
AIN– when the burnout current sources are enabled, the ADC will read a full scale positive value. If a
short-circuit exists between AIN+ and AIN– when the burnout current sources are enabled, the ADC will
read a value near zero. The burnout current sources should be disabled during normal ADC measurements.
Rev. 1.1
47
C8051F350/1/2/3
SFR Definition 5.1. ADC0CN: ADC0 Control
R
R
R
R/W
R/W
—
—
—
AD0POL
AD0BCE
Bit7
Bit6
Bit5
Bit4
Bit3
R/W
R/W
R/W
AD0GN
Bit2
Bit1
Reset Value
00010000
Bit0
SFR Address: 0xF4
Bits 7–5: Unused: Read = 000b, Write = don’t care.
Bit 4:
AD0POL: ADC0 Polarity.
0: ADC operates in Unipolar mode (straight binary result).
1: ADC operates in Bipolar mode (2's compliment result).
Bit 3:
AD0BCE: ADC0 Burnout Current Source Enable.
0: ADC Burnout current sources disabled.
1: ADC Burnout current sources enabled.
Bits 2:0 AD0GN: ADC0 Programmable Gain Setting.
000: PGA Gain = 1.
001: PGA Gain = 2.
010: PGA Gain = 4.
011: PGA Gain = 8.
100: PGA Gain = 16.
101: PGA Gain = 32.
110: PGA Gain = 64.
111: PGA Gain = 128.
This SFR can only be modified when ADC0 is in IDLE mode.
48
Rev. 1.1
C8051F350/1/2/3
SFR Definition 5.2. ADC0CF: ADC0 Configuration
R
R
R
R/W
R
R/W
R
R
Reset Value
00000000
—
—
—
AD0ISEL
—
AD0VREF
—
—
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xFB
Bits 7–5: Unused: Read = 000b, Write = don’t care.
Bit 4:
AD0ISEL: ADC0 Interrupt Source Select.
This bit selects which filter completion will set the AD0INT interrupt flag.
0: SINC3 filter.
1: FAST filter.
Bit 3:
Unused: Read = 0b, Write = don’t care.
Bit 2:
AD0VREF: ADC0 VREF Source Select.
0: ADC0 uses the internal VREF (2.5 V). Setting this bit to ‘0’ enables the internal Voltage
Reference.
1: ADC0 uses an external VREF.
Bits 1–0: Unused: Read = 00b, Write = don’t care.
This SFR can only be modified when ADC0 is in IDLE mode.
Rev. 1.1
49
C8051F350/1/2/3
SFR Definition 5.3. ADC0MD: ADC0 Mode
R/W
R
AD0EN
—
Bit7
Bit6
R/W
R/W
Reserved Reserved
Bit5
Bit4
R
R/W
—
Bit3
R/W
R/W
AD0SM
Bit2
Bit1
Reset Value
00000000
Bit0
SFR Address: 0xF3
Bit 7:
AD0EN: ADC0 Enable Bit.
0: ADC0 Disabled. ADC is in low-power shutdown.
1: ADC0 Enabled. ADC is active and ready to perform calibrations or conversions.
Note: Disabling the ADC automatically resets the AD0SM bits back to the "Idle" state.
Bit 6:
Unused: Read = 0b, Write = don’t care.
Bits 5–4: RESERVED: Must Write to 00b.
Bit 3:
Unused: Read = 0b, Write = don’t care.
Bits 2–0: AD0SM: ADC0 System Mode Select.
These bits define the operating mode for the ADC. They are used to initiate all ADC conversion and calibration cycles.
000: Idle
001: Full Internal Calibration (offset and gain).
010: Single Conversion.
011: Continuous Conversion.
100: Internal Offset Calibration.
101: Internal Gain Calibration.
110: System Offset Calibration.
111: System Gain Calibration.
Note: Any system mode change by the user during a conversion or calibration will
terminate the operation, and corrupt the result. To write to many of the other ADC registers, the AD0SM bits must be set to IDLE mode (000b).
Note: During an ADC conversion or calibration, the AD0SM bits may return intermediate values if they are read. It is not recommended to use these bits as indicator of the
ADC status. Only the ADC0STA register should be used as indicator of the ADC status.
50
Rev. 1.1
C8051F350/1/2/3
SFR Definition 5.4. ADC0CLK: ADC0 Modulator Clock Divisor
R/W
R/W
R/W
R/W
Bit7
Bit6
Bit5
Bit4
R/W
R/W
R/W
R/W
Bit2
Bit1
Bit0
ADC0CLK
Reset Value
00000000
Bit3
SFR Address: 0xF7
Bits 7–0: ADC0CLK: ADC0 Modulator Clock Divisor.
This register establishes the Modulator Clock (MDCLK), by dividing down the system clock
(SYSCLK). The input signal is sampled by the modulator at a frequency of MDCLK / 128.
For optimal performance, the divider should be chosen such that the modulator clock is
equal to 2.4576 MHz (modulator sampling rate = 19.2 kHz).
The system clock is divided according to the equation:
MDCLK = SYSCLK / (ADC0CLK + 1)
Note: The Modulator Sampling Rate is not the ADC Output Word Rate. See Section 5.1.4 for
details.
SFR Definition 5.5. ADC0DECH: ADC0 Decimation Ratio Register High Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
—
—
—
—
—
DECI10
DECI9
DECI8
00000111
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0x9B
Bits 7–3: Unused: Read = 00000b, Write = don’t care.
Bits 2–0: DECI[10:8]: ADC0 Decimation Ratio Register, Bits 10–8.
This register contains the high bits of the 11-bit ADC Decimation Ratio. The decimation ratio
determines the output word rate of ADC0, based on the Modulator Clock (MDCLK). See the
ADC0DECL register description for more information.
This SFR can only be modified when ADC0 is in IDLE mode.
Rev. 1.1
51
C8051F350/1/2/3
SFR Definition 5.6. ADC0DECL: ADC0 Decimation Ratio Register Low Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
DECI7
DECI6
DECI5
DECI4
DECI3
DECI2
DECI1
DECI0
11111111
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0x9A
Bits 7–0: DECI[7:0]: ADC0 Decimation Ratio Register, Bits 7–0.
This register contains the low byte of the 11-bit ADC Decimation Ratio. The decimation ratio
determines the number of modulator input samples used to generate a single output word
from the ADC.
The ADC0 decimation ratio is defined as:
Decimation Ratio = DECI[10:0] + 1
The corresponding sampling period and output word rate of ADC0 is:
ADC0 Conversion Period = [(DECI[10:0] + 1) * 128] / MDCLK
ADC0 Output Word Rate = MDCLK / [128 * (DECI[10:0] + 1)]
The minimum decimation ratio setting is 20. Any register setting below 19 will automatically
be interpreted as 19.
Important: When using the fast filter, the decimation ratio must be divisible by 8
(DECI[2:0] = 111b).
This SFR can only be modified when ADC0 is in IDLE mode.
SFR Definition 5.7. ADC0DAC: ADC0 Offset DAC
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
ADC0DAC
Bit7
Bit6
Bit5
Bit4
Bit3
Reset Value
00000000
Bit2
Bit1
Bit0
SFR Address: 0xBF
Bits 7–0: ADC0DAC: ADC0 PGA Offset DAC Magnitude.
This register determines the ADC0 Offset DAC Magnitude. The value in the offset DAC is a
signed-magnitude representation. Bit 7 represents the sign value (0 = positive, 1 = negative), while Bits 6–0 represent the magnitude.
This SFR can only be modified when ADC0 is in IDLE mode.
52
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C8051F350/1/2/3
SFR Definition 5.8. ADC0BUF: ADC0 Input Buffer Control
R/W
R/W
AD0BPHE AD0BPLE
Bit7
Bit6
R/W
R/W
AD0BPS
Bit5
Bit4
R/W
R/W
AD0BNHE AD0BNLE
Bit3
Bit2
R/W
R/W
AD0BNS
Bit1
Reset Value
00000000
Bit0
SFR Address: 0xBD
Bit 7:
AD0BPHE: Positive Channel High Buffer Enable.
0: Positive Channel High Input Buffer Disabled.
1: Positive Channel High Input Buffer Enabled.
Bit 6:
AD0BPLE: Positive Channel Low Enable.
0: Positive Channel Low Input Buffer Disabled.
1: Positive Channel Low Input Buffer Enabled.
Bits 5–4: AD0BPS: Positive Channel Input Selection.
00 = Bypass Input Buffer (default).
01 = Select Low Input Buffer Range.
10 = Select High Input Buffer Range.
11 = Reserved.
Bit 3:
AD0BNHE: Negative Channel High Buffer Enable.
0: Negative Channel High Input Buffer Disabled.
1: Negative Channel High Input Buffer Enabled.
Bit 2:
AD0BNLE: Negative Channel Low Enable.
0: Negative Channel Low Input Buffer Disabled.
1: Negative Channel Low Input Buffer Enabled.
Bits 1–0: AD0BNS: Negative Channel Input Selection.
00 = Bypass Input Buffer (default).
01 = Select Low Input Buffer Range.
10 = Select High Input Buffer Range.
11 = Reserved.
This SFR can only be modified when ADC0 is in IDLE mode.
Rev. 1.1
53
C8051F350/1/2/3
SFR Definition 5.9. ADC0STA: ADC0 Status
R
R
R/W
AD0BUSY AD0CBSY AD0INT
Bit7
Bit6
Bit5
R/W
AD0S3C
Bit4
R/W
R/W
R/W
AD0FFC AD0CALC AD0ERR
Bit3
Bit2
Bit1
R/W
Reset Value
AD0OVR 00000000
Bit0
Bit
Addressable
SFR Address: 0xE8
Bit 7:
Bit 6:
Bit 5:
Bit 4:
Bit 3:
Bit 2:
Bit 1:
Bit 0:
54
AD0BUSY: ADC0 Conversion In-Progress Flag.
0: ADC0 is not performing conversions.
1: ADC0 conversion in progress.
AD0CBSY: ADC0 Calibration In-Progress Flag.
0: ADC0 is not performing a calibration.
1: ADC0 calibration in progress.
AD0INT: ADC0 Conversion Complete Interrupt Flag.
This flag must be cleared in software.
0: ADC0 has not completed a conversion since the last time this flag was cleared.
1: ADC0 conversion is complete.
AD0S3C: ADC0 SINC3 Filter Clip Flag.
This error flag indicates that a clip has occurred in the SINC3 filter during the conversion
process.
0: ADC0 SINC3 filter clip did not occur.
1: ADC0 SINC3 filter clip occurred during conversion.
AD0FFC: ADC0 Fast Filter Clip Flag.
This error flag indicates that a clip has occurred in the fast filter during the conversion process.
0: ADC0 fast filter clip did not occur.
1: ADC0 fast filter clip occurred during conversion.
AD0CALC: ADC0 Calibration Complete Flag.
0: ADC0 calibration not complete.
1: ADC0 calibration complete.
AD0ERR: ADC0 Error Flag
This bit is set by hardware under the following conditions:
1) A conversion cycle produced an AD0OVR, AD0S3C, or AD0FFC error.
2) A calibration cycle produced a result that is beyond the limits of the offset or gain
register.
0: ADC0 error did not occur.
1: ADC0 error occurred.
AD0OVR: ADC0 Overrun Flag
This error flag indicates an overrun condition.
0: ADC0 Overrun did not occur.
1: ADC0 Overrun occurred.
Rev. 1.1
C8051F350/1/2/3
SFR Definition 5.10. ADC0COH: ADC0 Offset Calibration Register High Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
OCAL23
OCAL22
OCAL21
OCAL20
OCAL19
OCAL18
OCAL17
OCAL16
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xBC
Bits 7–0: OCAL[23:16]: ADC0 Offset Calibration Register High Byte.
This register contains the high byte of the 24-bit ADC Offset Calibration Value.
SFR Definition 5.11. ADC0COM: ADC0 Offset Calibration Register Middle Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
OCAL15
OCAL14
OCAL13
OCAL12
OCAL11
OCAL10
OCAL9
OCAL8
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xBB
Bits 7–0: OCAL[15:8]: ADC0 Offset Calibration Register Middle Byte.
This register contains the middle byte of the 24-bit ADC Offset Calibration Value.
SFR Definition 5.12. ADC0COL: ADC0 Offset Calibration Register Low Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
OCAL7
OCAL6
OCAL5
OCAL4
OCAL3
OCAL2
OCAL1
OCAL0
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xBA
Bits 7–0: OCAL[7:0]: ADC0 Offset Calibration Register Low Byte.
This register contains the low byte of the 24-bit ADC Offset Calibration Value.
Rev. 1.1
55
C8051F350/1/2/3
SFR Definition 5.13. ADC0CGH: ADC0 Gain Calibration Register High Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
GCAL23
GCAL22
GCAL21
GCAL20
GCAL19
GCAL18
GCAL17
GCAL16
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Reset Value
Variable
10000000
SFR Address: 0xAD
Bit0
Bits 7–0: GCAL[23:16]: ADC0 Gain Calibration Register High Byte.
This register contains the high byte of the 24-bit ADC Gain Calibration Value.
SFR Definition 5.14. ADC0CGM: ADC0 Gain Calibration Register Middle Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
GCAL15
GCAL14
GCAL13
GCAL12
GCAL11
GCAL10
GCAL9
GCAL8
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xAC
Bits 7–0: GCAL[15:8]: ADC0 Gain Calibration Register Middle Byte.
This register contains the middle byte of the 24-bit ADC Gain Calibration Value.
SFR Definition 5.15. ADC0CGL: ADC0 Gain Calibration Register Low Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
GCAL7
GCAL6
GCAL5
GCAL4
GCAL3
GCAL2
GCAL1
GCAL0
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xAB
Bits 7–0: GCAL[7:0]: ADC0 Gain Calibration Register Low Byte.
This register contains the low byte of the 24-bit ADC Gain Calibration Value.
56
Rev. 1.1
C8051F350/1/2/3
SFR Definition 5.16. ADC0H: ADC0 Conversion Register (SINC3 Filter) High Byte
R/W
R/W
R/W
R/W
Bit7
Bit6
Bit5
Bit4
R/W
R/W
R/W
R/W
Bit2
Bit1
Bit0
ADC0H
Reset Value
00000000
Bit3
SFR Address: 0xC5
Bits 7–0: ADC0H: ADC0 Conversion Register (SINC3 Filter) High Byte.
C8051F350/1: This register contains bits 23–16 of the 24-bit ADC SINC3 filter conversion
result.
C8051F352/3: This register contains bits 15–8 of the 16-bit ADC SINC3 filter conversion
result.
SFR Definition 5.17. ADC0M: ADC0 Conversion Register (SINC3 Filter) Middle Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
ADC0M
Bit7
Bit6
Bit5
Bit4
Reset Value
00000000
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xC4
Bits 7–0: ADC0M: ADC0 Conversion Register (SINC3 Filter) Middle Byte.
C8051F350/1: This register contains bits 15–8 of the 24-bit ADC SINC3 filter conversion
result.
C8051F352/3: This register contains bits 7–0 of the 16-bit ADC SINC3 filter conversion
result.
SFR Definition 5.18. ADC0L: ADC0 Conversion Register (SINC3 Filter) Low Byte
R/W
R/W
R/W
R/W
Bit7
Bit6
Bit5
Bit4
R/W
R/W
R/W
R/W
Bit2
Bit1
Bit0
ADC0L
Reset Value
00000000
Bit3
SFR Address: 0xC3
Bits 7–0: ADC0L: ADC0 Conversion Register (SINC3 Filter) Low Byte.
C8051F350/1: This register contains bits 7–0 of the 24-bit ADC SINC3 filter conversion
result.
C8051F352/3: This register contains all zeros (00000000b).
Rev. 1.1
57
C8051F350/1/2/3
SFR Definition 5.19. ADC0FH: ADC0 Conversion Register (Fast Filter) High Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
ADC0FH
Bit7
Bit6
Bit5
Bit4
Bit3
Reset Value
00000000
Bit2
Bit1
Bit0
SFR Address: 0xFE
Bits 7–0: ADC0FH: ADC0 Conversion Register (Fast Filter) High Byte.
C8051F350/1: This register contains bits 23–16 of the 24-bit ADC fast filter conversion
result.
C8051F352/3: This register contains bits 15–8 of the 16-bit ADC fast filter conversion result.
SFR Definition 5.20. ADC0FM: ADC0 Conversion Register (Fast Filter) Middle Byte
R/W
R/W
R/W
R/W
Bit7
Bit6
Bit5
Bit4
R/W
R/W
R/W
R/W
Bit2
Bit1
Bit0
ADC0FM
Bit3
Reset Value
00000000
SFR Address: 0xFD
Bits 7–0: ADC0FM: ADC0 Conversion Register (Fast Filter) Middle Byte.
C8051F350/1: This register contains bits 15–8 of the 24-bit ADC fast filter conversion result.
C8051F352/3: This register contains bits 7–0 of the 16-bit ADC fast filter conversion result.
SFR Definition 5.21. ADC0FL: ADC0 Conversion Register (Fast Filter) Low Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
ADC0FL
Bit7
Bit6
Bit5
Bit4
Bit3
Reset Value
00000000
Bit2
Bit1
Bit0
SFR Address: 0xFC
Bits 7–0: ADC0FL: ADC0 Conversion Register (Fast Filter) Low Byte.
C8051F350/1: This register contains bits 7–0 of the 24-bit ADC fast filter conversion result.
C8051F352/3: This register contains all zeros (00000000b).
58
Rev. 1.1
C8051F350/1/2/3
5.6.
Analog Multiplexer
ADC0 includes analog multiplexer circuitry with independent selection capability for the AIN+ and AIN–
inputs. Each input can be connected to one of ten possible input sources: AIN0.0 though AIN0.7, AGND, or
the on-chip temperature sensor circuitry (Figure 5.5). The ADC0MUX register (SFR Definition 5.22) controls the input mux selection for both input channels. The multiplexer configuration allows for measurement
of single-ended or differential signals. A single-ended measurement can be performed by connecting one
of the ADC inputs to AGND. Additionally, the temperature sensor can be measured in single-ended or differential mode. The temperature sensor is automatically enabled when it is selected with the ADC multiplexer. See Section “8. Temperature Sensor’ on page 77 for more details on the temperature sensor.
AD0PSEL3
AD0PSEL2
AD0PSEL1
AD0PSEL0
AD0NSEL3
AD0NSEL2
AD0NSEL1
AD0NSEL0
ADC0MUX
AIN0.0
AIN0.1
AIN0.2
AIN0.3
AIN0.4
AIN0.5
AIN0.6
AIN0.7
Temp+
Temperature
Sensor
AIN+
AGND
ADC0
Temp-
AIN0.0
AIN-
AIN0.1
AIN0.2
AIN0.3
AIN0.4
AIN0.5
AIN0.6
AIN0.7
AGND
Figure 5.5. ADC0 Multiplexer Connections
Rev. 1.1
59
C8051F350/1/2/3
SFR Definition 5.22. ADC0MUX: ADC0 Analog Multiplexer Control
R/W
R/W
Bit7
Bit6
R/W
R/W
R/W
R/W
Bit4
Bit3
Bit2
AD0PSEL
Bit5
R/W
R/W
AD0NSEL
Bit1
Reset Value
00000000
Bit0
SFR Address: 0xC6
Bits 7–4: AD0PSEL: ADC0 Positive Multiplexer Channel Select.
0000 = AIN0.0
0001 = AIN0.1
0010 = AIN0.2
0011 = AIN0.3
0100 = AIN0.4
0101 = AIN0.5
0110 = AIN0.6
0111 = AIN0.7
1111 = Temperature Sensor
All Other Settings = AGND
Bits 3–0: AD0NSEL: ADC0 Negative Multiplexer Channel Select.
0000 = AIN0.0
0001 = AIN0.1
0010 = AIN0.2
0011 = AIN0.3
0100 = AIN0.4
0101 = AIN0.5
0110 = AIN0.6
0111 = AIN0.7
1111 = Temperature Sensor
All Other Settings = AGND
This SFR should only be modified when ADC0 is in IDLE mode.
60
Rev. 1.1
C8051F350/1/2/3
Table 5.3. ADC0 Electrical Characteristics
VDD = AV+ = 3.0 V, VREF = 2.5 V External, PGA Gain = 1, MDCLK = 2.4576 MHz,
Decimation Ratio = 1920, –40 to +85 °C unless otherwise noted.
Parameter
Conditions
Min
Typ
Max
Units
24-bit ADC (C8051F350/1)
Resolution
24
bits
No Missing Codes
24
bits
Resolution
16
bits
No Missing Codes
16
bits
16-bit ADC (C8051F352/3)
All Devices
Integral Nonlinearity
Offset Error (Calibrated)
Offset Drift vs. Temperature
Gain Error (Calibrated)
Gain Drift vs. Temperature
Modulator Clock (MDCLK)
—
—
±15
ppm
FS
—
±5
—
ppm
—
10
—
nV/
°C
—
±0.002
—
%
—
±0.5
—
ppm/
°C
—
2.4576
—
MHz
Modulator Sampling Frequency
MDCLK/128
Output Word Rate
Hz
—
—
1000
sps
PGA Gain = 1, Bipolar
PGA Gain = 1, Unipolar
–VREF
0
—
—
+VREF
+VREF
V
Input Buffers OFF
0
—
AV+
V
Input Buffer ON
—
± 1.5
30
nA
Input Buffer OFF,
Gain = 1
—
7
—
MΩ
DC
50/60 Hz
95
110
100
—
—
dB
dB
High Buffer Input Range with respect
to AGND
PGA Gain = 1, 2, 4, or 8
PGA Gain = 16
PGA Gain = 32
PGA Gain = 64 or 128
1.4
1.45
1.5
1.6
—
—
—
—
AV+ – 0.1
AV+ – 0.15
AV+ – 0.2
AV+ – 0.25
V
V
V
V
Low Buffer Input Range with respect
to AGND
PGA Gain = 1, 2, 4, or 8
PGA Gain = 16
PGA Gain = 32
PGA Gain = 64 or 128
0.1
0.15
0.2
0.25
—
—
—
—
AV+ – 1.4
AV+ – 1.45
AV+ – 1.5
AV+ – 1.6
V
V
V
V
Positive (AIN+) Channel Current
VREF = 2.5 V
0.9
2
2.9
µA
Negative (AIN–) Channel Current
VREF = 2.5 V
–0.9
–2
–2.9
µA
Analog Inputs
Analog Input Voltage Range
(AIN+ – AIN–)
Absolute Voltage on AIN+ or AIN–
pin with respect to AGND
Input Current
Input Impedance
Common Mode Rejection Ratio
Input Buffers
Burnout Current Sources
Rev. 1.1
61
C8051F350/1/2/3
Table 5.3. ADC0 Electrical Characteristics (Continued)
VDD = AV+ = 3.0 V, VREF = 2.5 V External, PGA Gain = 1, MDCLK = 2.4576 MHz,
Decimation Ratio = 1920, –40 to +85 °C unless otherwise noted.
Parameter
Conditions
Min
Typ
Max
Units
AV+ Supply Current to ADC0
—
230
650
µA
AV+ Supply Current to Input Buffers
(Each Enabled Buffer)
—
90
125
µA
Power Supply Rejection
80
—
—
dB
Power Specifications
Table 5.4. ADC0 SINC3 Filter Typical RMS Noise (µV)
PGA Gain Setting
Decimation
Ratio
Output Word
Rate*
1
2
4
8
16
32
64
128
1920
10 Hz
2.38
1.23
0.68
0.41
0.24
0.16
0.12
0.11
768
25 Hz
3.90
2.04
1.14
0.68
0.44
0.33
0.28
0.27
640
30 Hz
4.50
2.39
1.31
0.81
0.54
0.42
0.36
0.36
384
50 Hz
6.00
3.21
1.86
1.20
0.86
0.73
0.66
0.66
320
60 Hz
7.26
3.96
2.32
1.51
1.11
0.97
0.89
0.89
192
100 Hz
13.1
7.11
4.24
2.85
2.16
1.91
1.79
1.77
80
240 Hz
93.2
47.7
24.8
13.9
9.34
7.61
6.97
6.67
40
480 Hz
537
267
135
69.5
38.8
25.7
20.9
18.9
20
960 Hz
2974
1586
771
379
196
108
70.0
45.4
*Note: Output Word Rate assuming Modulator Clock frequency = 2.4576 MHz
(sampling clock frequency = 19.2 kHz)
62
Rev. 1.1
C8051F350/1/2/3
Table 5.5. ADC0 SINC3 Filter Effective Resolution1
in Unipolar Mode (bits)
PGA Gain Setting
Decimation
Ratio
Output Word
Rate2
1
2
4
8
16
32
64
128
1920
10 Hz
20.00
19.95
19.81
19.54
19.31
18.90
18.31
17.44
768
25 Hz
19.29
19.22
19.06
18.81
18.44
17.85
17.09
16.14
640
30 Hz
19.08
19.00
18.86
18.56
18.14
17.51
16.73
15.73
384
50 Hz
18.67
18.57
18.36
17.99
17.47
16.71
15.85
14.85
320
60 Hz
18.39
18.27
18.04
17.66
17.10
16.30
15.42
14.42
192
100 Hz
17.54
17.42
17.17
16.74
16.14
15.32
14.41
13.43
80
240 Hz
14.71
14.68
14.62
14.46
14.03
13.33
12.45
11.52
40
480 Hz
12.18
12.19
12.18
12.13
11.98
11.57
10.87
10.01
20
960 Hz
9.72
9.62
9.66
9.69
9.64
9.50
9.12
8.75
Notes:
FullInputRange ( V )
1. Effective resolution = log 2  ---------------------------------------------------
RMS Noise ( V )
V REF
where Full Input Range = --------------------------- in Unipolar mode and RMS Noise is obtained from Table 5.4.
PGA Gain
2. Output Word Rate assuming Modular Clock frequency = 2.4576 MHz
(sampling clock frequency = 19.2 kHz)
Table 5.6. ADC0 SINC3 Filter Flicker-Free (Noise-Free) Resolution1
in Unipolar Mode (bits)
PGA Gain Setting
Decimation
Ratio
Output Word
Rate2
1
2
4
8
16
32
64
128
1920
10 Hz
17.28
17.23
17.09
16.82
16.59
16.17
15.59
14.72
768
25 Hz
16.57
16.50
16.34
16.09
15.72
15.13
14.37
13.42
640
30 Hz
16.36
16.27
16.14
15.84
15.42
14.78
14.00
13.00
384
50 Hz
15.95
15.85
15.64
15.27
14.75
13.99
13.13
12.13
320
60 Hz
15.67
15.55
15.32
14.94
14.38
13.57
12.70
11.70
192
100 Hz
14.82
14.70
14.45
14.02
13.42
12.60
11.69
10.71
80
240 Hz
11.99
11.96
11.90
11.73
11.31
10.60
9.73
8.79
40
480 Hz
9.46
9.47
9.45
9.41
9.25
8.85
8.15
7.29
20
960 Hz
6.99
6.90
6.94
6.96
6.92
6.78
6.40
6.03
Notes:
FullInputRange ( V )
1. Flicker-free (Noise-free) Resolution = log 2  ----------------------------------------------------
6.6 × RMS Noise ( V )
V REF
where Full Input Range = --------------------------- in Unipolar mode and RMS Noise is obtained from Table 5.4.
PGA Gain
2. Output Word Rate assuming Modular Clock frequency = 2.4576 MHz (sampling clock frequency = 19.2 kHz)
Rev. 1.1
63
C8051F350/1/2/3
Table 5.7. ADC0 Fast Filter Typical RMS Noise (µV)
PGA Gain Setting
Decimation
Ratio
Output Word
Rate*
1
2
4
8
16
32
64
128
1920
10 Hz
4.84
2.68
1.55
1.03
0.75
0.61
0.56
0.58
768
25 Hz
17.92
9.77
5.85
3.72
2.79
2.45
2.28
2.21
640
30 Hz
29.98
14.84
7.81
5.39
3.89
3.27
3.19
3.03
384
50 Hz
103.93
48.53
25.71
14.07
9.24
7.17
6.45
6.06
320
60 Hz
171.12
89.87
42.99
23.05
13.81
10.33
9.00
8.52
192
100 Hz
550.29
305.55
140.58
72.90
40.97
25.52
19.96
17.68
*Note: Output Word Rate assuming Modulator Clock frequency = 2.4576 MHz
(sampling clock frequency = 19.2 kHz)
Table 5.8. ADC0 Fast Filter Effective Resolution1 in Unipolar Mode (bits)
PGA Gain Setting
Decimation
Ratio
Output Word
Rate2
1
2
4
8
16
32
64
128
1920
10 Hz
18.98
18.83
18.62
18.21
17.67
16.97
16.09
15.04
768
25 Hz
17.09
16.97
16.71
16.36
15.77
14.96
14.06
13.11
640
30 Hz
16.35
16.36
16.29
15.82
15.29
14.54
13.58
12.65
384
50 Hz
14.55
14.65
14.57
14.44
14.05
13.41
12.56
11.65
320
60 Hz
13.83
13.76
13.83
13.73
13.47
12.88
12.08
11.16
192
100 Hz
12.15
12.00
12.12
12.07
11.90
11.58
10.93
10.11
Notes:
FullInputRange ( V )
1. Effective Resolution = log 2  ---------------------------------------------------
RMS Noise ( V )
V REF
where Full Input Range = --------------------------- in Unipolar mode and RMS Noise is obtained from Table 5.7.
PGA Gain
2. Output Word Rate assuming Modular Clock frequency = 2.4576 MHz (sampling clock frequency = 19.2 kHz)
64
Rev. 1.1
C8051F350/1/2/3
Table 5.9. ADC0 Fast Filter Flicker-Free (Noise-Free) Resolution1
in Unipolar Mode (bits)
PGA Gain Setting
Decimation
Ratio
Output Word
Rate2
1
2
4
8
16
32
64
128
1920
10 Hz
16.26
16.11
15.90
15.49
14.95
14.24
13.37
12.32
768
25 Hz
14.37
14.24
13.98
13.64
13.05
12.24
11.34
10.39
640
30 Hz
13.63
13.64
13.57
13.10
12.57
11.82
10.86
9.93
384
50 Hz
11.83
11.93
11.85
11.72
11.32
10.69
9.84
8.93
320
60 Hz
11.11
11.04
11.11
11.00
10.74
10.16
9.36
8.44
192
100 Hz
9.43
9.28
9.40
9.34
9.17
8.86
8.21
7.39
Notes:
FullInputRange ( V )
1. Flicker-free (Noise-free) Resolution = log 2  ----------------------------------------------------
6.6 × RMS Noise ( V )
V REF
where Full Input Range = --------------------------- in Unipolar mode and RMS Noise is obtained from Table 5.7.
PGA Gain
2. Output Word Rate assuming Modular Clock frequency = 2.4576 MHz (sampling clock frequency = 19.2 kHz)
Rev. 1.1
65
C8051F350/1/2/3
NOTES:
66
Rev. 1.1
C8051F350/1/2/3
6.
8-Bit Current Mode DACS (IDA0 and IDA1)
CNVSTR
Timer 3
Timer 2
Timer 1
Timer 0
IDAn
IDAnEN
IDAnCM2
IDAnCM1
IDAnCM0
IDAnCSC
8
Latch
IDAnOMD1
IDAnOMD0
IDAn
IDAnCN
The C8051F350/1/2/3 devices include two 8-bit current-mode Digital-to-Analog Converters (IDACs). The
maximum current output of the IDACs can be adjusted for four different current settings; 0.25 mA, 0.5 mA,
1 mA, and 2 mA. The IDACs can be individually enabled or disabled using the enable bits in the corresponding IDAC Control Register (IDA0CN or IDA1CN). An internal bandgap bias generator is used to generate a reference current for the IDACs whenever they are enabled. IDAC updates can be performed ondemand, scheduled on a Timer overflow, or synchronized with an external pin edge. Figure 6.1 shows a
block diagram of the IDAC circuitry.
8
IDAn
IDAn
Output
Figure 6.1. IDAC Functional Block Diagram
Rev. 1.1
67
C8051F350/1/2/3
6.1.
IDAC Output Scheduling
A flexible output update mechanism allows for seamless full-scale changes and supports jitter-free
updates for waveform generation. Three update modes are provided, allowing IDAC output updates on a
write to the IDAC’s data register, on a Timer overflow, or on an external pin edge.
6.1.1. Update Output On-Demand
In its default mode (IDAnCN.[6:4] = ‘111’) the IDAC output is updated “on-demand” with a write to the data
register (IDAn). In this mode, data is immediately latched into the IDAC after a write to its data register.
6.1.2. Update Output Based on Timer Overflow
The IDAC output update can be scheduled on a Timer overflow. This feature is useful in systems where the
IDAC is used to generate a waveform of a defined sampling rate, by eliminating the effects of variable
interrupt latency and instruction execution on the timing of the IDAC output. When the IDAnCM bits
(IDAnCN.[6:4]) are set to ‘000’, ‘001’, ‘010’ or ‘011’, writes to the IDAC data register (IDAn) are held until an
associated Timer overflow event (Timer 0, Timer 1, Timer 2 or Timer 3, respectively) occurs, at which time
the data register contents are copied to the IDAC input latch, allowing the IDAC output to change to the
new value.
6.1.3. Update Output Based on CNVSTR Edge
The IDAC output can also be configured to update on a rising edge, falling edge, or both edges of the
external CNVSTR signal. When the IDAnCM bits (IDAnCN.[6:4]) are set to ‘100’, ‘101’, or ‘110’, writes to
the IDAC data register (IDAn) are held until an edge occurs on the CNVSTR input pin. The particular setting of the IDAnCM bits determines whether the IDAC output is updated on rising, falling, or both edges of
CNVSTR. When a corresponding edge occurs, the data register contents are copied to the IDAC input
latch, allowing the IDAC output to change to the new value.
6.2.
IDAC Output Mapping
The data word mapping for the IDAC is shown in Figure 6.2. The full-scale output current of the IDAC is
selected using the IDAnOMD bits (IDAnCN[1:0]). By default, the IDAC is set to a full-scale output current of
0.25 mA. The IDAnOMD bits can also be configured to provide full-scale output currents of 0.5 mA, 1 mA,
or 2 mA.
IDAn Data Word
(D7 – D0)
0x00
0x01
0x80
0xFF
‘11’ (2 mA)
0 mA
1/256 x 2 mA
128/256 x 2 mA
255/256 x 2 mA
Output Current vs IDAnOMD bit setting
‘10’ (1 mA)
‘01’ (0.5 mA)
‘00’ (0.25 mA)
0 mA
0 mA
0 mA
1/256 x 1 mA
1/256 x 0.5 mA
1/256 x 0.25 mA
128/256 x 1 mA
128/256 x 0.5 mA 128/256 x 0.25 mA
255/256 x 1 mA
255/256 x 0.5 mA 255/256 x 0.25 mA
Figure 6.2. IDAC Data Word Mapping
68
Rev. 1.1
C8051F350/1/2/3
SFR Definition 6.1. IDA0CN: IDA0 Control
R/W
R/W
IDA0EN
Bit7
R/W
R/W
IDA0CM
Bit6
Bit5
Bit4
R/W
R
IDA0CSC
—
Bit3
Bit2
R/W
R/W
IDA0OMD
Bit1
Reset Value
01110000
Bit0
SFR Address: 0xB9
Bit 7:
IDA0EN: IDA0 Enable.
0: IDA0 Disabled.
1: IDA0 Enabled.
Bits 6–4: IDA0CM[2:0]: IDA0 Update Source Select bits.
000: DAC output updates on Timer 0 overflow.
001: DAC output updates on Timer 1 overflow.
010: DAC output updates on Timer 2 overflow.
011: DAC output updates on Timer 3 overflow.
100: DAC output updates on rising edge of CNVSTR.
101: DAC output updates on falling edge of CNVSTR.
110: DAC output updates on any edge of CNVSTR.
111: DAC output updates on write to IDA0.
Bit 3:
IDA0CSC: IDA0 Constant Supply Current.
0: Current draw on VDD is dependent on IDA0 Output Word.
1: Current draw on VDD is independent of IDA0 Output Word.
Bit 2:
Unused. Read = 0b, Write = Don’t Care.
Bits 1:0: IDA0OMD[1:0]: IDA0 Output Mode Select bits.
00: 0.25 mA full-scale output current.
01: 0.5 mA full-scale output current.
10: 1.0 mA full-scale output current.
11: 2.0 mA full-scale output current.
SFR Definition 6.2. IDA0: IDA0 Data Word
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0x96
Bits 7–0: IDA0 Data Word Bits.
Bits 7–0 hold the 8-bit IDA0 Data Word.
Rev. 1.1
69
C8051F350/1/2/3
SFR Definition 6.3. IDA1CN: IDA1 Control
R/W
R/W
IDA1EN
Bit7
R/W
R/W
IDA1CM
Bit6
Bit5
Bit4
R/W
R
IDA1CSC
—
Bit3
Bit2
R/W
R/W
IDA1OMD
Bit1
Reset Value
01110000
Bit0
SFR Address: 0xD7
Bit 7:
IDA1EN: IDA1 Enable.
0: IDA1 Disabled.
1: IDA1 Enabled.
Bits 6–4: IDA1CM[2:0]: IDA1 Update Source Select bits.
000: DAC output updates on Timer 0 overflow.
001: DAC output updates on Timer 1 overflow.
010: DAC output updates on Timer 2 overflow.
011: DAC output updates on Timer 3 overflow.
100: DAC output updates on rising edge of CNVSTR.
101: DAC output updates on falling edge of CNVSTR.
110: DAC output updates on any edge of CNVSTR.
111: DAC output updates on write to IDA1.
Bit 3:
IDA1CSC: IDA1 Constant Supply Current.
0: Current draw on VDD is dependent on IDA1 Output Word.
1: Current draw on VDD is independent of IDA1 Output Word.
Bit 2:
Unused. Read = 0b, Write = Don’t Care.
Bits 1:0: IDA1OMD[1:0]: IDA1 Output Mode Select bits.
00: 0.25 mA full-scale output current.
01: 0.5 mA full-scale output current.
10: 1.0 mA full-scale output current.
11: 2.0 mA full-scale output current.
SFR Definition 6.4. IDA1: IDA1 Data Word
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xDD
Bits 7–0: IDA1 Data Word Bits.
Bits 7–0 hold the 8-bit IDA1 Data Word.
70
Rev. 1.1
C8051F350/1/2/3
6.3.
IDAC External Pin Connections
The IDA0 output is connected to P1.6, and the IDA1 output is connected to P1.7. When the enable bit for
an IDAC (IDAnEN) is set to ‘0’, the IDAC output behaves as a normal GPIO pin. When the enable bit is set
to ‘1’, the digital output drivers and weak pull-up for the IDAC pin are automatically disabled, and the pin is
connected to the IDAC output. When using the IDACs, the IDAC pins should be skipped in the Crossbar by
setting the corresponding PnSKIP bits to a ‘1’. Figure 6.3 shows the pin connections for IDA0 and IDA1.
IDA0EN
IDA0
0
1
P1.6
IDA1EN
IDA1
0
1
P1.7
Figure 6.3. IDAC Pin Connections
Rev. 1.1
71
C8051F350/1/2/3
.
Table 6.1. IDAC Electrical Characteristics
–40 to +85 °C, VDD = 3.0 V Full-scale output current set to 2 mA unless otherwise specified.
Parameter
Conditions
Min
Typ
Max
Units
Static Performance
Resolution
8
Integral Nonlinearity
bits
—
±0.5
—
LSB
—
±0.5
±1
LSB
—
—
VDD – 1.2
V
—
2
—
nA/rtHz
—
0
—
LSB
1.6
2.0
2.4
mA
Gain-Error Tempco
—
4
—
µA/°C
VDD Power Supply Rejection
Ratio
—
30
—
µA/V
Output Capacitance
—
2
—
pF
Output Settling Time to 1/2 LSB
—
5
—
µs
Startup Time
—
5
—
µs
1 mA Full Scale Output Current
0.5 mA Full Scale Output Current
0.25 mA Full Scale Output Current
—
—
—
±1
±1
±1
—
—
—
%
%
%
Power Supply Current
(IDAnCSC = 0)
IOUT = Current sourced from IDAC
—
Power Supply Current
(IDAnCSC = 1)
2 mA Full Scale Output Current
1 mA Full Scale Output Current
0.5 mA Full Scale Output Current
0.25 mA Full Scale Output Current
—
—
—
—
Differential Nonlinearity
Guaranteed Monotonic
Output Compliance Range
Output Noise
IOUT = 2 mA; RLOAD = 100 Ω
Offset Error
Full Scale Output
2 mA Full Scale Setting
Dynamic Performance
Gain Variation From 2 mA
range
Power Consumption
72
Rev. 1.1
IOUT + 85 IOUT + 130
2085
1085
585
335
2130
1130
630
380
µA
µA
µA
µA
µA
C8051F350/1/2/3
7.
