AT90S1200

AT90S1200
Features
• Utilizes the AVR® RISC Architecture
• AVR – High-performance and Low-power RISC Architecture
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– 89 Powerful Instructions – Most Single Clock Cycle Execution
– 32 x 8 General Purpose Working Registers
– Up to 12 MIPS Throughput at 12 MHz
Data and Non-volatile Program Memory
– 1K Byte of In-System Programmable Flash
Endurance: 1,000 Write/Erase Cycles
– 64 Bytes of In-System Programmable EEPROM
Endurance: 100,000 Write/Erase Cycles
– Programming Lock for Flash Program and EEPROM Data Security
Peripheral Features
– One 8-bit Timer/Counter with Separate Prescaler
– On-chip Analog Comparator
– Programmable Watchdog Timer with On-chip Oscillator
– SPI Serial Interface for In-System Programming
Special Microcontroller Features
– Low-power Idle and Power-down Modes
– External and Internal Interrupt Sources
– Selectable On-chip RC Oscillator for Zero External Components
Specifications
– Low-power, High-speed CMOS Process Technology
– Fully Static Operation
Power Consumption at 4 MHz, 3V, 25°C
– Active: 2.0 mA
– Idle Mode: 0.4 mA
– Power-down Mode: <1 µA
I/O and Packages
– 15 Programmable I/O Lines
– 20-pin PDIP, SOIC and SSOP
Operating Voltages
– 2.7 - 6.0V (AT90S1200-4)
– 4.0 - 6.0V (AT90S1200-12)
Speed Grades
– 0 - 4 MHz, (AT90S1200-4)
– 0 - 12 MHz, (AT90S1200-12)
8-bit
Microcontroller
with 1K Byte
of In-System
Programmable
Flash
AT90S1200
Pin Configuration
Rev. 0838H–AVR–03/02
1
Description
The AT90S1200 is a low-power CMOS 8-bit microcontroller based on the AVR RISC
architecture. By executing powerful instructions in a single clock cycle, the AT90S1200
achieves throughputs approaching 1 MIPS per MHz allowing the system designer to
optimize power consumption versus processing speed.
The AVR core combines a rich instruction set with the 32 general purpose working registers. All the 32 registers are directly connected to the Arithmetic Logic Unit (ALU),
allowing two independent registers to be accessed in one single instruction executed in
one clock cycle. The resulting architecture is more code efficient while achieving
throughputs up to ten times faster than conventional CISC microcontrollers.
Block Diagram
Figure 1. The AT90S1200 Block Diagram
The architecture supports high-level languages efficiently as well as extremely dense
assembler code programs. The AT90S1200 provides the following features: 1K byte of
In-System Programmable Flash, 64 bytes EEPROM, 15 general purpose I/O lines, 32
general purpose working registers, internal and external interrupts, programmable
watchdog timer with internal oscillator, an SPI serial port for program downloading and
two software selectable power-saving modes. The Idle Mode stops the CPU while allow2
AT90S1200
0838H–AVR–03/02
AT90S1200
ing the Registers, Timer/Counter, Watchdog and Interrupt system to continue
functioning. The Power-down mode saves the register contents but freezes the Oscillator, disabling all other chip functions until the next External Interrupt or hardware Reset.
The device is manufactured using Atmel’s high-density nonvolatile memory technology.
The On-chip In-System Programmable Flash allows the program memory to be reprogrammed in-system through an SPI serial interface or by a conventional nonvolatile
memory programmer. By combining an enhanced RISC 8-bit CPU with In-System Programmable Flash on a monolithic chip, the Atmel AT90S1200 is a powerful
microcontroller that provides a highly flexible and cost-effective solution to many embedded control applications.
The AT90S1200 AVR is supported with a full suite of program and system development
tools including: macro assemblers, program debugger/simulators, in-circuit emulators,
and evaluation kits.
Pin Descriptions
VCC
Supply voltage pin.
GND
Ground pin.
Port B (PB7..PB0)
Port B is an 8-bit bi-directional I/O port. Port pins can provide internal pull-up resistors
(selected for each bit). PB0 and PB1 also serve as the positive input (AIN0) and the
negative input (AIN1), respectively, of the On-chip Analog Comparator. The Port B output buffers can sink 20 mA and thus drive LED displays directly. When pins PB0 to PB7
are used as inputs and are externally pulled low, they will source current if the internal
pull-up resistors are activated. The Port B pins are tri-stated when a reset condition
becomes active, even if the clock is not active.