Voltage Reference
There are two voltage reference options for the C8051F350/1/2/3 ADCs: the internal 2.5 V reference voltage, or an external reference voltage (see Figure 7.1). The AD0VREF bit in the ADC0CF register selects
the reference source.
The internal voltage reference circuit consists of a 1.25 V, temperature stable bandgap voltage reference
generator and a gain-of-two output buffer amplifier, to produce a 2.5 V voltage reference. When the internal voltage reference is used, it is driven out on the VREF+ pin. In this configuration, the VREF– must be
connected to the AGND pin external to the device. See Section “24. Revision Specific Behavior’ on
page 227 for more information. The internal voltage reference is enabled by setting the AD0EN bit in register ADC0MD to ‘1’ and clearing the AD0VREF bit in register ADC0CF to ‘0’ (See Section “5. 24 or 16-Bit
Analog to Digital Converter (ADC0)’ on page 41). Electrical specifications for the internal voltage reference
and bias generators are given in Table 7.1.
REF0CN
The internal oscillator bias generator is automatically enabled whenever the internal oscillator is enabled.
For power requirement characterization, the BIASE bit in register REF0CN can also be used to enable the
internal oscillator bias generator, when the oscillator itself is not enabled. Likewise, the REFBE bit in register REF0CN can be used to enable the internal bandgap generator, which is used by the ADC, the IDACs,
the Clock Multiplier, and the internal Voltage Reference. The internal reference bias generator is automatically enabled whenever a peripheral requires it. See SFR Definition 7.1 for the REF0CN register description.
Internal
EN Oscillator Bias
Generator
IOSCEN
To Internal
Oscillator
BIASE
REFBE
AD0EN
IDA0EN
IDA1EN
MULEN
Bypass
Capacitors
(Recommended)
External
Voltage
Reference
(Optional)
EN
Internal
Reference
Bias Generator
To ADC, IDACs,
Clock Multiplier
AD0EN
AD0VREF
EN
VREF+
2.5 V
Reference
Buffer
+
VREF–
VREF to ADC
Figure 7.1. Reference Circuitry Block Diagram
Rev. 1.1
73
C8051F350/1/2/3
SFR Definition 7.1. REF0CN: Reference Control
R
R
R
R
R
R
R/W
R/W
Reset Value
00000000
—
—
—
—
—
—
BIASE
REFBE
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xD1
NOTE: Modification of this register is not necessary in most applications. The appropriate circuitry is
enabled when it is needed by a peripheral.
Bits7–2: Unused. Read = 000000b; Write = don’t care.
Bit1:
BIASE: Internal Oscillator Bias Enable.
This bit is ORed with the Internal Oscillator Enable bit to enable the internal oscillator bias
generator.
0: Internal Oscillator Bias enable determined by Internal Oscillator Enable bit.
1: Internal Oscillator Bias Generator On.
Bit0:
REFBE: Internal Reference Bias Enable Bit.
This bit is ORed with the Enable bits for ADC0, IDAC0, IDAC1, and the Clock Multiplier to
enable the internal bandgap generator.
0: Internal Reference Bias enable determined by individual component.
1: Internal Reference Bias enabled.
74
Rev. 1.1
C8051F350/1/2/3
Table 7.1. Voltage Reference Electrical Characteristics
VDD = 3.0 V; –40 to +85 °C unless otherwise specified.
Parameter
Conditions
Min
Typ
Max
Units
25 °C ambient
2.35
2.45
2.50
V
To AGND
To AV+
—
—
9
20
—
—
mA
µA
—
15
—
ppm/°C
Load = 0 to 200 µA to AGND
—
0.5
—
ppm/µA
VREF Turn-on Time 1 (0.01%)
4.7 µF tantalum, 0.1 µF ceramic
bypass capacitors
—
3.9
—
ms
VREF Turn-on Time 2 (0.01%)
0.1 µF ceramic bypass capacitor
—
400
—
µs
VREF Turn-on Time 3 (0.01%)
no bypass capacitor
—
3
—
µs
—
50
—
dB
Input Voltage Range
(VREF+ – VREF–)
1
2.5
AV+
V
Voltage on VREF+ or VREF– pin
with respect to AGND
0
—
AV+
V
—
2
—
µA
—
120
—
dB
—
106
135
µA
Internal Reference
Output Voltage
VREF Short-Circuit Current
VREF Temperature Coefficient
Load Regulation
Power Supply Rejection
External Reference
Input Current
VREF = 2.5 V
Common Mode Rejection Ratio
Power Specifications
Internal Reference Bias and Band
Gap Generator
Rev. 1.1
75
C8051F350/1/2/3
NOTES:
76
Rev. 1.1
C8051F350/1/2/3
8.
Temperature Sensor
The temperature sensor system consists of two diodes with different temperature properties and two constant current sources. The two channels are connected to the ADC inputs internally, using the ADC’s analog multiplexer. The temperature sensor system can be used in single-ended or differential mode to
measure the temperature of the C8051F350/1/2/3. Single channel measurements produce more output
voltage per degree C, but are not as linear as differential measurements. See Table 8.1 for temperature
sensor electrical characteristics.
The temperature sensor channels are automatically enabled when they are selected by the ADC multiplexer. To use the temperature sensor for a single-channel measurement, the ADC multiplexer should be
configured with one channel connected to the temperature sensor, and the other connected to AGND. For
a differential measurement, the temperature sensor should be selected for both ADC channels.
The transfer functions for single-channel and differential measurements are shown in Figure 8.2 and
Figure 8.3, respectively. For slope and offset values, refer to Table 8.1.
AV+
To AIN+ Mux
To AIN- Mux
AIN+
Channel
AINChannel
AGND
Figure 8.1. Temperature Sensor Block Diagram
Table 8.1. Temperature Sensor Electrical Characteristics
VDD = 3.0 V; –40 to +85 °C unless otherwise specified.
Parameter
Linearity
Offset
Conditions
Single Channel Measurement
Differential Measurement
AIN+ Channel Measurement, Temp = 0 °C
Differential Measurement, Temp = 0 °C
Offset Error*
Slope
AIN+ Channel Measurement
Differential Measurement
Slope Error*
AV+ Supply Current
Single Channel Measurement
Differential Measurement
Min
—
—
—
—
—
—
Typ
±0.4
±0.01
757
54.3
±1
–1.73
205
±6.6
10
20
Max
—
—
—
—
—
—
Units
°C
°C
mV
mV
mV
mV/°C
uV/°C
µV/°C
µA
µA
*Note: Represents one standard deviation from the mean.
Rev. 1.1
77
C8051F350/1/2/3
VTEMP = (Slope x TempC) + Offset
Voltage
TempC = (VTEMP - Offset) / Slope
Offset (V at 0 Celsius)
Slope (V / deg C)
-50
0
50
100
Temperature (Celsius)
Figure 8.2. Single Channel Transfer Function
Voltage
Slope (V / deg C)
Offset (V at 0 Celsius)
VTEMP = (Slope x TempC) + Offset
TempC = (VTEMP - Offset) / Slope
-50
0
50
100
Temperature (Celsius)
Figure 8.3. Differential Transfer Function
78
Rev. 1.1
C8051F350/1/2/3
9.
Comparator0
C8051F350/1/2/3 devices include an on-chip programmable voltage comparator, Comparator0, shown in
Figure 9.1.
The Comparator offers programmable response time and hysteresis and two outputs that are optionally
available at the Port pins: a synchronous “latched” output (CP0), or an asynchronous “raw” output (CP0A).
The asynchronous CP0A signal is available even when the system clock is not active. This allows the
Comparator to operate and generate an output with the device in STOP mode. When assigned to a Port
pin, the Comparator output may be configured as open drain or push-pull (see Section “18.2. Port I/O Initialization’ on page 141). Comparator0 may also be used as a reset source (see Section
“14.5. Comparator0 Reset’ on page 118).
CPT0CN
VDD
CP0EN
CP0OUT
CP0RIF
CP0FIF
CP0HYP1
CP0HYP0
CP0HYN1
CP0HYN0
CP0 +
+
CP0 -
-
D
SET
CLR
D
Q
Q
SET
CLR
CP0
(synchronous output)
Q
Q
(SYNCHRONIZER)
CP0A
(asynchronous output)
GND
CPT0MD
Reset
Decision
Tree
CP0RIE
CP0FIE
CP0RIF
CP0FIF
CP0MD1
0
CP0EN
EA
1
0
0
0
1
1
CP0
Interrupt
1
CP0MD0
Figure 9.1. Comparator0 Functional Block Diagram
The Comparator output can be polled in software, used as an interrupt source, and/or routed to a Port pin.
When routed to a Port pin, the Comparator output is available asynchronous or synchronous to the system
clock; the asynchronous output is available even in STOP mode (with no system clock active). When disabled, the Comparator output (if assigned to a Port I/O pin) defaults to the logic low state, and its supply
current falls to less than 100 nA. Comparator inputs can be externally driven from –0.25 V to
(VDD) + 0.25 V without damage or upset. The complete Comparator electrical specifications are given in
Table 9.1.
The Comparator response time may be configured in software via the CPT0MD register (see SFR Definition 9.2). Selecting a longer response time reduces the Comparator supply current. See Table 9.1 for complete timing and power consumption specifications.
Rev. 1.1
79
C8051F350/1/2/3
VIN+
VIN-
CP0+
CP0-
+
CP0
_
OUT
CIRCUIT CONFIGURATION
Positive Hysteresis Voltage
(Programmed with CP0HYP Bits)
VIN-
INPUTS
Negative Hysteresis Voltage
(Programmed by CP0HYN Bits)
VIN+
VOH
OUTPUT
VOL
Negative Hysteresis
Disabled
Positive Hysteresis
Disabled
Maximum
Negative Hysteresis
Maximum
Positive Hysteresis
Figure 9.2. Comparator Hysteresis Plot
The Comparator hysteresis is software-programmable via its Comparator Control register CPT0CN. The
user can program both the amount of hysteresis voltage (referred to the input voltage) and the positive and
negative-going symmetry of this hysteresis around the threshold voltage.
The Comparator hysteresis is programmed using Bits3–0 in the Comparator Control Register CPT0CN
(shown in SFR Definition 9.1). The amount of negative hysteresis voltage is determined by the settings of
the CP0HYN bits. As shown in Figure 9.2, settings of 20, 10 or 5 mV of negative hysteresis can be programmed, or negative hysteresis can be disabled. In a similar way, the amount of positive hysteresis is
determined by the setting the CP0HYP bits.
Comparator interrupts can be generated on both rising-edge and falling-edge output transitions. (For Interrupt enable and priority control, see Section “12. Interrupt Handler’ on page 105). The CP0FIF flag is set to
logic 1 upon a Comparator falling-edge occurrence, and the CP0RIF flag is set to logic 1 upon the Comparator rising-edge occurrence. Once set, these bits remain set until cleared by software. The Comparator
rising-edge interrupt mask is enabled by setting CP0RIE to a logic 1. The Comparator0 falling-edge interrupt mask is enabled by setting CP0FIE to a logic 1.
The output state of the Comparator can be obtained at any time by reading the CP0OUT bit. The Comparator is enabled by setting the CP0EN bit to logic 1, and is disabled by clearing this bit to logic 0.
Note that false rising edges and falling edges can be detected when the comparator is first powered on or
if changes are made to the hysteresis or response time control bits. Therefore, it is recommended that the
rising-edge and falling-edge flags be explicitly cleared to logic 0 a short time after the comparator is
enabled or its mode bits have been changed. This Power Up Time is specified in Table 9.1 on page 85.
80
Rev. 1.1
C8051F350/1/2/3
SFR Definition 9.1. CPT0CN: Comparator0 Control
R/W
R
R/W
R/W
CP0EN
CP0OUT
CP0RIF
CP0FIF
Bit7
Bit6
Bit5
Bit4
R/W
R/W
R/W
R/W
Reset Value
CP0HYP1 CP0HYP0 CP0HYN1 CP0HYN0 00000000
Bit3
Bit2
Bit1
Bit0
SFR Address: 0x9C
Bit7:
CP0EN: Comparator0 Enable Bit.
0: Comparator0 Disabled.
1: Comparator0 Enabled.
Bit6:
CP0OUT: Comparator0 Output State Flag.
0: Voltage on CP0+ < CP0–.
1: Voltage on CP0+ > CP0–.
Bit5:
CP0RIF: Comparator0 Rising-Edge Flag. Must be cleared by software.
0: No Comparator0 Rising Edge has occurred since this flag was last cleared.
1: Comparator0 Rising Edge has occurred.
Bit4:
CP0FIF: Comparator0 Falling-Edge Flag. Must be cleared by software.
0: No Comparator0 Falling-Edge has occurred since this flag was last cleared.
1: Comparator0 Falling-Edge has occurred.
Bits3–2: CP0HYP1–0: Comparator0 Positive Hysteresis Control Bits.
00: Positive Hysteresis Disabled.
01: Positive Hysteresis = 5 mV.
10: Positive Hysteresis = 10 mV.
11: Positive Hysteresis = 20 mV.
Bits1–0: CP0HYN1–0: Comparator0 Negative Hysteresis Control Bits.
00: Negative Hysteresis Disabled.
01: Negative Hysteresis = 5 mV.
10: Negative Hysteresis = 10 mV.
11: Negative Hysteresis = 20 mV.
Rev. 1.1
81
C8051F350/1/2/3
SFR Definition 9.2. CPT0MD: Comparator0 Mode Selection
R
R
R/W
R/W
R
R
R/W
—
—
CP0RIE
CP0FIE
—
—
CP0MD1
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
R/W
Reset Value
CP0MD0 00000010
Bit0
SFR Address: 0x9D
Bits7–6: UNUSED. Read = 00b, Write = don’t care.
Bit5:
CP0RIE: Comparator0 Rising-Edge Interrupt Enable.
0:
Comparator0 Rising-edge interrupt disabled.
1:
Comparator0 Rising-edge interrupt enabled.
Bit4:
CP0FIE: Comparator0 Falling-Edge Interrupt Enable.
0:
Comparator0 Falling-edge interrupt disabled.
1:
Comparator0 Falling-edge interrupt enabled.
Bits3–2: UNUSED. Read = 00b, Write = don’t care.
Bits1–0: CP0MD1–CP0MD0: Comparator0 Mode Select
These bits select the response time for Comparator0.
82
Mode
0
1
2
CP0MD1
0
0
1
CP0MD0
0
1
0
3
1
1
Notes
Fastest Response Time
—
—
Lowest Power Consumption
Rev. 1.1
C8051F350/1/2/3
9.1.
Comparator0 Inputs and Outputs
Figure 9.3 shows the external pin connections for the comparator. The positive and negative inputs to the
comparator can each be routed to one of eight different pins using the comparator mux. Comparator outputs can optionally be routed to port pins using the Crossbar circuitry.
The comparator inputs (CP0+ and CP0–) are selected in the CPT0MX register (SFR Definition 9.3). The
CMX0P1–CMX0P0 bits select the comparator’s positive input; the CMX0N1–CMX0N0 bits select the comparator’s negative input. Important Note About Comparator Inputs: The Port pins selected as comparator inputs should be configured as analog inputs in their associated Port configuration register, and
configured to be skipped by the Crossbar.
Two versions of the comparator output can be routed to port pins, using the Port I/O Crossbar. The raw
(asynchronous) comparator output CP0A is enabled using bit 5 in the XBR0 register, and will be available
at P1.4. The CP0 output (synchronized to SYSCLK) is available at P1.5 when it is enabled with bit 4 in the
XBR0 register.
P0.0
P0.2
P0.4
P1.0
CP0AE
VDD
P1.2
CP0E
XBR0
P0.6
P1.4
P1.6
CP0 +
+
0
D
CP0 -
SET
Q
D
SET
P1.5
Q
1
-
CLR
Q
CLR
Q
CP0
P0.1
(SYNCHRONIZER)
P0.3
0
GND
P1.4
1
P0.5
CP0A
P0.7
CMX0P0
CMX0P1
CMX0P2
CMX0P3
CMX0N0
P1.7
CMX0N1
P1.5
CMX0N2
P1.3
CMX0N3
P1.1
CPT0MX
Figure 9.3. Comparator Pin Connections
Rev. 1.1
83
C8051F350/1/2/3
SFR Definition 9.3. CPT0MX: Comparator0 MUX Selection
R/W
R/W
R/W
R/W
R/W
CMX0N3 CMX0N2 CMX0N1 CMX0N0 CMX0P3
Bit7
Bit6
Bit5
Bit4
Bit3
R/W
R/W
R/W
Reset Value
CMX0P2
CMX0P1
CMX0P0
11111111
Bit2
Bit1
Bit0
SFR Address: 0x9F
Bits7–4: CMX0N3–CMX0N0: Comparator0 Negative Input MUX Select.
These bits select which Port pin is used as the Comparator0 negative input.
CMX0N3 CMX0N2 CMX0N1 CMX0N0
0
0
0
0
0
0
0
1
0
0
1
0
0
0
1
1
0
1
0
0
0
1
0
1
0
1
1
0
0
1
1
1
1
x
x
x
Negative Input
P0.1
P0.3
P0.5
P0.7
P1.1
P1.3
P1.5
P1.7
None
Bits3–0: CMX0P3–CMX0P0: Comparator0 Positive Input MUX Select.
These bits select which Port pin is used as the Comparator0 positive input.
CMX0P3 CMX0P2 CMX0P1 CMX0P0
0
0
0
0
0
0
0
1
0
0
1
0
0
0
1
1
0
1
0
0
0
1
0
1
0
1
1
0
0
1
1
1
1
x
x
x
84
Rev. 1.1
Positive Input
P0.0
P0.2
P0.4
P0.6
P1.0
P1.2
P1.4
P1.6
None
C8051F350/1/2/3
Table 9.1. Comparator Electrical Characteristics
VDD = 3.0 V, –40 to +85 °C unless otherwise noted.
Parameter
Response Time:
Mode 0, Vcm* = 1.5 V
Response Time:
Mode 1, Vcm* = 1.5 V
Response Time:
Mode 2, Vcm* = 1.5 V
Response Time:
Mode 3, Vcm* = 1.5 V
Conditions
Min
Typ
Max
Units
CP0+ – CP0– = 100 mV
—
100
—
ns
CP0+ – CP0– = –100 mV
—
250
—
ns
CP0+ – CP0– = 100 mV
—
175
—
ns
CP0+ – CP0– = –100 mV
—
500
—
ns
CP0+ – CP0– = 100 mV
—
320
—
ns
CP0+ – CP0– = –100 mV
—
1100
—
ns
CP0+ – CP0– = 100 mV
—
1050
—
ns
CP0+ – CP0– = –100 mV
—
5200
—
ns
—
1.5
4
mV/V
Common-Mode Rejection
Ratio
Positive Hysteresis 1
CP0HYP1-0 = 00
—
0
1
mV
Positive Hysteresis 2
CP0HYP1-0 = 01
2
5
10
mV
Positive Hysteresis 3
CP0HYP1-0 = 10
7
10
20
mV
Positive Hysteresis 4
CP0HYP1-0 = 11
15
20
30
mV
Negative Hysteresis 1
CP0HYN1-0 = 00
0
1
mV
Negative Hysteresis 2
CP0HYN1-0 = 01
2
5
10
mV
Negative Hysteresis 3
CP0HYN1-0 = 10
7
10
20
mV
Negative Hysteresis 4
CP0HYN1-0 = 11
15
20
30
mV
–0.25
—
VDD + 0.25
V
Input Capacitance
—
4
—
pF
Input Bias Current
—
0.001
—
nA
Input Offset Voltage
–5
—
+5
mV
Power Supply Rejection
—
0.1
—
mV/V
Power-up Time
—
10
—
µs
Mode 0
—
9.6
20.0
µA
Mode 1
—
3.8
10.0
µA
Mode 2
—
1.6
5.0
µA
Mode 3
—
0.3
2.0
µA
Inverting or Non-Inverting
Input Voltage Range
Power Supply
Supply Current at DC
*Note: Vcm is the common-mode voltage on CP0+ and CP0–.
Rev. 1.1
85
C8051F350/1/2/3
NOTES:
86
Rev. 1.1
C8051F350/1/2/3
10. CIP-51 Microcontroller
The MCU system controller core is the CIP-51 microcontroller. The CIP-51 is fully compatible with the
MCS-51™ instruction set. Standard 803x/805x assemblers and compilers can be used to develop software. The C8051F35x family has a superset of all the peripherals included with a standard 8051. See Section “1. System Overview’ on page 17 for more information about the available peripherals. The CIP-51
includes on-chip debug hardware which interfaces directly with the analog and digital subsystems, providing a complete data acquisition or control-system solution in a single integrated circuit.
The CIP-51 Microcontroller core implements the standard 8051 organization and peripherals as well as
additional custom peripherals and functions to extend its capability (see Figure 10.1 for a block diagram).
The CIP-51 core includes the following features:
- Fully Compatible with MCS-51 Instruction
Set
- 50 MIPS Peak Throughput
- 256 Bytes of Internal RAM
-
Extended Interrupt Handler
Reset Input
Power Management Modes
Integrated Debug Logic
D8
D8
ACCUMULATOR
STACK POINTER
TMP1
TMP2
SRAM
ADDRESS
REGISTER
PSW
SRAM
(256 X 8)
D8
D8
D8
ALU
D8
DATA BUS
B REGISTER
D8
D8
D8
DATA BUS
DATA BUS
SFR_ADDRESS
BUFFER
D8
DATA POINTER
D8
D8
SFR
BUS
INTERFACE
SFR_CONTROL
SFR_WRITE_DATA
SFR_READ_DATA
DATA BUS
PC INCREMENTER
PROGRAM COUNTER (PC)
PRGM. ADDRESS REG.
MEM_ADDRESS
D8
MEM_CONTROL
A16
MEMORY
INTERFACE
MEM_WRITE_DATA
MEM_READ_DATA
PIPELINE
RESET
D8
CONTROL
LOGIC
SYSTEM_IRQs
CLOCK
D8
STOP
IDLE
POWER CONTROL
REGISTER
INTERRUPT
INTERFACE
EMULATION_IRQ
D8
Figure 10.1. CIP-51 Block Diagram
Rev. 1.1
87
C8051F350/1/2/3
Performance
The CIP-51 employs a pipelined architecture that greatly increases its instruction throughput over the standard 8051 architecture. In a standard 8051, all instructions except for MUL and DIV take 12 or 24 system
clock cycles to execute, and usually have a maximum system clock of 12 MHz. By contrast, the CIP-51
core executes 70% of its instructions in one or two system clock cycles, with no instructions taking more
than eight system clock cycles.
With the CIP-51's system clock running at 50 MHz, it has a peak throughput of 50 MIPS. The CIP-51 has a
total of 109 instructions. The table below shows the total number of instructions that require each execution
time.
Clocks to Execute
1
2
2/3
3
3/4
4
4/5
5
8
Number of Instructions
26
50
5
14
7
3
1
2
1
Programming and Debugging Support
In-system programming of the Flash program memory and communication with on-chip debug support
logic is accomplished via the Cygnal 2-Wire (C2) interface. Note that the re-programmable Flash can also
be read and changed a single byte at a time by the application software using the MOVC and MOVX
instructions. This feature allows program memory to be used for non-volatile data storage as well as updating program code under software control.
The on-chip debug support logic facilitates full speed in-circuit debugging, allowing the setting of hardware
breakpoints, starting, stopping and single stepping through program execution (including interrupt service
routines), examination of the program's call stack, and reading/writing the contents of registers and memory. This method of on-chip debugging is completely non-intrusive, requiring no RAM, Stack, timers, or
other on-chip resources.
The CIP-51 is supported by development tools from Silicon Labs and third party vendors. Silicon Labs provides an integrated development environment (IDE) including editor, macro assembler, debugger and programmer. The IDE's debugger and programmer interface to the CIP-51 via the on-chip debug logic to
provide fast and efficient in-system device programming and debugging. Third party macro assemblers
and C compilers are also available.
88
Rev. 1.1
C8051F350/1/2/3
10.1. Instruction Set
The instruction set of the CIP-51 System Controller is fully compatible with the standard MCS-51™ instruction set. Standard 8051 development tools can be used to develop software for the CIP-51. All CIP-51
instructions are the binary and functional equivalent of their MCS-51™ counterparts, including opcodes,
addressing modes and effect on PSW flags. However, instruction timing is different than that of the standard 8051.
10.1.1. Instruction and CPU Timing
In many 8051 implementations, a distinction is made between machine cycles and clock cycles, with
machine cycles varying from 2 to 12 clock cycles in length. However, the CIP-51 implementation is based
solely on clock cycle timing. All instruction timings are specified in terms of clock cycles.
Due to the pipelined architecture of the CIP-51, most instructions execute in the same number of clock
cycles as there are program bytes in the instruction. Conditional branch instructions take one less clock
cycle to complete when the branch is not taken as opposed to when the branch is taken. Table 10.1 is the
CIP-51 Instruction Set Summary, which includes the mnemonic, number of bytes, and number of clock
cycles for each instruction.
10.1.2. MOVX Instruction and Program Memory
The MOVX instruction is typically used to access data stored in XDATA memory space. In the CIP-51, the
MOVX instruction can also be used to write or erase on-chip program memory space implemented as reprogrammable Flash memory. The Flash access feature provides a mechanism for the CIP-51 to update
program code and use the program memory space for non-volatile data storage. Refer to Section
“15. Flash Memory’ on page 121 for further details.
Table 10.1. CIP-51 Instruction Set Summary
Mnemonic
ADD A, Rn
ADD A, direct
ADD A, @Ri
ADD A, #data
ADDC A, Rn
ADDC A, direct
ADDC A, @Ri
ADDC A, #data
SUBB A, Rn
SUBB A, direct
SUBB A, @Ri
SUBB A, #data
INC A
INC Rn
INC direct
INC @Ri
DEC A
DEC Rn
Description
Arithmetic Operations
Add register to A
Add direct byte to A
Add indirect RAM to A
Add immediate to A
Add register to A with carry
Add direct byte to A with carry
Add indirect RAM to A with carry
Add immediate to A with carry
Subtract register from A with borrow
Subtract direct byte from A with borrow
Subtract indirect RAM from A with borrow
Subtract immediate from A with borrow
Increment A
Increment register
Increment direct byte
Increment indirect RAM
Decrement A
Decrement register
Rev. 1.1
Bytes
Clock
Cycles
1
2
1
2
1
2
1
2
1
2
1
2
1
1
2
1
1
1
1
2
2
2
1
2
2
2
1
2
2
2
1
1
2
2
1
1
89
C8051F350/1/2/3
Table 10.1. CIP-51 Instruction Set Summary (Continued)
Mnemonic
DEC direct
DEC @Ri
INC DPTR
MUL AB
DIV AB
DA A
ANL A, Rn
ANL A, direct
ANL A, @Ri
ANL A, #data
ANL direct, A
ANL direct, #data
ORL A, Rn
ORL A, direct
ORL A, @Ri
ORL A, #data
ORL direct, A
ORL direct, #data
XRL A, Rn
XRL A, direct
XRL A, @Ri
XRL A, #data
XRL direct, A
XRL direct, #data
CLR A
CPL A
RL A
RLC A
RR A
RRC A
SWAP A
MOV A, Rn
MOV A, direct
MOV A, @Ri
MOV A, #data
MOV Rn, A
MOV Rn, direct
MOV Rn, #data
MOV direct, A
MOV direct, Rn
MOV direct, direct
MOV direct, @Ri
MOV direct, #data
90
Description
Decrement direct byte
Decrement indirect RAM
Increment Data Pointer
Multiply A and B
Divide A by B
Decimal adjust A
Logical Operations
AND Register to A
AND direct byte to A
AND indirect RAM to A
AND immediate to A
AND A to direct byte
AND immediate to direct byte
OR Register to A
OR direct byte to A
OR indirect RAM to A
OR immediate to A
OR A to direct byte
OR immediate to direct byte
Exclusive-OR Register to A
Exclusive-OR direct byte to A
Exclusive-OR indirect RAM to A
Exclusive-OR immediate to A
Exclusive-OR A to direct byte
Exclusive-OR immediate to direct byte
Clear A
Complement A
Rotate A left
Rotate A left through Carry
Rotate A right
Rotate A right through Carry
Swap nibbles of A
Data Transfer
Move Register to A
Move direct byte to A
Move indirect RAM to A
Move immediate to A
Move A to Register
Move direct byte to Register
Move immediate to Register
Move A to direct byte
Move Register to direct byte
Move direct byte to direct byte
Move indirect RAM to direct byte
Move immediate to direct byte
Rev. 1.1
2
1
1
1
1
1
Clock
Cycles
2
2
1
4
8
1
1
2
1
2
2
3
1
2
1
2
2
3
1
2
1
2
2
3
1
1
1
1
1
1
1
1
2
2
2
2
3
1
2
2
2
2
3
1
2
2
2
2
3
1
1
1
1
1
1
1
1
2
1
2
1
2
2
2
2
3
2
3
1
2
2
2
1
2
2
2
2
3
2
3
Bytes
C8051F350/1/2/3
Table 10.1. CIP-51 Instruction Set Summary (Continued)
Mnemonic
MOV @Ri, A
MOV @Ri, direct
MOV @Ri, #data
MOV DPTR, #data16
MOVC A, @A+DPTR
MOVC A, @A+PC
MOVX A, @Ri
MOVX @Ri, A
MOVX A, @DPTR
MOVX @DPTR, A
PUSH direct
POP direct
XCH A, Rn
XCH A, direct
XCH A, @Ri
XCHD A, @Ri
CLR C
CLR bit
SETB C
SETB bit
CPL C
CPL bit
ANL C, bit
ANL C, /bit
ORL C, bit
ORL C, /bit
MOV C, bit
MOV bit, C
JC rel
JNC rel
JB bit, rel
JNB bit, rel
JBC bit, rel
ACALL addr11
LCALL addr16
RET
RETI
AJMP addr11
LJMP addr16
SJMP rel
JMP @A+DPTR
JZ rel
JNZ rel
Description
Move A to indirect RAM
Move direct byte to indirect RAM
Move immediate to indirect RAM
Load DPTR with 16-bit constant
Move code byte relative DPTR to A
Move code byte relative PC to A
Move external data (8-bit address) to A
Move A to external data (8-bit address)
Move external data (16-bit address) to A
Move A to external data (16-bit address)
Push direct byte onto stack
Pop direct byte from stack
Exchange Register with A
Exchange direct byte with A
Exchange indirect RAM with A
Exchange low nibble of indirect RAM with A
Boolean Manipulation
Clear Carry
Clear direct bit
Set Carry
Set direct bit
Complement Carry
Complement direct bit
AND direct bit to Carry
AND complement of direct bit to Carry
OR direct bit to carry
OR complement of direct bit to Carry
Move direct bit to Carry
Move Carry to direct bit
Jump if Carry is set
Jump if Carry is not set
Jump if direct bit is set
Jump if direct bit is not set
Jump if direct bit is set and clear bit
Program Branching
Absolute subroutine call
Long subroutine call
Return from subroutine
Return from interrupt
Absolute jump
Long jump
Short jump (relative address)
Jump indirect relative to DPTR
Jump if A equals zero
Jump if A does not equal zero
Rev. 1.1
1
2
2
3
1
1
1
1
1
1
2
2
1
2
1
1
Clock
Cycles
2
2
2
3
3
3
3
3
3
3
2
2
1
2
2
2
1
2
1
2
1
2
2
2
2
2
2
2
2
2
3
3
3
1
2
1
2
1
2
2
2
2
2
2
2
2/3
2/3
3/4
3/4
3/4
2
3
1
1
2
3
2
1
2
2
3
4
5
5
3
4
3
3
2/3
2/3
Bytes
91
C8051F350/1/2/3
Table 10.1. CIP-51 Instruction Set Summary (Continued)
Mnemonic
CJNE A, direct, rel
CJNE A, #data, rel
CJNE Rn, #data, rel
CJNE @Ri, #data, rel
DJNZ Rn, rel
DJNZ direct, rel
NOP
Description
Compare direct byte to A and jump if not equal
Compare immediate to A and jump if not equal
Compare immediate to Register and jump if not
equal
Compare immediate to indirect and jump if not
equal
Decrement Register and jump if not zero
Decrement direct byte and jump if not zero
No operation
3
3
Clock
Cycles
3/4
3/4
3
3/4
3
4/5
2
3
1
2/3
3/4
1
Bytes
Notes on Registers, Operands and Addressing Modes:
Rn - Register R0–R7 of the currently selected register bank.
@Ri - Data RAM location addressed indirectly through R0 or R1.
rel - 8-bit, signed (two’s complement) offset relative to the first byte of the following instruction. Used by
SJMP and all conditional jumps.
direct - 8-bit internal data location’s address. This could be a direct-access Data RAM location (0x00–
0x7F) or an SFR (0x80–0xFF).
#data - 8-bit constant
#data16 - 16-bit constant
bit - Direct-accessed bit in Data RAM or SFR
addr11 - 11-bit destination address used by ACALL and AJMP. The destination must be within the same
2 kB page of program memory as the first byte of the following instruction.
addr16 - 16-bit destination address used by LCALL and LJMP. The destination may be anywhere within
the 8 kB program memory space.
There is one unused opcode (0xA5) that performs the same function as NOP.
All mnemonics copyrighted © Intel Corporation 1980.
92
Rev. 1.1
C8051F350/1/2/3
10.2. Register Descriptions
Following are descriptions of SFRs related to the operation of the CIP-51 System Controller. Reserved bits
should not be set to logic l. Future product versions may use these bits to implement new features in which
case the reset value of the bit will be logic 0, selecting the feature's default state. Detailed descriptions of
the remaining SFRs are included in the sections of the datasheet associated with their corresponding system function.
SFR Definition 10.1. SP: Stack Pointer
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Reset Value
00000111
SFR Address: 0x81
Bits7–0: SP: Stack Pointer.
The Stack Pointer holds the location of the top of the stack. The stack pointer is incremented
before every PUSH operation. The SP register defaults to 0x07 after reset.
SFR Definition 10.2. DPL: Data Pointer Low Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0x82
Bits7–0: DPL: Data Pointer Low.
The DPL register is the low byte of the 16-bit DPTR. DPTR is used to access indirectly
addressed XRAM and Flash memory.
SFR Definition 10.3. DPH: Data Pointer High Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0x83
Bits7–0: DPH: Data Pointer High.
The DPH register is the high byte of the 16-bit DPTR. DPTR is used to access indirectly
addressed XRAM and Flash memory.
Rev. 1.1
93
C8051F350/1/2/3
SFR Definition 10.4. PSW: Program Status Word
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R
Reset Value
CY
AC
F0
RS1
RS0
OV
F1
PARITY
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Bit
Addressable
SFR Address: 0xD0
Bit7:
CY: Carry Flag.
This bit is set when the last arithmetic operation resulted in a carry (addition) or a borrow
(subtraction). It is cleared to 0 by all other arithmetic operations.
Bit6:
AC: Auxiliary Carry Flag
This bit is set when the last arithmetic operation resulted in a carry into (addition) or a borrow
from (subtraction) the high order nibble. It is cleared to 0 by all other arithmetic operations.
Bit5:
F0: User Flag 0.
This is a bit-addressable, general purpose flag for use under software control.
Bits4–3: RS1–RS0: Register Bank Select.
These bits select which register bank is used during register accesses.
RS1
0
0
1
1
Bit2:
Bit1:
Bit0:
94
RS0
0
1
0
1
Register Bank
0
1
2
3
Address
0x00 – 0x07
0x08 – 0x0F
0x10 – 0x17
0x18 – 0x1F
OV: Overflow Flag.
This bit is set to 1 under the following circumstances:
• An ADD, ADDC, or SUBB instruction causes a sign-change overflow.
• A MUL instruction results in an overflow (result is greater than 255).
• A DIV instruction causes a divide-by-zero condition.
The OV bit is cleared to 0 by the ADD, ADDC, SUBB, MUL, and DIV instructions in all other
cases.
F1: User Flag 1.
This is a bit-addressable, general purpose flag for use under software control.
PARITY: Parity Flag.
This bit is set to 1 if the sum of the eight bits in the accumulator is odd and cleared if the sum
is even.
Rev. 1.1
C8051F350/1/2/3
SFR Definition 10.5. ACC: Accumulator
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
ACC.7
ACC.6
ACC.5
ACC.4
ACC.3
ACC.2
ACC.1
ACC.0
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Bit
Addressable
SFR Address: 0xE0
Bits7–0: ACC: Accumulator.
This register is the accumulator for arithmetic operations.
SFR Definition 10.6. B: B Register
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
B.7
B.6
B.5
B.4
B.3
B.2
B.1
B.0
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Bit
Addressable
SFR Address: 0xF0
Bits7–0: B: B Register.
This register serves as a second accumulator for certain arithmetic operations.
Rev. 1.1
95
C8051F350/1/2/3
10.3. Power Management Modes
The CIP-51 core has two software programmable power management modes: Idle and Stop. Idle mode
halts the CPU while leaving the peripherals and internal clocks active. In Stop mode, the CPU is halted, all
interrupts and timers (except the Missing Clock Detector) are inactive, and the internal oscillator is stopped
(analog peripherals remain in their selected states; the external oscillator is not effected). Since clocks are
running in Idle mode, power consumption is dependent upon the system clock frequency and the number
of peripherals left in active mode before entering Idle. Stop mode consumes the least power. SFR Definition 10.7 describes the Power Control Register (PCON) used to control the CIP-51's power management
modes.
Although the CIP-51 has Idle and Stop modes built in (as with any standard 8051 architecture), power
management of the entire MCU is better accomplished by enabling/disabling individual peripherals as
needed. Each analog peripheral can be disabled when not in use and placed in low power mode. Digital
peripherals, such as timers or serial buses, draw little power when they are not in use. Turning off the oscillators lowers power consumption considerably; however a reset is required to restart the MCU.
10.3.1. Idle Mode
Setting the Idle Mode Select bit (PCON.0) causes the CIP-51 to halt the CPU and enter Idle mode as soon
as the instruction that sets the bit completes execution. All internal registers and memory maintain their
original data. All analog and digital peripherals can remain active during Idle mode.
Idle mode is terminated when an enabled interrupt is asserted or a reset occurs. The assertion of an
enabled interrupt will cause the Idle Mode Selection bit (PCON.0) to be cleared and the CPU to resume
operation. The pending interrupt will be serviced and the next instruction to be executed after the return
from interrupt (RETI) will be the instruction immediately following the one that set the Idle Mode Select bit.
If Idle mode is terminated by an internal or external reset, the CIP-51 performs a normal reset sequence
and begins program execution at address 0x0000.
If enabled, the Watchdog Timer (WDT) will eventually cause an internal watchdog reset and thereby terminate the Idle mode. This feature protects the system from an unintended permanent shutdown in the event
of an inadvertent write to the PCON register. If this behavior is not desired, the WDT may be disabled by
software prior to entering the Idle mode if the WDT was initially configured to allow this operation. This provides the opportunity for additional power savings, allowing the system to remain in the Idle mode indefinitely, waiting for an external stimulus to wake up the system.
10.3.2. Stop Mode
Setting the Stop Mode Select bit (PCON.1) causes the CIP-51 to enter Stop mode as soon as the instruction that sets the bit completes execution. In Stop mode the internal oscillator, CPU, and all digital peripherals are stopped; the state of the external oscillator circuit is not affected. Each analog peripheral (including
the external oscillator circuit) may be shut down individually prior to entering Stop Mode. Stop mode can
only be terminated by an internal or external reset. On reset, the CIP-51 performs the normal reset
sequence and begins program execution at address 0x0000.
If enabled, the Missing Clock Detector will cause an internal reset and thereby terminate the Stop mode.
The Missing Clock Detector should be disabled if the CPU is to be put to in STOP mode for longer than the
MCD timeout period of 100 μs.
96
Rev. 1.1
C8051F350/1/2/3
SFR Definition 10.7. PCON: Power Control
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
—
—
—
—
—
—
STOP
IDLE
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0x87
Bits7–3: Reserved.
Bit1:
STOP: STOP Mode Select.
Writing a ‘1’ to this bit will place the CIP-51 into STOP mode. This bit will always read ‘0’.
1: CIP-51 forced into power-down mode. (Turns off internal oscillator).
Bit0:
IDLE: IDLE Mode Select.
Writing a ‘1’ to this bit will place the CIP-51 into IDLE mode. This bit will always read ‘0’.
1: CIP-51 forced into IDLE mode. (Shuts off clock to CPU, but clock to Timers, Interrupts,
and all peripherals remain active.)
Rev. 1.1
97
C8051F350/1/2/3
NOTES:
98
Rev. 1.1
C8051F350/1/2/3
13. Prefetch Engine
The C8051F350/1/2/3 family of devices incorporate a 2-byte prefetch engine. Because the access time of
the Flash memory is 40 ns, and the minimum instruction time is 20 ns, the prefetch engine is necessary for
full-speed code execution. Instructions are read from Flash memory two bytes at a time by the prefetch
engine, and given to the CIP-51 processor core to execute. When running linear code (code without any
jumps or branches), the prefetch engine allows instructions to be executed at full speed. When a code
branch occurs, the processor may be stalled for up to two clock cycles while the next set of code bytes is
retrieved from Flash memory. The FLRT bit (FLSCL.4) determines how many clock cycles are used to read
each set of two code bytes from Flash. When operating from a system clock of 25 MHz or less, the FLRT
bit should be set to ‘0’ so that the prefetch engine takes only one clock cycle for each read. When operating with a system clock of greater than 25 MHz (up to 50 MHz), the FLRT bit should be set to ‘1’, so that
each prefetch code read lasts for two clock cycles.
SFR Definition 13.1. PFE0CN: Prefetch Engine Control
R
R
R/W
R
R
R
R
PFEN
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
R/W
Reset Value
FLBWE
00100000
Bit0
SFR Address: 0xE3
Bits 7–6: Unused. Read = 00b; Write = Don’t Care
Bit 5:
PFEN: Prefetch Enable.
This bit enables the prefetch engine.
0: Prefetch engine is disabled.
1: Prefetch engine is enabled.
Bits 4–1: Unused. Read = 0000b; Write = Don’t Care
Bit 0:
FLBWE: Flash Block Write Enable.
This bit allows block writes to Flash memory from software.
0: Each byte of a software Flash write is written individually.
1: Flash bytes are written in groups of two.
Rev. 1.1
113
C8051F350/1/2/3
NOTES:
114
Rev. 1.1
C8051F350/1/2/3
14. Reset Sources
Reset circuitry allows the controller to be easily placed in a predefined default condition. On entry to this
reset state, the following occur:
•
•
•
•
CIP-51 halts program execution
Special Function Registers (SFRs) are initialized to their defined reset values
External Port pins are forced to a known state
Interrupts and timers are disabled.
All SFRs are reset to the predefined values noted in the SFR detailed descriptions. The contents of internal
data memory are unaffected during a reset; any previously stored data is preserved. However, since the
stack pointer SFR is reset, the stack is effectively lost, even though the data on the stack is not altered.
The Port I/O latches are reset to 0xFF (all logic ones) in open-drain mode. Weak pull-ups are enabled
during and after the reset. For VDD Monitor and power-on resets, the /RST pin is driven low until the device
exits the reset state.
On exit from the reset state, the program counter (PC) is reset, and the system clock defaults to the internal oscillator. Refer to Section “17. Oscillators’ on page 129 for information on selecting and configuring
the system clock source. The Watchdog Timer is enabled with the system clock divided by 12 as its clock
source (Section “23.3. Watchdog Timer Mode’ on page 220 details the use of the Watchdog Timer). Program execution begins at location 0x0000.
VDD
Power On
Reset
Supply
Monitor
'0'
Enable
(wired-OR)
/RST
+
C0RSEF
Missing
Clock
Detector
(oneshot)
EN
Reset
Funnel
PCA
WDT
(Software Reset)
SWRSF
Errant
FLASH
Operation
EN
System
Clock
WDT
Enable
Px.x
+
-
Comparator 0
MCD
Enable
Px.x
CIP-51
Microcontroller
Core
System Reset
Extended Interrupt
Handler
Figure 14.1. Reset Sources
Rev. 1.1
115
C8051F350/1/2/3
14.1. Power-On Reset
During power-up, the device is held in a reset state and the /RST pin is driven low until VDD settles above
VRST. An additional delay occurs before the device is released from reset; the delay decreases as the VDD
ramp time increases (VDD ramp time is defined as how fast VDD ramps from 0 V to VRST). Figure 14.2.
plots the power-on and VDD monitor reset timing. For valid ramp times (less than 1 ms), the power-on reset
delay (TPORDelay) is typically less than 0.3 ms.
Note: The maximum VDD ramp time is 1 ms; slower ramp times may cause the device to be released from
reset before VDD reaches the VRST level.
volts
On exit from a power-on reset, the PORSF flag (RSTSRC.1) is set by hardware to logic 1. When PORSF is
set, all of the other reset flags in the RSTSRC Register are indeterminate (PORSF is cleared by all other
resets). Since all resets cause program execution to begin at the same location (0x0000) software can
read the PORSF flag to determine if a power-up was the cause of reset. The contents of internal data
memory should be assumed to be undefined after a power-on reset. The VDD monitor is enabled following
a power-on reset.
VDD
2.70
2.55
VRST
VD
D
2.0
1.0
t
Logic HIGH
Logic LOW
/RST
TPORDelay
VDD
Monitor
Reset
Power-On
Reset
Figure 14.2. Power-On and VDD Monitor Reset Timing
116
Rev. 1.1
C8051F350/1/2/3
14.2. Power-Fail Reset / VDD Monitor
When a power-down transition or power irregularity causes VDD to drop below VRST, the power supply
monitor will drive the /RST pin low and hold the CIP-51 in a reset state (see Figure 14.2). When VDD
returns to a level above VRST, the CIP-51 will be released from the reset state. Note that even though internal data memory contents are not altered by the power-fail reset, it is impossible to determine if VDD
dropped below the level required for data retention. If the PORSF flag reads ‘1’, the data may no longer be
valid. The VDD monitor is enabled and selected as a reset source after power-on resets; however its
defined state (enabled/disabled) is not altered by any other reset source. For example, if the VDD monitor
is disabled by software, and a software reset is performed, the VDD monitor will still be disabled after the
reset. To protect the integrity of Flash contents, it is strongly recommended that the VDD monitor
remain enabled and selected as a reset source if software contains routines which erase or write
Flash memory.
The VDD monitor must be enabled before it is selected as a reset source. Selecting the VDD monitor as a
reset source before it is enabled and stabilized may cause a system reset. The procedure for re-enabling
the VDD monitor and configuring the VDD monitor as a reset source is shown below:
Step 1. Enable the VDD monitor (VDMEN bit in VDM0CN = ‘1’).
Step 2. Wait for the VDD monitor to stabilize (see Table 14.1 for the VDD Monitor turn-on time).
Note: This delay should be omitted if software contains routines which erase or
write Flash memory.
Step 3. Select the VDD monitor as a reset source (PORSF bit in RSTSRC = ‘1’).
See Figure 14.2 for VDD monitor timing; note that the reset delay is not incurred after a VDD monitor reset.
See Table 14.1 for complete electrical characteristics of the VDD monitor.
SFR Definition 14.1. VDM0CN: VDD Monitor Control
R/W
VDMEN
Bit7
R
R
R
R
R
R
R
VDDSTAT Reserved Reserved Reserved Reserved Reserved Reserved
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Reset Value
Variable
Bit0
SFR Address: 0xFF
Bit7:
VDMEN: VDD Monitor Enable.
This bit is turns the VDD monitor circuit on/off. The VDD Monitor cannot generate system
resets until it is also selected as a reset source in register RSTSRC (SFR Definition 14.2).
The VDD Monitor must be allowed to stabilize before it is selected as a reset source. Selecting the VDD monitor as a reset source before it has stabilized may generate a system
reset. See Table 14.1 for the minimum VDD Monitor turn-on time.
0: VDD Monitor Disabled.
1: VDD Monitor Enabled (default).
Bit6:
VDD STAT: VDD Status.
This bit indicates the current power supply status (VDD Monitor output).
0: VDD is at or below the VDD monitor threshold.
1: VDD is above the VDD monitor threshold.
Bits5–0: Reserved. Read = Variable. Write = don’t care.
Rev. 1.1
117
C8051F350/1/2/3
14.3. External Reset
The external /RST pin provides a means for external circuitry to force the device into a reset state. Asserting an active-low signal on the /RST pin generates a reset; an external pull-up and/or decoupling of the
/RST pin may be necessary to avoid erroneous noise-induced resets. See Table 14.1 for complete /RST
pin specifications. The PINRSF flag (RSTSRC.0) is set on exit from an external reset.
14.4. Missing Clock Detector Reset
The Missing Clock Detector (MCD) is a one-shot circuit that is triggered by the system clock. If the system
clock remains high or low for more than 100 µs, the one-shot will time out and generate a reset. After a
MCD reset, the MCDRSF flag (RSTSRC.2) will read ‘1’, signifying the MCD as the reset source; otherwise,
this bit reads ‘0’. Writing a ‘1’ to the MCDRSF bit enables the Missing Clock Detector; writing a ‘0’ disables
it. The state of the /RST pin is unaffected by this reset.
14.5. Comparator0 Reset
Comparator0 can be configured as a reset source by writing a ‘1’ to the C0RSEF flag (RSTSRC.5).
Comparator0 should be enabled and allowed to settle prior to writing to C0RSEF to prevent any turn-on
chatter on the output from generating an unwanted reset. The Comparator0 reset is active-low: if the noninverting input voltage (on CP0+) is less than the inverting input voltage (on CP0–), the device is put into
the reset state. After a Comparator0 reset, the C0RSEF flag (RSTSRC.5) will read ‘1’ signifying
Comparator0 as the reset source; otherwise, this bit reads ‘0’. The state of the /RST pin is unaffected by
this reset.
14.6. PCA Watchdog Timer Reset
The programmable Watchdog Timer (WDT) function of the Programmable Counter Array (PCA) can be
used to prevent software from running out of control during a system malfunction. The PCA WDT function
can be enabled or disabled by software as described in Section “23.3. Watchdog Timer Mode’ on
page 220; the WDT is enabled and clocked by SYSCLK / 12 following any reset. If a system malfunction
prevents user software from updating the WDT, a reset is generated and the WDTRSF bit (RSTSRC.5) is
set to ‘1’. The state of the /RST pin is unaffected by this reset.
14.7. Flash Error Reset
If a Flash read/write/erase or program read targets an illegal address, a system reset is generated. This
may occur due to any of the following:
•
•
•
•
A Flash write or erase is attempted above user code space. This occurs when PSWE is set to ‘1’ and a
MOVX write operation targets an address above address 0x1DFF.
A Flash read is attempted above user code space. This occurs when a MOVC operation targets an
address above address 0x1DFF.
A Program read is attempted above user code space. This occurs when user code attempts to branch
to an address above 0x1DFF.
A Flash read, write or erase attempt is restricted due to a Flash security setting (see Section
“15.3. Security Options’ on page 123).
The FERROR bit (RSTSRC.6) is set following a Flash error reset. The state of the /RST pin is unaffected
by this reset.
14.8. Software Reset
Software may force a reset by writing a ‘1’ to the SWRSF bit (RSTSRC.4). The SWRSF bit will read ‘1’ following a software forced reset. The state of the /RST pin is unaffected by this reset.
118
Rev. 1.1
C8051F350/1/2/3
SFR Definition 14.2. RSTSRC: Reset Source
R
—
Bit7
R
R/W
FERROR C0RSEF
Bit6
Bit5
R/W
SWRSF
Bit4
R
R/W
WDTRSF MCDRSF
Bit3
Bit2
R/W
R
Reset Value
PORSF
PINRSF
Variable
Bit1
Bit0
SFR Address: 0xEF
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
UNUSED. Read = 0. Write = don’t care.
FERROR: Flash Error Indicator.
0: Source of last reset was not a Flash read/write/erase error.
1: Source of last reset was a Flash read/write/erase error.
C0RSEF: Comparator0 Reset Enable and Flag.
0: Read: Source of last reset was not Comparator0. Write: Comparator0 is not a reset
source.
1: Read: Source of last reset was Comparator0. Write: Comparator0 is a reset source
(active-low).
SWRSF: Software Reset Force and Flag.
0: Read: Source of last reset was not a write to the SWRSF bit. Write: No Effect.
1: Read: Source of last was a write to the SWRSF bit. Write: Forces a system reset.
WDTRSF: Watchdog Timer Reset Flag.
0: Source of last reset was not a WDT timeout.
1: Source of last reset was a WDT timeout.
MCDRSF: Missing Clock Detector Flag.
0: Read: Source of last reset was not a Missing Clock Detector timeout. Write: Missing
Clock Detector disabled.
1: Read: Source of last reset was a Missing Clock Detector timeout. Write: Missing Clock
Detector enabled; triggers a reset if a missing clock condition is detected.
PORSF: Power-On Reset Force and Flag.
This bit is set anytime a power-on reset occurs. Writing this bit enables/disables the VDD
monitor as a reset source. Note: writing ‘1’ to this bit before the VDD monitor is enabled
and stabilized may cause a system reset. See register VDM0CN (SFR Definition 14.1)
0: Read: Last reset was not a power-on or VDD monitor reset. Write: VDD monitor is not a
reset source.
1: Read: Last reset was a power-on or VDD monitor reset; all other reset flags indeterminate.
Write: VDD monitor is a reset source.
PINRSF: HW Pin Reset Flag.
0: Source of last reset was not /RST pin.
1: Source of last reset was /RST pin.
Rev. 1.1
119
C8051F350/1/2/3
Table 14.1. Reset Electrical Characteristics
–40 to +85 °C unless otherwise specified.
Parameter
Conditions
Min
Typ
Max
Units
IOL = 8.5 mA, VDD = 2.7 to 3.6 V
—
—
0.6
V
/RST Input High Voltage
0.7 x VDD
—
—
V
/RST Input Low Voltage
—
—
0.3 x VDD
—
25
40
µA
2.40
2.55
2.70
V
Time from last system clock rising
edge to reset initiation
100
220
600
µs
Delay between release of any reset
source and code execution at location 0x0000
5.0
—
—
µs
Minimum /RST Low Time to
Generate a System Reset
15
—
—
µs
VDD Monitor Turn-on Time
100
—
—
µs
—
20
50
µA
—
—
1
ms
/RST Output Low Voltage
/RST Input Pullup Current
/RST = 0.0 V
VDD Monitor Threshold (VRST)
Missing Clock Detector Timeout
Reset Time Delay
VDD Monitor Supply Current
VDD Ramp Time
120
VDD = 0 V to VRST
Rev. 1.1
C8051F350/1/2/3
15. Flash Memory
On-chip, re-programmable Flash memory is included for program code and non-volatile data storage. The
Flash memory can be programmed in-system through the C2 interface or by software using the MOVX
instruction. Once cleared to logic 0, a Flash bit must be erased to set it back to logic 1. Flash bytes would
typically be erased (set to 0xFF) before being reprogrammed. The write and erase operations are automatically timed by hardware for proper execution; data polling to determine the end of the write/erase operation is not required. Code execution is stalled during a Flash write/erase operation. Refer to Table 15.1 for
complete Flash memory electrical characteristics.
15.1. Programming The Flash Memory
The simplest means of programming the Flash memory is through the C2 interface using programming
tools provided by Silicon Labs or a third party vendor. This is the only means for programming a non-initialized device. For details on the C2 commands to program Flash memory, see Section “25. C2 Interface’ on
page 229.
To ensure the integrity of Flash contents, it is strongly recommended that the on-chip VDD Monitor
be enabled in any system that includes code that writes and/or erases Flash memory from software.
15.1.1. Flash Lock and Key Functions
Flash writes and erases by user software are protected with a lock and key function. The Flash Lock and
Key Register (FLKEY) must be written with the correct key codes, in sequence, before Flash operations
may be performed. The key codes are: 0xA5, 0xF1. The timing does not matter, but the codes must be
written in order. If the key codes are written out of order, or the wrong codes are written, Flash writes and
erases will be disabled until the next system reset. Flash writes and erases will also be disabled if a Flash
write or erase is attempted before the key codes have been written properly. The Flash lock resets after
each write or erase; the key codes must be written again before a following Flash operation can be performed. The FLKEY register is detailed in SFR Definition 15.2.
15.1.2. Flash Erase Procedure
The Flash memory can be programmed by software using the MOVX write instruction with the address and
data byte to be programmed provided as normal operands. Before writing to Flash memory using MOVX,
Flash write operations must be enabled by: (1) setting the PSWE Program Store Write Enable bit
(PSCTL.0) to logic 1 (this directs the MOVX writes to target Flash memory); and (2) Writing the Flash key
codes in sequence to the Flash Lock register (FLKEY). The PSWE bit remains set until cleared by software.
A write to Flash memory can clear bits to logic 0 but cannot set them; only an erase operation can set bits
to logic 1 in Flash. A byte location to be programmed should be erased before a new value is written.
The Flash memory is organized in 512-byte pages. The erase operation applies to an entire page (setting
all bytes in the page to 0xFF). To erase an entire 512-byte page, perform the following steps:
Step 1.
Step 2.
Step 3.
Step 4.
Step 5.
Step 6.
Disable interrupts (recommended).
Set thePSEE bit (register PSCTL).
Set the PSWE bit (register PSCTL).
Write the first key code to FLKEY: 0xA5.
Write the second key code to FLKEY: 0xF1.
Using the MOVX instruction, write a data byte to any location within the 512-byte page to
be erased.
Step 7. Clear the PSWE and PSEE bits.
Step 8. Re-enable interrupts.
Rev. 1.1
121
C8051F350/1/2/3
15.1.3. Flash Write Procedure
Bytes in Flash memory can be written one byte at a time, or in groups of two. The FLBWE bit in register
PFE0CN (SFR Definition 13.1) controls whether a single byte or a block of two bytes is written to Flash
during a write operation. When FLBWE is cleared to ‘0’, the Flash will be written one byte at a time. When
FLBWE is set to ‘1’, the Flash will be written in two-byte blocks. Block writes are performed in the same
amount of time as single-byte writes, which can save time when storing large amounts of data to Flash
memory.
During a single-byte write to Flash, bytes are written individually, and a Flash write will be performed after
each MOVX write instruction. The recommended procedure for writing Flash in single bytes is:
Step 1.
Step 2.
Step 3.
Step 4.
Step 5.
Step 6.
Step 7.
Disable interrupts.
Clear the FLBWE bit (register PFE0CN) to select single-byte write mode.
Set the PSWE bit (register PSCTL).
Clear the PSEE bit (register PSCTL).
Write the first key code to FLKEY: 0xA5.
Write the second key code to FLKEY: 0xF1.
Using the MOVX instruction, write a single data byte to the desired location within the 512byte sector.
Step 8. Clear the PSWE bit.
Step 9. Re-enable interrupts.
Steps 5–7 must be repeated for each byte to be written.
For block Flash writes, the Flash write procedure is only performed after the last byte of each block is written with the MOVX write instruction. A Flash write block is two bytes long, from even addresses to odd
addresses. Writes must be performed sequentially (i.e. addresses ending in 0b and 1b must be written in
order). The Flash write will be performed following the MOVX write that targets the address ending in 1b. If
a byte in the block does not need to be updated in Flash, it should be written to 0xFF. The recommended
procedure for writing Flash in blocks is:
Step 1.
Step 2.
Step 3.
Step 4.
Step 5.
Step 6.
Step 7.
Disable interrupts.
Set the FLBWE bit (resgister PFE0CN) to select block write mode.
Set the PSWE bit (register PSCTL).
Clear the PSEE bit (register PSCTL).
Write the first key code to FLKEY: 0xA5.
Write the second key code to FLKEY: 0xF1.
Using the MOVX instruction, write the first data byte to the even block location (ending in
0b).
Step 8. Write the first key code to FLKEY: 0xA5.
Step 9. Write the second key code to FLKEY: 0xF1.
Step 10. Using the MOVX instruction, write the second data byte to the odd block location (ending
in 1b).
Step 11. Clear the PSWE bit.
Step 12. Re-enable interrupts.
Steps 5–10 must be repeated for each block to be written.
122
Rev. 1.1
C8051F350/1/2/3
15.2. Non-volatile Data Storage
The Flash memory can be used for non-volatile data storage as well as program code. This allows data
such as calibration coefficients to be calculated and stored at run time. Data is written using the MOVX
write instruction and read using the MOVC instruction. Note: MOVX read instructions always target XRAM.
15.3. Security Options
The CIP-51 provides security options to protect the Flash memory from inadvertent modification by software as well as to prevent the viewing of proprietary program code and constants. The Program Store
Write Enable (bit PSWE in register PSCTL) and the Program Store Erase Enable (bit PSEE in register
PSCTL) bits protect the Flash memory from accidental modification by software. PSWE must be explicitly
set to ‘1’ before software can modify the Flash memory; both PSWE and PSEE must be set to ‘1’ before
software can erase Flash memory. Additional security features prevent proprietary program code and data
constants from being read or altered across the C2 interface.
A Security Lock Byte located at the last byte of Flash user space offers protection of the Flash program
memory from access (reads, writes, or erases) by unprotected code or the C2 interface. The Flash security
mechanism allows the user to lock n 512-byte Flash pages, starting at page 0 (addresses 0x0000 to
0x01FF), where n is the 1’s complement number represented by the Security Lock Byte. Note that the
page containing the Flash Security Lock Byte is locked when any other Flash pages are locked. See example below.
Security Lock Byte:
1’s Complement:
Flash pages locked:
Addresses locked:
11111101b
00000010b
3 (First two Flash pages + Lock Byte Page)
0x0000 to 0x03FF (first two Flash pages) and
0x1C00 to 0x1DFF (Lock Byte Page)
Reserved
0x1E00
Locked when any
other Flash pages are
locked
Lock Byte
0x1DFF
0x1DFE
0x1C00
Flash memory organized
in 512-byte pages
Unlocked Flash Pages
Access limit set
according to the Flash
security lock byte
0x0000
Figure 15.1. Flash Memory Map
Rev. 1.1
123
C8051F350/1/2/3
The level of Flash security depends on the Flash access method. The three Flash access methods that
can be restricted are reads, writes, and erases from the C2 debug interface, user firmware executing on
unlocked pages, and user firmware executing on locked pages.
Accessing Flash from the C2 debug interface:
1.
2.
3.
4.
5.
6.
Any unlocked page may be read, written, or erased.
Locked pages cannot be read, written, or erased.
The page containing the Lock Byte may be read, written, or erased if it is unlocked.
Reading the contents of the Lock Byte is always permitted only if no pages are locked.
Locking additional pages (changing ‘1’s to ‘0’s in the Lock Byte) is not permitted.
Unlocking Flash pages (changing ‘0’s to ‘1’s in the Lock Byte) requires the C2 Device Erase
command, which erases all Flash pages including the page containing the Lock Byte and the
Lock Byte itself.
7. The Reserved Area cannot be read, written, or erased.
Accessing Flash from user firmware executing from an unlocked page:
1. Any unlocked page except the page containing the Lock Byte may be read, written, or erased.
2. Locked pages cannot be read, written, or erased. An erase attempt on the page containing the
Lock Byte will result in a Flash Error device reset.
3. The page containing the Lock Byte cannot be erased. It may be read or written only if it is
unlocked. An erase attempt on the page containing the Lock Byte will result in a Flash Error
device reset.
4. Reading the contents of the Lock Byte is always permitted.
5. Locking additional pages (changing ‘1’s to ‘0’s in the Lock Byte) is not permitted.
6. Unlocking Flash pages (changing ‘0’s to ‘1’s in the Lock Byte) is not permitted.
7. The Reserved Area cannot be read, written, or erased. Any attempt to access the reserved
area, or any other locked page, will result in a Flash Error device reset.
Accessing Flash from user firmware executing from a locked page:
1. Any unlocked page except the page containing the Lock Byte may be read, written, or erased.
2. Any locked page except the page containing the Lock Byte may be read, written, or erased. An
erase attempt on the page containing the Lock Byte will result in a Flash Error device reset.
3. The page containing the Lock Byte cannot be erased. It may only be read or written. An erase
attempt on the page containing the Lock Byte will result in a Flash Error device reset.
4. Reading the contents of the Lock Byte is always permitted.
5. Locking additional pages (changing ‘1’s to ‘0’s in the Lock Byte) is not permitted.
6. Unlocking Flash pages (changing ‘0’s to ‘1’s in the Lock Byte) is not permitted.
7. The Reserved Area cannot be read, written, or erased. Any attempt to access the reserved
area, or any other locked page, will result in a Flash Error device reset.
124
Rev. 1.1
C8051F350/1/2/3
SFR Definition 15.1. PSCTL: Program Store R/W Control
R
R
R
R
R
R
R/W
R/W
Reset Value
—
—
—
—
—
—
PSEE
PSWE
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0x8F
Bits7–2: UNUSED: Read = 000000b, Write = don’t care.
Bit1:
PSEE: Program Store Erase Enable
Setting this bit (in combination with PSWE) allows an entire page of Flash program memory
to be erased. If this bit is logic 1 and Flash writes are enabled (PSWE is logic 1), a write to
Flash memory using the MOVX instruction will erase the entire page that contains the location addressed by the MOVX instruction. The value of the data byte written does not matter.
0: Flash program memory erasure disabled.
1: Flash program memory erasure enabled.
Bit0:
PSWE: Program Store Write Enable
Setting this bit allows writing a byte of data to the Flash program memory using the MOVX
write instruction. The Flash location should be erased before writing data.
0: Writes to Flash program memory disabled.
1: Writes to Flash program memory enabled; the MOVX write instruction targets Flash
memory.
SFR Definition 15.2. FLKEY: Flash Lock and Key
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Reset Value
00000000
SFR Address: 0xB7
Bits7–0: FLKEY: Flash Lock and Key Register
Write:
This register provides a lock and key function for Flash erasures and writes. Flash writes
and erases are enabled by writing 0xA5 followed by 0xF1 to the FLKEY register. Flash
writes and erases are automatically disabled after the next write or erase is complete. If any
writes to FLKEY are performed incorrectly, or if a Flash write or erase operation is attempted
while these operations are disabled, the Flash will be permanently locked from writes or erasures until the next device reset. If an application never writes to Flash, it can intentionally
lock the Flash by writing a non-0xA5 value to FLKEY from software.
Read:
When read, bits 1–0 indicate the current Flash lock state.
00: Flash is write/erase locked.
01: The first key code has been written (0xA5).
10: Flash is unlocked (writes/erases allowed).
11: Flash writes/erases disabled until the next reset.
Rev. 1.1
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C8051F350/1/2/3
SFR Definition 15.3. FLSCL: Flash Scale
R/W
R/W
R/W
R/W
Reserved Reserved Reserved
Bit7
Bit6
Bit5
FLRT
R/W
R/W
R/W
R/W
Reset Value
Reserved Reserved Reserved Reserved 00000000
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xB6
Bits7–5: RESERVED. Read = 000b. Must Write 000b.
Bit 4:
FLRT: Flash Read Time.
This bit should be programmed to the smallest allowed value, according to the system clock
speed.
0: SYSCLK < 25 MHz.
1: SYSCLK < 50 MHz.
Bits3–0: RESERVED. Read = 0000b. Must Write 0000b.
Table 15.1. Flash Electrical Characteristics
VDD = 2.7 to 3.6 V; –40 to +85 ºC unless otherwise specified.
Parameter
Flash Size
Conditions
Min
Typ
Max
Units
C8051F350/1/2/3
8192*
—
—
bytes
20 k
100 k
—
Erase/Write
Endurance
Erase Cycle Time
50 MHz System Clock
10
15
20
ms
Write Cycle Time
50 MHz System Clock
40
55
70
µs
*Note: 512 bytes at addresses 0x1E00 to 0x1FFF are reserved.
126
Rev. 1.1
C8051F350/1/2/3
16. External RAM
The C8051F350/1/2/3 devices include 512 bytes of RAM mapped into the external data memory space. All
of these address locations may be accessed using the external move instruction (MOVX) and the data
pointer (DPTR), or using MOVX indirect addressing mode. If the MOVX instruction is used with an 8-bit
address operand (such as @R1), then the high byte of the 16-bit address is provided by the External Memory Interface Control Register (EMI0CN as shown in SFR Definition 16.1). Note: the MOVX instruction is
also used for writes to the Flash memory. See Section “15. Flash Memory’ on page 121 for details. The
MOVX instruction accesses XRAM by default.
For a 16-bit MOVX operation (@DPTR), the upper 7-bits of the 16-bit external data memory address word
are "don't cares". As a result, the 512-byte RAM is mapped modulo style over the entire 64 k external data
memory address range. For example, the XRAM byte at address 0x0000 is shadowed at addresses
0x0200, 0x0400, 0x0600, 0x0800, etc. This is a useful feature when performing a linear memory fill, as the
address pointer doesn't have to be reset when reaching the RAM block boundary.
SFR Definition 16.1. EMI0CN: External Memory Interface Control
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
—
—
—
—
—
—
—
PGSEL
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xAA
Bits 7–1: UNUSED. Read = 0000000b. Write = don’t care.
Bit 0:
PGSEL: XRAM Page Select.
The EMI0CN register provides the high byte of the 16-bit external data memory address
when using an 8-bit MOVX command, effectively selecting a 256-byte page of RAM. Since
the upper (unused) bits of the register are always zero, the PGSEL determines which page
of XRAM is accessed.
For Example: If EMI0CN = 0x01, addresses 0x0100 through 0x01FF will be accessed.
Rev. 1.1
127
C8051F350/1/2/3
NOTES:
128
Rev. 1.1
C8051F350/1/2/3
11. Memory Organization and SFRs
The memory organization of the C8051F350/1/2/3 is similar to that of a standard 8051. There are two separate memory spaces: program memory and data memory. Program and data memory share the same
address space but are accessed via different instruction types. The memory map is shown in Figure 11.1.
DATA MEMORY (RAM)
INTERNAL DATA ADDRESS SPACE
PROGRAM/DATA MEMORY
(Flash)
0x1FFF
0x1E00
0xFF
RESERVED
0x1DFF
0x80
0x7F
Upper 128 RAM
(Indirect Addressing
Only)
(Direct and Indirect
Addressing)
8 kB Flash
(In-System
Programmable in 512
Byte Sectors)
0x30
0x2F
0x20
0x1F
0x00
Bit Addressable
Special Function
Register's
(Direct Addressing Only)
Lower 128 RAM
(Direct and Indirect
Addressing)
General Purpose
Registers
EXTERNAL DATA ADDRESS SPACE
0x0000
0xFFFF
Same 512 bytes as from
0x0000 to 0x01FF, wrapped
on 512-byte boundaries
0x0200
0x01FF
0x0000
XRAM - 512 Bytes
(accessable using MOVX
instruction)
Figure 11.1. Memory Map
11.1. Program Memory
The CIP-51 core has a 64 kB program memory space. The C8051F350/1/2/3 implements 8 kB of this program memory space as in-system, re-programmable Flash memory, organized in a contiguous block from
addresses 0x0000 to 0x1DFF. Addresses above 0x1DFF are reserved.
Program memory is normally assumed to be read-only. However, the C8051F350/1/2/3 can write to program memory by setting the Program Store Write Enable bit (PSCTL.0) and using the MOVX write instruction. This feature provides a mechanism for updates to program code and use of the program memory
space for non-volatile data storage. Refer to Section “15. Flash Memory’ on page 121 for further details.
Rev. 1.1
99
C8051F350/1/2/3
11.2. Data Memory
The C8051F350/1/2/3 includes 256 bytes of internal RAM mapped into the data memory space from 0x00
through 0xFF. The lower 128 bytes of data memory are used for general purpose registers and scratch pad
memory. Either direct or indirect addressing may be used to access the lower 128 bytes of data memory.
Locations 0x00 through 0x1F are addressable as four banks of general purpose registers, each bank consisting of eight byte-wide registers. The next 16 bytes, locations 0x20 through 0x2F, may either be
addressed as bytes or as 128 bit locations accessible with the direct addressing mode.
The upper 128 bytes of data memory are accessible only by indirect addressing. This region occupies the
same address space as the Special Function Registers (SFRs) but is physically separate from the SFR space.
The addressing mode used by an instruction when accessing locations above 0x7F determines whether the
CPU accesses the upper 128 bytes of data memory space or the SFRs. Instructions that use direct addressing will access the SFR space. Instructions using indirect addressing above 0x7F access the upper 128 bytes
of data memory. Figure 11.1 illustrates the data memory organization of the C8051F350/1/2/3.
The C8051F35x family also includes 512 bytes of on-chip RAM mapped into the external memory (XDATA)
space. This RAM can be accessed using the CIP-51 core’s MOVX instruction. More information on the
XRAM memory can be found in Section “16. External RAM’ on page 127.
11.3. General Purpose Registers
The lower 32 bytes of data memory (locations 0x00 through 0x1F) may be addressed as four banks of
general-purpose registers. Each bank consists of eight byte-wide registers designated R0 through R7.
Only one of these banks may be enabled at a time. Two bits in the program status word, RS0 (PSW.3) and
RS1 (PSW.4), select the active register bank (see description of the PSW in SFR Definition 10.4). This
allows fast context switching when entering subroutines and interrupt service routines. Indirect addressing
modes use registers R0 and R1 as index registers.
11.4. Bit Addressable Locations
In addition to direct access to data memory organized as bytes, the sixteen data memory locations at 0x20
through 0x2F are also accessible as 128 individually addressable bits. Each bit has a bit address from
0x00 to 0x7F. Bit 0 of the byte at 0x20 has bit address 0x00 while bit 7 of the byte at 0x20 has bit address
0x07. Bit 7 of the byte at 0x2F has bit address 0x7F. A bit access is distinguished from a full byte access by
the type of instruction used (bit source or destination operands as opposed to a byte source or destination).
The MCS-51™ assembly language allows an alternate notation for bit addressing of the form XX.B where
XX is the byte address and B is the bit position within the byte. For example, the instruction:
MOV
C, 22.3h
moves the Boolean value at 0x13 (bit 3 of the byte at location 0x22) into the Carry flag.
11.5. Stack
A programmer's stack can be located anywhere in the 256-byte data memory. The stack area is designated using the Stack Pointer (SP, 0x81) SFR. The SP will point to the last location used. The next value
pushed on the stack is placed at SP+1 and then SP is incremented. A reset initializes the stack pointer to
location 0x07. Therefore, the first value pushed on the stack is placed at location 0x08, which is also the
first register (R0) of register bank 1. Thus, if more than one register bank is to be used, the SP should be
initialized to a location in the data memory not being used for data storage. The stack depth can extend up
to 256 bytes.
100
Rev. 1.1
C8051F350/1/2/3
11.6. Special Function Registers
The direct-access data memory locations from 0x80 to 0xFF constitute the special function registers
(SFRs). The SFRs provide control and data exchange with the CIP-51's resources and peripherals. The
CIP-51 duplicates the SFRs found in a typical 8051 implementation as well as implementing additional
SFRs used to configure and access the sub-systems unique to the MCU. This allows the addition of new
functionality while retaining compatibility with the MCS-51™ instruction set. Table 11.1 lists the SFRs
implemented in the CIP-51 System Controller.
The SFR registers are accessed anytime the direct addressing mode is used to access memory locations
from 0x80 to 0xFF. SFRs with addresses ending in 0x0 or 0x8 (e.g. P0, TCON, IE, etc.) are bit-addressable
as well as byte-addressable. All other SFRs are byte-addressable only. Unoccupied addresses in the SFR
space are reserved for future use. Accessing these areas will have an indeterminate effect and should be
avoided. Refer to the corresponding pages of the datasheet, as indicated in Table 11.2, for a detailed
description of each register.
Table 11.1. Special Function Register (SFR) Memory Map
F8 SPI0CN
PCA0L
PCA0H
ADC0CF
ADC0FL
ADC0FM
ADC0FH
B
P0MDIN
P1MDIN
ADC0MD ADC0CN
EIP1
F0
E8 ADC0STA PCA0CPL0 PCA0CPH0 PCA0CPL1 PCA0CPH1 PCA0CPL2 PCA0CPH2
ACC
XBR0
XBR1
PFE0CN
IT01CF
EIE1
E0
PCA0MD PCA0CPM0 PCA0CPM1 PCA0CPM2
IDA1
D8 PCA0CN
PSW
REF0CN
P0SKIP
P1SKIP
D0
TMR2RLL TMR2RLH
TMR2L
TMR2H
C8 TMR2CN
SMB0CF SMB0DAT
ADC0L
ADC0M
ADC0H
ADC0MUX
C0 SMB0CN
IP
IDA0CN ADC0COL ADC0COM ADC0COH ADC0BUF
CKMUL
B8
OSCXCN
OSCICN
OSCICL
FLSCL
B0
IE
CLKSEL
EMI0CN ADC0CGL ADC0CGM ADC0CGH
A8
P2
SPI0CFG SPI0CKR SPI0DAT P0MDOUT P1MDOUT P2MDOUT
A0
ADC0DEC
98 SCON0
SBUF0 ADC0DECL
CPT0CN
CPT0MD
H
P1
TMR3CN TMR3RLL TMR3RLH
TMR3L
TMR3H
IDA0
90
TCON
TMOD
TL0
TL1
TH0
TH1
CKCON
88
P0
SP
DPL
DPH
80
0(8)
1(9)
2(A)
3(B)
4(C)
5(D)
6(E)
VDM0CN
ADC0CLK
RSTSRC
IDA1CN
ADC0DAC
FLKEY
CPT0MX
PSCTL
PCON
7(F)
(bit
addressable)
Rev. 1.1
101
C8051F350/1/2/3
Table 11.2. Special Function Registers
SFRs are listed in alphabetical order. All undefined SFR locations are reserved
Register
Address
Description
ACC
0xE0
Accumulator
ADC0BUF
0xBD
ADC0 Buffer Control
ADC0CF
0xFB
ADC0 Configuration
ADC0CGH
0xAD
ADC0 Gain Calibration High
ADC0CGL
0xAB
ADC0 Gain Calibration Low
ADC0CGM
0xAC
ADC0 Gain Calibration Middle
ADC0CLK
0xF7
ADC0 Clock
ADC0CN
0xF4
ADC0 Control
ADC0COH
0xBC
ADC0 Offset Calibration High
ADC0COL
0xBA
ADC0 Offset Calibration Low
ADC0COM
0xBB
ADC0 Offset Calibration Middle
ADC0DAC
0xBF
ADC0 Offset DAC
ADC0DECH
0x9B
ADC0 Decimation High
ADC0DECL
0x9A
ADC0 Decimation Low
ADC0FH
0xFE
ADC0 Fast Filter Output High
ADC0FL
0xFC
ADC0 Fast Filter Output Low
ADC0FM
0xFD
ADC0 Fast Filter Output Middle
ADC0H
0xC5
ADC0 Output High
ADC0L
0xC3
ADC0 Output Low
ADC0M
0xC4
ADC0 Output Middle
ADC0MD
0xF3
ADC0 Mode
ADC0MUX
0xC6
ADC0 Multiplexer
ADC0STA
0xE8
ADC0 Status
B
0xF0
B Register
CKCON
0x8E
Clock Control
CLKMUL
0xBE
Clock Multiplier
CLKSEL
0xA9
Clock Select
CPT0CN
0x9C
Comparator0 Control
CPT0MD
0x9D
Comparator0 Mode Selection
CPT0MX
0x9F
Comparator0 MUX Selection
DPH
0x83
Data Pointer High
DPL
0x82
Data Pointer Low
EIE1
0xE6
Extended Interrupt Enable 1
EIP1
0xF6
Extended Interrupt Priority 1
EMI0CN
0xAA
External Memory Interface Control
FLKEY
0xB7
Flash Lock and Key
FLSCL
0xB6
Flash Scale
IDA0
0x96
Current Mode DAC0 Low
IDA0CN
0xB9
Current Mode DAC0 Control
IDA1
0xDD
Current Mode DAC1 Low
IDA1CN
0xD7
Current Mode DAC1 Control
IE
0xA8
Interrupt Enable
IP
0xB8
Interrupt Priority
IT01CF
0xE4
INT0/INT1 Configuration
102
Rev. 1.1
Page
95
53
49
56
56
56
51
48
55
55
55
52
51
52
58
58
58
57
57
57
50
60
54
95
201
135
136
81
82
84
93
93
109
110
127
125
126
69
69
70
70
107
108
112
C8051F350/1/2/3
Table 11.2. Special Function Registers (Continued)
SFRs are listed in alphabetical order. All undefined SFR locations are reserved
Register
Address
Description
OSCICL
0xB3
Internal Oscillator Calibration
OSCICN
0xB2
Internal Oscillator Control
OSCXCN
0xB1
External Oscillator Control
P0
0x80
Port 0 Latch
P0MDIN
0xF1
Port 0 Input Mode Configuration
P0MDOUT
0xA4
Port 0 Output Mode Configuration
P0SKIP
0xD4
Port 0 Skip
P1
0x90
Port 1 Latch
P1MDIN
0xF2
Port 1 Input Mode Configuration
P1MDOUT
0xA5
Port 1 Output Mode Configuration
P1SKIP
0xD5
Port 1 Skip
P2
0xA0
Port 2 Latch
P2MDOUT
0xA6
Port 2 Output Mode Configuration
PCA0CN
0xD8
PCA Control
PCA0CPH0
0xEA
PCA Capture 0 High
PCA0CPH1
0xEC
PCA Capture 1 High
PCA0CPH2
0xEE
PCA Capture 2 High
PCA0CPL0
0xE9
PCA Capture 0 Low
PCA0CPL1
0xEB
PCA Capture 1 Low
PCA0CPL2
0xED
PCA Capture 2 Low
PCA0CPM0
0xDA
PCA Module 0 Mode
PCA0CPM1
0xDB
PCA Module 1 Mode
PCA0CPM2
0xDC
PCA Module 2 Mode
PCA0H
0xFA
PCA Counter High
PCA0L
0xF9
PCA Counter Low
PCA0MD
0xD9
PCA Mode
PCON
0x87
Power Control
PFE0CN
0xE3
Prefetch Engine Control
PSCTL
0x8F
Program Store R/W Control
PSW
0xD0
Program Status Word
REF0CN
0xD1
Voltage Reference Control
RSTSRC
0xEF
Reset Source Configuration/Status
SBUF0
0x99
UART0 Data Buffer
SCON0
0x98
UART0 Control
SMB0CF
0xC1
SMBus Configuration
SMB0CN
0xC0
SMBus Control
SMB0DAT
0xC2
SMBus Data
SP
0x81
Stack Pointer
SPI0CFG
0xA1
SPI Configuration
SPI0CKR
0xA2
SPI Clock Rate Control
SPI0CN
0xF8
SPI Control
SPI0DAT
0xA3
SPI Data
TCON
0x88
Timer/Counter Control
TH0
0x8C
Timer/Counter 0 High
TH1
0x8D
Timer/Counter 1 High
Rev. 1.1
Page
130
130
134
145
145
146
146
147
147
148
148
149
149
222
226
226
226
226
226
226
224
224
224
225
225
223
97
113
125
94
74
119
177
176
158
160
162
93
187
189
188
190
199
202
202
103
C8051F350/1/2/3
Table 11.2. Special Function Registers (Continued)
SFRs are listed in alphabetical order. All undefined SFR locations are reserved
Register
Address
Description
TL0
0x8A
Timer/Counter 0 Low
TL1
0x8B
Timer/Counter 1 Low
TMOD
0x89
Timer/Counter Mode
TMR2CN
0xC8
Timer/Counter 2 Control
TMR2H
0xCD
Timer/Counter 2 High
TMR2L
0xCC
Timer/Counter 2 Low
TMR2RLH
0xCB
Timer/Counter 2 Reload High
TMR2RLL
0xCA
Timer/Counter 2 Reload Low
TMR3CN
0x91
Timer/Counter 3Control
TMR3H
0x95
Timer/Counter 3 High
TMR3L
0x94
Timer/Counter 3 Low
TMR3RLH
0x93
Timer/Counter 3 Reload High
TMR3RLL
0x92
Timer/Counter 3 Reload Low
VDD Monitor Control
VDM0CN
0xFF
XBR0
0xE1
Port I/O Crossbar Control 0
XBR1
0xE2
Port I/O Crossbar Control 1
104
Rev. 1.1
Page
202
202
200
205
206
206
206
206
209
210
210
210
210
117
142
143
C8051F350/1/2/3
12. Interrupt Handler
The C8051F35x family includes an extended interrupt system supporting a total of 12 interrupt sources
with two priority levels. The allocation of interrupt sources between on-chip peripherals and external input
pins varies according to the specific version of the device. Each interrupt source has one or more associated interrupt-pending flag(s) located in an SFR. When a peripheral or external source meets a valid interrupt condition, the associated interrupt-pending flag is set to logic 1.