Port B also serves the functions of various special features of the AT90S1200 as listed
on page 30.
Port D (PD6..PD0)
Port D has seven bi-directional I/O pins with internal pull-up resistors, PD6..PD0. The
Port D output buffers can sink 20 mA. As inputs, Port D pins that are externally pulled
low will source current if the pull-up resistors are activated. The Port D pins are tri-stated
when a reset condition becomes active, even if the clock is not active.
Port D also serves the functions of various special features of the AT90S1200 as listed
on page 34.
RESET
Reset input. A low level on this pin for more than 50 ns will generate a reset, even if the
clock is not running. Shorter pulses are not guaranteed to generate a reset.
XTAL1
Input to the inverting oscillator amplifier and input to the internal clock operating circuit.
XTAL2
Output from the inverting oscillator amplifier.
Crystal Oscillator
XTAL1 and XTAL2 are input and output, respectively, of an inverting amplifier which can
be configured for use as an On-chip Oscillator, as shown in Figure 2. Either a quartz
crystal or a ceramic resonator may be used. To drive the device from an external clock
source, XTAL2 should be left unconnected while XTAL1 is driven as shown in Figure 3.
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Figure 2. Oscillator Connections
MAX 1 HC BUFFER
HC
C2
C1
XTAL2
XTAL1
GND
Note:
When using the MCU Oscillator as a clock for an external device, an HC buffer should be
connected as indicated in the figure.
Figure 3. External Clock Drive Configuration
On-chip RC Oscillator
4
An On-chip RC Oscillator running at a fixed frequency of 1 MHz can be selected as the
MCU clock source. If enabled, the AT90S1200 can operate with no external components. A control bit (RCEN) in the Flash Memory selects the On-chip RC Oscillator as
the clock source when programmed (“0”). The AT90S1200 is normally shipped with this
bit unprogrammed (“1”). Parts with this bit programmed can be ordered as
AT90S1200A. The RCEN-bit can be changed by parallel programming only. When
using the On-chip RC Oscillator for Serial Program downloading, the RCEN bit must be
programmed in Parallel Programming mode first.
AT90S1200
0838H–AVR–03/02
AT90S1200
Architectural
Overview
The fast-access register file concept contains 32 x 8-bit general purpose working registers with a single clock cycle access time. This means that during one single clock cycle,
one ALU (Arithmetic Logic Unit) operation is executed. Two operands are output from
the register file, the operation is executed, and the result is stored back in the register
file – in one clock cycle.
Figure 4. The AT90S1200 AVR RISC Architecture
The ALU supports arithmetic and logic functions between registers or between a constant and a register. Single register operations are also executed in the ALU. Figure 4
shows the AT90S1200 AVR RISC microcontroller architecture. The AVR uses a Harvard architecture concept – with separate memories and buses for program and data
memories. The program memory is accessed with a 2-stage pipeline. While one instruction is being executed, the next instruction is pre-fetched from the program memory.
This concept enables instructions to be executed in every clock cycle. The program
memory is In-System Programmable Flash memory.
With the relative jump and relative call instructions, the whole 512 address space is
directly accessed. All AVR instructions have a single 16-bit word format, meaning that
every program memory address contains a single 16-bit instruction.
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During interrupts and subroutine calls, the return address Program Counter (PC) is
stored on the stack. The stack is a 3-level-deep hardware stack dedicated for subroutines and interrupts.
The I/O memory space contains 64 addresses for CPU peripheral functions such as
Control Registers, Timer/Counters, A/D Converters and other I/O functions. The memory spaces in the AVR architecture are all linear and regular memory maps.
A flexible interrupt module has its control registers in the I/O space with an additional
global interrupt enable bit in the status register. All the different interrupts have a separ a te i nt er r up t v e c to r i n t h e i n te r r u pt v ec t or t a bl e at th e b e gi n ni n g of th e
program memory. The different interrupts have priority in accordance with their interrupt
vector position. The lower the interrupt vector address, the higher the priority.
General Purpose
Register File
Figure 5 shows the structure of the 32 general purpose registers in the CPU.
Figure 5. AVR CPU General Purpose Working Registers
7
0
R0
R1
R2
General
…
Purpose
…
Working
R28
Registers
R29
R30 (Z-Register)
R31
All the register operating instructions in the instruction set have direct and single cycle
access to all registers. The only exception is the five constant arithmetic and logic
instructions SBCI, SUBI, CPI, ANDI, ORI between a constant and a register and the LDI
instruction for load immediate constant data. These instructions apply to the second half
of the registers in the register file (R16..R31). The general SBC, SUB, CP, AND, OR
and all other operations between two registers or on a single register apply to the entire
register file.