If interrupts are enabled for the source, an interrupt request is generated when the interrupt-pending flag is
set. As soon as execution of the current instruction is complete, the CPU generates an LCALL to a predetermined address to begin execution of an interrupt service routine (ISR). Each ISR must end with an RETI
instruction, which returns program execution to the next instruction that would have been executed if the
interrupt request had not occurred. If interrupts are not enabled, the interrupt-pending flag is ignored by the
hardware and program execution continues as normal. (The interrupt-pending flag is set to logic 1 regardless of the interrupt's enable/disable state.)
Each interrupt source can be individually enabled or disabled through the use of an associated interrupt
enable bit in the Interrupt Enable and Extended Interrupt Enable SFRs. However, interrupts must first be
globally enabled by setting the EA bit (IE.7) to logic 1 before the individual interrupt enables are recognized. Setting the EA bit to logic 0 disables all interrupt sources regardless of the individual interruptenable settings. Note that interrupts which occur when the EA bit is set to logic 0 will be held in a pending
state, and will not be serviced until the EA bit is set back to logic 1.
Some interrupt-pending flags are automatically cleared by the hardware when the CPU vectors to the ISR.
However, most are not cleared by the hardware and must be cleared by software before returning from the
ISR. If an interrupt-pending flag remains set after the CPU completes the return-from-interrupt (RETI)
instruction, a new interrupt request will be generated immediately and the CPU will re-enter the ISR after
the completion of the next instruction.
12.1. MCU Interrupt Sources and Vectors
The MCUs support 12 interrupt sources. Software can simulate an interrupt by setting any interrupt-pending flag to logic 1. If interrupts are enabled for the flag, an interrupt request will be generated and the CPU
will vector to the ISR address associated with the interrupt-pending flag. MCU interrupt sources, associated vector addresses, priority order and control bits are summarized in Table 12.1 on page 106. Refer to
the datasheet section associated with a particular on-chip peripheral for information regarding valid interrupt conditions for the peripheral and the behavior of its interrupt-pending flag(s).
12.2. Interrupt Priorities
Each interrupt source can be individually programmed to one of two priority levels: low or high. A low priority interrupt service routine can be preempted by a high priority interrupt. A high priority interrupt cannot be
preempted. Each interrupt has an associated interrupt priority bit in an SFR (IP or EIP1) used to configure
its priority level. Low priority is the default. If two interrupts are recognized simultaneously, the interrupt with
the higher priority is serviced first. If both interrupts have the same priority level, a fixed priority order is
used to arbitrate, given in Table 12.1.
12.3. Interrupt Latency
Interrupt response time depends on the state of the CPU when the interrupt occurs. Pending interrupts are
sampled and priority decoded each system clock cycle. Therefore, the fastest possible response time is 5
system clock cycles: 1 clock cycle to detect the interrupt and 4 clock cycles to complete the LCALL to the
ISR. If an interrupt is pending when a RETI is executed, a single instruction is executed before an LCALL
Rev. 1.1
105
C8051F350/1/2/3
is made to service the pending interrupt. Therefore, the maximum response time for an interrupt (when no
other interrupt is currently being serviced or the new interrupt is of greater priority) occurs when the CPU is
performing an RETI instruction followed by a DIV as the next instruction. In this case, the response time is
18 system clock cycles: 1 clock cycle to detect the interrupt, 5 clock cycles to execute the RETI, 8 clock
cycles to complete the DIV instruction and 4 clock cycles to execute the LCALL to the ISR. If the CPU is
executing an ISR for an interrupt with equal or higher priority, the new interrupt will not be serviced until the
current ISR completes, including the RETI and following instruction.
Reset
Interrupt Priority
Vector Order
Pending Flag
Cleared by HW?
Interrupt Source
Bit addressable?
Table 12.1. Interrupt Summary
N/A N/A
Enable
Flag
Priority
Control
Always
Enabled
Always
Highest
0x0000
Top
None
0x0003
0
IE0 (TCON.1)
Y
Y
EX0 (IE.0) PX0 (IP.0)
0x000B
1
TF0 (TCON.5)
Y
Y
ET0 (IE.1) PT0 (IP.1)
External Interrupt 0
(/INT0)
Timer 0 Overflow
External Interrupt 1
(/INT1)
Timer 1 Overflow
0x0013
2
IE1 (TCON.3)
Y
Y
EX1 (IE.2) PX1 (IP.2)
0x001B
3
Y
Y
ET1 (IE.3) PT1 (IP.3)
UART0
0x0023
4
Y
N
ES0 (IE.4) PS0 (IP.4)
Timer 2 Overflow
0x002B
5
Y
N
ET2 (IE.5) PT2 (IP.5)
SPI0
0x0033
6
TF1 (TCON.7)
RI0 (SCON0.0)
TI0 (SCON0.1)
TF2H (TMR2CN.7)
TF2L (TMR2CN.6)
SPIF (SPI0CN.7)
WCOL (SPI0CN.6)
MODF (SPI0CN.5)
RXOVRN (SPI0CN.4)
Y
N
SMB0
0x003B
7
SI (SMB0CN.0)
Y
N
RESERVED
RESERVED
0x0043
0x004B
8
9
N/A
N/A
ADC0
0x0053
10
AD0INT (ADC0STA.5)
Programmable Counter
Array
0x005B
11
Comparator0
0x0063
12
RESERVED
0x006B
13
Timer 3 Overflow
0x0073
14
106
N/A N/A
N/A N/A
Y
N
CF (PCA0CN.7)
Y
N
CCFn (PCA0CN.n)
CP0FIF (CPT0CN.4)
N
N
CP0RIF (CPT0CN.5)
N/A
N/A N/A
TF3H (TMR3CN.7)
N
N
TF3L (TMR3CN.6)
Rev. 1.1
ESPI0
(IE.6)
PSPI0
(IP.6)
ESMB0
(EIE1.0)
N/A
N/A
EADC0
(EIE1.3)
EPCA0
(EIE1.4)
ECP0
(EIE1.5)
N/A
ET3
(EIE1.7)
PSMB0
(EIP1.0)
N/A
N/A
PADC0
(EIP1.3)
PPCA0
(EIP1.4)
PCP0
(EIP1.5)
N/A
PT3
(EIP1.7)
C8051F350/1/2/3
12.4. Interrupt Register Descriptions
The SFRs used to enable the interrupt sources and set their priority level are described below. Refer to the
datasheet section associated with a particular on-chip peripheral for information regarding valid interrupt
conditions for the peripheral and the behavior of its interrupt-pending flag(s).
SFR Definition 12.1. IE: Interrupt Enable
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
EA
ESPI0
ET2
ES0
ET1
EX1
ET0
EX0
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Bit
Addressable
SFR Address: 0xA8
Bit 7:
Bit 6:
Bit 5:
Bit 4:
Bit 3:
Bit 2:
Bit 1:
Bit 0:
EA: Enable All Interrupts.
This bit globally enables/disables all interrupts. It overrides the individual interrupt mask settings.
0: Disable all interrupt sources.
1: Enable each interrupt according to its individual mask setting.
ESPI0: Enable Serial Peripheral Interface (SPI0) Interrupt.
This bit sets the masking of the SPI0 interrupts.
0: Disable all SPI0 interrupts.
1: Enable interrupt requests generated by SPI0.
ET2: Enable Timer 2 Interrupt.
This bit sets the masking of the Timer 2 interrupt.
0: Disable Timer 2 interrupt.
1: Enable interrupt requests generated by the TF2L or TF2H flags.
ES0: Enable UART0 Interrupt.
This bit sets the masking of the UART0 interrupt.
0: Disable UART0 interrupt.
1: Enable UART0 interrupt.
ET1: Enable Timer 1 Interrupt.
This bit sets the masking of the Timer 1 interrupt.
0: Disable all Timer 1 interrupt.
1: Enable interrupt requests generated by the TF1 flag.
EX1: Enable External Interrupt 1.
This bit sets the masking of External Interrupt 1.
0: Disable external interrupt 1.
1: Enable interrupt requests generated by the /INT1 input.
ET0: Enable Timer 0 Interrupt.
This bit sets the masking of the Timer 0 interrupt.
0: Disable all Timer 0 interrupt.
1: Enable interrupt requests generated by the TF0 flag.
EX0: Enable External Interrupt 0.
This bit sets the masking of External Interrupt 0.
0: Disable external interrupt 0.
1: Enable interrupt requests generated by the /INT0 input.
Rev. 1.1
107
C8051F350/1/2/3
SFR Definition 12.2. IP: Interrupt Priority
R
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
—
PSPI0
PT2
PS0
PT1
PX1
PT0
PX0
10000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Bit
Addressable
SFR Address: 0xB8
Bit 7:
Bit 6:
Bit 5:
Bit 4:
Bit 3:
Bit 2:
Bit 1:
Bit 0:
108
UNUSED. Read = 1, Write = don't care.
PSPI0: Serial Peripheral Interface (SPI0) Interrupt Priority Control.
This bit sets the priority of the SPI0 interrupt.
0: SPI0 interrupt set to low priority level.
1: SPI0 interrupt set to high priority level.
PT2: Timer 2 Interrupt Priority Control.
This bit sets the priority of the Timer 2 interrupt.
0: Timer 2 interrupt set to low priority level.
1: Timer 2 interrupt set to high priority level.
PS0: UART0 Interrupt Priority Control.
This bit sets the priority of the UART0 interrupt.
0: UART0 interrupt set to low priority level.
1: UART0 interrupt set to high priority level.
PT1: Timer 1 Interrupt Priority Control.
This bit sets the priority of the Timer 1 interrupt.
0: Timer 1 interrupt set to low priority level.
1: Timer 1 interrupt set to high priority level.
PX1: External Interrupt 1 Priority Control.
This bit sets the priority of the External Interrupt 1 interrupt.
0: External Interrupt 1 set to low priority level.
1: External Interrupt 1 set to high priority level.
PT0: Timer 0 Interrupt Priority Control.
This bit sets the priority of the Timer 0 interrupt.
0: Timer 0 interrupt set to low priority level.
1: Timer 0 interrupt set to high priority level.
PX0: External Interrupt 0 Priority Control.
This bit sets the priority of the External Interrupt 0 interrupt.
0: External Interrupt 0 set to low priority level.
1: External Interrupt 0 set to high priority level.
Rev. 1.1
C8051F350/1/2/3
SFR Definition 12.3. EIE1: Extended Interrupt Enable 1
R/W
R/W
R/W
R/W
R/W
ET3
Reserved
ECP0
EPCA0
EADC0
Bit7
Bit6
Bit5
Bit4
Bit3
R/W
R/W
Reserved Reserved
Bit2
Bit1
R/W
Reset Value
ESMB0
00000000
Bit0
SFR Address: 0xE6
Bit 7:
ET3: Enable Timer 3 Interrupt.
This bit sets the masking of the Timer 3 interrupt.
0: Disable Timer 3 interrupts.
1: Enable interrupt requests generated by the TF3L or TF3H flags.
Bit 6:
RESERVED. Read = 0. Must Write 0.
Bit 5:
ECP0: Enable Comparator0 (CP0) Interrupt.
This bit sets the masking of the CP0 interrupt.
0: Disable CP0 interrupts.
1: Enable interrupt requests generated by the CP0RIF or CP0FIF flags.
Bit 4:
EPCA0: Enable Programmable Counter Array (PCA0) Interrupt.
This bit sets the masking of the PCA0 interrupts.
0: Disable all PCA0 interrupts.
1: Enable interrupt requests generated by PCA0.
Bit 3:
EADC0: Enable ADC0 Conversion Complete Interrupt.
This bit sets the masking of the ADC0 Conversion Complete interrupt.
0: Disable ADC0 Conversion Complete interrupt.
1: Enable interrupt requests generated by the AD0INT flag.
Bits 2–1: RESERVED. Read = 00. Must Write 00.
Bit 0:
ESMB0: Enable SMBus (SMB0) Interrupt.
This bit sets the masking of the SMB0 interrupt.
0: Disable all SMB0 interrupts.
1: Enable interrupt requests generated by SMB0.
Rev. 1.1
109
C8051F350/1/2/3
SFR Definition 12.4. EIP1: Extended Interrupt Priority 1
R/W
R/W
R/W
R/W
R/W
PT3
Reserved
PCP0
PPCA0
PADC0
Bit7
Bit6
Bit5
Bit4
Bit3
R/W
R/W
Reserved Reserved
Bit2
R/W
Reset Value
PSMB0
00000000
Bit1
Bit0
SFR Address: 0xF6
Bit 7:
PT3: Timer 3 Interrupt Priority Control.
This bit sets the priority of the Timer 3 interrupt.
0: Timer 3 interrupts set to low priority level.
1: Timer 3 interrupts set to high priority level.
Bit 6:
RESERVED. Read = 0. Must Write 0.
Bit 5:
PCP0: Comparator0 (CP0) Interrupt Priority Control.
This bit sets the priority of the CP0 interrupt.
0: CP0 interrupt set to low priority level.
1: CP0 interrupt set to high priority level.
Bit 4:
PPCA0: Programmable Counter Array (PCA0) Interrupt Priority Control.
This bit sets the priority of the PCA0 interrupt.
0: PCA0 interrupt set to low priority level.
1: PCA0 interrupt set to high priority level.
Bit 3:
PADC0 ADC0 Conversion Complete Interrupt Priority Control.
This bit sets the priority of the ADC0 Conversion Complete interrupt.
0: ADC0 Conversion Complete interrupt set to low priority level.
1: ADC0 Conversion Complete interrupt set to high priority level.
Bits 2–1: RESERVED. Read = 00. Must Write 00.
Bit 0:
PSMB0: SMBus (SMB0) Interrupt Priority Control.
This bit sets the priority of the SMB0 interrupt.
0: SMB0 interrupt set to low priority level.
1: SMB0 interrupt set to high priority level.
110
Rev. 1.1
C8051F350/1/2/3
12.5. External Interrupts
The /INT0 and /INT1 external interrupt sources are configurable as active high or low, edge or level sensitive. The IN0PL (/INT0 Polarity) and IN1PL (/INT1 Polarity) bits in the IT01CF register select active high or
active low; the IT0 and IT1 bits in TCON (Section “22.1. Timer 0 and Timer 1’ on page 195) select level or
edge sensitive. The table below lists the possible configurations.
IT0
1
1
0
0
IN0PL
0
1
0
1
/INT0 Interrupt
Active low, edge sensitive
Active high, edge sensitive
Active low, level sensitive
Active high, level sensitive
IT1
1
1
0
0
IN1PL
0
1
0
1
/INT1 Interrupt
Active low, edge sensitive
Active high, edge sensitive
Active low, level sensitive
Active high, level sensitive
/INT0 and /INT1 are assigned to Port pins as defined in the IT01CF register (see SFR Definition 12.5).
Note that /INT0 and /INT0 Port pin assignments are independent of any Crossbar assignments. /INT0 and
/INT1 will monitor their assigned Port pins without disturbing the peripheral that was assigned the Port pin
via the Crossbar. To assign a Port pin only to /INT0 and/or /INT1, configure the Crossbar to skip the
selected pin(s). This is accomplished by setting the associated bit in register XBR0 (see Section
“18.1. Priority Crossbar Decoder’ on page 139 for complete details on configuring the Crossbar).
IE0 (TCON.1) and IE1 (TCON.3) serve as the interrupt-pending flags for the /INT0 and /INT1 external
interrupts, respectively. If an /INT0 or /INT1 external interrupt is configured as edge-sensitive, the corresponding interrupt-pending flag is automatically cleared by the hardware when the CPU vectors to the ISR.
When configured as level sensitive, the interrupt-pending flag remains logic 1 while the input is active as
defined by the corresponding polarity bit (IN0PL or IN1PL); the flag remains logic 0 while the input is inactive. The external interrupt source must hold the input active until the interrupt request is recognized. It
must then deactivate the interrupt request before execution of the ISR completes or another interrupt
request will be generated.
Rev. 1.1
111
C8051F350/1/2/3
SFR Definition 12.5. IT01CF: INT0/INT1 Configuration
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
IN1PL
IN1SL2
IN1SL1
IN1SL0
IN0PL
IN0SL2
IN0SL1
IN0SL0
00000001
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xE4
Note: Refer to SFR Definition 22.1 for INT0/1 edge- or level-sensitive interrupt selection.
Bit 7:
IN1PL: /INT1 Polarity
0: /INT1 input is active low.
1: /INT1 input is active high.
Bits 6–4: IN1SL2–0: /INT1 Port Pin Selection Bits
These bits select which Port pin is assigned to /INT1. Note that this pin assignment is independent of the Crossbar; /INT1 will monitor the assigned Port pin without disturbing the
peripheral that has been assigned the Port pin via the Crossbar. The Crossbar will not
assign the Port pin to a peripheral if it is configured to skip the selected pin (accomplished by
setting to ‘1’ the corresponding bit in register P0SKIP).
IN1SL2–0
000
001
010
011
100
101
110
111
/INT1 Port Pin
P0.0
P0.1
P0.2
P0.3
P0.4
P0.5
P0.6
P0.7
Bit 3:
IN0PL: /INT0 Polarity
0: /INT0 interrupt is active low.
1: /INT0 interrupt is active high.
Bits 2–0: INT0SL2–0: /INT0 Port Pin Selection Bits
These bits select which Port pin is assigned to /INT0. Note that this pin assignment is independent of the Crossbar. /INT0 will monitor the assigned Port pin without disturbing the
peripheral that has been assigned the Port pin via the Crossbar. The Crossbar will not
assign the Port pin to a peripheral if it is configured to skip the selected pin (accomplished by
setting to ‘1’ the corresponding bit in register P0SKIP).
IN0SL2–0
000
001
010
011
100
101
110
111
112
/INT0 Port Pin
P0.0
P0.1
P0.2
P0.3
P0.4
P0.5
P0.6
P0.7
Rev. 1.1
C8051F350/1/2/3
17. Oscillators
C8051F350/1/2/3 devices include a programmable internal oscillator, an external oscillator drive circuit,
and a clock multiplier. The internal oscillator can be enabled/disabled and calibrated using the OSCICN
and OSCICL registers, as shown in Figure 17.1. The system clock (SYSCLK) can be derived from the
internal oscillator, external oscillator circuit, or the clock multiplier. The clock multiplier can produce three
possible outputs: Internal Oscillator x 2, External Oscillator x 2, or External Oscillator x 4. Oscillator electrical specifications are given in Table 17.1 on page 136.
OSCICL
OSCICN
CLKSEL
CLKSL1
CLKSL0
Option 3
XTAL2
VDD
IFCN1
IFCN0
IOSCEN
IFRDY
Option 2
XTAL2
EN
Programmable
Internal Clock
Generator
Option 1
IOSC
n
XTAL1
EXOSC
Input
Circuit
OSC
SYSCLK
XTAL2
XTLVLD
EXOSC
OSCXCN
x4
Clock Multiplier
MULSEL1
MULSEL0
XFCN2
XFCN1
XFCN0
EXOSC / 2
XTLVLD
XOSCMD2
XOSCMD1
XOSCMD0
Option 4
XTAL2
IOSC/2
MULEN
MULINIT
MULRDY
10MΩ
CLKMUL
Figure 17.1. Oscillator Diagram
17.1. Programmable Internal Oscillator
All C8051F350/1/2/3 devices include a programmable internal oscillator that defaults as the system clock
after a system reset. The internal oscillator period can be programmed via the OSCICL register, shown in
SFR Definition 17.2. On C8051F350/1/2/3 devices, OSCICL is factory calibrated to obtain a 24.5 MHz frequency.
Electrical specifications for the precision internal oscillator are given in Table 17.1 on page 136. Note that
the system clock may be derived from the programmed internal oscillator divided by 1, 2, 4, or 8, as
defined by the IFCN bits in register OSCICN. The divide value defaults to 8 following a reset.
Rev. 1.1
129
C8051F350/1/2/3
SFR Definition 17.1. OSCICN: Internal Oscillator Control
R/W
R
R
R
R
R
R/W
R/W
Reset Value
IOSCEN
IFRDY
—
—
—
—
IFCN1
IFCN0
11000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xB2
Bit7:
IOSCEN: Internal Oscillator Enable Bit.
0: Internal Oscillator Disabled.
1: Internal Oscillator Enabled.
Bit6:
IFRDY: Internal Oscillator Frequency Ready Flag.
0: Internal Oscillator is not running at programmed frequency.
1: Internal Oscillator is running at programmed frequency.
Bits5–2: UNUSED. Read = 0000b, Write = don't care.
Bits1–0: IFCN1–0: Internal Oscillator Frequency Control Bits.
00: SYSCLK derived from Internal Oscillator divided by 8.
01: SYSCLK derived from Internal Oscillator divided by 4.
10: SYSCLK derived from Internal Oscillator divided by 2.
11: SYSCLK derived from Internal Oscillator divided by 1.
SFR Definition 17.2. OSCICL: Internal Oscillator Calibration
R
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Reset Value
Variable
SFR Address: 0xB3
Bit7:
UNUSED. Read = 0. Write = don’t care.
Bits 6–0: OSCICL: Internal Oscillator Calibration Register.
This register determines the internal oscillator period. On C8051F350/1/2/3 devices, the
reset value is factory calibrated to generate an internal oscillator frequency of 24.5 MHz.
130
Rev. 1.1
C8051F350/1/2/3
17.2. External Oscillator Drive Circuit
The external oscillator circuit may drive an external crystal, ceramic resonator, capacitor, or RC network. A
CMOS clock may also provide a clock input. For a crystal or ceramic resonator configuration, the crystal/resonator must be wired across the XTAL1 and XTAL2 pins as shown in Option 1 of Figure 17.1. A
10 MΩ resistor also must be wired across the XTAL1 and XTAL2 pins for the crystal/resonator configuration. In RC, capacitor, or CMOS clock configuration, the clock source should be wired to the XTAL2 pin as
shown in Option 2, 3, or 4 of Figure 17.1. The type of external oscillator must be selected in the OSCXCN
register, and the frequency control bits (XFCN) must be selected appropriately (see SFR Definition 17.3)
Important Note on External Oscillator Usage: Port pins must be configured when using the external
oscillator circuit. When the external oscillator drive circuit is enabled in crystal/resonator mode, Port pins
P0.2 and P0.3 are used as XTAL1 and XTAL2 respectively. When the external oscillator drive circuit is
enabled in capacitor, RC, or CMOS clock mode, Port pin P0.3 is used as XTAL2. The Port I/O Crossbar
should be configured to skip the Port pins used by the oscillator circuit; see Section “18.1. Priority Crossbar
Decoder’ on page 139 for Crossbar configuration. Additionally, when using the external oscillator circuit in
crystal/resonator, capacitor, or RC mode, the associated Port pins should be configured as analog inputs.
In CMOS clock mode, the associated pin should be configured as a digital input. See Section “18.2. Port
I/O Initialization’ on page 141 for details on Port input mode selection.
17.2.1. Clocking Timers Directly Through the External Oscillator
The external oscillator source divided by eight is a clock option for the timers (Section “22. Timers’ on
page 195) and the Programmable Counter Array (PCA) (Section “23. Programmable Counter Array’ on
page 211). When the external oscillator is used to clock these peripherals, but is not used as the system
clock, the external oscillator frequency must be less than or equal to the system clock frequency. In this
configuration, the clock supplied to the peripheral (external oscillator / 8) is synchronized with the system
clock; the jitter associated with this synchronization is limited to ±0.5 system clock cycles.
17.2.2. External Crystal Example
If a crystal or ceramic resonator is used as an external oscillator source for the MCU, the circuit should be
configured as shown in Figure 17.1, Option 1. The External Oscillator Frequency Control value (XFCN)
should be chosen from the Crystal column of the table in SFR Definition 17.3 (OSCXCN register). For
example, a 12 MHz crystal requires an XFCN setting of 111b.
When the crystal oscillator is first enabled, the oscillator amplitude detection circuit requires a settling time
to achieve proper bias. Introducing a delay of 1 ms between enabling the oscillator and checking the
XTLVLD bit will prevent a premature switch to the external oscillator as the system clock. Switching to the
external oscillator before the crystal oscillator has stabilized can result in unpredictable behavior. The recommended procedure is:
Step 1.
Step 2.
Step 3.
Step 4.
Step 5.
Step 6.
Force the XTAL1 and XTAL2 pins low by writing 0’s to the port latch.
Configure XTAL1 and XTAL2 as analog inputs.
Enable the external oscillator.
Wait at least 1 ms.
Poll for XTLVLD => ‘1’.
Switch the system clock to the external oscillator.
Note: Tuning-fork crystals may require additional settling time before XTLVLD returns a valid result.
Rev. 1.1
131
C8051F350/1/2/3
The capacitors shown in the external crystal configuration provide the load capacitance required by the
crystal for correct oscillation. These capacitors are “in series” as seen by the crystal and “in parallel” with
the stray capacitance of the XTAL1 and XTAL2 pins.
Note: The load capacitance depends upon the crystal and the manufacturer. Please refer to the crystal
datasheet when completing these calculations.
For example, a tuning-fork crystal of 32.768 kHz with a recommended load capacitance of 12.5 pF should
use the configuration shown in Figure 17.1, Option 1. The total value of the capacitors and the stray
capacitance of the XTAL pins should equal 25 pF. With a stray capacitance of 3 pF per pin, the 22 pF
capacitors yield an equivalent capacitance of 12.5 pF across the crystal, as shown in Figure 17.2.
22 pF
XTAL1
10 MΩ
32.768 kHz
XTAL2
22 pF
Figure 17.2. 32.768 kHz External Crystal Example
Important note on external crystals: Crystal oscillator circuits are quite sensitive to PCB layout. The
crystal should be placed as close as possible to the XTAL pins on the device. The traces should be as
short as possible and shielded with ground plane from any other traces which could introduce noise or
interference.
132
Rev. 1.1
C8051F350/1/2/3
17.2.3. External RC Example
If an RC network is used as an external oscillator source for the MCU, the circuit should be configured as
shown in Figure 17.1, Option 2. The capacitor should be no greater than 100 pF; however for very small
capacitors, the total capacitance may be dominated by parasitic capacitance in the PCB layout. To determine the required External Oscillator Frequency Control value (XFCN) in the OSCXCN Register, first
select the RC network value to produce the desired frequency of oscillation. If the frequency desired is
100 kHz, let R = 246 kΩ and C = 50 pF:
f = 1.23( 103 ) / RC = 1.23 ( 103 ) / [ 246 * 50 ] = 0.1 MHz = 100 kHz
Referring to the table in SFR Definition 17.3, the required XFCN setting is 010b. Programming XFCN to a
higher setting in RC mode will improve frequency accuracy at an increased external oscillator supply current.
17.2.4. External Capacitor Example
If a capacitor is used as an external oscillator for the MCU, the circuit should be configured as shown in
Figure 17.1, Option 3. The capacitor should be no greater than 100 pF; however for very small capacitors,
the total capacitance may be dominated by parasitic capacitance in the PCB layout. To determine the
required External Oscillator Frequency Control value (XFCN) in the OSCXCN Register, select the capacitor to be used and find the frequency of oscillation from the equations below. Assume VDD = 3.0 V and
f = 150 kHz:
f = KF / (C x VDD)
0.150 MHz = KF / (C x 3.0)
Since the frequency of roughly 150 kHz is desired, select the K Factor from the table in SFR Definition 17.3
as KF = 22:
0.150 MHz = 22 / (C x 3.0)
C x 3.0 = 22 / 0.150 MHz
C = 146.6 / 3.0 pF = 48.8 pF
Therefore, the XFCN value to use in this example is 011b and C = 50 pF.
Rev. 1.1
133
C8051F350/1/2/3
SFR Definition 17.3. OSCXCN: External Oscillator Control
R
R/W
R/W
R/W
R
R/W
R/W
R/W
Reset Value
—
XFCN2
XFCN1
XFCN0
00000000
Bit3
Bit2
Bit1
XTLVLD XOSCMD2 XOSCMD1 XOSCMD0
Bit7
Bit6
Bit5
Bit4
Bit0
SFR Address: 0xB1
Bit7:
XTLVLD: Crystal Oscillator Valid Flag.
(Read only when XOSCMD = 11x.)
0: Crystal Oscillator is unused or not yet stable.
1: Crystal Oscillator is running and stable.
Bits6–4: XOSCMD2–0: External Oscillator Mode Bits.
00x: External Oscillator circuit off.
010: External CMOS Clock Mode.
011: External CMOS Clock Mode with divide by 2 stage.
100: RC Oscillator Mode.
101: Capacitor Oscillator Mode.
110: Crystal Oscillator Mode.
111: Crystal Oscillator Mode with divide by 2 stage.
Bit3:
RESERVED. Read = 0, Write = don't care.
Bits2–0: XFCN2–0: External Oscillator Frequency Control Bits.
000–111: See table below:
XFCN
000
001
010
011
100
101
110
111
Crystal (XOSCMD = 11x)
f ≤ 32 kHz
32 kHz < f ≤ 84 kHz
84 kHz < f ≤ 225 kHz
225 kHz < f ≤ 590 kHz
590 kHz < f ≤ 1.5 MHz
1.5 MHz < f ≤ 4 MHz
4 MHz < f ≤ 10 MHz
10 MHz < f ≤ 30 MHz
RC (XOSCMD = 10x)
f ≤ 25 kHz
25 kHz < f ≤ 50 kHz
50 kHz < f ≤ 100 kHz
100 kHz < f ≤ 200 kHz
200 kHz < f ≤ 400 kHz
400 kHz < f ≤ 800 kHz
800 kHz < f ≤ 1.6 MHz
1.6 MHz < f ≤ 3.2 MHz
CRYSTAL MODE (Circuit from Figure 17.1, Option 1; XOSCMD = 11x)
Choose XFCN value to match crystal or resonator frequency.
RC MODE (Circuit from Figure 17.1, Option 2; XOSCMD = 10x)
Choose XFCN value to match frequency range:
f = 1.23(103) / (R * C), where
f = frequency of clock in MHz
C = capacitor value in pF
R = Pull-up resistor value in kΩ
C MODE (Circuit from Figure 17.1, Option 3; XOSCMD = 10x)
Choose K Factor (KF) for the oscillation frequency desired:
f = KF / (C * VDD), where
f = frequency of clock in MHz
C = capacitor value the XTAL2 pin in pF
VDD = Power Supply on MCU in volts
134
Rev. 1.1
C (XOSCMD = 10x)
K Factor = 0.87
K Factor = 2.6
K Factor = 7.7
K Factor = 22
K Factor = 65
K Factor = 180
K Factor = 664
K Factor = 1590
C8051F350/1/2/3
17.3. Clock Multiplier
The Clock Multiplier generates an output clock which is 4 times the input clock frequency. The Clock Multiplier’s input can be selected from the external oscillator, or 1/2 the internal or external oscillators. This produces three possible outputs: Internal Oscillator x 2, External Oscillator x 2, or External Oscillator x 4. See
Section “17.4. System Clock Selection’ on page 136 for details on system clock selection.
The Clock Multiplier is configured via the CLKMUL register (SFR Definition 17.4). The procedure for configuring and enabling the Clock Multiplier is as follows:
1.
2.
3.
4.
5.
6.
Reset the Multiplier by writing 0x00 to register CLKMUL.
Select the Multiplier input source via the MULSEL bits.
Enable the Multiplier with the MULEN bit (CLKMUL | = 0x80).
Delay for >5 µs.
Initialize the Multiplier with the MULINIT bit (CLKMUL | = 0xC0).
Poll for MULRDY => ‘1’.
Important Note: When using an external oscillator as the input to the Clock Multiplier, the external
source must be enabled and stable before the Multiplier is initialized. See Section “17.4. System
Clock Selection’ on page 136 for details on selecting an external oscillator source.
SFR Definition 17.4. CLKMUL: Clock Multiplier Control
R/W
MULEN
Bit7
R/W
R
MULINIT MULRDY
Bit6
Bit5
R/W
R/W
R/W
—
—
—
Bit4
Bit3
Bit2
R/W
R/W
MULSEL
Bit1
Reset Value
00000000
Bit0
SFR Address: 0xBE
Bit7:
MULEN: Clock Multiplier Enable
0: Clock Multiplier disabled.
1: Clock Multiplier enabled.
Bit6:
MULINIT: Clock Multiplier Initialize
This bit should be a ‘0’ when the Clock Multiplier is enabled. Once enabled, writing a ‘1’ to
this bit will initialize the Clock Multiplier. The MULRDY bit reads ‘1’ when the Clock Multiplier
is stabilized.
Bit5:
MULRDY: Clock Multiplier Ready
This read-only bit indicates the status of the Clock Multiplier.
0: Clock Multiplier not ready.
1: Clock Multiplier ready (locked).
Bits4–2: Unused. Read = 000b; Write = don’t care.
Bits1–0: MULSEL: Clock Multiplier Input Select
These bits select the clock supplied to the Clock Multiplier.
MULSEL
00
01
10
11
Selected Input Clock
Internal Oscillator / 2
External Oscillator
External Oscillator / 2
RESERVED
Rev. 1.1
Clock Multipler Output
Internal Oscillator x 2
External Oscillator x 4
External Oscillator x 2
RESERVED
135
C8051F350/1/2/3
17.4. System Clock Selection
The internal oscillator requires little start-up time and may be selected as the system clock immediately following the OSCICN write that enables the internal oscillator. External crystals and ceramic resonators typically require a start-up time before they are settled and ready for use. The Crystal Valid Flag (XTLVLD in
register OSCXCN) is set to ‘1’ by hardware when the external oscillator is settled. To avoid reading a
false XTLVLD, in crystal mode software should delay at least 1 ms between enabling the external
oscillator and checking XTLVLD. RC and C modes typically require no startup time.
The CLKSL[1:0] bits in register CLKSEL select which oscillator source is used as the system clock.
CLKSL[1:0] must be set to 01b for the system clock to run from the external oscillator; however the external oscillator may still clock certain peripherals (timers, PCA) when the internal oscillator is selected as the
system clock. The system clock may be switched on-the-fly between the internal oscillator, external oscillator, and Clock Multiplier so long as the selected clock source is enabled and has settled.
SFR Definition 17.5. CLKSEL: Clock Select
R
R
R
R
R
R
—
—
—
—
—
—
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
R/W
R/W
CLKSL
Bit1
Reset Value
00000000
Bit0
SFR Address: 0xA9
Bits7–2: Unused. Read = 000000b; Write = don’t care.
Bits1–0: CLKSL1–0: System Clock Select
These bits select the system clock source.
CLKSL
00
01
10
11
Selected Clock
Internal Oscillator (as determined by the
IFCN bits in register OSCICN)
External Oscillator
Clock Multiplier
RESERVED
Table 17.1. Oscillator Electrical Characteristics
–40 to +85 °C unless otherwise specified.
Parameter
Internal Oscillator Frequency
Internal Oscillator Supply
Current (from VDD)
136
Conditions
Reset Frequency
OSCICN.7 = 1
Rev. 1.1
Min
24
—
Typ
24.5
450
Max
25
—
Units
MHz
µA
C8051F350/1/2/3
18. Port Input/Output
Digital and analog resources are available through 17 I/O pins. Port pins are organized as two byte-wide
Ports and one 1-bit Port. Each of the Port pins can be defined as general-purpose I/O (GPIO) or analog
input/output; Port pins P0.0 - P1.7 can be assigned to one of the internal digital resources as shown in
Figure 18.3. The designer has complete control over which functions are assigned, limited only by the
number of physical I/O pins. This resource assignment flexibility is achieved through the use of a Priority
Crossbar Decoder. Note that the state of a Port I/O pin can always be read in the corresponding Port latch,
regardless of the Crossbar settings.
The Crossbar assigns the selected internal digital resources to the I/O pins based on the Priority Decoder
(Figure 18.3 and Figure 18.4). The registers XBR0 and XBR1, defined in SFR Definition 18.1 and SFR
Definition 18.2, are used to select internal digital functions.
All Port I/Os are 5 V tolerant (refer to Figure 18.2 for the Port cell circuit). The Port I/O cells are configured
as either push-pull or open-drain in the Port Output Mode registers (PnMDOUT, where n = 0,1,2). Complete Electrical Specifications for Port I/O are given in Table 18.1 on page 150.
XBR0, XBR1,
PnSKIP Registers
PnMDOUT,
PnMDIN Registers
Priority
Decoder
(Internal Digital Signals)
Highest
Priority
2
UART
CP0
Outputs
Digital
Crossbar
4
SPI
SMBus
8
4
T0, T1
8
2
SYSCLK
PCA
Lowest
Priority
2
P0
I/O
Cells
P0.0
P1
I/O
Cells
P1.0
P0.7
P1.7
2
8
(Port Latches)
P0
(P0.0-P0.7)
8
P1
P2
(P1.0-P1.7)
P2
I/O
Cell
(P2.0)
P2.0
Figure 18.1. Port I/O Functional Block Diagram
Rev. 1.1
137
C8051F350/1/2/3
/WEAK-PULLUP
VDD
PUSH-PULL
/PORT-OUTENABLE
VDD
(WEAK)
PORT
PAD
PORT-OUTPUT
GND
Analog Select
ANALOG INPUT
PORT-INPUT
Figure 18.2. Port I/O Cell Block Diagram
138
Rev. 1.1
C8051F350/1/2/3
18.1. Priority Crossbar Decoder
The Priority Crossbar Decoder (Figure 18.3) assigns a priority to each I/O function, starting at the top with
UART0. When a digital resource is selected, the least-significant unassigned Port pin is assigned to that
resource (excluding UART0, which will be assigned to pins P0.4 and P0.5, and the Comparator0 outputs,
which will be assigned to P1.4 and P1.5). If a Port pin is assigned, the Crossbar skips that pin when
assigning the next selected resource. Additionally, the Crossbar will skip Port pins whose associated bits in
the PnSKIP registers are set. The PnSKIP registers allow software to skip Port pins that are to be used for
analog input, dedicated functions, or GPIO.
Important Note on Crossbar Configuration: If a Port pin is claimed by a peripheral without use of the
Crossbar, its corresponding PnSKIP bit should be set. This applies to P0.3 and/or P0.2 for the external
oscillator, P0.6 for the external CNVSTR signal, P1.6 for IDA0, P1.7 for IDA1, and any selected ADC or
comparator inputs. The Crossbar skips selected pins as if they were already assigned, and moves to the
next unassigned pin. Figure 18.3 shows the Crossbar Decoder priority with no Port pins skipped (P0SKIP,
P1SKIP = 0x00); Figure 18.4 shows the Crossbar Decoder priority with the XTAL1 (P0.2) and XTAL2
(P0.3) pins skipped (P0SKIP = 0x0C).
P0
SF Signals
PIN I/O
0
1
x1
2
x2
3
P1
4
CNVSTR
5
6
7
0
1
2
0
0
0
P2
3
4
5
0
0
0
IDA0 IDA1
6
7
0
TX0
RX0
CP0A
CP0
SCK
MISO
MOSI
(*4-Wire SPI Only)
NSS*
SDA
SCL
/SYSCLK
CEX0
CEX1
CEX2
ECI
T0
T1
0
0
0
0
0
0
0
0
0
0
P1SKIP[0:7]
P0SKIP[0:7]
Port pin potentially assignable to peripheral
SF Signals
Special Function Signals are not assigned by the crossbar.
When these signals are enabled, the CrossBar must be
manually configured to skip their corresponding port pins.
Figure 18.3. Crossbar Priority Decoder with No Pins Skipped
Rev. 1.1
139
C8051F350/1/2/3
P0
SF Signals
PIN I/O
0
1
x1
2
x2
3
P1
4
5
CNVSTR
6
7
0
1
2
P2
3
4
5
0
0
0
IDA0 IDA1
6
7
0
TX0
RX0
CP0A
CP0
SCK
MISO
MOSI
(*4-Wire SPI Only)
NSS*
SDA
SCL
/SYSCLK
CEX0
CEX1
CEX2
ECI
T0
T1
0
0
1
1
0
0
0
0
0
0
0
P0SKIP[0:7]
0
0
P1SKIP[0:7]
Port pin potentially assignable to peripheral
SF Signals
Special Function Signals are not assigned by the crossbar.
When these signals are enabled, the CrossBar must be
manually configured to skip their corresponding port pins.
Figure 18.4. Crossbar Priority Decoder with Crystal Pins Skipped
Registers XBR0 and XBR1 are used to assign the digital I/O resources to the physical I/O Port pins. Note
that when the SMBus is selected, the Crossbar assigns both pins associated with the SMBus (SDA and
SCL); when the UART is selected, the Crossbar assigns both pins associated with the UART (TX and RX).
UART0 pin assignments are fixed for bootloading purposes: UART TX0 is always assigned to P0.4; UART
RX0 is always assigned to P0.5. Comparator outputs are also fixed: CP0A will appear only on P1.4, CP0
will appear only on P1.5. Standard Port I/Os appear contiguously after the prioritized functions have been
assigned.
Important Note: The SPI can be operated in either 3-wire or 4-wire modes, pending the state of the NSSMD1–NSSMD0 bits in register SPI0CN. According to the SPI mode, the NSS signal may or may not be
routed to a Port pin.
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18.2. Port I/O Initialization
Port I/O initialization consists of the following steps:
Step 1. Select the input mode (analog or digital) for all Port pins, using the Port Input Mode
register (PnMDIN).
Step 2. Select the output mode (open-drain or push-pull) for all Port pins, using the Port Output
Mode register (PnMDOUT).
Step 3. Select any pins to be skipped by the I/O Crossbar using the Port Skip registers (PnSKIP).
Step 4. Assign Port pins to desired peripherals.
Step 5. Enable the Crossbar (XBARE = ‘1’).
All Port pins must be configured as either analog or digital inputs. Any pins to be used as Comparator or
ADC inputs should be configured as an analog inputs. When a pin is configured as an analog input, its
weak pull-up, digital driver, and digital receiver are disabled. This process saves power and reduces noise
on the analog input. Pins configured as digital inputs may still be used by analog peripherals; however this
practice is not recommended.
Additionally, all analog input pins should be configured to be skipped by the Crossbar (accomplished by
setting the associated bits in PnSKIP). Port input mode is set in the PnMDIN register, where a ‘1’ indicates
a digital input, and a ‘0’ indicates an analog input. All pins default to digital inputs on reset. See SFR Definition 18.4 for the PnMDIN register details.
The output driver characteristics of the I/O pins are defined using the Port Output Mode registers (PnMDOUT). Each Port Output driver can be configured as either open drain or push-pull. This selection is
required even for the digital resources selected in the XBRn registers, and is not automatic. The only
exception to this is the SMBus (SDA, SCL) pins, which are configured as open-drain regardless of the
PnMDOUT settings. When the WEAKPUD bit in XBR1 is ‘0’, a weak pull-up is enabled for all Port I/O configured as open-drain. WEAKPUD does not affect the push-pull Port I/O. Furthermore, the weak pull-up is
turned off on an output that is driving a ‘0’ to avoid unnecessary power dissipation.
Registers XBR0 and XBR1 must be loaded with the appropriate values to select the digital I/O functions
required by the design. Setting the XBARE bit in XBR1 to ‘1’ enables the Crossbar. Until the Crossbar is
enabled, the external pins remain as standard Port I/O (in input mode), regardless of the XBRn Register
settings. For given XBRn Register settings, one can determine the I/O pin-out using the Priority Decode
Table.
The Crossbar must be enabled to use Port pins as standard Port I/O in output mode. Port output drivers
are disabled while the Crossbar is disabled.
Rev. 1.1
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SFR Definition 18.1. XBR0: Port I/O Crossbar Register 0
R
R
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
—
—
CP0AE
CP0E
SYSCKE
SMB0E
SPI0E
URT0E
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xE1
Bits7–6: UNUSED. Read = 00b, Write = don’t care.
Bit5:
CP0AE: Comparator0 Asynchronous Output Enable
0: Asynchronous CP0 unavailable at Port pin.
1: Asynchronous CP0 routed to Port pin P1.4.
Bit4:
CP0E: Comparator0 Output Enable
0: CP0 unavailable at Port pin.
1: CP0 routed to Port pin P1.5.
Bit3:
SYSCKE: /SYSCLK Output Enable
0: /SYSCLK unavailable at Port pin.
1: /SYSCLK output routed to Port pin.
Bit2:
SMB0E: SMBus I/O Enable
0: SMBus I/O unavailable at Port pins.
1: SMBus I/O routed to Port pins.
Bit1:
SPI0E: SPI I/O Enable
0: SPI I/O unavailable at Port pins.
1: SPI I/O routed to Port pins. Note that the SPI can be assigned either 3 or 4 GPIO pins.
Bit0:
URT0E: UART I/O Output Enable
0: UART I/O unavailable at Port pin.
1: UART TX0, RX0 routed to Port pins P0.4 and P0.5.
142
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SFR Definition 18.2. XBR1: Port I/O Crossbar Register 1
R/W
R/W
R/W
R/W
R/W
R
WEAKPUD
XBARE
T1E
T0E
ECIE
—
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
R/W
R/W
PCA0ME
Bit1
Reset Value
00000000
Bit0
SFR Address: 0xE2
Bit7:
WEAKPUD: Port I/O Weak Pull-up Disable.
0: Weak Pull-ups enabled (except for Ports whose I/O are configured as analog input).
1: Weak Pull-ups disabled.
Bit6:
XBARE: Crossbar Enable.
0: Crossbar disabled.
1: Crossbar enabled.
Bit5:
T1E: T1 Enable
0: T1 unavailable at Port pin.
1: T1 routed to Port pin.
Bit4:
T0E: T0 Enable
0: T0 unavailable at Port pin.
1: T0 routed to Port pin.
Bit3:
ECIE: PCA0 External Counter Input Enable
0: ECI unavailable at Port pin.
1: ECI routed to Port pin.
Bit2:
Unused. Read = 0b. Write = don’t care.
Bits1–0: PCA0ME: PCA Module I/O Enable Bits.
00: All PCA I/O unavailable at Port pins.
01: CEX0 routed to Port pin.
10: CEX0, CEX1 routed to Port pins.
11: CEX0, CEX1, CEX2 routed to Port pins.
Rev. 1.1
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C8051F350/1/2/3
18.3. General Purpose Port I/O
Port pins that remain unassigned by the Crossbar and are not used by analog peripherals can be used for
general purpose I/O. Ports P0–P2 are accessed through corresponding special function registers (SFRs)
that are both byte addressable and bit addressable. When writing to a Port, the value written to the SFR is
latched to maintain the output data value at each pin. When reading, the logic levels of the Port's input pins
are returned regardless of the XBRn settings (i.e., even when the pin is assigned to another signal by the
Crossbar, the Port register can always read its corresponding Port I/O pin). The exception to this is the
execution of the read-modify-write instructions that target a Port Latch register as the destination. The
read-modify-write instructions when operating on a Port SFR are the following: ANL, ORL, XRL, JBC, CPL,
INC, DEC, DJNZ and MOV, CLR or SETB, when the destination is an individual bit in a Port SFR. For
these instructions, the value of the register (not the pin) is read, modified, and written back to the SFR.
144
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SFR Definition 18.3. P0: Port0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
P0.7
P0.6
P0.5
P0.4
P0.3
P0.2
P0.1
P0.0
11111111
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Bit
Addressable
SFR Address: 0x80
Bits7–0: P0.[7:0]
Write - Output appears on I/O pins per Crossbar Registers.
0: Logic Low Output.
1: Logic High Output (high impedance if corresponding P0MDOUT.n bit = 0).
Read - Always reads ‘0’ if selected as analog input in register P0MDIN. Directly reads Port
pin when configured as digital input.
0: P0.n pin is logic low.
1: P0.n pin is logic high.
SFR Definition 18.4. P0MDIN: Port0 Input Mode
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Reset Value
11111111
SFR Address: 0xF1
Bits7–0: Analog Input Configuration Bits for P0.7–P0.0 (respectively).
Port pins configured as analog inputs have their weak pull-up, digital driver, and digital
receiver disabled.
0: Corresponding P0.n pin is configured as an analog input.
1: Corresponding P0.n pin is not configured as an analog input.
Rev. 1.1
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SFR Definition 18.5. P0MDOUT: Port0 Output Mode
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Reset Value
00000000
SFR Address: 0xA4
Bits7–0: Output Configuration Bits for P0.7–P0.0 (respectively): ignored if corresponding bit in register P0MDIN is logic 0.
0: Corresponding P0.n Output is open-drain.
1: Corresponding P0.n Output is push-pull.
(Note: When SDA and SCL appear on any of the Port I/O, each are open-drain regardless
of the value of P0MDOUT).
SFR Definition 18.6. P0SKIP: Port0 Skip
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xD4
Bits7–0: P0SKIP[7:0]: Port0 Crossbar Skip Enable Bits.
These bits select Port pins to be skipped by the Crossbar Decoder. Port pins used as analog inputs (for ADC or Comparator) or used as special functions (VREF input, external oscillator circuit, CNVSTR input) should be skipped by the Crossbar.
0: Corresponding P0.n pin is not skipped by the Crossbar.
1: Corresponding P0.n pin is skipped by the Crossbar.
146
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SFR Definition 18.7. P1: Port1
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
P1.7
P1.6
P1.5
P1.4
P1.3
P1.2
P1.1
P1.0
11111111
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Bit
Addressable
SFR Address: 0x90
Bits7–0: P1.[7:0]
Write - Output appears on I/O pins per Crossbar Registers.
0: Logic Low Output.
1: Logic High Output (high impedance if corresponding P1MDOUT.n bit = 0).
Read - Always reads ‘0’ if selected as analog input in register P1MDIN. Directly reads Port
pin when configured as digital input.
0: P1.n pin is logic low.
1: P1.n pin is logic high.
SFR Definition 18.8. P1MDIN: Port1 Input Mode
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Reset Value
11111111
SFR Address: 0xF2
Bits7–0: Analog Input Configuration Bits for P1.7–P1.0 (respectively).
Port pins configured as analog inputs have their weak pull-up, digital driver, and digital
receiver disabled.
0: Corresponding P1.n pin is configured as an analog input.
1: Corresponding P1.n pin is not configured as an analog input.
Rev. 1.1
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SFR Definition 18.9. P1MDOUT: Port1 Output Mode
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Reset Value
00000000
SFR Address: 0xA5
Bits7–0: Output Configuration Bits for P1.7–P1.0 (respectively): ignored if corresponding bit in register P1MDIN is logic 0.
0: Corresponding P1.n Output is open-drain.
1: Corresponding P1.n Output is push-pull.
SFR Definition 18.10. P1SKIP: Port1 Skip
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xD5
Bits7–0: P1SKIP[7:0]: Port1 Crossbar Skip Enable Bits.
These bits select Port pins to be skipped by the Crossbar Decoder. Port pins used as analog inputs (for ADC or Comparator) or used as special functions (VREF input, external oscillator circuit, CNVSTR input) should be skipped by the Crossbar.
0: Corresponding P1.n pin is not skipped by the Crossbar.
1: Corresponding P1.n pin is skipped by the Crossbar.
148
Rev. 1.1
C8051F350/1/2/3
SFR Definition 18.11. P2: Port2
R
R
R
R
R
R
R
R/W
Reset Value
—
—
—
—
—
—
—
P2.0
00000001
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Bit
Addressable
SFR Address: 0xA0
Bits7–1: Unused. Read = 0000000b. Write = don’t care.
Bit0:
P2.0
Write - Output appears on I/O pins per Crossbar Registers.
0: Logic Low Output.
1: Logic High Output (high impedance if corresponding P2MDOUT.n bit = 0).
Read - Directly reads Port pin.
0: P2.n pin is logic low.
1: P2.n pin is logic high.
SFR Definition 18.12. P2MDOUT: Port2 Output Mode
R
R
R
R
R
R
R
—
—
—
—
—
—
—
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
R/W
Reset Value
00000000
Bit0
SFR Address: 0xA6
Bits7–1: Unused. Read = 0000000b. Write = don’t care.
Bit0:
Output Configuration Bit for P2.0.
0: P2.0 Output is open-drain.
1: P2.0 Output is push-pull.
Rev. 1.1
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Table 18.1. Port I/O DC Electrical Characteristics
VDD = 2.7 to 3.6 V, –40 to +85 °C unless otherwise specified.
Parameters
Conditions
Min
Typ
Max
Units
IOH = –3 mA, Port I/O push-pull
IOH = –10 µA, Port I/O push-pull
IOH = –10 mA, Port I/O push-pull
VDD – 0.7
VDD – 0.1
—
—
—
VDD – 0.8
—
—
—
V
Output High Voltage
Output Low Voltage
IOL = 8.5 mA
IOL = 10 µA
IOL = 25 mA
—
—
—
—
—
1.0
0.6
0.1
—
V
Input High Voltage
2.0
—
—
V
Input Low Voltage
—
—
0.8
V
—
—
±1
50
µA
25
Input Leakage Current
150
Weak Pull-up Off
Weak Pull-up On, VIN = 0 V
Rev. 1.1
C8051F350/1/2/3
19. SMBus
The SMBus I/O interface is a two-wire, bi-directional serial bus. The SMBus is compliant with the System
Management Bus Specification, version 1.1, and compatible with the I2C serial bus. Reads and writes to
the interface by the system controller are byte oriented with the SMBus interface autonomously controlling
the serial transfer of the data. Data can be transferred at up to 1/20th of the system clock as a master or
slave (this can be faster than allowed by the SMBus specification, depending on the system clock used). A
method of extending the clock-low duration is available to accommodate devices with different speed
capabilities on the same bus.
The SMBus interface may operate as a master and/or slave, and may function on a bus with multiple masters. The SMBus provides control of SDA (serial data), SCL (serial clock) generation and synchronization,
arbitration logic, and START/STOP control and generation. Three SFRs are associated with the SMBus:
SMB0CF configures the SMBus; SMB0CN controls the status of the SMBus; and SMB0DAT is the data
register, used for both transmitting and receiving SMBus data and slave addresses.
SMB0CN
MT S S A A A S
A X T T CRC I
SMAOK B K
T O
R L
E D
QO
R E
S
T
SMB0CF
E I B E S S S S
N N U XMMMM
S H S T B B B B
M Y H T F CC
B
OOT S S
L E E 1 0
D
00
T0 Overflow
01
T1 Overflow
10
TMR2H Overflow
11
TMR2L Overflow
SMBUS CONTROL LOGIC
Interrupt
Request
Arbitration
SCL Synchronization
SCL Generation (Master Mode)
SDA Control
Data Path
IRQ Generation
Control
SCL
FILTER
SCL
Control
C
R
O
S
S
B
A
R
N
SDA
Control
SMB0DAT
7 6 5 4 3 2 1 0
Port I/O
SDA
FILTER
N
Figure 19.1. SMBus Block Diagram
Rev. 1.1
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19.1. Supporting Documents
It is assumed the reader is familiar with or has access to the following supporting documents:
1. The I2C-Bus and How to Use It (including specifications), Philips Semiconductor.
2. The I2C-Bus Specification -- Version 2.0, Philips Semiconductor.
3. System Management Bus Specification -- Version 1.1, SBS Implementers Forum.
19.2. SMBus Configuration
Figure 19.2 shows a typical SMBus configuration. The SMBus specification allows any recessive voltage
between 3.0 V and 5.0 V; different devices on the bus may operate at different voltage levels. The bi-directional SCL (serial clock) and SDA (serial data) lines must be connected to a positive power supply voltage
through a pull-up resistor or similar circuit. Every device connected to the bus must have an open-drain or
open-collector output for both the SCL and SDA lines, so that both are pulled high (recessive state) when
the bus is free. The maximum number of devices on the bus is limited only by the requirement that the rise
and fall times on the bus not exceed 300 ns and 1000 ns, respectively.
VDD = 5V
VDD = 3V
VDD = 5V
VDD = 3V
Master
Device
Slave
Device 1
Slave
Device 2
SDA
SCL
Figure 19.2. Typical SMBus Configuration
19.3. SMBus Operation
Two types of data transfers are possible: data transfers from a master transmitter to an addressed slave
receiver (WRITE), and data transfers from an addressed slave transmitter to a master receiver (READ).
The master device initiates both types of data transfers and provides the serial clock pulses on SCL. The
SMBus interface may operate as a master or a slave, and multiple master devices on the same bus are
supported. If two or more masters attempt to initiate a data transfer simultaneously, an arbitration scheme
is employed with a single master always winning the arbitration. Note that it is not necessary to specify one
device as the Master in a system; any device who transmits a START and a slave address becomes the
master for the duration of that transfer.
A typical SMBus transaction consists of a START condition followed by an address byte (Bits7–1: 7-bit
slave address; Bit0: R/W direction bit), one or more bytes of data, and a STOP condition. Each byte that is
received (by a master or slave) must be acknowledged (ACK) with a low SDA during a high SCL (see
Figure 19.3). If the receiving device does not ACK, the transmitting device will read a NACK (not acknowledge), which is a high SDA during a high SCL.
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The direction bit (R/W) occupies the least-significant bit position of the address byte. The direction bit is set
to logic 1 to indicate a "READ" operation and cleared to logic 0 to indicate a "WRITE" operation.
All transactions are initiated by a master, with one or more addressed slave devices as the target. The
master generates the START condition and then transmits the slave address and direction bit. If the transaction is a WRITE operation from the master to the slave, the master transmits the data a byte at a time
waiting for an ACK from the slave at the end of each byte. For READ operations, the slave transmits the
data waiting for an ACK from the master at the end of each byte. At the end of the data transfer, the master
generates a STOP condition to terminate the transaction and free the bus. Figure 19.3 illustrates a typical
SMBus transaction.
SCL
SDA
SLA6
START
SLA5-0
Slave Address + R/W
R/W
D7
ACK
D6-0
Data Byte
NACK
STOP
Figure 19.3. SMBus Transaction
19.3.1. Arbitration
A master may start a transfer only if the bus is free. The bus is free after a STOP condition or after the SCL
and SDA lines remain high for a specified time (see Section “19.3.4. SCL High (SMBus Free) Timeout’ on
page 154). In the event that two or more devices attempt to begin a transfer at the same time, an arbitration scheme is employed to force one master to give up the bus. The master devices continue transmitting
until one attempts a HIGH while the other transmits a LOW. Since the bus is open-drain, the bus will be
pulled LOW. The master attempting the HIGH will detect a LOW SDA and lose the arbitration. The winning
master continues its transmission without interruption; the losing master becomes a slave and receives the
rest of the transfer if addressed. This arbitration scheme is non-destructive: one device always wins, and
no data is lost.
Rev. 1.1
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19.3.2. Clock Low Extension
SMBus provides a clock synchronization mechanism, similar to I2C, which allows devices with different
speed capabilities to coexist on the bus. A clock-low extension is used during a transfer in order to allow
slower slave devices to communicate with faster masters. The slave may temporarily hold the SCL line
LOW to extend the clock low period, effectively decreasing the serial clock frequency.
19.3.3. SCL Low Timeout
If the SCL line is held low by a slave device on the bus, no further communication is possible. Furthermore,
the master cannot force the SCL line high to correct the error condition. To solve this problem, the SMBus
protocol specifies that devices participating in a transfer must detect any clock cycle held low longer than
25 ms as a “timeout” condition. Devices that have detected the timeout condition must reset the communication no later than 10 ms after detecting the timeout condition.
When the SMBTOE bit in SMB0CF is set, Timer 3 is used to detect SCL low timeouts. Timer 3 is forced to
reload when SCL is high, and allowed to count when SCL is low. With Timer 3 enabled and configured to
overflow after 25 ms (and SMBTOE set), the Timer 3 interrupt service routine can be used to reset (disable
and re-enable) the SMBus in the event of an SCL low timeout.
19.3.4. SCL High (SMBus Free) Timeout
The SMBus specification stipulates that if the SCL and SDA lines remain high for more that 50 µs, the bus
is designated as free. When the SMBFTE bit in SMB0CF is set, the bus will be considered free if SCL and
SDA remain high for more than 10 SMBus clock source periods. If the SMBus is waiting to generate a
Master START, the START will be generated following this timeout. Note that a clock source is required for
free timeout detection, even in a slave-only implementation.
154
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19.4. Using the SMBus
The SMBus can operate in both Master and Slave modes. The interface provides timing and shifting control for serial transfers; higher level protocol is determined by user software. The SMBus interface provides
the following application-independent features:
•
•
•
•
•
•
•
Byte-wise serial data transfers
Clock signal generation on SCL (Master Mode only) and SDA data synchronization
Timeout/bus error recognition, as defined by the SMB0CF configuration register
START/STOP timing, detection, and generation
Bus arbitration
Interrupt generation
Status information
SMBus interrupts are generated for each data byte or slave address that is transferred. When transmitting,
this interrupt is generated after the ACK cycle so that software may read the received ACK value; when
receiving data, this interrupt is generated before the ACK cycle so that software may define the outgoing
ACK value. See Section “19.5. SMBus Transfer Modes’ on page 163 for more details on transmission
sequences.
Interrupts are also generated to indicate the beginning of a transfer when a master (START generated), or
the end of a transfer when a slave (STOP detected). Software should read the SMB0CN (SMBus Control
register) to find the cause of the SMBus interrupt. The SMB0CN register is described in Section
“19.4.2. SMB0CN Control Register’ on page 159; Table 19.4 provides a quick SMB0CN decoding reference.
SMBus configuration options include:
•
•
•
•
Timeout detection (SCL Low Timeout and/or Bus Free Timeout)
SDA setup and hold time extensions
Slave event enable/disable
Clock source selection
These options are selected in the SMB0CF register, as described in Section “19.4.1. SMBus Configuration
Register’ on page 156.
Rev. 1.1
155
C8051F350/1/2/3
19.4.1. SMBus Configuration Register
The SMBus Configuration register (SMB0CF) is used to enable the SMBus Master and/or Slave modes,
select the SMBus clock source, and select the SMBus timing and timeout options. When the ENSMB bit is
set, the SMBus is enabled for all master and slave events. Slave events may be disabled by setting the
INH bit. With slave events inhibited, the SMBus interface will still monitor the SCL and SDA pins; however,
the interface will NACK all received addresses and will not generate any slave interrupts. When the INH bit
is set, all slave events will be inhibited following the next START (interrupts will continue for the duration of
the current transfer).
Table 19.1. SMBus Clock Source Selection
SMBCS1
0
0
1
1
SMBCS0
0
1
0
1
SMBus Clock Source
Timer 0 Overflow
Timer 1 Overflow
Timer 2 High Byte Overflow
Timer 2 Low Byte Overflow
The SMBCS1–0 bits select the SMBus clock source, which is used only when operating as a master or
when the Free Timeout detection is enabled. When operating as a master, overflows from the selected
source determine the absolute minimum SCL low and high times as defined in Equation 19.1. Note that the
selected clock source may be shared by other peripherals so long as the timer is left running at all times.
For example, Timer 1 overflows may generate the SMBus and UART baud rates simultaneously. Timer
configuration is covered in Section “22. Timers’ on page 195.
1
T HighMin = T LowMin = ---------------------------------------------f ClockSourceOverflow
Equation 19.1. Minimum SCL High and Low Times
The selected clock source should be configured to establish the minimum SCL High and Low times as per
Equation 19.1. When the interface is operating as a master (and SCL is not driven or extended by any
other devices on the bus), the typical SMBus bit rate is approximated by Equation 19.2.
f ClockSourceOverflow
BitRate = ---------------------------------------------3
Equation 19.2. Typical SMBus Bit Rate
156
Rev. 1.1
C8051F350/1/2/3
Figure 19.4 shows the typical SCL generation described by Equation 19.2. Notice that THIGH is typically
twice as large as TLOW. The actual SCL output may vary due to other devices on the bus (SCL may be
extended low by slower slave devices, or driven low by contending master devices). The bit rate when
operating as a master will never exceed the limits defined by equation Equation 19.1.
Timer Source
Overflows
SCL
TLow
SCL High Timeout
THigh
Figure 19.4. Typical SMBus SCL Generation
Setting the EXTHOLD bit extends the minimum setup and hold times for the SDA line. The minimum SDA
setup time defines the absolute minimum time that SDA is stable before SCL transitions from low-to-high.
The minimum SDA hold time defines the absolute minimum time that the current SDA value remains stable
after SCL transitions from high-to-low. EXTHOLD should be set so that the minimum setup and hold times
meet the SMBus Specification requirements of 250 ns and 300 ns, respectively. Table 19.2 shows the minimum setup and hold times for the two EXTHOLD settings. Setup and hold time extensions are typically
necessary when SYSCLK is above 10 MHz.
Table 19.2. Minimum SDA Setup and Hold Times
EXTHOLD
Minimum SDA Setup Time
Tlow – 4 system clocks
Minimum SDA Hold Time
0
OR
3 system clocks
1
1 system clock + s/w delay*
11 system clocks
12 system clocks
*Note: Setup Time for ACK bit transmissions and the MSB of all data transfers. The s/w
delay occurs between the time SMB0DAT or ACK is written and when SI is cleared.
Note that if SI is cleared in the same write that defines the outgoing ACK value, s/w
delay is zero.
With the SMBTOE bit set, Timer 3 should be configured to overflow after 25 ms in order to detect SCL low
timeouts (see Section “19.3.3. SCL Low Timeout’ on page 154). The SMBus interface will force Timer 3 to
reload while SCL is high, and allow Timer 3 to count when SCL is low. The Timer 3 interrupt service routine
should be used to reset SMBus communication by disabling and re-enabling the SMBus.
SMBus Free Timeout detection can be enabled by setting the SMBFTE bit. When this bit is set, the bus will
be considered free if SDA and SCL remain high for more than 10 SMBus clock source periods (see
Figure 19.4). When a Free Timeout is detected, the interface will respond as if a STOP was detected (an
interrupt will be generated, and STO will be set).
Rev. 1.1
157
C8051F350/1/2/3
SFR Definition 19.1. SMB0CF: SMBus Clock/Configuration
R/W
R/W
R
ENSMB
INH
BUSY
Bit7
Bit6
Bit5
R/W
R/W
R/W
R/W
EXTHOLD SMBTOE SMBFTE SMBCS1
Bit4
Bit3
Bit2
Bit1
R/W
Reset Value
SMBCS0 00000000
Bit0
SFR Address: 0xC1
Bit7:
ENSMB: SMBus Enable.
This bit enables/disables the SMBus interface. When enabled, the interface constantly monitors the SDA and SCL pins.
0: SMBus interface disabled.
1: SMBus interface enabled.
Bit6:
INH: SMBus Slave Inhibit.
When this bit is set to logic 1, the SMBus does not generate an interrupt when slave events
occur. This effectively removes the SMBus slave from the bus. Master Mode interrupts are
not affected.
0: SMBus Slave Mode enabled.
1: SMBus Slave Mode inhibited.
Bit5:
BUSY: SMBus Busy Indicator.
This bit is set to logic 1 by hardware when a transfer is in progress. It is cleared to logic 0
when a STOP or free-timeout is sensed.
Bit4:
EXTHOLD: SMBus Setup and Hold Time Extension Enable.
This bit controls the SDA setup and hold times according to Table 19.2.
0: SDA Extended Setup and Hold Times disabled.
1: SDA Extended Setup and Hold Times enabled.
Bit3:
SMBTOE: SMBus SCL Timeout Detection Enable.
This bit enables SCL low timeout detection. If set to logic 1, the SMBus forces Timer 3 to
reload while SCL is high and allows Timer 3 to count when SCL goes low. If Timer 3 is configured in split mode (T3SPLIT is set), only the high byte of Timer 3 is held in reload while
SCL is high. Timer 3 should be programmed to generate interrupts at 25 ms, and the
Timer 3 interrupt service routine should reset SMBus communication.
Bit2:
SMBFTE: SMBus Free Timeout Detection Enable.
When this bit is set to logic 1, the bus will be considered free if SCL and SDA remain high for
more than 10 SMBus clock source periods.
Bits1–0: SMBCS1–SMBCS0: SMBus Clock Source Selection.
These two bits select the SMBus clock source, which is used to generate the SMBus bit
rate. The selected device should be configured according to Equation 19.1.
SMBCS1
0
0
1
1
158
SMBCS0
0
1
0
1
SMBus Clock Source
Timer 0 Overflow
Timer 1 Overflow
Timer 2 High Byte Overflow
Timer 2 Low Byte Overflow
Rev. 1.1
C8051F350/1/2/3
19.4.2. SMB0CN Control Register
SMB0CN is used to control the interface and to provide status information (see SFR Definition 19.2). The
higher four bits of SMB0CN (MASTER, TXMODE, STA, and STO) form a status vector that can be used to
jump to service routines. MASTER and TXMODE indicate the master/slave state and transmit/receive
modes, respectively.
STA and STO indicate that a START and/or STOP has been detected or generated since the last SMBus
interrupt. STA and STO are also used to generate START and STOP conditions when operating as a master. Writing a ‘1’ to STA will cause the SMBus interface to enter Master Mode and generate a START when
the bus becomes free (STA is not cleared by hardware after the START is generated). Writing a ‘1’ to STO
while in Master Mode will cause the interface to generate a STOP and end the current transfer after the
next ACK cycle. If STO and STA are both set (while in Master Mode), a STOP followed by a START will be
generated.
As a receiver, writing the ACK bit defines the outgoing ACK value; as a transmitter, reading the ACK bit
indicates the value received on the last ACK cycle. ACKRQ is set each time a byte is received, indicating
that an outgoing ACK value is needed. When ACKRQ is set, software should write the desired outgoing
value to the ACK bit before clearing SI. A NACK will be generated if software does not write the ACK bit
before clearing SI. SDA will reflect the defined ACK value immediately following a write to the ACK bit;
however SCL will remain low until SI is cleared. If a received slave address is not acknowledged, further
slave events will be ignored until the next START is detected.
The ARBLOST bit indicates that the interface has lost an arbitration. This may occur anytime the interface
is transmitting (master or slave). A lost arbitration while operating as a slave indicates a bus error condition. ARBLOST is cleared by hardware each time SI is cleared.
The SI bit (SMBus Interrupt Flag) is set at the beginning and end of each transfer, after each byte frame, or
when an arbitration is lost; see Table 19.3 for more details.
Important note about the SI bit: The SMBus interface is stalled while SI is set; thus SCL is held low, and
the bus is stalled until software clears SI.
Table 19.3 lists all sources for hardware changes to the SMB0CN bits. Refer to Table 19.4 for SMBus status decoding using the SMB0CN register.
Rev. 1.1
159
C8051F350/1/2/3
SFR Definition 19.2. SMB0CN: SMBus Control
R
R
MASTER TXMODE
Bit7
Bit6
R/W
R/W
STA
STO
Bit5
Bit4
R
R
ACKRQ ARBLOST
Bit3
Bit2
R/W
R/W
Reset Value
ACK
SI
00000000
Bit1
Bit0
Bit
Addressable
SFR Address: 0xC0
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
160
MASTER: SMBus Master/Slave Indicator.
This read-only bit indicates when the SMBus is operating as a master.
0: SMBus operating in Slave Mode.
1: SMBus operating in Master Mode.
TXMODE: SMBus Transmit Mode Indicator.
This read-only bit indicates when the SMBus is operating as a transmitter.
0: SMBus in Receiver Mode.
1: SMBus in Transmitter Mode.
STA: SMBus Start Flag.
Write:
0: No Start generated.
1: When operating as a master, a START condition is transmitted if the bus is free (If the bus
is not free, the START is transmitted after a STOP is received or a timeout is detected). If
STA is set by software as an active Master, a repeated START will be generated after the
next ACK cycle.
Read:
0: No Start or repeated Start detected.
1: Start or repeated Start detected.
STO: SMBus Stop Flag.
Write:
0: No STOP condition is transmitted.
1: Setting STO to logic 1 causes a STOP condition to be transmitted after the next ACK
cycle. When the STOP condition is generated, hardware clears STO to logic 0. If both STA
and STO are set, a STOP condition is transmitted followed by a START condition.
Read:
0: No Stop condition detected.
1: Stop condition detected (if in Slave Mode) or pending (if in Master Mode).
ACKRQ: SMBus Acknowledge Request
This read-only bit is set to logic 1 when the SMBus has received a byte and needs the ACK
bit to be written with the correct ACK response value.
ARBLOST: SMBus Arbitration Lost Indicator.
This read-only bit is set to logic 1 when the SMBus loses arbitration while operating as a
transmitter. A lost arbitration while a slave indicates a bus error condition.
ACK: SMBus Acknowledge Flag.
This bit defines the out-going ACK level and records incoming ACK levels. It should be written each time a byte is received (when ACKRQ=1), or read after each byte is transmitted.
0: A "not acknowledge" has been received (if in Transmitter Mode) OR will be transmitted (if
in Receiver Mode).
1: An "acknowledge" has been received (if in Transmitter Mode) OR will be transmitted (if in
Receiver Mode).
SI: SMBus Interrupt Flag.
This bit is set by hardware under the conditions listed in Table 19.3. SI must be cleared by
software. While SI is set, SCL is held low and the SMBus is stalled.
Rev. 1.1
C8051F350/1/2/3
Table 19.3. Sources for Hardware Changes to SMB0CN
Bit
MASTER
TXMODE
STA
STO
ACKRQ
ARBLOST
ACK
SI
Set by Hardware When:
• A START is generated.
• START is generated.
• SMB0DAT is written before the start of an
SMBus frame.
• A START followed by an address byte is
received.
• A STOP is detected while addressed as a
slave.
• Arbitration is lost due to a detected STOP.
• A byte has been received and an ACK
response value is needed.
• A repeated START is detected as a MASTER
when STA is low (unwanted repeated START).
• SCL is sensed low while attempting to generate a STOP or repeated START condition.
• SDA is sensed low while transmitting a ‘1’
(excluding ACK bits).
• The incoming ACK value is low (ACKNOWLEDGE).
• A START has been generated.
• Lost arbitration.
• A byte has been transmitted and an
ACK/NACK received.
• A byte has been received.
• A START or repeated START followed by a
slave address + R/W has been received.
• A STOP has been received.
Rev. 1.1
Cleared by Hardware When:
• A STOP is generated.
• Arbitration is lost.
• A START is detected.
• Arbitration is lost.
• SMB0DAT is not written before the
start of an SMBus frame.
• Must be cleared by software.
• A pending STOP is generated.
• After each ACK cycle.
• Each time SI is cleared.
• The incoming ACK value is high (NOT
ACKNOWLEDGE).
• Must be cleared by software.
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C8051F350/1/2/3
19.4.3. Data Register
The SMBus Data register SMB0DAT holds a byte of serial data to be transmitted or one that has just been
received. Software may safely read or write to the data register when the SI flag is set. Software should not
attempt to access the SMB0DAT register when the SMBus is enabled and the SI flag is cleared to logic 0,
as the interface may be in the process of shifting a byte of data into or out of the register.
Data in SMB0DAT is always shifted out MSB first. After a byte has been received, the first bit of received
data is located at the MSB of SMB0DAT. While data is being shifted out, data on the bus is simultaneously
being shifted in. SMB0DAT always contains the last data byte present on the bus. In the event of lost arbitration, the transition from master transmitter to slave receiver is made with the correct data or address in
SMB0DAT.
SFR Definition 19.3. SMB0DAT: SMBus Data
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xC2
Bits7–0: SMB0DAT: SMBus Data.
The SMB0DAT register contains a byte of data to be transmitted on the SMBus serial interface or a byte that has just been received on the SMBus serial interface. The CPU can read
from or write to this register whenever the SI serial interrupt flag (SMB0CN.0) is set to
logic 1. The serial data in the register remains stable as long as the SI flag is set. When the
SI flag is not set, the system may be in the process of shifting data in/out and the CPU
should not attempt to access this register.
162
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19.5. SMBus Transfer Modes
The SMBus interface may be configured to operate as master and/or slave. At any particular time, it will be
operating in one of the following four modes: Master Transmitter, Master Receiver, Slave Transmitter, or
Slave Receiver. The SMBus interface enters Master Mode any time a START is generated, and remains in
Master Mode until it loses an arbitration or generates a STOP. An SMBus interrupt is generated at the end
of all SMBus byte frames; however, note that the interrupt is generated before the ACK cycle when operating as a receiver, and after the ACK cycle when operating as a transmitter.
19.5.1. Master Transmitter Mode
Serial data is transmitted on SDA while the serial clock is output on SCL. The SMBus interface generates
the START condition and transmits the first byte containing the address of the target slave and the data
direction bit. In this case the data direction bit (R/W) will be logic 0 (WRITE). The master then transmits
one or more bytes of serial data. After each byte is transmitted, an acknowledge bit is generated by the
slave. The transfer is ended when the STO bit is set and a STOP is generated. Note that the interface will
switch to Master Receiver Mode if SMB0DAT is not written following a Master Transmitter interrupt.
Figure 19.5 shows a typical Master Transmitter sequence. Two transmit data bytes are shown, though any
number of bytes may be transmitted. Notice that the ‘data byte transferred’ interrupts occur after the ACK
cycle in this mode.