Register 30 also serves as an 8-bit pointer for indirect address of the register file.
ALU – Arithmetic Logic
Unit
The high-performance AVR ALU operates in direct connection with all the 32 general
purpose working registers. Within a single clock cycle, ALU operations between registers in the register file are executed. The ALU operations are divided into three main
categories – arithmetic, logic and bit-functions.
In-System
Programmable Flash
Program Memory
The AT90S1200 contains 1K bytes On-chip In-System Programmable Flash memory for
program storage. Since all instructions are single 16-bit words, the Flash is organized as
512 x 16. The Flash memory has an endurance of at least 1000 write/erase cycles.
The AT90S1200 Program Counter is 9 bits wide, thus addressing the 512 words Flash
program memory.
See page 37 for a detailed description on Flash data downloading.
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AT90S1200
Program and Data
Addressing Modes
The AT90S1200 AVR RISC Microcontroller supports powerful and efficient addressing
modes. This section describes the different addressing modes supported in the
AT90S1200. In the figures, OP means the operation code part of the instruction word.
To simplify, not all figures show the exact location of the addressing bits.
Register Direct, Single
Register Rd
Figure 6. Direct Single Register Addressing
The operand is contained in register d (Rd).
Register Indirect
Figure 7. Indirect Register Addressing
The register accessed is the one pointed to by the Z-register (R30).
Register Direct, Two Registers
Rd and Rr
Figure 8. Direct Register Addressing, Two Registers
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Operands are contained in register r (Rr) and d (Rd). The result is stored in register d
(Rd).
I/O Direct
Figure 9. I/O Direct Addressing
Operand address is contained in 6 bits of the instruction word. n is the destination or
source register address.
Relative Program Addressing,
RJMP and RCALL
Figure 10. Relative Program Memory Addressing
Program execution continues at address PC + k + 1. The relative address k is -2048 to
2047.
Subroutine and Interrupt
Hardware Stack
The AT90S1200 uses a 3 level deep hardware stack for subroutines and interrupts. The
hardware stack is 9 bits wide and stores the Program Counter (PC) return address while
subroutines and interrupts are executed.
RCALL instructions and interrupts push the PC return address onto stack level 0, and
the data in the other stack levels 1 - 2 are pushed one level deeper in the stack. When a
RET or RETI instruction is executed the returning PC is fetched from stack level 0, and
the data in the other stack levels 1 - 2 are popped one level in the stack.
If more than three subsequent subroutine calls or interrupts are executed, the first values written to the stack are overwritten.
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AT90S1200
EEPROM Data Memory
The AT90S1200 contains 64 bytes of data EEPROM memory. It is organized as a separate data space, in which single bytes can be read and written. The EEPROM has an
endurance of at least 100,000 write/erase cycles. The access between the EEPROM
and the CPU is described on page 25 specifying the EEPROM address register, the
EEPROM data register, and the EEPROM control register. For the SPI data downloading, see page 44 for a detailed description.
Instruction Execution
Timing
This section describes the general access timing concepts for instruction execution and
internal memory access.
The AVR CPU is driven by the System Clock Ø, directly generated from the external
clock crystal for the chip. No internal clock division is used.
Figure 11 shows the parallel instruction fetches and instruction executions enabled by
the Harvard architecture and the fast-access register file concept. This is the basic pipelining concept to obtain up to 1 MIPS per MHz with the corresponding unique results for
functions per cost, functions per clocks, and functions per power-unit.
Figure 11. The Parallel Instruction Fetches and Instruction Executions
T1
T2
T3
T4
System Clock Ø
1st Instruction Fetch
1st Instruction Execute
2nd Instruction Fetch
2nd Instruction Execute
3rd Instruction Fetch
3rd Instruction Execute
4th Instruction Fetch
Figure 12 shows the internal timing concept for the register file. In a single clock cycle
an ALU operation using two register operands is executed, and the result is stored back
to the destination register.
Figure 12. Single-cycle ALU Operation
T1
T2
T3
T4
System Clock Ø
Total Execution Time
Register Operands Fetch
ALU Operation Execute
Result Write Back
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I/O Memory
The I/O space definition of the AT90S1200 is shown in the following table.
Table 1. The AT90S1200 I/O Space
Address Hex
Name
Function
$3F
SREG
Status REGister
$3B
GIMSK
General Interrupt MaSK register
$39
TIMSK
Timer/Counter Interrupt MaSK register
$38
TIFR
$35
MCUCR
MCU general Control Register
$33
TCCR0
Timer/Counter0 Control Register
$32
TCNT0
Timer/Counter0 (8-bit)
$21
WDTCR
Watchdog Timer Control Register
$1E
EEAR
EEPROM Address Register
$1D
EEDR
EEPROM Data Register
$1C
EECR
EEPROM Control Register
$18
PORTB
Data Register, Port B
$17
DDRB
Data Direction Register, Port B
$16
PINB
Input Pins, Port B
$12
PORTD
Data Register, Port D
$11
DDRD
Data Direction Register, Port D
$10
PIND
Input Pins, Port D
$08
ACSR
Analog Comparator Control and Status Register
Note:
Timer/Counter Interrupt Flag register
Reserved and unused locations are not shown in the table.
All AT90S1200 I/Os and peripherals are placed in the I/O space. The different I/O locations are accessed by the IN and OUT instructions transferring data between the 32
general purpose working registers and the I/O space. I/O registers within the address
range $00 - $1F are directly bit-accessible using the SBI and CBI instructions. In these
registers, the value of single bits can be checked by using the SBIS and SBIC instructions. Refer to the instruction set chapter for more details.
For compatibility with future devices, reserved bits should be written to zero if accessed.
Reserved I/O memory addresses should never be written.
Some of the status flags are cleared by writing a logical one to them. Note that the CBI
and SBI instructions will operate on all bits in the I/O register, writing a one back into any
flag read as set, thus clearing the flag. The CBI and SBI instructions work with registers
$00 to $1F only.
The different I/O and peripherals control registers are explained in the following
sections.
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AT90S1200
Status Register – SREG
The AVR status register (SREG) at I/O space location $3F is defined as:
Bit
7
6
5
4
3
2
1
0
$3F
I
T
H
S
V
N
Z
C
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
SREG
• Bit 7 – I: Global Interrupt Enable
The global interrupt enable bit must be set (one) for the interrupts to be enabled. The
individual interrupt enable control is then performed in separate control registers. If the
global interrupt enable bit is cleared (zero), none of the interrupts are enabled independent of the individual interrupt enable settings. The I-bit is cleared by hardware after an
interrupt has occurred, and is set by the RETI instruction to enable subsequent
interrupts.
• Bit 6 – T: Bit Copy Storage
The bit copy instructions BLD (Bit LoaD) and BST (Bit STore) use the T-bit as source
and destination for the operated bit. A bit from a register in the register file can be copied
into T by the BST instruction, and a bit in T can be copied into a bit in a register in the
register file by the BLD instruction.
• Bit 5 – H: Half-carry Flag
The half-carry flag H indicates a half carry in some arithmetic operations. See the
Instruction Set description for detailed information.
• Bit 4 – S: Sign Bit, S = N⊕V
The S-bit is always an exclusive or between the negative flag N and the two’s complement overflow flag V. See the Instruction Set description for detailed information.
• Bit 3 – V: Two’s Complement Overflow Flag
The two’s complement overflow flag V supports two’s complement arithmetics. See the
Instruction Set description for detailed information.
• Bit 2 – N: Negative Flag
The negative flag N indicates a negative result after the different arithmetic and logic
operations. See the Instruction Set description for detailed information.
• Bit 1 – Z: Zero Flag
The zero flag Z indicates a zero result after the different arithmetic and logic operations.
See the Instruction Set description for detailed information.
• Bit 0 – C: Carry Flag
The carry flag C indicates a carry in an arithmetic or logic operation. See the Instruction
Set description for detailed information.
Note that the status register is not automatically stored when entering an interrupt routine and restored when returning from an interrupt routine. This must be handled by
software.
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Reset and Interrupt
Handling
The AT90S1200 provides three different interrupt sources. These interrupts and the
separate reset vector, each have a separate program vector in the program memory
space. All the interrupts are assigned individual enable bits that must be set (one)
together with the I-bit in the Status Register in order to enable the interrupt.
The lowest addresses in the program memory space are automatically defined as the
Reset and Interrupt vectors. The complete list of vectors is shown in Table 2. The list
also determines the priority levels of the different interrupts. The lower the address the
higher is the priority level. RESET has the highest priority, and next is INT0 (the External
Interrupt Request 0), etc.