S
SLA
W
Interrupt
A
Interrupt
Data Byte
A
Data Byte
Interrupt
A
P
Interrupt
S = START
P = STOP
A = ACK
W = WRITE
SLA = Slave Address
Received by SMBus
Interface
Transmitted by
SMBus Interface
Figure 19.5. Typical Master Transmitter Sequence
Rev. 1.1
163
C8051F350/1/2/3
19.5.2. Master Receiver Mode
Serial data is received on SDA while the serial clock is output on SCL. The SMBus interface generates the
START condition and transmits the first byte containing the address of the target slave and the data direction bit. In this case the data direction bit (R/W) will be logic 1 (READ). Serial data is then received from the
slave on SDA while the SMBus outputs the serial clock. The slave transmits one or more bytes of serial
data. After each byte is received, ACKRQ is set to ‘1’ and an interrupt is generated. Software must write
the ACK bit (SMB0CN.1) to define the outgoing acknowledge value (Note: writing a ‘1’ to the ACK bit generates an ACK; writing a ‘0’ generates a NACK). Software should write a ‘0’ to the ACK bit after the last
byte is received, to transmit a NACK. The interface exits Master Receiver Mode after the STO bit is set and
a STOP is generated. Note that the interface will switch to Master Transmitter Mode if SMB0DAT is written
while an active Master Receiver. Figure 19.6 shows a typical Master Receiver sequence. Two received
data bytes are shown, though any number of bytes may be received. Notice that the ‘data byte transferred’
interrupts occur before the ACK cycle in this mode.
S
SLA
R
Interrupt
A
Interrupt
Data Byte
A
Interrupt
Data Byte
N
Interrupt
S = START
P = STOP
A = ACK
N = NACK
R = READ
SLA = Slave Address
Received by SMBus
Interface
Transmitted by
SMBus Interface
Figure 19.6. Typical Master Receiver Sequence
164
Rev. 1.1
P
C8051F350/1/2/3
19.5.3. Slave Receiver Mode
Serial data is received on SDA and the clock is received on SCL. When slave events are enabled (INH =
0), the interface enters Slave Receiver Mode when a START followed by a slave address and direction bit
(WRITE in this case) is received. Upon entering Slave Receiver Mode, an interrupt is generated and the
ACKRQ bit is set. Software responds to the received slave address with an ACK, or ignores the received
slave address with a NACK. If the received slave address is ignored, slave interrupts will be inhibited until
the next START is detected. If the received slave address is acknowledged, zero or more data bytes are
received. Software must write the ACK bit after each received byte to ACK or NACK the received byte. The
interface exits Slave Receiver Mode after receiving a STOP. Note that the interface will switch to Slave
Transmitter Mode if SMB0DAT is written while an active Slave Receiver. Figure 19.7 shows a typical Slave
Receiver sequence. Two received data bytes are shown, though any number of bytes may be received.
Notice that the ‘data byte transferred’ interrupts occur before the ACK cycle in this mode.
Interrupt
S
SLA
W
A
Interrupt
Data Byte
A
Interrupt
Data Byte
A
P
Interrupt
S = START
P = STOP
A = ACK
W = WRITE
SLA = Slave Address
Received by SMBus
Interface
Transmitted by
SMBus Interface
Figure 19.7. Typical Slave Receiver Sequence
Rev. 1.1
165
C8051F350/1/2/3
19.5.4. Slave Transmitter Mode
Serial data is transmitted on SDA and the clock is received on SCL. When slave events are enabled (INH
= 0), the interface enters Slave Receiver Mode (to receive the slave address) when a START followed by a
slave address and direction bit (READ in this case) is received. Upon entering Slave Transmitter Mode, an
interrupt is generated and the ACKRQ bit is set. Software responds to the received slave address with an
ACK, or ignores the received slave address with a NACK. If the received slave address is ignored, slave
interrupts will be inhibited until a START is detected. If the received slave address is acknowledged, data
should be written to SMB0DAT to be transmitted. The interface enters Slave Transmitter Mode, and transmits one or more bytes of data. After each byte is transmitted, the master sends an acknowledge bit; if the
acknowledge bit is an ACK, SMB0DAT should be written with the next data byte. If the acknowledge bit is
a NACK, SMB0DAT should not be written to before SI is cleared (Note: an error condition may be generated if SMB0DAT is written following a received NACK while in Slave Transmitter Mode). The interface
exits Slave Transmitter Mode after receiving a STOP. Note that the interface will switch to Slave Receiver
Mode if SMB0DAT is not written following a Slave Transmitter interrupt. Figure 19.8 shows a typical Slave
Transmitter sequence. Two transmitted data bytes are shown, though any number of bytes may be transmitted. Notice that the ‘data byte transferred’ interrupts occur after the ACK cycle in this mode.
Interrupt
S
SLA
R
A
Interrupt
Data Byte
A
Data Byte
Interrupt
N
P
Interrupt
S = START
P = STOP
N = NACK
R = READ
SLA = Slave Address
Received by SMBus
Interface
Transmitted by
SMBus Interface
Figure 19.8. Typical Slave Transmitter Sequence
166
Rev. 1.1
C8051F350/1/2/3
19.6. SMBus Status Decoding
The current SMBus status can be easily decoded using the SMB0CN register. In the table below, STATUS
VECTOR refers to the four upper bits of SMB0CN: MASTER, TXMODE, STA, and STO. Note that the
shown response options are only the typical responses; application-specific procedures are allowed as
long as they conform to the SMBus specification. Highlighted responses are allowed but do not conform to
the SMBus specification.
Table 19.4. SMBus Status Decoding
Values
Written
Status
Vector
ACKRQ
ARBLOST
ACK
1110
0
0
X A master START was generated.
0
0
0
0
1
0
0
X
1
0
X
0
1
X
Load next data byte into
SMB0DAT.
0
0
X
End transfer with STOP.
0
1
X
End transfer with STOP and
start another transfer.
1
1
X
Send repeated START.
1
0
X
Switch to Master Receiver
Mode (clear SI without writing new data to SMB0DAT).
0
0
X
Load slave address + R/W
into SMB0DAT.
Set STA to restart transfer.
A master data or address byte
was transmitted; NACK received. Abort transfer.
1100
0
ACK
Typical Response Options
STO
Current SMbus State
STA
Master Transmitter
Mode
Values Read
A master data or address byte
was transmitted; ACK received.
Rev. 1.1
167
C8051F350/1/2/3
Table 19.4. SMBus Status Decoding (Continued)
Values
Written
Slave Transmitter
168
0100
0101
ACK
X
ACK
0
Typical Response Options
STO
1
ARBLOST
ACKRQ
Status
Vector
1000
Current SMbus State
STA
Master Receiver
Mode
Values Read
Acknowledge received byte;
Read SMB0DAT.
0
0
1
Send NACK to indicate last
byte, and send STOP.
0
1
0
Send NACK to indicate last
byte, and send STOP followed by START.
1
1
0
Send ACK followed by
repeated START.
1
0
1
1
0
0
Send ACK and switch to
Master Transmitter Mode
(write to SMB0DAT before
clearing SI).
0
0
1
Send NACK and switch to
Master Transmitter Mode
(write to SMB0DAT before
clearing SI).
0
0
0
A master data byte was received; Send NACK to indicate last
ACK requested.
byte, and send repeated
START.
0
0
0
A slave byte was transmitted;
NACK received.
No action required (expecting STOP condition).
0
0
X
0
0
1
A slave byte was transmitted;
ACK received.
Load SMB0DAT with next
data byte to transmit.
0
0
X
0
1
X
A Slave byte was transmitted;
error detected.
No action required (expecting Master to end transfer).
0
0
X
0
X
A illegal STOP or bus error was
X detected while a Slave Transmis- Clear STO.
sion was in progress.
0
0
X
Rev. 1.1
C8051F350/1/2/3
Table 19.4. SMBus Status Decoding (Continued)
Values
Written
A slave address was received;
ACK requested.
0010
Slave Receiver
1
0010
0001
1
Lost arbitration as master; slave
X address received; ACK
requested.
ACK
ACK
X
Typical Response Options
STO
0
Current SMbus State
STA
1
ARBLOST
ACKRQ
Status
Vector
Mode
Values Read
Acknowledge received
address.
0
0
1
Do not acknowledge
received address.
0
0
0
Acknowledge received
address.
0
0
1
Do not acknowledge
received address.
0
0
0
Reschedule failed transfer;
do not acknowledge received
address.
1
0
0
0
0
X
1
0
X
0
0
0
0
0
X
0
0
X
1
0
X
Acknowledge received byte;
Read SMB0DAT.
0
0
1
Do not acknowledge
received byte.
0
0
0
0
0
0
1
0
0
0
1
X
Lost arbitration while attempting a Abort failed transfer.
repeated START.
Reschedule failed transfer.
1
1
X
Lost arbitration while attempting a No action required (transfer
STOP.
complete/aborted).
0
0
A STOP was detected while
X addressed as a Slave Transmitter Clear STO.
or Slave Receiver.
0
1
X
1
0
X
Lost arbitration due to a detected Abort transfer.
STOP.
Reschedule failed transfer.
A slave byte was received; ACK
requested.
0000
1
1
X
Lost arbitration while transmitting Abort failed transfer.
a data byte as master.
Reschedule failed transfer.
Rev. 1.1
169
C8051F350/1/2/3
NOTES:
170
Rev. 1.1
C8051F350/1/2/3
20. UART0
UART0 is an asynchronous, full duplex serial port offering modes 1 and 3 of the standard 8051 UART.
Enhanced baud rate support allows a wide range of clock sources to generate standard baud rates (details
in Section “20.1. Enhanced Baud Rate Generation’ on page 172). Received data buffering allows UART0
to start reception of a second incoming data byte before software has finished reading the previous data
byte.
UART0 has two associated SFRs: Serial Control Register 0 (SCON0) and Serial Data Buffer 0 (SBUF0).
The single SBUF0 location provides access to both transmit and receive registers. Writes to SBUF0
always access the Transmit register. Reads of SBUF0 always access the buffered Receive register;
it is not possible to read data from the Transmit register.
With UART0 interrupts enabled, an interrupt is generated each time a transmit is completed (TI0 is set in
SCON0), or a data byte has been received (RI0 is set in SCON0). The UART0 interrupt flags are not
cleared by hardware when the CPU vectors to the interrupt service routine. They must be cleared manually
by software, allowing software to determine the cause of the UART0 interrupt (transmit complete or receive
complete).
SFR Bus
Write to
SBUF
TB8
SBUF
(TX Shift)
SET
D
Q
TX
CLR
Crossbar
Zero Detector
Stop Bit
Shift
Start
Data
Tx Control
Tx Clock
Send
Tx IRQ
SCON
TI
Serial
Port
Interrupt
MCE
REN
TB8
RB8
TI
RI
SMODE
UART Baud
Rate Generator
Port I/O
RI
Rx IRQ
Rx Clock
Rx Control
Start
Shift
0x1FF
Load
SBUF
RB8
Input Shift Register
(9 bits)
Load SBUF
SBUF
(RX Latch)
Read
SBUF
SFR Bus
RX
Crossbar
Figure 20.1. UART0 Block Diagram
Rev. 1.1
171
C8051F350/1/2/3
20.1. Enhanced Baud Rate Generation
The UART0 baud rate is generated by Timer 1 in 8-bit auto-reload mode. The TX clock is generated by
TL1; the RX clock is generated by a copy of TL1 (shown as RX Timer in Figure 20.2), which is not useraccessible. Both TX and RX Timer overflows are divided by two to generate the TX and RX baud rates.
The RX Timer runs when Timer 1 is enabled, and uses the same reload value (TH1). However, an
RX Timer reload is forced when a START condition is detected on the RX pin. This allows a receive to
begin any time a START is detected, independent of the TX Timer state.
Timer 1
TL1
UART
Overflow
2
TX Clock
Overflow
2
RX Clock
TH1
Start
Detected
RX Timer
Figure 20.2. UART0 Baud Rate Logic
Timer 1 should be configured for Mode 2, 8-bit auto-reload (see Section “22.1.3. Mode 2: 8-bit
Counter/Timer with Auto-Reload’ on page 197). The Timer 1 reload value should be set so that overflows
will occur at two times the desired UART baud rate frequency. Note that Timer 1 may be clocked by one of
six sources: SYSCLK, SYSCLK / 4, SYSCLK / 12, SYSCLK / 48, the external oscillator clock / 8, or an
external input T1. The UART0 baud rate is determined by Equation 20.1-A and Equation 20.1-B.
A)
1
UartBaudRate = --- × T1_Overflow_Rate
2
B)
T1 CLK
T1_Overflow_Rate = -------------------------256 – TH1
Equation 20.1. UART0 Baud Rate
Where T1CLK is the frequency of the clock supplied to Timer 1, and T1H is the high byte of Timer 1 (reload
value). Timer 1 clock frequency is selected as described in Section “22. Timers’ on page 195. A quick reference for typical baud rates and system clock frequencies is given in Table 20.1 through Table 20.6. Note
that the internal oscillator may still generate the system clock when the external oscillator is driving
Timer 1.
172
Rev. 1.1
C8051F350/1/2/3
20.2. Operational Modes
UART0 provides standard asynchronous, full duplex communication. The UART mode (8-bit or 9-bit) is
selected by the S0MODE bit (SCON0.7). Typical UART connection options are shown below.
TX
RS-232
LEVEL
XLTR
RS-232
RX
C8051Fxxx
OR
TX
TX
RX
RX
MCU
C8051Fxxx
Figure 20.3. UART Interconnect Diagram
20.2.1. 8-Bit UART
8-Bit UART mode uses a total of 10 bits per data byte: one start bit, eight data bits (LSB first), and one stop
bit. Data are transmitted LSB first from the TX0 pin and received at the RX0 pin. On receive, the eight data
bits are stored in SBUF0 and the stop bit goes into RB80 (SCON0.2).
Data transmission begins when software writes a data byte to the SBUF0 register. The TI0 Transmit Interrupt Flag (SCON0.1) is set at the end of the transmission (the beginning of the stop-bit time). Data reception can begin any time after the REN0 Receive Enable bit (SCON0.4) is set to logic 1. After the stop bit is
received, the data byte will be loaded into the SBUF0 receive register if the following conditions are met:
RI0 must be logic 0, and if MCE0 is logic 1, the stop bit must be logic 1. In the event of a receive data overrun, the first received 8 bits are latched into the SBUF0 receive register and the following overrun data bits
are lost.
If these conditions are met, the eight bits of data is stored in SBUF0, the stop bit is stored in RB80 and the
RI0 flag is set. If these conditions are not met, SBUF0 and RB80 will not be loaded and the RI0 flag will not
be set. An interrupt will occur if enabled when either TI0 or RI0 is set.
MARK
SPACE
START
BIT
D0
D1
D2
D3
D4
D5
D6
D7
STOP
BIT
BIT TIMES
BIT SAMPLING
Figure 20.4. 8-Bit UART Timing Diagram
Rev. 1.1
173
C8051F350/1/2/3
20.2.2. 9-Bit UART
9-bit UART mode uses a total of eleven bits per data byte: a start bit, 8 data bits (LSB first), a programmable ninth data bit, and a stop bit. The state of the ninth transmit data bit is determined by the value in TB80
(SCON0.3), which is assigned by user software. It can be assigned the value of the parity flag (bit P in register PSW) for error detection, or used in multiprocessor communications. On receive, the ninth data bit
goes into RB80 (SCON0.2) and the stop bit is ignored.
Data transmission begins when an instruction writes a data byte to the SBUF0 register. The TI0 Transmit
Interrupt Flag (SCON0.1) is set at the end of the transmission (the beginning of the stop-bit time). Data
reception can begin any time after the REN0 Receive Enable bit (SCON0.4) is set to ‘1’. After the stop bit
is received, the data byte will be loaded into the SBUF0 receive register if the following conditions are met:
(1) RI0 must be logic 0, and (2) if MCE0 is logic 1, the 9th bit must be logic 1 (when MCE0 is logic 0, the
state of the ninth data bit is unimportant). If these conditions are met, the eight bits of data are stored in
SBUF0, the ninth bit is stored in RB80, and the RI0 flag is set to ‘1’. If the above conditions are not met,
SBUF0 and RB80 will not be loaded and the RI0 flag will not be set to ‘1’. A UART0 interrupt will occur if
enabled when either TI0 or RI0 is set to ‘1’.
MARK
SPACE
START
BIT
D0
D1
D2
D3
D4
D5
D6
D7
D8
STOP
BIT
BIT TIMES
BIT SAMPLING
Figure 20.5. 9-Bit UART Timing Diagram
20.3. Multiprocessor Communications
9-Bit UART mode supports multiprocessor communication between a master processor and one or more
slave processors by special use of the ninth data bit. When a master processor wants to transmit to one or
more slaves, it first sends an address byte to select the target(s). An address byte differs from a data byte
in that its ninth bit is logic 1; in a data byte, the ninth bit is always set to logic 0.
Setting the MCE0 bit (SCON0.5) of a slave processor configures its UART such that when a stop bit is
received, the UART will generate an interrupt only if the ninth bit is logic 1 (RB80 = 1) signifying an address
byte has been received. In the UART interrupt handler, software will compare the received address with
the slave's own assigned 8-bit address. If the addresses match, the slave will clear its MCE0 bit to enable
interrupts on the reception of the following data byte(s). Slaves that weren't addressed leave their MCE0
bits set and do not generate interrupts on the reception of the following data bytes, thereby ignoring the
data. Once the entire message is received, the addressed slave resets its MCE0 bit to ignore all transmissions until it receives the next address byte.
Multiple addresses can be assigned to a single slave and/or a single address can be assigned to multiple
slaves, thereby enabling "broadcast" transmissions to more than one slave simultaneously. The master
processor can be configured to receive all transmissions or a protocol can be implemented such that the
master/slave role is temporarily reversed to enable half-duplex transmission between the original master
and slave(s).
174
Rev. 1.1
C8051F350/1/2/3
Master
Device
Slave
Device
Slave
Device
Slave
Device
V+
RX
TX
RX
TX
RX
TX
RX
TX
Figure 20.6. UART Multi-Processor Mode Interconnect Diagram
Rev. 1.1
175
C8051F350/1/2/3
SFR Definition 20.1. SCON0: Serial Port 0 Control
R/W
R
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
S0MODE
—
MCE0
REN0
TB80
RB80
TI0
RI0
01000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Bit
Addressable
SFR Address: 0x98
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
176
S0MODE: Serial Port 0 Operation Mode.
This bit selects the UART0 Operation Mode.
0: 8-bit UART with Variable Baud Rate.
1: 9-bit UART with Variable Baud Rate.
UNUSED. Read = 1b. Write = don’t care.
MCE0: Multiprocessor Communication Enable.
The function of this bit is dependent on the Serial Port 0 Operation Mode.
S0MODE = 0: Checks for valid stop bit.
0: Logic level of stop bit is ignored.
1: RI0 will only be activated if stop bit is logic level 1.
S0MODE = 1: Multiprocessor Communications Enable.
0: Logic level of ninth bit is ignored.
1: RI0 is set and an interrupt is generated only when the ninth bit is logic 1.
REN0: Receive Enable.
This bit enables/disables the UART receiver.
0: UART0 reception disabled.
1: UART0 reception enabled.
TB80: Ninth Transmission Bit.
The logic level of this bit will be assigned to the ninth transmission bit in 9-bit UART Mode. It
is not used in 8-bit UART Mode. Set or cleared by software as required.
RB80: Ninth Receive Bit.
RB80 is assigned the value of the STOP bit in Mode 0; it is assigned the value of the 9th
data bit in Mode 1.
TI0: Transmit Interrupt Flag.
Set by hardware when a byte of data has been transmitted by UART0 (after the 8th bit in 8bit UART Mode, or at the beginning of the STOP bit in 9-bit UART Mode). When the UART0
interrupt is enabled, setting this bit causes the CPU to vector to the UART0 interrupt service
routine. This bit must be cleared manually by software.
RI0: Receive Interrupt Flag.
Set to ‘1’ by hardware when a byte of data has been received by UART0 (set at the STOP bit
sampling time). When the UART0 interrupt is enabled, setting this bit to ‘1’ causes the CPU
to vector to the UART0 interrupt service routine. This bit must be cleared manually by software.
Rev. 1.1
C8051F350/1/2/3
SFR Definition 20.2. SBUF0: Serial (UART0) Port Data Buffer
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Reset Value
00000000
SFR Address: 0x99
Bits7–0: SBUF0[7:0]: Serial Data Buffer Bits 7–0 (MSB–LSB)
This SFR accesses two registers; a transmit shift register and a receive latch register. When
data is written to SBUF0, it goes to the transmit shift register and is held for serial transmission. Writing a byte to SBUF0 initiates the transmission. A read of SBUF0 returns the contents of the receive latch.
Rev. 1.1
177
C8051F350/1/2/3
SYSCLK from
Internal Osc.
Table 20.1. Timer Settings for Standard Baud Rates
Using the Internal Oscillator
Target
Baud Rate
(bps)
230400
115200
57600
28800
14400
9600
2400
1200
Baud Rate
% Error
–0.32%
–0.32%
0.15%
–0.32%
0.15%
–0.32%
–0.32%
0.15%
Frequency: 24.5 MHz
Oscilla- Timer Clock SCA1–SCA0
tor Divide
Source
(pre-scale
Factor
select)*
106
SYSCLK
XX
212
SYSCLK
XX
426
SYSCLK
XX
848
SYSCLK / 4
01
1704
SYSCLK / 12
00
2544
SYSCLK / 12
00
10176
SYSCLK / 48
10
20448
SYSCLK / 48
10
X = Don’t care
T1M*
1
1
1
0
0
0
0
0
Timer 1
Reload
Value (hex)
0xCB
0x96
0x2B
0x96
0xB9
0x96
0x96
0x2B
*Note: SCA1–SCA0 and T1M bit definitions can be found in Section 22.1.
SYSCLK from SYSCLK from
Internal Osc. External Osc.
Table 20.2. Timer Settings for Standard Baud Rates
Using an External 25.0 MHz Oscillator
Target
Baud Rate
(bps)
230400
115200
57600
28800
14400
9600
2400
1200
57600
28800
14400
Baud Rate
% Error
9600
0.15%
–0.47%
0.45%
–0.01%
0.45%
–0.01%
0.15%
0.45%
–0.01%
–0.47%
–0.47%
0.45%
Frequency: 25.0 MHz
Oscilla- Timer Clock SCA1–SCA0
tor Divide
Source
(pre-scale
Factor
select)*
108
SYSCLK
XX
218
SYSCLK
XX
434
SYSCLK
XX
872
SYSCLK / 4
01
1736
SYSCLK / 4
01
2608
EXTCLK / 8
11
10464
SYSCLK / 48
10
20832
SYSCLK / 48
10
432
EXTCLK / 8
11
864
EXTCLK / 8
11
1744
EXTCLK / 8
11
2608
EXTCLK / 8
11
T1M*
1
1
1
0
0
0
0
0
0
0
0
Timer 1
Reload
Value (hex)
0xCA
0x93
0x27
0x93
0x27
0x5D
0x93
0x27
0xE5
0xCA
0x93
0
0x5D
X = Don’t care
*Note: SCA1–SCA0 and T1M bit definitions can be found in Section 22.1.
178
Rev. 1.1
C8051F350/1/2/3
SYSCLK from
Internal Osc.
SYSCLK from
External Osc.
Table 20.3. Timer Settings for Standard Baud Rates
Using an External 22.1184 MHz Oscillator
Target
Baud Rate
(bps)
230400
115200
57600
28800
14400
9600
2400
1200
230400
115200
57600
28800
14400
9600
Baud Rate
% Error
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
Frequency: 22.1184 MHz
Oscilla- Timer Clock SCA1–SCA0
tor Divide
Source
(pre-scale
Factor
select)*
96
SYSCLK
XX
192
SYSCLK
XX
384
SYSCLK
XX
768
SYSCLK / 12
00
1536
SYSCLK / 12
00
2304
SYSCLK / 12
00
9216
SYSCLK / 48
10
18432
SYSCLK / 48
10
96
EXTCLK / 8
11
192
EXTCLK / 8
11
384
EXTCLK / 8
11
768
EXTCLK / 8
11
1536
EXTCLK / 8
11
2304
EXTCLK / 8
11
X = Don’t care
T1M*
1
1
1
0
0
0
0
0
0
0
0
0
0
0
Timer 1
Reload
Value (hex)
0xD0
0xA0
0x40
0xE0
0xC0
0xA0
0xA0
0x40
0xFA
0xF4
0xE8
0xD0
0xA0
0x70
*Note: SCA1–SCA0 and T1M bit definitions can be found in Section 22.1.
SYSCLK from
Internal Osc.
SYSCLK from
External Osc.
Table 20.4. Timer Settings for Standard Baud Rates
Using an External 18.432 MHz Oscillator
Target
Baud Rate
(bps)
230400
115200
57600
28800
14400
9600
2400
1200
230400
115200
57600
28800
14400
9600
Baud Rate
% Error
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
Frequency: 18.432 MHz
Oscilla- Timer Clock
SCA1–SCA0
tor Divide
Source
(pre-scale
Factor
select)*
80
SYSCLK
XX
160
SYSCLK
XX
320
SYSCLK
XX
640
SYSCLK / 4
01
1280
SYSCLK / 4
01
1920
SYSCLK / 12
00
7680
SYSCLK / 48
10
15360
SYSCLK / 48
10
80
EXTCLK / 8
11
160
EXTCLK / 8
11
320
EXTCLK / 8
11
640
EXTCLK / 8
11
1280
EXTCLK / 8
11
1920
EXTCLK / 8
11
X = Don’t care
T1M*
1
1
1
0
0
0
0
0
0
0
0
0
0
0
Timer 1
Reload
Value (hex)
0xD8
0xB0
0x60
0xB0
0x60
0xB0
0xB0
0x60
0xFB
0xF6
0xEC
0xD8
0xB0
0x88
*Note: SCA1–SCA0 and T1M bit definitions can be found in Section 22.1.
Rev. 1.1
179
C8051F350/1/2/3
SYSCLK from
Internal Osc.
SYSCLK from
External Osc.
Table 20.5. Timer Settings for Standard Baud Rates
Using an External 11.0592 MHz Oscillator
Target
Baud Rate
(bps)
230400
115200
57600
28800
14400
9600
2400
1200
230400
115200
57600
28800
14400
9600
Baud Rate
% Error
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
Frequency: 11.0592 MHz
Oscilla- Timer Clock SCA1–SCA0
tor Divide
Source
(pre-scale
Factor
select)*
48
SYSCLK
XX
96
SYSCLK
XX
192
SYSCLK
XX
384
SYSCLK
XX
768
SYSCLK / 12
00
1152
SYSCLK / 12
00
4608
SYSCLK / 12
00
9216
SYSCLK / 48
10
48
EXTCLK / 8
11
96
EXTCLK / 8
11
192
EXTCLK / 8
11
384
EXTCLK / 8
11
768
EXTCLK / 8
11
1152
EXTCLK / 8
11
X = Don’t care
T1M*
1
1
1
1
0
0
0
0
0
0
0
0
0
0
Timer 1
Reload
Value (hex)
0xE8
0xD0
0xA0
0x40
0xE0
0xD0
0x40
0xA0
0xFD
0xFA
0xF4
0xE8
0xD0
0xB8
*Note: SCA1–SCA0 and T1M bit definitions can be found in Section 22.1.
SYSCLK from
Internal Osc.
SYSCLK from
External Osc.
Table 20.6. Timer Settings for Standard Baud Rates
Using an External 3.6864 MHz Oscillator
Target
Baud Rate
(bps)
230400
115200
57600
28800
14400
9600
2400
1200
230400
115200
57600
28800
14400
9600
Baud
Rate%
Error
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
Frequency: 3.6864 MHz
Oscilla- Timer Clock
SCA1–SCA0
tor Divide
Source
(pre-scale
Factor
select)*
16
SYSCLK
XX
32
SYSCLK
XX
64
SYSCLK
XX
128
SYSCLK
XX
256
SYSCLK
XX
384
SYSCLK
XX
1536
SYSCLK / 12
00
3072
SYSCLK / 12
00
16
EXTCLK / 8
11
32
EXTCLK / 8
11
64
EXTCLK / 8
11
128
EXTCLK / 8
11
256
EXTCLK / 8
11
384
EXTCLK / 8
11
X = Don’t care
T1M*
1
1
1
1
1
1
0
0
0
0
0
0
0
0
*Note: SCA1–SCA0 and T1M bit definitions can be found in Section 22.1.
180
Rev. 1.1
Timer 1
Reload
Value (hex)
0xF8
0xF0
0xE0
0xC0
0x80
0x40
0xC0
0x80
0xFF
0xFE
0xFC
0xF8
0xF0
0xE8
C8051F350/1/2/3
21. Serial Peripheral Interface (SPI0)
The Serial Peripheral Interface (SPI0) provides access to a flexible, full-duplex synchronous serial bus.
SPI0 can operate as a master or slave device in both 3-wire or 4-wire modes, and supports multiple masters and slaves on a single SPI bus. The slave-select (NSS) signal can be configured as an input to select
SPI0 in slave mode, or to disable Master Mode operation in a multi-master environment, avoiding contention on the SPI bus when more than one master attempts simultaneous data transfers. NSS can also be
configured as a chip-select output in master mode, or disabled for 3-wire operation. Additional general purpose port I/O pins can be used to select multiple slave devices in master mode.
SFR Bus
SYSCLK
SPI0CN
SPIBSY
MSTEN
CKPHA
CKPOL
SLVSEL
NSSIN
SRMT
RXBMT
SPIF
WCOL
MODF
RXOVRN
NSSMD1
NSSMD0
TXBMT
SPIEN
SPI0CFG
SCR7
SCR6
SCR5
SCR4
SCR3
SCR2
SCR1
SCR0
SPI0CKR
Clock Divide
Logic
SPI CONTROL LOGIC
Data Path
Control
SPI IRQ
Pin Interface
Control
MOSI
Tx Data
SPI0DAT
SCK
Transmit Data Buffer
Shift Register
7 6 5 4 3 2 1 0
Rx Data
Pin
Control
Logic
Receive Data Buffer
MISO
C
R
O
S
S
B
A
R
Port I/O
NSS
Read
SPI0DAT
Write
SPI0DAT
SFR Bus
Figure 21.1. SPI Block Diagram
Rev. 1.1
181
C8051F350/1/2/3
21.1. Signal Descriptions
The four signals used by SPI0 (MOSI, MISO, SCK, NSS) are described below.
21.1.1. Master Out, Slave In (MOSI)
The master-out, slave-in (MOSI) signal is an output from a master device and an input to slave devices. It
is used to serially transfer data from the master to the slave. This signal is an output when SPI0 is operating as a master and an input when SPI0 is operating as a slave. Data is transferred most-significant bit
first. When configured as a master, MOSI is driven by the MSB of the shift register in both 3- and 4-wire
mode.
21.1.2. Master In, Slave Out (MISO)
The master-in, slave-out (MISO) signal is an output from a slave device and an input to the master device.
It is used to serially transfer data from the slave to the master. This signal is an input when SPI0 is operating as a master and an output when SPI0 is operating as a slave. Data is transferred most-significant bit
first. The MISO pin is placed in a high-impedance state when the SPI module is disabled and when the SPI
operates in 4-wire mode as a slave that is not selected. When acting as a slave in 3-wire mode, MISO is
always driven by the MSB of the shift register.
21.1.3. Serial Clock (SCK)
The serial clock (SCK) signal is an output from the master device and an input to slave devices. It is used
to synchronize the transfer of data between the master and slave on the MOSI and MISO lines. SPI0 generates this signal when operating as a master. The SCK signal is ignored by a SPI slave when the slave is
not selected (NSS = 1) in 4-wire slave mode.
21.1.4. Slave Select (NSS)
The function of the slave-select (NSS) signal is dependent on the setting of the NSSMD1 and NSSMD0
bits in the SPI0CN register. There are three possible modes that can be selected with these bits:
1. NSSMD[1:0] = 00: 3-Wire Master or 3-Wire Slave Mode: SPI0 operates in 3-wire mode, and
NSS is disabled. When operating as a slave device, SPI0 is always selected in 3-wire mode.
Since no select signal is present, SPI0 must be the only slave on the bus in 3-wire mode. This
is intended for point-to-point communication between a master and one slave.
2. NSSMD[1:0] = 01: 4-Wire Slave or Multi-Master Mode: SPI0 operates in 4-wire mode, and
NSS is enabled as an input. When operating as a slave, NSS selects the SPI0 device. When
operating as a master, a 1-to-0 transition of the NSS signal disables the master function of
SPI0 so that multiple master devices can be used on the same SPI bus.
3. NSSMD[1:0] = 1x: 4-Wire Master Mode: SPI0 operates in 4-wire mode, and NSS is enabled as
an output. The setting of NSSMD0 determines what logic level the NSS pin will output. This
configuration should only be used when operating SPI0 as a master device.
See Figure 21.2, Figure 21.3, and Figure 21.4 for typical connection diagrams of the various operational
modes. Note that the setting of NSSMD bits affects the pinout of the device. When in 3-wire master or
3-wire slave mode, the NSS pin will not be mapped by the crossbar. In all other modes, the NSS signal will
be mapped to a pin on the device. See Section “18. Port Input/Output’ on page 137 for general purpose
port I/O and crossbar information.
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21.2. SPI0 Master Mode Operation
A SPI master device initiates all data transfers on a SPI bus. SPI0 is placed in master mode by setting the
Master Enable flag (MSTEN, SPI0CN.6). Writing a byte of data to the SPI0 data register (SPI0DAT) when
in master mode writes to the transmit buffer. If the SPI shift register is empty, the byte in the transmit buffer
is moved to the shift register, and a data transfer begins. The SPI0 master immediately shifts out the data
serially on the MOSI line while providing the serial clock on SCK. The SPIF (SPI0CN.7) flag is set to logic
1 at the end of the transfer. If interrupts are enabled, an interrupt request is generated when the SPIF flag
is set. While the SPI0 master transfers data to a slave on the MOSI line, the addressed SPI slave device
simultaneously transfers data to the SPI master on the MISO line in a full-duplex operation. Therefore, the
SPIF flag serves as both a transmit-complete and receive-data-ready flag. The data byte received from the
slave is transferred MSB-first into the master's shift register. When a byte is fully shifted into the register, it
is moved to the receive buffer where it can be read by the processor by reading SPI0DAT.
When configured as a master, SPI0 can operate in one of three different modes: multi-master mode, 3-wire
single-master mode, and 4-wire single-master mode. The default, multi-master mode is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 1. In this mode, NSS is an input to the device, and is
used to disable the master SPI0 when another master is accessing the bus. When NSS is pulled low in this
mode, MSTEN (SPI0CN.6) and SPIEN (SPI0CN.0) are set to 0 to disable the SPI master device, and a
Mode Fault is generated (MODF, SPI0CN.5 = 1). Mode Fault will generate an interrupt if enabled. SPI0
must be manually re-enabled in software under these circumstances. In multi-master systems, devices will
typically default to being slave devices while they are not acting as the system master device. In multi-master mode, slave devices can be addressed individually (if needed) using general-purpose I/O pins.
Figure 21.2 shows a connection diagram between two master devices in multiple-master mode.
3-wire single-master mode is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 0. In this
mode, NSS is not used, and is not mapped to an external port pin through the crossbar. Any slave devices
that must be addressed in this mode should be selected using general-purpose I/O pins. Figure 21.3
shows a connection diagram between a master device in 3-wire master mode and a slave device.
4-wire single-master mode is active when NSSMD1 (SPI0CN.3) = 1. In this mode, NSS is configured as an
output pin, and can be used as a slave-select signal for a single SPI device. In this mode, the output value
of NSS is controlled (in software) with the bit NSSMD0 (SPI0CN.2). Additional slave devices can be
addressed using general-purpose I/O pins. Figure 21.4 shows a connection diagram for a master device in
4-wire master mode and two slave devices.
Rev. 1.1
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C8051F350/1/2/3
Master
Device 1
NSS
GPIO
MISO
MISO
MOSI
MOSI
SCK
SCK
GPIO
NSS
Master
Device 2
Figure 21.2. Multiple-Master Mode Connection Diagram
Master
Device
MISO
MISO
MOSI
MOSI
SCK
SCK
Slave
Device
Figure 21.3. 3-Wire Single Master and Slave Mode Connection Diagram
Master
Device
GPIO
MISO
MISO
MOSI
MOSI
SCK
SCK
NSS
NSS
MISO
MOSI
Slave
Device
Slave
Device
SCK
NSS
Figure 21.4. 4-Wire Single Master and Slave Mode Connection Diagram
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21.3. SPI0 Slave Mode Operation
When SPI0 is enabled and not configured as a master, it will operate as a SPI slave. As a slave, bytes are
shifted in through the MOSI pin and out through the MISO pin by a master device controlling the SCK signal. A bit counter in the SPI0 logic counts SCK edges. When 8 bits have been shifted into the shift register,
the SPIF flag is set to logic 1, and the byte is copied into the receive buffer. Data is read from the receive
buffer by reading SPI0DAT. A slave device cannot initiate transfers. Data to be transferred to the master
device is pre-loaded into the shift register by writing to SPI0DAT. Writes to SPI0DAT are double-buffered,
and are placed in the transmit buffer first. If the shift register is empty, the contents of the transmit buffer
will immediately be transferred into the shift register. When the shift register already contains data, the SPI
will load the shift register with the transmit buffer’s contents after the last SCK edge of the next (or current)
SPI transfer.
When configured as a slave, SPI0 can be configured for 4-wire or 3-wire operation. The default, 4-wire
slave mode, is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 1. In 4-wire mode, the
NSS signal is routed to a port pin and configured as a digital input. SPI0 is enabled when NSS is logic 0,
and disabled when NSS is logic 1. The bit counter is reset on a falling edge of NSS. Note that the NSS signal must be driven low at least 2 system clocks before the first active edge of SCK for each byte transfer.
Figure 21.4 shows a connection diagram between two slave devices in 4-wire slave mode and a master
device.
3-wire slave mode is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 0. NSS is not
used in this mode, and is not mapped to an external port pin through the crossbar. Since there is not a way
of uniquely addressing the device in 3-wire slave mode, SPI0 must be the only slave device present on the
bus. It is important to note that in 3-wire slave mode there is no external means of resetting the bit counter
that determines when a full byte has been received. The bit counter can only be reset by disabling and reenabling SPI0 with the SPIEN bit. Figure 21.3 shows a connection diagram between a slave device in 3wire slave mode and a master device.
21.4. SPI0 Interrupt Sources
When SPI0 interrupts are enabled, the following four flags will generate an interrupt when they are set to
logic 1:
Note that all of the following bits must be cleared by software.
1. The SPI Interrupt Flag, SPIF (SPI0CN.7) is set to logic 1 at the end of each byte transfer. This
flag can occur in all SPI0 modes.
2. The Write Collision Flag, WCOL (SPI0CN.6) is set to logic 1 if a write to SPI0DAT is attempted
when the transmit buffer has not been emptied to the SPI shift register. When this occurs, the
write to SPI0DAT will be ignored, and the transmit buffer will not be written.This flag can occur
in all SPI0 modes.
3. The Mode Fault Flag MODF (SPI0CN.5) is set to logic 1 when SPI0 is configured as a master,
and for multi-master mode and the NSS pin is pulled low. When a Mode Fault occurs, the
MSTEN and SPIEN bits in SPI0CN are set to logic 0 to disable SPI0 and allow another master
device to access the bus.
4. The Receive Overrun Flag RXOVRN (SPI0CN.4) is set to logic 1 when configured as a slave,
and a transfer is completed while the receive buffer still holds an unread byte from a previous
transfer. The new byte is not transferred to the receive buffer, allowing the previously received
data byte to be read. The data byte which caused the overrun is lost.
Rev. 1.1
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21.5. Serial Clock Timing
Four combinations of serial clock phase and polarity can be selected using the clock control bits in the
SPI0 Configuration Register (SPI0CFG). The CKPHA bit (SPI0CFG.5) selects one of two clock phases
(edge used to latch the data). The CKPOL bit (SPI0CFG.4) selects between an active-high or active-low
clock. Both master and slave devices must be configured to use the same clock phase and polarity. SPI0
should be disabled (by clearing the SPIEN bit, SPI0CN.0) when changing the clock phase or polarity. The
clock and data line relationships are shown in Figure 21.5.
The SPI0 Clock Rate Register (SPI0CKR) as shown in SFR Definition 21.3 controls the master mode
serial clock frequency. This register is ignored when operating in slave mode. When the SPI is configured
as a master, the maximum data transfer rate (bits/sec) is one-half the system clock frequency or 12.5 MHz,
whichever is slower. When the SPI is configured as a slave, the maximum data transfer rate (bits/sec) for
full-duplex operation is 1/10 the system clock frequency, provided that the master issues SCK, NSS (in 4wire slave mode), and the serial input data synchronously with the slave’s system clock. If the master
issues SCK, NSS, and the serial input data asynchronously, the maximum data transfer rate (bits/sec)
must be less than 1/10 the system clock frequency. In the special case where the master only wants to
transmit data to the slave and does not need to receive data from the slave (i.e. half-duplex operation), the
SPI slave can receive data at a maximum data transfer rate (bits/sec) of 1/4 the system clock frequency.
This is provided that the master issues SCK, NSS, and the serial input data synchronously with the slave’s
system clock.
SCK
(CKPOL=0, CKPHA=0)
SCK
(CKPOL=0, CKPHA=1)
SCK
(CKPOL=1, CKPHA=0)
SCK
(CKPOL=1, CKPHA=1)
MISO/MOSI
MSB
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Figure 21.5. Data/Clock Timing Relationship
21.6. SPI Special Function Registers
SPI0 is accessed and controlled through four special function registers in the system controller: SPI0CN
Control Register, SPI0DAT Data Register, SPI0CFG Configuration Register, and SPI0CKR Clock Rate
Register. The four special function registers related to the operation of the SPI0 Bus are described in the
following figures.
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SFR Definition 21.1. SPI0CFG: SPI0 Configuration
R
R/W
R/W
R/W
R
R
R
R
Reset Value
SPIBSY
MSTEN
CKPHA
CKPOL
SLVSEL
NSSIN
SRMT
RXBMT
00000111
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xA1
Bit 7:
Bit 6:
Bit 5:
Bit 4:
Bit 3:
Bit 2:
Bit 1:
Bit 0:
SPIBSY: SPI Busy (read only).
This bit is set to logic 1 when a SPI transfer is in progress (Master or Slave Mode).
MSTEN: Master Mode Enable.
0: Disable master mode. Operate in slave mode.
1: Enable master mode. Operate as a master.
CKPHA: SPI0 Clock Phase.
This bit controls the SPI0 clock phase.
0: Data centered on first edge of SCK period.*
1: Data centered on second edge of SCK period.*
CKPOL: SPI0 Clock Polarity.
This bit controls the SPI0 clock polarity.
0: SCK line low in idle state.
1: SCK line high in idle state.
SLVSEL: Slave Selected Flag (read only).
This bit is set to logic 1 whenever the NSS pin is low indicating SPI0 is the selected slave. It
is cleared to logic 0 when NSS is high (slave not selected). This bit does not indicate the
instantaneous value at the NSS pin, but rather a de-glitched version of the pin input.
NSSIN: NSS Instantaneous Pin Input (read only).
This bit mimics the instantaneous value that is present on the NSS port pin at the time that
the register is read. This input is not de-glitched.
SRMT: Shift Register Empty (Valid in Slave Mode, read only).
This bit will be set to logic 1 when all data has been transferred in/out of the shift register,
and there is no new information available to read from the transmit buffer or write to the
receive buffer. It returns to logic 0 when a data byte is transferred to the shift register from
the transmit buffer or by a transition on SCK.
NOTE: SRMT = 1 when in Master Mode.
RXBMT: Receive Buffer Empty (Valid in Slave Mode, read only).
This bit will be set to logic 1 when the receive buffer has been read and contains no new
information. If there is new information available in the receive buffer that has not been read,
this bit will return to logic 0.
NOTE: RXBMT = 1 when in Master Mode.
*Note: See Table 21.1 for timing parameters.
Rev. 1.1
187
C8051F350/1/2/3
SFR Definition 21.2. SPI0CN: SPI0 Control
R/W
R/W
R/W
SPIF
WCOL
MODF
Bit7
Bit6
Bit5
R/W
R/W
R/W
RXOVRN NSSMD1 NSSMD0
Bit4
Bit3
Bit2
R
R/W
Reset Value
TXBMT
SPIEN
00000110
Bit1
Bit0
Bit
Addressable
SFR Address: 0xF8
Bit 7:
SPIF: SPI0 Interrupt Flag.
This bit is set to logic 1 by hardware at the end of a data transfer. If interrupts are enabled,
setting this bit causes the CPU to vector to the SPI0 interrupt service routine. This bit is not
automatically cleared by hardware. It must be cleared by software.
Bit 6:
WCOL: Write Collision Flag.
This bit is set to logic 1 by hardware (and generates a SPI0 interrupt) to indicate a write to
the SPI0 data register was attempted while a data transfer was in progress. This bit is not
automatically cleared by hardware. It must be cleared by software.
Bit 5:
MODF: Mode Fault Flag.
This bit is set to logic 1 by hardware (and generates a SPI0 interrupt) when a master mode
collision is detected (NSS is low, MSTEN = 1, and NSSMD[1:0] = 01). This bit is not automatically cleared by hardware. It must be cleared by software.
Bit 4:
RXOVRN: Receive Overrun Flag (Slave Mode only).
This bit is set to logic 1 by hardware (and generates a SPI0 interrupt) when the receive buffer still holds unread data from a previous transfer and the last bit of the current transfer is
shifted into the SPI0 shift register. This bit is not automatically cleared by hardware. It must
be cleared by software.
Bits 3–2: NSSMD1–NSSMD0: Slave Select Mode.
Selects between the following NSS operation modes:
(See Section “21.2. SPI0 Master Mode Operation’ on page 183 and Section “21.3. SPI0
Slave Mode Operation’ on page 185).
00: 3-Wire Slave or 3-wire Master Mode. NSS signal is not routed to a port pin.
01: 4-Wire Slave or Multi-Master Mode (Default). NSS is always an input to the device.
1x: 4-Wire Single-Master Mode. NSS signal is mapped as an output from the device and will
assume the value of NSSMD0.
Bit 1:
TXBMT: Transmit Buffer Empty.
This bit will be set to logic 0 when new data has been written to the transmit buffer. When
data in the transmit buffer is transferred to the SPI shift register, this bit will be set to logic 1,
indicating that it is safe to write a new byte to the transmit buffer.
Bit 0:
SPIEN: SPI0 Enable.
This bit enables/disables the SPI.
0: SPI disabled.
1: SPI enabled.
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SFR Definition 21.3. SPI0CKR: SPI0 Clock Rate
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
SCR7
SCR6
SCR5
SCR4
SCR3
SCR2
SCR1
SCR0
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xA2
Bits 7–0: SCR7–SCR0: SPI0 Clock Rate.
These bits determine the frequency of the SCK output when the SPI0 module is configured
for master mode operation. The SCK clock frequency is a divided version of the system
clock, and is given in the following equation, where SYSCLK is the system clock frequency
and SPI0CKR is the 8-bit value held in the SPI0CKR register.
SYSCLK
f SCK = ------------------------------------------------2 × ( SPI0CKR + 1 )
for 0 <= SPI0CKR <= 255
Example: If SYSCLK = 2 MHz and SPI0CKR = 0x04,
2000000
f SCK = -------------------------2 × (4 + 1)
f SCK = 200kHz
Rev. 1.1
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C8051F350/1/2/3
SFR Definition 21.4. SPI0DAT: SPI0 Data
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xA3
Bits 7–0: SPI0DAT: SPI0 Transmit and Receive Data.
The SPI0DAT register is used to transmit and receive SPI0 data. Writing data to SPI0DAT
places the data into the transmit buffer and initiates a transfer when in Master Mode. A read
of SPI0DAT returns the contents of the receive buffer.
190
Rev. 1.1
C8051F350/1/2/3
SCK*
T
MCKH
T
MCKL
T
MIS
T
MIH
MISO
MOSI
* SCK is shown for CKPOL = 0. SCK is the opposite polarity for CKPOL = 1.
Figure 21.6. SPI Master Timing (CKPHA = 0)
SCK*
T
MCKH
T
MIS
T
MCKL
T
MIH
MISO
MOSI
* SCK is shown for CKPOL = 0. SCK is the opposite polarity for CKPOL = 1.
Figure 21.7. SPI Master Timing (CKPHA = 1)
Rev. 1.1
191
C8051F350/1/2/3
NSS
T
T
SE
T
CKL
SD
SCK*
T
CKH
T
T
SIS
SIH
MOSI
T
T
SEZ
T
SOH
SDZ
MISO
* SCK is shown for CKPOL = 0. SCK is the opposite polarity for CKPOL = 1.
Figure 21.8. SPI Slave Timing (CKPHA = 0)
NSS
T
T
SE
T
CKL
SD
SCK*
T
CKH
T
SIS
T
SIH
MOSI
T
SEZ
T
T
SOH
SDZ
MISO
* SCK is shown for CKPOL = 0. SCK is the opposite polarity for CKPOL = 1.
Figure 21.9. SPI Slave Timing (CKPHA = 1)
192
Rev. 1.1
C8051F350/1/2/3
Table 21.1. SPI Slave Timing Parameters
Parameter
Description
Min
Max
Units
Master Mode Timing* (See Figure 21.6 and Figure 21.7)
TMCKH
SCK High Time
1 x TSYSCLK
—
ns
TMCKL
SCK Low Time
1 x TSYSCLK
—
ns
TMIS
MISO Valid to SCK Sample Edge
20
—
ns
TMIH
SCK Sample Edge to MISO Change
0
—
ns
Slave Mode Timing* (See Figure 21.8 and Figure 21.9)
TSE
NSS Falling to First SCK Edge
2 x TSYSCLK
—
ns
TSD
Last SCK Edge to NSS Rising
2 x TSYSCLK
—
ns
TSEZ
NSS Falling to MISO Valid
—
4 x TSYSCLK
ns
TSDZ
NSS Rising to MISO High-Z
—
4 x TSYSCLK
ns
TCKH
SCK High Time
5 x TSYSCLK
—
ns
TCKL
SCK Low Time
5 x TSYSCLK
—
ns
TSIS
MOSI Valid to SCK Sample Edge
2 x TSYSCLK
—
ns
TSIH
SCK Sample Edge to MOSI Change
2 x TSYSCLK
—
ns
TSOH
SCK Shift Edge to MISO Change
—
4 x TSYSCLK
ns
*Note: TSYSCLK is equal to one period of the device system clock (SYSCLK) in ns.
Rev. 1.1
193
C8051F350/1/2/3
NOTES:
194
Rev. 1.1
C8051F350/1/2/3
22. Timers
Each MCU includes four counter/timers: two are 16-bit counter/timers compatible with those found in the
standard 8051, and two are 16-bit auto-reload timer for use with other device peripherals or for general
purpose use. These timers can be used to measure time intervals, count external events and generate
periodic interrupt requests. Timer 0 and Timer 1 are nearly identical and have four primary modes of operation. Timer 2 and Timer 3 offer 16-bit and split 8-bit timer functionality with auto-reload.
Timer 0 and Timer 1 Modes:
13-bit counter/timer
16-bit counter/timer
8-bit counter/timer with autoreload
Two 8-bit counter/timers (Timer 0
only)
Timer 2 Modes:
Timer 3 Modes:
16-bit timer with auto-reload
16-bit timer with auto-reload
Two 8-bit timers with auto-reload
Two 8-bit timers with auto-reload
Timers 0 and 1 may be clocked by one of five sources, determined by the Timer Mode Select bits (T1M–
T0M) and the Clock Scale bits (SCA1–SCA0). The Clock Scale bits define a pre-scaled clock from which
Timer 0 and/or Timer 1 may be clocked (See SFR Definition 22.3 for pre-scaled clock selection).
Timer 0/1 may then be configured to use this pre-scaled clock signal or the system clock. Timer 2 and
Timer 3 may be clocked by the system clock, the system clock divided by 12, or the external oscillator
clock source divided by 8.
Timer 0 and Timer 1 may also be operated as counters. When functioning as a counter, a counter/timer
register is incremented on each high-to-low transition at the selected input pin (T0 or T1). Events with a frequency of up to one-fourth the system clock's frequency can be counted. The input signal need not be periodic, but it must be held at a given level for at least two full system clock cycles to ensure the level is
properly sampled.
22.1. Timer 0 and Timer 1
Each timer is implemented as a 16-bit register accessed as two separate bytes: a low byte (TL0 or TL1)
and a high byte (TH0 or TH1). The Counter/Timer Control register (TCON) is used to enable Timer 0 and
Timer 1 as well as indicate status. Timer 0 interrupts can be enabled by setting the ET0 bit in the IE register
(Section “12.4. Interrupt Register Descriptions’ on page 107); Timer 1 interrupts can be enabled by setting
the ET1 bit in the IE register (Section 12.4). Both counter/timers operate in one of four primary modes
selected by setting the Mode Select bits T1M1–T0M0 in the Counter/Timer Mode register (TMOD). Each
timer can be configured independently. Each operating mode is described below.
22.1.1. Mode 0: 13-bit Counter/Timer
Timer 0 and Timer 1 operate as 13-bit counter/timers in Mode 0. The following describes the configuration
and operation of Timer 0. However, both timers operate identically, and Timer 1 is configured in the same
manner as described for Timer 0.
The TH0 register holds the eight MSBs of the 13-bit counter/timer. TL0 holds the five LSBs in bit positions
TL0.4–TL0.0. The three upper bits of TL0 (TL0.7–TL0.5) are indeterminate and should be masked out or
ignored when reading. As the 13-bit timer register increments and overflows from 0x1FFF (all ones) to
0x0000, the timer overflow flag TF0 (TCON.5) is set and an interrupt will occur if Timer 0 interrupts are
enabled.
Rev. 1.1
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C8051F350/1/2/3
The C/T0 bit (TMOD.2) selects the counter/timer's clock source. When C/T0 is set to logic 1, high-to-low
transitions at the selected Timer 0 input pin (T0) increment the timer register (Refer to Section
“18.1. Priority Crossbar Decoder’ on page 139 for information on selecting and configuring external I/O
pins). Clearing C/T selects the clock defined by the T0M bit (CKCON.3). When T0M is set, Timer 0 is
clocked by the system clock. When T0M is cleared, Timer 0 is clocked by the source selected by the Clock
Scale bits in CKCON (see SFR Definition 22.3).
Setting the TR0 bit (TCON.4) enables the timer when either GATE0 (TMOD.3) is logic 0 or the input signal
/INT0 is active as defined by bit IN0PL in register IT01CF (see SFR Definition 12.5). Setting GATE0 to ‘1’
allows the timer to be controlled by the external input signal /INT0 (see Section “12.4. Interrupt Register
Descriptions’ on page 107), facilitating pulse width measurements.
TR0
GATE0
X
0
1
0
1
1
1
1
X = Don't Care
/INT0
X
X
0
1
Counter/Timer
Disabled
Enabled
Disabled
Enabled
Setting TR0 does not force the timer to reset. The timer registers should be loaded with the desired initial
value before the timer is enabled.
TL1 and TH1 form the 13-bit register for Timer 1 in the same manner as described above for TL0 and TH0.
Timer 1 is configured and controlled using the relevant TCON and TMOD bits just as with Timer 0. The
input signal /INT1 is used with Timer 1; the /INT1 polarity is defined by bit IN1PL in register IT01CF (see
SFR Definition 12.5).
CKCON
T T T T T T S
3 3 2 2 1 0 C
MMMMMMA
H L H L
1
Pre-scaled Clock
TMOD
S
C
A
0
G
A
T
E
1
C
/
T
1
T
1
M
1
T
1
M
0
G
A
T
E
0
C
/
T
0
IT01CF
T
0
M
1
T
0
M
0
I
N
1
P
L
I
N
1
S
L
2
I
N
1
S
L
1
I
N
1
S
L
0
I
N
0
P
L
I
N
0
S
L
2
I
N
0
S
L
1
I
N
0
S
L
0
0
0
SYSCLK
1
1
TR0
TCLK
TL0
(5 bits)
TH0
(8 bits)
GATE0
Crossbar
/INT0
IN0PL
TCON
T0
TF1
TR1
TF0
TR0
IE1
IT1
IE0
IT0
Interrupt
XOR
Figure 22.1. T0 Mode 0 Block Diagram
22.1.2. Mode 1: 16-bit Counter/Timer
Mode 1 operation is the same as Mode 0, except that the counter/timer registers use all 16 bits. The
counter/timers are enabled and configured in Mode 1 in the same manner as for Mode 0.
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C8051F350/1/2/3
22.1.3. Mode 2: 8-bit Counter/Timer with Auto-Reload
Mode 2 configures Timer 0 and Timer 1 to operate as 8-bit counter/timers with automatic reload of the start
value. TL0 holds the count and TH0 holds the reload value. When the counter in TL0 overflows from all
ones to 0x00, the timer overflow flag TF0 (TCON.5) is set and the counter in TL0 is reloaded from TH0. If
Timer 0 interrupts are enabled, an interrupt will occur when the TF0 flag is set. The reload value in TH0 is
not changed. TL0 must be initialized to the desired value before enabling the timer for the first count to be
correct. When in Mode 2, Timer 1 operates identically to Timer 0.
Both counter/timers are enabled and configured in Mode 2 in the same manner as Mode 0. Setting the
TR0 bit (TCON.4) enables the timer when either GATE0 (TMOD.3) is logic 0 or when the input signal /INT0
is active as defined by bit IN0PL in register IT01CF (see Section “12.5. External Interrupts’ on page 111 for
details on the external input signals /INT0 and /INT1).
CKCON
T T T T T T S
3 3 2 2 1 0 C
MMMMMMA
H L H L
1
Pre-scaled Clock
TMOD
S
C
A
0
G
A
T
E
1
C
/
T
1
T
1
M
1
T
1
M
0
G
A
T
E
0
C
/
T
0
IT01CF
T
0
M
1
T
0
M
0
I
N
1
P
L
I
N
1
S
L
2
I
N
1
S
L
1
I
N
1
S
L
0
I
N
0
P
L
I
N
0
S
L
2
I
N
0
S
L
1
I
N
0
S
L
0
0
0
SYSCLK
1
1
T0
TL0
(8 bits)
TCON
TCLK
TR0
Crossbar
GATE0
TH0
(8 bits)
/INT0
IN0PL
TF1
TR1
TF0
TR0
IE1
IT1
IE0
IT0
Interrupt
Reload
XOR
Figure 22.2. T0 Mode 2 Block Diagram
Rev. 1.1
197
C8051F350/1/2/3
22.1.4. Mode 3: Two 8-bit Counter/Timers (Timer 0 Only)
In Mode 3, Timer 0 is configured as two separate 8-bit counter/timers held in TL0 and TH0. The
counter/timer in TL0 is controlled using the Timer 0 control/status bits in TCON and TMOD: TR0, C/T0,
GATE0 and TF0. TL0 can use either the system clock or an external input signal as its timebase. The TH0
register is restricted to a timer function sourced by the system clock or prescaled clock. TH0 is enabled
using the Timer 1 run control bit TR1. TH0 sets the Timer 1 overflow flag TF1 on overflow and thus controls
the Timer 1 interrupt.
Timer 1 is inactive in Mode 3. When Timer 0 is operating in Mode 3, Timer 1 can be operated in Modes 0,
1 or 2, but cannot be clocked by external signals nor set the TF1 flag and generate an interrupt. However,
the Timer 1 overflow can be used to generate baud rates for the SMBus and UART. While Timer 0 is operating in Mode 3, Timer 1 run control is handled through its mode settings. To run Timer 1 while Timer 0 is in
Mode 3, set the Timer 1 Mode as 0, 1, or 2. To disable Timer 1, configure it for Mode 3.
CKCON
TMOD
T T T T T TSS
3 3 2 2 1 0 CC
MMMMMM A A
HLHL
1 0
Pre-scaled Clock
G
A
T
E
1
C
/
T
1
T T
1 1
MM
1 0
G
A
T
E
0
C
/
T
0
T T
0 0
MM
1 0
0
TR1
SYSCLK
TH0
(8 bits)
1
TCON
0
1
T0
TL0
(8 bits)
TR0
Crossbar
/INT0
GATE0
IN0PL
XOR
Figure 22.3. T0 Mode 3 Block Diagram
198
Rev. 1.1
TF1
TR1
TF0
TR0
IE1
IT1
IE0
IT0
Interrupt
Interrupt
C8051F350/1/2/3
SFR Definition 22.1. TCON: Timer Contro
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
TF1
TR1
TF0
TR0
IE1
IT1
IE0
IT0
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Bit
Addressable
SFR Address: 0x88
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
TF1: Timer 1 Overflow Flag.
Set by hardware when Timer 1 overflows. This flag can be cleared by software but is automatically cleared when the CPU vectors to the Timer 1 interrupt service routine.
0: No Timer 1 overflow detected.
1: Timer 1 has overflowed.
TR1: Timer 1 Run Control.
0: Timer 1 disabled.
1: Timer 1 enabled.
TF0: Timer 0 Overflow Flag.
Set by hardware when Timer 0 overflows. This flag can be cleared by software but is automatically cleared when the CPU vectors to the Timer 0 interrupt service routine.
0: No Timer 0 overflow detected.
1: Timer 0 has overflowed.
TR0: Timer 0 Run Control.
0: Timer 0 disabled.
1: Timer 0 enabled.
IE1: External Interrupt 1.
This flag is set by hardware when an edge/level of type defined by IT1 is detected. It can be
cleared by software but is automatically cleared when the CPU vectors to the External Interrupt 1 service routine if IT1 = 1. When IT1 = 0, this flag is set to ‘1’ when /INT1 is active as
defined by bit IN1PL in register IT01CF (see SFR Definition 12.5).
IT1: Interrupt 1 Type Select.
This bit selects whether the configured /INT1 interrupt will be edge or level sensitive. /INT1
is configured active low or high by the IN1PL bit in the IT01CF register (see SFR Definition
12.5).
0: /INT1 is level triggered.
1: /INT1 is edge triggered.
IE0: External Interrupt 0.
This flag is set by hardware when an edge/level of type defined by IT0 is detected. It can be
cleared by software but is automatically cleared when the CPU vectors to the External Interrupt 0 service routine if IT0 = 1. When IT0 = 0, this flag is set to ‘1’ when /INT0 is active as
defined by bit IN0PL in register IT01CF (see SFR Definition 12.5).
IT0: Interrupt 0 Type Select.
This bit selects whether the configured /INT0 interrupt will be edge or level sensitive. /INT0
is configured active low or high by the IN0PL bit in register IT01CF (see SFR Definition
12.5).
0: /INT0 is level triggered.
1: /INT0 is edge triggered.
Rev. 1.1
199
C8051F350/1/2/3
SFR Definition 22.2. TMOD: Timer Mode
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
GATE1
C/T1
T1M1
T1M0
GATE0
C/T0
T0M1
T0M0
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0x89
Bit7:
GATE1: Timer 1 Gate Control.
0: Timer 1 enabled when TR1 = 1 irrespective of /INT1 logic level.
1: Timer 1 enabled only when TR1 = 1 AND /INT1 is active as defined by bit IN1PL in register IT01CF (see SFR Definition 12.5).
Bit6:
C/T1: Counter/Timer 1 Select.
0: Timer Function: Timer 1 incremented by clock defined by T1M bit (CKCON.4).
1: Counter Function: Timer 1 incremented by high-to-low transitions on external input pin
(T1).
Bits5–4: T1M1–T1M0: Timer 1 Mode Select.
These bits select the Timer 1 operation mode.
T1M1
0
0
T1M0
0
1
1
0
1
1
Mode
Mode 0: 13-bit counter/timer
Mode 1: 16-bit counter/timer
Mode 2: 8-bit counter/timer with autoreload
Mode 3: Timer 1 inactive
Bit3:
GATE0: Timer 0 Gate Control.
0: Timer 0 enabled when TR0 = 1 irrespective of /INT0 logic level.
1: Timer 0 enabled only when TR0 = 1 AND /INT0 is active as defined by bit IN0PL in register IT01CF (see SFR Definition 12.5).
Bit2:
C/T0: Counter/Timer Select.
0: Timer Function: Timer 0 incremented by clock defined by T0M bit (CKCON.3).
1: Counter Function: Timer 0 incremented by high-to-low transitions on external input pin
(T0).
Bits1–0: T0M1–T0M0: Timer 0 Mode Select.
These bits select the Timer 0 operation mode.
200
T0M1
0
0
T0M0
0
1
1
0
1
1
Mode
Mode 0: 13-bit counter/timer
Mode 1: 16-bit counter/timer
Mode 2: 8-bit counter/timer with autoreload
Mode 3: Two 8-bit counter/timers
Rev. 1.1
C8051F350/1/2/3
SFR Definition 22.3. CKCON: Clock Control
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
T3MH
T3ML
T2MH
T2ML
T1M
T0M
SCA1
SCA0
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0x8E
Bit7:
T3MH: Timer 3 High Byte Clock Select.
This bit selects the clock supplied to the Timer 3 high byte if Timer 3 is configured in split 8bit timer mode. T3MH is ignored if Timer 3 is in any other mode.
0: Timer 3 high byte uses the clock defined by the T3XCLK bit in TMR3CN.
1: Timer 3 high byte uses the system clock.
Bit6:
T3ML: Timer 3 Low Byte Clock Select.
This bit selects the clock supplied to Timer 3. If Timer 3 is configured in split 8-bit timer
mode, this bit selects the clock supplied to the lower 8-bit timer.
0: Timer 3 low byte uses the clock defined by the T3XCLK bit in TMR3CN.
1: Timer 3 low byte uses the system clock.
Bit5:
T2MH: Timer 2 High Byte Clock Select.
This bit selects the clock supplied to the Timer 2 high byte if Timer 2 is configured in split 8bit timer mode. T2MH is ignored if Timer 2 is in any other mode.
0: Timer 2 high byte uses the clock defined by the T2XCLK bit in TMR2CN.
1: Timer 2 high byte uses the system clock.
Bit4:
T2ML: Timer 2 Low Byte Clock Select.
This bit selects the clock supplied to Timer 2. If Timer 2 is configured in split 8-bit timer
mode, this bit selects the clock supplied to the lower 8-bit timer.
0: Timer 2 low byte uses the clock defined by the T2XCLK bit in TMR2CN.
1: Timer 2 low byte uses the system clock.
Bit3:
T1M: Timer 1 Clock Select.
This select the clock source supplied to Timer 1. T1M is ignored when C/T1 is set to logic 1.
0: Timer 1 uses the clock defined by the prescale bits, SCA1–SCA0.
1: Timer 1 uses the system clock.
Bit2:
T0M: Timer 0 Clock Select.
This bit selects the clock source supplied to Timer 0. T0M is ignored when C/T0 is set to
logic 1.
0: Counter/Timer 0 uses the clock defined by the prescale bits, SCA1–SCA0.
1: Counter/Timer 0 uses the system clock.
Bits1–0: SCA1–SCA0: Timer 0/1 Prescale Bits.
These bits control the division of the clock supplied to Timer 0 and Timer 1 if configured to
use prescaled clock inputs.
SCA1
0
0
1
1
SCA0
0
1
0
1
Prescaled Clock
System clock divided by 12
System clock divided by 4
System clock divided by 48
External clock divided by 8
Note: External clock divided by 8 is synchronized with the
system clock.
Rev. 1.1
201
C8051F350/1/2/3
SFR Definition 22.4. TL0: Timer 0 Low Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Reset Value
00000000
SFR Address: 0x8A
Bits 7–0: TL0: Timer 0 Low Byte.
The TL0 register is the low byte of the 16-bit Timer 0.
SFR Definition 22.5. TL1: Timer 1 Low Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0x8B
Bits 7–0: TL1: Timer 1 Low Byte.
The TL1 register is the low byte of the 16-bit Timer 1.
SFR Definition 22.6. TH0: Timer 0 High Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0x8C
Bits 7–0: TH0: Timer 0 High Byte.
The TH0 register is the high byte of the 16-bit Timer 0.
SFR Definition 22.7. TH1: Timer 1 High Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0x8D
Bits 7–0: TH1: Timer 1 High Byte.
The TH1 register is the high byte of the 16-bit Timer 1.
202
Rev. 1.1
C8051F350/1/2/3
22.2. Timer 2
Timer 2 is a 16-bit timer formed by two 8-bit SFRs: TMR2L (low byte) and TMR2H (high byte). Timer 2 may
operate in 16-bit auto-reload mode or (split) 8-bit auto-reload mode. The T2SPLIT bit (TMR2CN.3) defines
the Timer 2 operation mode.
Timer 2 may be clocked by the system clock, the system clock divided by 12, or the external oscillator
source divided by 8. The external clock mode is ideal for real-time clock (RTC) functionality, where the
internal oscillator drives the system clock while Timer 2 (and/or the PCA) is clocked by an external precision oscillator. Note that the external oscillator source divided by 8 is synchronized with the system clock.
22.2.1. 16-bit Timer with Auto-Reload
When T2SPLIT (TMR2CN.3) is zero, Timer 2 operates as a 16-bit timer with auto-reload. Timer 2 can be
clocked by SYSCLK, SYSCLK divided by 12, or the external oscillator clock source divided by 8. As the
16-bit timer register increments and overflows from 0xFFFF to 0x0000, the 16-bit value in the Timer 2
reload registers (TMR2RLH and TMR2RLL) is loaded into the Timer 2 register as shown in Figure 22.4,
and the Timer 2 High Byte Overflow Flag (TMR2CN.7) is set. If Timer 2 interrupts are enabled (if IE.5 is
set), an interrupt will be generated on each Timer 2 overflow. Additionally, if Timer 2 interrupts are enabled
and the TF2LEN bit is set (TMR2CN.5), an interrupt will be generated each time the lower 8 bits (TMR2L)
overflow from 0xFF to 0x00.
CKCON
TTTTTTSS
3 3 2 2 1 0CC
T2XCLK M M M M M M A A
HLHL
1 0
0
TMR2L
Overflow
0
TR2
External Clock / 8
SYSCLK
1
TCLK
TMR2L
TMR2H
TMR2CN
SYSCLK / 12
1
TF2H
TF2L
TF2LEN
Interrupt
T2SPLIT
TR2
T2XCLK
TMR2RLL TMR2RLH
Reload
Figure 22.4. Timer 2 16-Bit Mode Block Diagram
Rev. 1.1
203
C8051F350/1/2/3
22.2.2. 8-bit Timers with Auto-Reload
When T2SPLIT is set, Timer 2 operates as two 8-bit timers (TMR2H and TMR2L). Both 8-bit timers operate in auto-reload mode as shown in Figure 22.5. TMR2RLL holds the reload value for TMR2L; TMR2RLH
holds the reload value for TMR2H. The TR2 bit in TMR2CN handles the run control for TMR2H. TMR2L is
always running when configured for 8-bit Mode.
Each 8-bit timer may be configured to use SYSCLK, SYSCLK divided by 12, or the external oscillator clock
source divided by 8. The Timer 2 Clock Select bits (T2MH and T2ML in CKCON) select either SYSCLK or
the clock defined by the Timer 2 External Clock Select bit (T2XCLK in TMR2CN), as follows:
T2MH
T2XCLK
0
0
1
0
1
X
TMR2H Clock
Source
SYSCLK / 12
External Clock / 8
SYSCLK
T2ML
T2XCLK
0
0
1
0
1
X
TMR2L Clock
Source
SYSCLK / 12
External Clock / 8
SYSCLK
The TF2H bit is set when TMR2H overflows from 0xFF to 0x00; the TF2L bit is set when TMR2L overflows
from 0xFF to 0x00. When Timer 2 interrupts are enabled (IE.5), an interrupt is generated each time
TMR2H overflows. If Timer 2 interrupts are enabled and TF2LEN (TMR2CN.5) is set, an interrupt is generated each time either TMR2L or TMR2H overflows. When TF2LEN is enabled, software must check the
TF2H and TF2L flags to determine the source of the Timer 2 interrupt. The TF2H and TF2L interrupt flags
are not cleared by hardware and must be manually cleared by software.
CKCON
TTTTTTSS
3 3 2 2 1 0 CC
MMMMMMA A
HLHL
1 0
T2XCLK
SYSCLK / 12
TMR2RLH
Reload
0
0
External Clock / 8
1
TCLK
TR2
TMR2H
TMR2RLL
SYSCLK
Reload
TMR2CN
1
TF2H
TF2L
TF2LEN
T2SPLIT
TR2
T2XCLK
1
TCLK
TMR2L
0
Figure 22.5. Timer 2 8-Bit Mode Block Diagram
204
Rev. 1.1
Interrupt
C8051F350/1/2/3
SFR Definition 22.8. TMR2CN: Timer 2 Control
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
TF2H
TF2L
TF2LEN
—
T2SPLIT
TR2
—
T2XCLK
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Bit
Addressable
SFR Address: 0xC8
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
TF2H: Timer 2 High Byte Overflow Flag.
Set by hardware when the Timer 2 high byte overflows from 0xFF to 0x00. In 16 bit mode,
this will occur when Timer 2 overflows from 0xFFFF to 0x0000. When the Timer 2 interrupt is
enabled, setting this bit causes the CPU to vector to the Timer 2 interrupt service routine.
TF2H is not automatically cleared by hardware and must be cleared by software.
TF2L: Timer 2 Low Byte Overflow Flag.
Set by hardware when the Timer 2 low byte overflows from 0xFF to 0x00. When this bit is
set, an interrupt will be generated if TF2LEN is set and Timer 2 interrupts are enabled. TF2L
will set when the low byte overflows regardless of the Timer 2 mode. This bit is not automatically cleared by hardware.
TF2LEN: Timer 2 Low Byte Interrupt Enable.
This bit enables/disables Timer 2 Low Byte interrupts. If TF2LEN is set and Timer 2 interrupts are enabled, an interrupt will be generated when the low byte of Timer 2 overflows.
This bit should be cleared when operating Timer 2 in 16-bit mode.
0: Timer 2 Low Byte interrupts disabled.
1: Timer 2 Low Byte interrupts enabled.
UNUSED. Read = 0b. Write = don’t care.
T2SPLIT: Timer 2 Split Mode Enable.
When this bit is set, Timer 2 operates as two 8-bit timers with auto-reload.
0: Timer 2 operates in 16-bit auto-reload mode.
1: Timer 2 operates as two 8-bit auto-reload timers.
TR2: Timer 2 Run Control.
This bit enables/disables Timer 2. In 8-bit mode, this bit enables/disables TMR2H only;
TMR2L is always enabled in this mode.
0: Timer 2 disabled.
1: Timer 2 enabled.
UNUSED. Read = 0b. Write = don’t care.
T2XCLK: Timer 2 External Clock Select.
This bit selects the external clock source for Timer 2. If Timer 2 is in 8-bit mode, this bit
selects the external oscillator clock source for both timer bytes. However, the Timer 2 Clock
Select bits (T2MH and T2ML in register CKCON) may still be used to select between the
external clock and the system clock for either timer.
0: Timer 2 external clock selection is the system clock divided by 12.
1: Timer 2 external clock selection is the external clock divided by 8. Note that the external
oscillator source divided by 8 is synchronized with the system clock.
Rev. 1.1
205
C8051F350/1/2/3
SFR Definition 22.9. TMR2RLL: Timer 2 Reload Register Low Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Reset Value
00000000
SFR Address: 0xCA
Bits 7–0: TMR2RLL: Timer 2 Reload Register Low Byte.
TMR2RLL holds the low byte of the reload value for Timer 2.
SFR Definition 22.10. TMR2RLH: Timer 2 Reload Register High Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xCB
Bits 7–0: TMR2RLH: Timer 2 Reload Register High Byte.
The TMR2RLH holds the high byte of the reload value for Timer 2.
SFR Definition 22.11. TMR2L: Timer 2 Low Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Reset Value
00000000
SFR Address: 0xCC
Bits 7–0: TMR2L: Timer 2 Low Byte.
In 16-bit mode, the TMR2L register contains the low byte of the 16-bit Timer 2. In 8-bit mode,
TMR2L contains the 8-bit low byte timer value.
SFR Definition 22.12. TMR2H Timer 2 High Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Reset Value
00000000
SFR Address: 0xCD
Bits 7–0: TMR2H: Timer 2 High Byte.
In 16-bit mode, the TMR2H register contains the high byte of the 16-bit Timer 2. In 8-bit
mode, TMR2H contains the 8-bit high byte timer value.
206
Rev. 1.1
C8051F350/1/2/3
22.3. Timer 3
Timer 3 is a 16-bit timer formed by two 8-bit SFRs: TMR3L (low byte) and TMR3H (high byte). Timer 3 may
operate in 16-bit auto-reload mode or (split) 8-bit auto-reload mode. The T3SPLIT bit (TMR3CN.3) defines
the Timer 3 operation mode.
Timer 3 may be clocked by the system clock, the system clock divided by 12, or the external oscillator
source divided by 8. The external clock mode is ideal for real-time clock (RTC) functionality, where the
internal oscillator drives the system clock while Timer 3 (and/or the PCA) is clocked by an external precision oscillator. Note that the external oscillator source divided by 8 is synchronized with the system clock.
22.3.1. 16-bit Timer with Auto-Reload
When T3SPLIT (TMR3CN.3) is zero, Timer 3 operates as a 16-bit timer with auto-reload. Timer 3 can be
clocked by SYSCLK, SYSCLK divided by 12, or the external oscillator clock source divided by 8. As the
16-bit timer register increments and overflows from 0xFFFF to 0x0000, the 16-bit value in the Timer 3
reload registers (TMR3RLH and TM3RLL) is loaded into the Timer 3 register as shown in Figure 22.6, and
the Timer 3 High Byte Overflow Flag (TMR3CN.7) is set. If Timer 3 interrupts are enabled, an interrupt will
be generated each Timer 3 overflow. Additionally, if Timer 3 interrupts are enabled and the TF3LEN bit is
set (TMR3CN.5), an interrupt will be generated each time the lower 8 bits (TMR3L) overflow from 0xFF to
0x00.
CKCON
TTTTTTSS
3 3 2 2 1 0 CC
T3XCLK M M M M M M A A
HLHL
1 0
SYSCLK / 12
0
0
SYSCLK
1
TCLK
TMR3L
TMR3H
TMR3CN
TR3
External Clock / 8
1
TF3H
TF3L
TF3LEN
Interrupt
T3SPLIT
TR3
T3XCLK
TMR3RLL TMR3RLH
Reload
Figure 22.6. Timer 3 16-Bit Mode Block Diagram
Rev. 1.1
207
C8051F350/1/2/3
22.3.2. 8-bit Timers with Auto-Reload
When T3SPLIT is set, Timer 3 operates as two 8-bit timers (TMR3H and TMR3L). Both 8-bit timers operate in auto-reload mode as shown in Figure 22.7. TMR3RLL holds the reload value for TMR3L; TMR3RLH
holds the reload value for TMR3H. The TR3 bit in TMR3CN handles the run control for TMR3H. TMR3L is
always running when configured for 8-bit Mode.
Each 8-bit timer may be configured to use SYSCLK, SYSCLK divided by 12, or the external oscillator clock
source divided by 8. The Timer 3 Clock Select bits (T3MH and T3ML in CKCON) select either SYSCLK or
the clock defined by the Timer 3 External Clock Select bit (T3XCLK in TMR3CN), as follows:
T3MH
T3XCLK
0
0
1
0
1
X
TMR3H Clock
Source
SYSCLK / 12
External Clock / 8
SYSCLK
T3ML
T3XCLK
0
0
1
0
1
X
TMR3L Clock
Source
SYSCLK / 12
External Clock / 8
SYSCLK
The TF3H bit is set when TMR3H overflows from 0xFF to 0x00; the TF3L bit is set when TMR3L overflows
from 0xFF to 0x00. When Timer 3 interrupts are enabled (IE.5), an interrupt is generated each time
TMR3H overflows. If Timer 3 interrupts are enabled and TF3LEN (TMR3CN.5) is set, an interrupt is generated each time either TMR3L or TMR3H overflows. When TF3LEN is enabled, software must check the
TF3H and TF3L flags to determine the source of the Timer 3 interrupt. The TF3H and TF3L interrupt flags
are not cleared by hardware and must be manually cleared by software.
CKCON
TTTTTTSS
3 3 2 2 1 0 CC
MMMMMM A A
HLHL
1 0
T3XCLK
SYSCLK / 12
TMR3RLH
Reload
0
0
External Clock / 8
1
TCLK
TR3
TMR3H
TMR3RLL
SYSCLK
Reload
TMR3CN
1
TF3H
TF3L
TF3LEN
T3SPLIT
TR3
T3XCLK
1
TCLK
TMR3L
0
Figure 22.7. Timer 3 8-Bit Mode Block Diagram
208
Rev. 1.1
Interrupt
C8051F350/1/2/3
SFR Definition 22.13. TMR3CN: Timer 3 Control
R/W
R/W
R/W
R/W
R/W
R/W
TF3H
TF3L
Bit7
Bit6
R/W
R/W
Reset Value
TF3LEN
—
T3SPLIT
Bit5
Bit4
Bit3
TR3
—
T3XCLK
00000000
Bit2
Bit1
Bit0
SFR Address: 0x91
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
TF3H: Timer 3 High Byte Overflow Flag.
Set by hardware when the Timer 3 high byte overflows from 0xFF to 0x00. In 16 bit mode,
this will occur when Timer 3 overflows from 0xFFFF to 0x0000. When the Timer 3 interrupt is
enabled, setting this bit causes the CPU to vector to the Timer 3 interrupt service routine.
TF3H is not automatically cleared by hardware and must be cleared by software.
TF3L: Timer 3 Low Byte Overflow Flag.
Set by hardware when the Timer 3 low byte overflows from 0xFF to 0x00. When this bit is
set, an interrupt will be generated if TF3LEN is set and Timer 3 interrupts are enabled. TF3L
will set when the low byte overflows regardless of the Timer 3 mode. This bit is not automatically cleared by hardware.
TF3LEN: Timer 3 Low Byte Interrupt Enable.
This bit enables/disables Timer 3 Low Byte interrupts. If TF3LEN is set and Timer 3 interrupts are enabled, an interrupt will be generated when the low byte of Timer 3 overflows.
This bit should be cleared when operating Timer 3 in 16-bit mode.
0: Timer 3 Low Byte interrupts disabled.
1: Timer 3 Low Byte interrupts enabled.
UNUSED. Read = 0b. Write = don’t care.
T3SPLIT: Timer 3 Split Mode Enable.
When this bit is set, Timer 3 operates as two 8-bit timers with auto-reload.
0: Timer 3 operates in 16-bit auto-reload mode.
1: Timer 3 operates as two 8-bit auto-reload timers.
TR3: Timer 3 Run Control.
This bit enables/disables Timer 3. In 8-bit mode, this bit enables/disables TMR3H only;
TMR3L is always enabled in this mode.
0: Timer 3 disabled.
1: Timer 3 enabled.
UNUSED. Read = 0b. Write = don’t care.
T3XCLK: Timer 3 External Clock Select.
This bit selects the external clock source for Timer 3. If Timer 3 is in 8-bit mode, this bit
selects the external oscillator clock source for both timer bytes. However, the Timer 3 Clock
Select bits (T3MH and T3ML in register CKCON) may still be used to select between the
external clock and the system clock for either timer.
0: Timer 3 external clock selection is the system clock divided by 12.
1: Timer 3 external clock selection is the external clock divided by 8. Note that the external
oscillator source divided by 8 is synchronized with the system clock.
Rev. 1.1
209
C8051F350/1/2/3
SFR Definition 22.14. TMR3RLL: Timer 3 Reload Register Low Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Reset Value
00000000
SFR Address: 0x92
Bits 7–0: TMR3RLL: Timer 3 Reload Register Low Byte.
TMR3RLL holds the low byte of the reload value for Timer 3.
SFR Definition 22.15. TMR3RLH: Timer 3 Reload Register High Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0x93
Bits 7–0: TMR3RLH: Timer 3 Reload Register High Byte.
The TMR3RLH holds the high byte of the reload value for Timer 3.
SFR Definition 22.16. TMR3L: Timer 3 Low Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0x94
Bits 7–0: TMR3L: Timer 3 Low Byte.
In 16-bit mode, the TMR3L register contains the low byte of the 16-bit Timer 3. In 8-bit mode,
TMR3L contains the 8-bit low byte timer value.
SFR Definition 22.17. TMR3H Timer 3 High Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Reset Value
00000000
SFR Address: 0x95
Bits 7–0: TMR3H: Timer 3 High Byte.
In 16-bit mode, the TMR3H register contains the high byte of the 16-bit Timer 3. In 8-bit
mode, TMR3H contains the 8-bit high byte timer value.
210
Rev. 1.1
C8051F350/1/2/3
23. Programmable Counter Array
The Programmable Counter Array (PCA0) provides enhanced timer functionality while requiring less CPU
intervention than the standard 8051 counter/timers. The PCA consists of a dedicated 16-bit counter/timer
and three 16-bit capture/compare modules. Each capture/compare module has its own associated I/O line
(CEXn) which is routed through the Crossbar to Port I/O when enabled (See Section “18.1. Priority Crossbar Decoder’ on page 139 for details on configuring the Crossbar). The counter/timer is driven by a programmable timebase that can select between six sources: system clock, system clock divided by four,
system clock divided by twelve, the external oscillator clock source divided by 8, Timer 0 overflow, or an
external clock signal on the ECI input pin. Each capture/compare module may be configured to operate
independently in one of six modes: Edge-Triggered Capture, Software Timer, High-Speed Output, Frequency Output, 8-Bit PWM, or 16-Bit PWM (each mode is described in Section “23.2. Capture/Compare
Modules’ on page 213). The external oscillator clock option is ideal for real-time clock (RTC) functionality,
allowing the PCA to be clocked by a precision external oscillator while the internal oscillator drives the system clock. The PCA is configured and controlled through the system controller's Special Function Registers. The PCA block diagram is shown in Figure 23.1
Important Note: The PCA Module 2 may be used as a watchdog timer (WDT), and is enabled in this mode
following a system reset. Access to certain PCA registers is restricted while WDT mode is enabled.
See Section “23.3. Watchdog Timer Mode’ on page 220 for details.
SYSCLK/12
SYSCLK/4
Timer 0 Overflow
ECI
PCA
CLOCK
MUX
16-Bit Counter/Timer
SYSCLK
External Clock/8
Capture/Compare
Module 0
Capture/Compare
Module 1
Capture/Compare
Module 2 / WDT
CEX2
CEX1
CEX0
ECI
Crossbar
Port I/O
Figure 23.1. PCA Block Diagram
Rev. 1.1
211
C8051F350/1/2/3
23.1. PCA Counter/Timer
The 16-bit PCA counter/timer consists of two 8-bit SFRs: PCA0L and PCA0H. PCA0H is the high byte
(MSB) of the 16-bit counter/timer and PCA0L is the low byte (LSB). Reading PCA0L automatically latches
the value of PCA0H into a “snapshot” register; the following PCA0H read accesses this “snapshot” register.
Reading the PCA0L Register first guarantees an accurate reading of the entire 16-bit PCA0 counter.
Reading PCA0H or PCA0L does not disturb the counter operation. The CPS2–CPS0 bits in the PCA0MD
register select the timebase for the counter/timer as shown in Table 23.1.
When the counter/timer overflows from 0xFFFF to 0x0000, the Counter Overflow Flag (CF) in PCA0MD is
set to logic 1 and an interrupt request is generated if CF interrupts are enabled. Setting the ECF bit in
PCA0MD to logic 1 enables the CF flag to generate an interrupt request. The CF bit is not automatically
cleared by hardware when the CPU vectors to the interrupt service routine, and must be cleared by software (Note: PCA0 interrupts must be globally enabled before CF interrupts are recognized. PCA0 interrupts are globally enabled by setting the EA bit (IE.7) and the EPCA0 bit in EIE1 to logic 1). Clearing the
CIDL bit in the PCA0MD register allows the PCA to continue normal operation while the CPU is in Idle
mode.
Table 23.1. PCA Timebase Input Options
CPS2
0
0
0
CPS1
0
0
1
CPS0
0
1
0
0
1
1
1
1
0
0
0
1
Timebase
System clock divided by 12
System clock divided by 4
Timer 0 overflow
High-to-low transitions on ECI (max rate = system clock divided
by 4)
System clock
External oscillator source divided by 8*
*Note: External oscillator source divided by 8 is synchronized with the system clock.
IDLE
PCA0MD
CWW
I D D
D T L
L E C
K
C
P
S
2
C
P
S
1
PCA0CN
CE
PC
SF
0
CC
FR
C
C
F
4
C
C
F
3
C
C
F
2
C
C
F
1
C
C
F
0
To SFR Bus
PCA0L
read
Snapshot
Register
SYSCLK/12
SYSCLK/4
Timer 0 Overflow
ECI
SYSCLK
External Clock/8
000
001
010
0
011
1
PCA0H
PCA0L
Overflow
100
101
To PCA Modules
Figure 23.2. PCA Counter/Timer Block Diagram
212
To PCA Interrupt System
CF
Rev. 1.1
C8051F350/1/2/3
23.2. Capture/Compare Modules
Each module can be configured to operate independently in one of six operation modes: Edge-triggered
Capture, Software Timer, High Speed Output, Frequency Output, 8-Bit Pulse Width Modulator, or 16-Bit
Pulse Width Modulator. Each module has Special Function Registers (SFRs) associated with it in the CIP51 system controller. These registers are used to exchange data with a module and configure the module's
mode of operation.
Table 23.2 summarizes the bit settings in the PCA0CPMn registers used to select the PCA capture/compare module’s operating modes. Setting the ECCFn bit in a PCA0CPMn register enables the module's
CCFn interrupt. Note: PCA0 interrupts must be globally enabled before individual CCFn interrupts are recognized. PCA0 interrupts are globally enabled by setting the EA bit and the EPCA0 bit to logic 1. See
Figure 23.3 for details on the PCA interrupt configuration.
Table 23.2. PCA0CPM Register Settings for PCA Capture/Compare Modules
PWM16 ECOM
CAPP CAPN
MAT
TOG
PWM
ECCF
X
X
1
0
0
0
0
X
X
X
0
1
0
0
0
X
X
X
1
1
0
0
0
X
0
0
0
0
0
1
1
X
X
X
0
1
1
0
0
0
0
1
1
1
X
X
X
X
X
X
X
X
0
1
1
0
1
0
1
0
1
0
1
0
X = Don’t Care
Operation Mode
Capture triggered by positive edge
on CEXn
Capture triggered by negative
edge on CEXn
Capture triggered by transition on
CEXn
Software Timer
High Speed Output
Frequency Output
8-Bit Pulse Width Modulator
16-Bit Pulse Width Modulator
(for n = 0 to 2)
PCA0CPMn
P ECCMT P E
WC A A AOWC
MOPP TGMC
1 MP N n n n F
6 n n n
n
n
PCA0CN
CC
FR
CCC
CCC
FFF
2 1 0
PCA0MD
C WW
I DD
DT L
LEC
K
CCCE
PPPC
SSSF
2 1 0
0
PCA Counter/
Timer Overflow
1
ECCF0
EPCA0
0
PCA Module 0
(CCF0)
1
EA
0
0
1
1
Interrupt
Priority
Decoder
ECCF1
0
PCA Module 1
(CCF1)
1
ECCF2
PCA Module 2
(CCF2)
0
1
Figure 23.3. PCA Interrupt Block Diagram
Rev. 1.1
213
C8051F350/1/2/3
23.2.1. Edge-triggered Capture Mode
In this mode, a valid transition on the CEXn pin causes the PCA to capture the value of the PCA
counter/timer and load it into the corresponding module's 16-bit capture/compare register (PCA0CPLn and
PCA0CPHn). The CAPPn and CAPNn bits in the PCA0CPMn register are used to select the type of transition that triggers the capture: low-to-high transition (positive edge), high-to-low transition (negative edge),
or either transition (positive or negative edge). When a capture occurs, the Capture/Compare Flag (CCFn)
in PCA0CN is set to logic 1 and an interrupt request is generated if CCF interrupts are enabled. The CCFn
bit is not automatically cleared by hardware when the CPU vectors to the interrupt service routine, and
must be cleared by software. If both CAPPn and CAPNn bits are set to logic 1, then the state of the Port
pin associated with CEXn can be read directly to determine whether a rising-edge or falling-edge caused
the capture.
PCA Interrupt
PCA0CPMn
P E CCMT P E
WC A A AOWC
MOPP TGMC
1 MPN n n n F
6 n n n
n
n
x 0 0 x
0
Port I/O
Crossbar
CEXn
CCCCC
CCCCC
FFFFF
4 3 2 1 0
(to CCFn)
x 0
PCA0CN
CC
FR
1
PCA0CPLn
PCA0CPHn
Capture
0
1
PCA
Timebase
PCA0L
PCA0H
Figure 23.4. PCA Capture Mode Diagram
Note: The CEXn input signal must remain high or low for at least 2 system clock cycles to be recognized by
the hardware.
214
Rev. 1.1
C8051F350/1/2/3
23.2.2. Software Timer (Compare) Mode
In Software Timer mode, the PCA counter/timer value is compared to the module's 16-bit capture/compare
register (PCA0CPHn and PCA0CPLn). When a match occurs, the Capture/Compare Flag (CCFn) in
PCA0CN is set to logic 1 and an interrupt request is generated if CCF interrupts are enabled. The CCFn bit
is not automatically cleared by hardware when the CPU vectors to the interrupt service routine, and must
be cleared by software. Setting the ECOMn and MATn bits in the PCA0CPMn register enables Software
Timer mode.
Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Capture/Compare registers, the low byte should always be written first. Writing to PCA0CPLn clears the
ECOMn bit to ‘0’; writing to PCA0CPHn sets ECOMn to ‘1’.
Write to
PCA0CPLn
0
ENB
Reset
Write to
PCA0CPHn
PCA Interrupt
ENB
1
PCA0CPMn
P ECCMT P E
WC A A AOWC
MOPP TGMC
1 MP N n n n F
6 n n n
n
n
x
0 0
PCA0CN
PCA0CPLn
CC
FR
PCA0CPHn
CCCCC
CCCCC
FFFFF
4 3 2 1 0
0 0 x
Enable
16-bit Comparator
PCA
Timebase
PCA0L
Match
0
1
PCA0H
Figure 23.5. PCA Software Timer Mode Diagram
Rev. 1.1
215
C8051F350/1/2/3
23.2.3. High Speed Output Mode
In High Speed Output mode, a module’s associated CEXn pin is toggled each time a match occurs
between the PCA Counter and the module's 16-bit capture/compare register (PCA0CPHn and
PCA0CPLn) Setting the TOGn, MATn, and ECOMn bits in the PCA0CPMn register enables the HighSpeed Output mode.
Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Capture/Compare registers, the low byte should always be written first. Writing to PCA0CPLn clears the
ECOMn bit to ‘0’; writing to PCA0CPHn sets ECOMn to ‘1’.
Write to
PCA0CPLn
0
ENB
Reset
Write to
PCA0CPHn
PCA0CPMn
P ECCMT P E
WC A A A OWC
MOPP TGMC
1 MP N n n n F
6 n n n
n
n
ENB
1
x
0 0
0 x
PCA Interrupt
PCA0CN
PCA0CPLn
Enable
CC
FR
PCA0CPHn
Match
16-bit Comparator
CCCCC
CCCCC
FFFFF
4 3 2 1 0
0
1
TOGn
Toggle
PCA
Timebase
0 CEXn
1
PCA0L
Crossbar
PCA0H
Figure 23.6. PCA High Speed Output Mode Diagram
216
Rev. 1.1
Port I/O
C8051F350/1/2/3
23.2.4. Frequency Output Mode
Frequency Output Mode produces a programmable-frequency square wave on the module’s associated
CEXn pin. The capture/compare module high byte holds the number of PCA clocks to count before the output is toggled. The frequency of the square wave is then defined by Equation 23.1.
F PCA
F CEXn = ----------------------------------------2 × PCA0CPHn
Note: A value of 0x00 in the PCA0CPHn register is equal to 256 for this equation.
Equation 23.1. Square Wave Frequency Output
Where FPCA is the frequency of the clock selected by the CPS2–0 bits in the PCA mode register,
PCA0MD. The lower byte of the capture/compare module is compared to the PCA counter low byte; on a
match, CEXn is toggled and the offset held in the high byte is added to the matched value in PCA0CPLn.
Frequency Output Mode is enabled by setting the ECOMn, TOGn, and PWMn bits in the PCA0CPMn register.
Write to
PCA0CPLn
0
ENB
Reset
PCA0CPMn
Write to
PCA0CPHn
ENB
1
P ECCMT P E
WC A A AOWC
MOPP TGMC
1 MP N n n n F
6 n n n
n
n
x
0 0 0
PCA0CPLn
8-bit Adder
PCA0CPHn
Adder
Enable
TOGn
Toggle
x
Enable
PCA Timebase
8-bit
Comparator
match
0 CEXn
1
Crossbar
Port I/O
PCA0L
Figure 23.7. PCA Frequency Output Mode
Rev. 1.1
217
C8051F350/1/2/3
23.2.5. 8-Bit Pulse Width Modulator Mode
Each module can be used independently to generate a pulse width modulated (PWM) output on its associated CEXn pin. The frequency of the output is dependent on the timebase for the PCA counter/timer. The
duty cycle of the PWM output signal is varied using the module's PCA0CPLn capture/compare register.
When the value in the low byte of the PCA counter/timer (PCA0L) is equal to the value in PCA0CPLn, the
output on the CEXn pin will be set. When the count value in PCA0L overflows, the CEXn output will be
reset (see Figure 23.8). Also, when the counter/timer low byte (PCA0L) overflows from 0xFF to 0x00,
PCA0CPLn is reloaded automatically with the value stored in the module’s capture/compare high byte
(PCA0CPHn) without software intervention. Setting the ECOMn and PWMn bits in the PCA0CPMn register
enables 8-Bit Pulse Width Modulator mode. The duty cycle for 8-Bit PWM Mode is given by Equation 23.2.
Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Capture/Compare registers, the low byte should always be written first. Writing to PCA0CPLn clears the
ECOMn bit to ‘0’; writing to PCA0CPHn sets ECOMn to ‘1’.
( 256 – PCA0CPHn )
DutyCycle = --------------------------------------------------256
Equation 23.2. 8-Bit PWM Duty Cycle
Using Equation 23.2, the largest duty cycle is 100% (PCA0CPHn = 0), and the smallest duty cycle is
0.39% (PCA0CPHn = 0xFF). A 0% duty cycle may be generated by clearing the ECOMn bit to ‘0’.
Write to
PCA0CPLn
0
PCA0CPHn
ENB
Reset
Write to
PCA0CPHn
ENB
1
PCA0CPMn
P ECCMT P E
WC A A AOWC
MOPP TGMC
1 MP N n n n F
6 n n n
n
n
0
0 0 x 0
PCA0CPLn
x
Enable
8-bit
Comparator
match
S
R
PCA Timebase
SET
CLR
Q
CEXn
Q
PCA0L
Overflow
Figure 23.8. PCA 8-Bit PWM Mode Diagram
218
Rev. 1.1
Crossbar
Port I/O
C8051F350/1/2/3
23.2.6. 16-Bit Pulse Width Modulator Mode
A PCA module may also be operated in 16-Bit PWM mode. In this mode, the 16-bit capture/compare module defines the number of PCA clocks for the low time of the PWM signal. When the PCA counter matches
the module contents, the output on CEXn is asserted high; when the counter overflows, CEXn is asserted
low. To output a varying duty cycle, new value writes should be synchronized with PCA CCFn match interrupts. 16-Bit PWM Mode is enabled by setting the ECOMn, PWMn, and PWM16n bits in the PCA0CPMn
register. For a varying duty cycle, match interrupts should be enabled (ECCFn = 1 AND MATn = 1) to help
synchronize the capture/compare register writes. The duty cycle for 16-Bit PWM Mode is given by
Equation 23.3.
Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Capture/Compare registers, the low byte should always be written first. Writing to PCA0CPLn clears the
ECOMn bit to ‘0’; writing to PCA0CPHn sets ECOMn to ‘1’.
( 65536 – PCA0CPn )
DutyCycle = ----------------------------------------------------65536
Equation 23.3. 16-Bit PWM Duty Cycle
Using Equation 23.3, the largest duty cycle is 100% (PCA0CPn = 0), and the smallest duty cycle is
0.0015% (PCA0CPn = 0xFFFF). A 0% duty cycle may be generated by clearing the ECOMn bit to ‘0’.
Write to
PCA0CPLn
0
ENB
Reset
Write to
PCA0CPHn
ENB
1
PCA0CPMn
P ECCMT P E
WC A A AOWC
MOPP TGMC
1 MP N n n n F
6 n n n
n
n
1
0 0 x 0
PCA0CPHn
PCA0CPLn
x
Enable
16-bit Comparator
match
S
R
PCA Timebase
PCA0H
SET
CLR
Q
CEXn
Crossbar
Port I/O
Q
PCA0L
Overflow
Figure 23.9. PCA 16-Bit PWM Mode
Rev. 1.1
219
C8051F350/1/2/3
23.3. Watchdog Timer Mode
A programmable watchdog timer (WDT) function is available through the PCA Module 2. The WDT is used
to generate a reset if the time between writes to the WDT update register (PCA0CPH2) exceed a specified
limit. The WDT can be configured and enabled/disabled as needed by software.
With the WDTE bit set in the PCA0MD register, Module 2 operates as a watchdog timer (WDT). The Module 2 high byte is compared to the PCA counter high byte; the Module 2 low byte holds the offset to be
used when WDT updates are performed. The Watchdog Timer is enabled on reset. Writes to some
PCA registers are restricted while the Watchdog Timer is enabled.
23.3.1. Watchdog Timer Operation
While the WDT is enabled:
•
•
•
•
•
•
PCA counter is forced on.
Writes to PCA0L and PCA0H are not allowed.
PCA clock source bits (CPS2–CPS0) are frozen.
PCA Idle control bit (CIDL) is frozen.
Module 2 is forced into software timer mode.
Writes to the Module 2 mode register (PCA0CPM2) are disabled.
While the WDT is enabled, writes to the CR bit will not change the PCA counter state; the counter will run
until the WDT is disabled. The PCA counter run control (CR) will read zero if the WDT is enabled but user
software has not enabled the PCA counter. If a match occurs between PCA0CPH2 and PCA0H while the
WDT is enabled, a reset will be generated. To prevent a WDT reset, the WDT may be updated with a write
of any value to PCA0CPH2. Upon a PCA0CPH2 write, PCA0H plus the offset held in PCA0CPL2 is loaded
into PCA0CPH2 (See Figure 23.10).
PCA0MD
CWW
I DD
DT L
L E C
K
CCCE
PPPC
SSSF
2 1 0
PCA0CPH2
Enable
PCA0CPL2
Write to
PCA0CPH2
8-bit Adder
8-bit
Comparator
PCA0H
Match
Reset
PCA0L Overflow
Adder
Enable
Figure 23.10. PCA Module 2 with Watchdog Timer Enabled
Note that the 8-bit offset held in PCA0CPH2 is compared to the upper byte of the 16-bit PCA counter. This
offset value is the number of PCA0L overflows before a reset. Up to 256 PCA clocks may pass before the
first PCA0L overflow occurs, depending on the value of the PCA0L when the update is performed. The
total offset is then given (in PCA clocks) by Equation 23.4, where PCA0L is the value of the PCA0L register
at the time of the update.
220
Rev. 1.1
C8051F350/1/2/3
Offset = ( 256 × PCA0CPL2 ) + ( 256 – PCA0L )
Equation 23.4. Watchdog Timer Offset in PCA Clocks
The WDT reset is generated when PCA0L overflows while there is a match between PCA0CPH2 and
PCA0H. Software may force a WDT reset by writing a ‘1’ to the CCF2 flag (PCA0CN.2) while the WDT is
enabled.
23.3.2. Watchdog Timer Usage
To configure the WDT, perform the following tasks:
• Disable the WDT by writing a ‘0’ to the WDTE bit.
• Select the desired PCA clock source (with the CPS2–CPS0 bits).
• Load PCA0CPL2 with the desired WDT update offset value.
• Configure the PCA Idle mode (set CIDL if the WDT should be suspended while the CPU is in Idle
mode).
• Enable the WDT by setting the WDTE bit to ‘1’.
• Write a value to PCA0CPH2 to reload the WDT.
The PCA clock source and Idle mode select cannot be changed while the WDT is enabled. The watchdog
timer is enabled by setting the WDTE or WDLCK bits in the PCA0MD register. When WDLCK is set, the
WDT cannot be disabled until the next system reset. If WDLCK is not set, the WDT is disabled by clearing
the WDTE bit.
The WDT is enabled following any reset. The PCA0 counter clock defaults to the system clock divided by
12, PCA0L defaults to 0x00, and PCA0CPL2 defaults to 0x00. Using Equation 23.4, this results in a WDT
timeout interval of 256 PCA clock cycles, or 3072 system clock cycles. Table 23.3 lists some example timeout intervals for typical system clocks.
Table 23.3. Watchdog Timer Timeout Intervals1
System Clock (Hz)
24,500,000
24,500,000
24,500,000
18,432,000
18,432,000
18,432,000
11,059,200
11,059,200
11,059,200
3,062,5002
3,062,5002
3,062,5002
32,000
32,000
32,000
PCA0CPL2
255
128
32
255
128
32
255
128
32
255
128
32
255
128
32
Timeout Interval (ms)
32.1
16.2
4.1
42.7
21.5
5.5
71.1
35.8
9.2
257
129.5
33.1
24576
12384
3168
Notes:
1. Assumes SYSCLK / 12 as the PCA clock source, and a PCA0L
value of 0x00 at the update time.
2. SYSCLK reset frequency = Internal oscillator frequency divided by 8.
Rev. 1.1
221
C8051F350/1/2/3
23.4. Register Descriptions for PCA
Following are detailed descriptions of the special function registers related to the operation of the PCA.
SFR Definition 23.1. PCA0CN: PCA Control
R/W
R/W
R
R
R
R/W
R/W
R/W
Reset Value
CF
CR
—
—
—
CCF2
CCF1
CCF0
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Bit
Addressable
SFR Address: 0xD8
Bit7:
CF: PCA Counter/Timer Overflow Flag.
Set by hardware when the PCA Counter/Timer overflows from 0xFFFF to 0x0000. When the
Counter/Timer Overflow (CF) interrupt is enabled, setting this bit causes the CPU to vector
to the PCA interrupt service routine. This bit is not automatically cleared by hardware and
must be cleared by software.
Bit6:
CR: PCA Counter/Timer Run Control.
This bit enables/disables the PCA Counter/Timer.
0: PCA Counter/Timer disabled.
1: PCA Counter/Timer enabled.
Bits5–3: UNUSED. Read = 000b, Write = don't care.
Bit2:
CCF2: PCA Module 2 Capture/Compare Flag.
This bit is set by hardware when a match or capture occurs. When the CCF2 interrupt is
enabled, setting this bit causes the CPU to vector to the PCA interrupt service routine. This
bit is not automatically cleared by hardware and must be cleared by software.
Bit1:
CCF1: PCA Module 1 Capture/Compare Flag.
This bit is set by hardware when a match or capture occurs. When the CCF1 interrupt is
enabled, setting this bit causes the CPU to vector to the PCA interrupt service routine. This
bit is not automatically cleared by hardware and must be cleared by software.
Bit0:
CCF0: PCA Module 0 Capture/Compare Flag.
This bit is set by hardware when a match or capture occurs. When the CCF0 interrupt is
enabled, setting this bit causes the CPU to vector to the PCA interrupt service routine. This
bit is not automatically cleared by hardware and must be cleared by software.
222
Rev. 1.1
C8051F350/1/2/3
SFR Definition 23.2. PCA0MD: PCA Mode
R/W
R/W
R/W
R
R/W
R/W
R/W
R/W
Reset Value
CIDL
WDTE
WDLCK
—
CPS2
CPS1
CPS0
ECF
01000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Bit
Addressable
SFR Address: 0xD9
Bit7:
CIDL: PCA Counter/Timer Idle Control.
Specifies PCA behavior when CPU is in Idle Mode.
0: PCA continues to function normally while the system controller is in Idle Mode.
1: PCA operation is suspended while the system controller is in Idle Mode.
Bit6:
WDTE: Watchdog Timer Enable
If this bit is set, PCA Module 2 is used as the watchdog timer.
0: Watchdog Timer disabled.
1: PCA Module 2 enabled as Watchdog Timer.
Bit5:
WDLCK: Watchdog Timer Lock
This bit locks/unlocks the Watchdog Timer Enable. When WDLCK is set, the Watchdog
Timer may not be disabled until the next system reset.
0: Watchdog Timer Enable unlocked.
1: Watchdog Timer Enable locked.
Bit4:
UNUSED. Read = 0b, Write = don't care.
Bits3–1: CPS2–CPS0: PCA Counter/Timer Pulse Select.
These bits select the timebase source for the PCA counter.
CPS2
0
0
0
CPS1
0
0
1
CPS0
0
1
0
0
1
1
1
1
1
1
0
0
1
1
0
1
0
1
Timebase
System clock divided by 12
System clock divided by 4
Timer 0 overflow
High-to-low transitions on ECI (max rate = system clock
divided by 4)
System clock
External clock divided by 8*
Reserved
Reserved
*Note: External oscillator source divided by 8 is synchronized with the system clock.
Bit0:
ECF: PCA Counter/Timer Overflow Interrupt Enable.
This bit sets the masking of the PCA Counter/Timer Overflow (CF) interrupt.
0: Disable the CF interrupt.
1: Enable a PCA Counter/Timer Overflow interrupt request when CF (PCA0CN.7) is set.
Note: When the WDTE bit is set to ‘1’, the PCA0MD register cannot be modified. To change the
contents of the PCA0MD register, the Watchdog Timer must first be disabled.
Rev. 1.1
223
C8051F350/1/2/3
SFR Definition 23.3. PCA0CPMn: PCA Capture/Compare Mode
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
PWM16n
ECOMn
CAPPn
CAPNn
MATn
TOGn
PWMn
ECCFn
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: PCA0CPM0: 0xDA, PCA0CPM1: 0xDB, PCA0CPM2: 0xDC
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
224
PWM16n: 16-bit Pulse Width Modulation Enable.
This bit selects 16-bit mode when Pulse Width Modulation mode is enabled (PWMn = 1).
0: 8-bit PWM selected.
1: 16-bit PWM selected.
ECOMn: Comparator Function Enable.
This bit enables/disables the comparator function for PCA module n.
0: Disabled.
1: Enabled.
CAPPn: Capture Positive Function Enable.
This bit enables/disables the positive edge capture for PCA module n.
0: Disabled.
1: Enabled.
CAPNn: Capture Negative Function Enable.
This bit enables/disables the negative edge capture for PCA module n.
0: Disabled.
1: Enabled.
MATn: Match Function Enable.
This bit enables/disables the match function for PCA module n. When enabled, matches of
the PCA counter with a module's capture/compare register cause the CCFn bit in PCA0MD
register to be set to logic 1.
0: Disabled.
1: Enabled.
TOGn: Toggle Function Enable.
This bit enables/disables the toggle function for PCA module n. When enabled, matches of
the PCA counter with a module's capture/compare register cause the logic level on the
CEXn pin to toggle. If the PWMn bit is also set to logic 1, the module operates in Frequency
Output Mode.
0: Disabled.
1: Enabled.
PWMn: Pulse Width Modulation Mode Enable.
This bit enables/disables the PWM function for PCA module n. When enabled, a pulse width
modulated signal is output on the CEXn pin. 8-bit PWM is used if PWM16n is cleared; 16-bit
mode is used if PWM16n is set to logic 1. If the TOGn bit is also set, the module operates in
Frequency Output Mode.
0: Disabled.
1: Enabled.
ECCFn: Capture/Compare Flag Interrupt Enable.
This bit sets the masking of the Capture/Compare Flag (CCFn) interrupt.
0: Disable CCFn interrupts.
1: Enable a Capture/Compare Flag interrupt request when CCFn is set.
Rev. 1.1
C8051F350/1/2/3
SFR Definition 23.4. PCA0L: PCA Counter/Timer Low Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Reset Value
00000000
SFR Address: 0xF9
Bits 7–0: PCA0L: PCA Counter/Timer Low Byte.
The PCA0L register holds the low byte (LSB) of the 16-bit PCA Counter/Timer.
SFR Definition 23.5. PCA0H: PCA Counter/Timer High Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR
Address:
SFR Address: 0xFA
Bits 7–0: PCA0H: PCA Counter/Timer High Byte.
The PCA0H register holds the high byte (MSB) of the 16-bit PCA Counter/Timer.
Rev. 1.1
225
C8051F350/1/2/3
SFR Definition 23.6. PCA0CPLn: PCA Capture Module Low Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Reset Value
00000000
SFR Address: PCA0CPL0: 0xE9, PCA0CPL1: 0xEB, PCA0CPL2: 0xED
Bits7–0: PCA0CPLn: PCA Capture Module Low Byte.
The PCA0CPLn register holds the low byte (LSB) of the 16-bit capture module n.
SFR Definition 23.7. PCA0CPHn: PCA Capture Module High Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Reset Value
00000000
SFR Address: PCA0CPH0: 0xEA, PCA0CPH1: 0xEB, PCA0CPH2: 0xEE
Bits7–0: PCA0CPHn: PCA Capture Module High Byte.
The PCA0CPHn register holds the high byte (MSB) of the 16-bit capture module n.
226
Rev. 1.1
C8051F350/1/2/3
24. Revision Specific Behavior
This chapter describes a functional difference between C8051F35x “REV B” and “REV C” or later devices.
The functionality of the VREF- pin differs between these revisions.
24.1. Revision Identification
The Lot ID Code on the top side of the device package can be used for decoding device revision information. On C8051F350/2 devices, the revision letter is the first letter of the Lot ID Code. On C8051F351/3
devices, the revision letter is the first of the Lot ID Code. Figure 24.1 shows how to find the revision on the
top side of the device package.
C8051F350/2 Package Marking
C8051F351/3 Package Marking
SILABS
F351
CCNAKX
0537+
C8051F350
CCNAVT
0450
Revision Letter
Revision Letter
Figure 24.1. Reading Package Marking
24.1. VREF- pin
The required connection for the VREF- pin differs between the "REV B" and "REV C" and later devices.
On "REV B" devices, when the internal voltage reference is enabled, the VREF- pin is internally connected
to GND so the VREF- pin can be left unconnected externally.
On "REV C" and later devices, when the internal voltage reference is enabled, the VREF- pin is not internally connected to GND. The VREF- pin must be connected to GND externally for the voltage reference to
operate properly.
Rev. 1.1
227
C8051F350/1/2/3
NOTES:
228
Rev. 1.1
C8051F350/1/2/3
25. C2 Interface
C8051F350/1/2/3 devices include an on-chip Silicon Labs 2-Wire (C2) debug interface to allow Flash programming and in-system debugging with the production part installed in the end application. The C2 interface uses a clock signal (C2CK) and a bi-directional C2 data signal (C2D) to transfer information between
the device and a host system. See the C2 Interface Specification for details on the C2 protocol.
25.1. C2 Interface Registers
The following describes the C2 registers necessary to allow Flash programming and in-system debugging
with the production part installed through the C2 interface. All C2 registers are accessed through the C2
interface as described in the C2 Interface Specification.
C2 Register Definition 25.1. C2ADD: C2 Address
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Bits7–0: The C2ADD register is accessed via the C2 interface to select the target Data register for
C2 Data Read and Data Write commands.
Address
0x00
0x01
0x02
0xB4
Description
Selects the Device ID register for Data Read instructions
Selects the Revision ID register for Data Read instructions
Selects the C2 Flash Programming Control register for Data
Read/Write instructions
Selects the C2 Flash Programming Data register for Data
Read/Write instructions
C2 Register Definition 25.2. DEVICEID: C2 Device ID
Reset Value
00001011
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
This read-only register returns the 8-bit device ID: 0x0B (C8051F350/1/2/3).
Rev. 1.1
229
C8051F350/1/2/3
C2 Register Definition 25.3. REVID: C2 Revision ID
Reset Value
Variable
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
This read-only register returns the 8-bit revision ID.
C2 Register Definition 25.4. FPCTL: C2 Flash Programming Control
Reset Value
00000000
Bit7
Bits7–0
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
FPCTL: Flash Programming Control Register.
This register is used to enable Flash programming via the C2 interface. To enable C2 Flash
programming, the following codes must be written in order: 0x02, 0x01. Note that once C2
Flash programming is enabled, a system reset must be issued to resume normal operation.
C2 Register Definition 25.5. FPDAT: C2 Flash Programming Data
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Bits7–0: FPDAT: C2 Flash Programming Data Register.
This register is used to pass Flash commands, addresses, and data during C2 Flash
accesses. Valid commands are listed below.
Code
0x06
0x07
0x08
0x03
230
Command
Flash Block Read
Flash Block Write
Flash Page Erase
Device Erase
Rev. 1.1
C8051F350/1/2/3
25.2. C2 Pin Sharing
The C2 protocol allows the C2 pins to be shared with user functions so that in-system debugging and
Flash programming functions may be performed. This is possible because C2 communication is typically
performed when the device is in the halt state, where all on-chip peripherals and user software are stalled.
In this halted state, the C2 interface can safely ‘borrow’ the C2CK (/RST) and C2D (P2.0) pins. In most
applications, external resistors are required to isolate C2 interface traffic from the user application. A typical isolation configuration is shown in Figure 25.1.
C8051Fxxx
/Reset (a)
C2CK
Input (b)
C2D
Output (c)
C2 Interface Master
Figure 25.1. Typical C2 Pin Sharing
The configuration in Figure 25.1 assumes the following:
1. The user input (b) cannot change state while the target device is halted.
2. The /RST pin on the target device is used as an input only.
Additional resistors may be necessary depending on the specific application.
Rev. 1.1
231
C8051F350/1/2/3
DOCUMENT CHANGE LIST
Revision 0.4 to Revision 1.0
•
•
•
•
•
•
•
•
•
•
•
•
Removed preliminary tag and updated various specifications.
Updated package labeling and added "Lead-free (RoHS Compliant)" in Table 1.1, “Product Selection
Guide,” on page 18.
ADC chapter: Added Table 5.5, Table 5.6, Table 5.7, Table 5.8, and Table 5.9 on pages 63–65.
Temperature Sensor chapter: Added Offset Error and Slope Error specifications to Table 8.1, “Temperature Sensor Electrical Characteristics,” on page 77.
Reset Sources chapter: Table 14.1, “Reset Electrical Characteristics,” on page 120: Added VDD Ramp
Time and changed “VDD POR Threshold” to “VDD Monitor Threshold.”
Flash Memory chapter: Clarified descriptions of Flash security features.
Oscillators chapter: Clarified external crystal initialization steps and added a specific 32.768 kHz crystal example.
Oscillators chapter: Clarified external capacitor example.
Port I/O chapter: Figure 18.3 and Figure 18.4, Crossbar Priority Decoder Tables: Changed
PnSKIP[7:0] to PnSKIP[0:7] to match the Port I/O order.
SMBus chapter: SFR Definition 19.1, SMB0CF register: Added a description of the behavior of Timer 3
in split mode if SMBTOE is set.
PCA chapter: Updated Watchdog timer timeout intervals in Table 23.3 on page 221.
C2 chapter: Removed references to “boundary scans.”
Revision 1.0 to Revision 1.1
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
232
Clarified text in Table 2.1, “Absolute Maximum Ratings,” on page 29.
Updated Digital Supply Current values in Table 3.1, “Global DC Electrical Characteristics,” on page 30.
Removed sentence in Section “5.2. Calibrating the ADC’ on page 44 that indicated the AD0CALC bit is
cleared by clearing the AD0INT flag.
Updated Table 5.3, “ADC0 Electrical Characteristics,” on page 61.
- ADC input current
- Burnout Current Source values
- AV+ Supply Current values
Added second note to SFR Definition 5.3.
Updated Table 6.1, “IDAC Electrical Characteristics,” on page 72.
- IDAC0 Gain-error Temp Co.
- IDAC0 Power consumption values
Clarified usage of VREF– pin in text and figure in 7. ‘Voltage Reference” on page 73.
Updated Table 7.1, “Voltage Reference Electrical Characteristics,” on page 75.
- VREF output voltage max and min
- Power Specifications
Corrected pins used by Comparator0 output in Section “9.1. Comparator0 Inputs and Outputs’ on
page 83.
Updated Comparator Power Consumptions values in Table 9.1, “Comparator Electrical Characteristics,” on page 85.
Corrected maximum SMBus speed in Section “19. SMBus’ on page 151.
Updated Table 19.4, “SMBus Status Decoding,” on page 167.
- Slave Transmitter (0101 0XX)
- Slave Receiver (0001 00X)
Fixed Equation 23.4.
Added last step to procedure described in Section “23.3.2. Watchdog Timer Usage’ on page 221.
Changed Note 2 in Table 23.3, “Watchdog Timer Timeout Intervals1,” on page 221.
Added Section “24. Revision Specific Behavior’ on page 227.
Rev. 1.1
C8051F350/1/2/3
NOTES:
Rev. 1.1
233
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