Table 2. Reset and Interrupt Vectors
Vector No.
Program Address
Source
Interrupt Definition
1
$000
RESET
Hardware Pin, Power-on Reset and
Watchdog Reset
2
$001
INT0
4
$002
TIMER0, OVF0
5
$003
ANA_COMP
External Interrupt Request 0
Timer/Counter0 Overflow
Analog Comparator
The most typical and general program setup for the Reset and Interrupt Vector
Addresses are:
Address
Labels
Code
Comments
$000
rjmp
RESET
; Reset Handler
$001
rjmp
EXT_INT0
; IRQ0 Handler
$002
rjmp
TIM0_OVF
; Timer0 Overflow Handler
$003
rjmp
ANA_COMP
; Analog Comparator Handler
MAIN:
<instr>
xxx
; Main program start
…
…
;
$004
…
Reset Sources
…
The AT90S1200 has three sources of reset:
•
Power-on Reset. The MCU is reset when the supply voltage is below the power-on
Reset threshold (VPOT).
•
External Reset. The MCU is reset when a low level is present on the RESET pin for
more than 50 ns.
•
Watchdog Reset. The MCU is reset when the Watchdog Timer period expires and
the Watchdog is enabled.
During Reset, all I/O registers are then set to their initial values, and the program starts
execution from address $000. The instruction placed in address $000 must be an RJMP
(relative jump) instruction to the reset handling routine. If the program never enables an
interrupt source, the interrupt vectors are not used, and regular program code can be
placed at these locations. The circuit diagram in Figure 13 shows the reset logic. Table 3
defines the timing and electrical parameters of the reset circuitry. Note that Power-on
Reset timing is clocked by the internal RC Oscillator. Refer to characterization data for
RC Oscillator frequency at other VCC voltages.
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0838H–AVR–03/02
AT90S1200
Figure 13. Reset Logic
Power-on Reset
Circuit
VCC
POR
Reset Circuit
S
Q
R
Q
Counter Reset
RESET
Watchdog
Timer
On-chip
RC Oscillator
Time-out
14-stage Ripple Counter
Internal Reset
100 - 500K
Table 3. Reset Characteristics (VCC = 5.0V)
Symbol
VPOT(1)
Min
Typ
Max
Units
Power-on Reset Threshold Voltage (rising)
0.8
1.2
1.6
V
Power-on Reset Threshold Voltage (falling)
0.2
0.4
0.6
V
VRST
Pin Threshold Voltage
–
–
0.85 VCC
V
tPOR
Power-on Reset Period
2.0
3.0
4.0
ms
tTOUT
Reset Delay Time-out Period (The Time-out
period equals 16K WDT cycles. See “Typical
Characteristics” on page 51. for typical WDT
frequency at different voltages).
11.0
16.0
21.0
ms
Note:
Power-on Reset
Parameter
1. The Power-on Reset will not work unless the supply voltage has been below VPOT
(falling).
A Power-on Reset (POR) circuit ensures that the device is reset from power-on. As
shown in Figure 13, an internal timer clocked from the Watchdog timer oscillator prevents the MCU from starting until after a certain period after VCC has reached the Poweron Threshold voltage (VPOT), regardless of the VCC rise time (see Figure 14).
Figure 14. MCU Start-up, RESET Tied to VCC.
VCC
RESET
TIME-OUT
VPOT
VRST
tTOUT
INTERNAL
RESET
If the built-in start-up delay is sufficient, RESET can be connected to VCC directly or via
an external pull-up resistor. By holding the RESET pin low for a period after VCC has
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been applied, the Power-on Reset period can be extended. Refer to Figure 15 for a timing example on this.
Figure 15. MCU Start-up, RESET Controlled Externally
VCC
RESET
VPOT
VRST
TIME-OUT
tTOUT
INTERNAL
RESET
External Reset
An External Reset is generated by a low level on the RESET pin. Reset pulses longer
than 50 ns will generate a reset, even if the clock is not running. Shorter pulses are not
guaranteed to generate a reset. When the applied signal reaches the Reset Threshold
Voltage (VRST) on its positive edge, the delay timer starts the MCU after the Time-out
period tTOUT has expired.
Figure 16. External Reset during Operation
VCC
RESET
TIME-OUT
INTERNAL
RESET
Watchdog Reset
14
When the Watchdog times out, it will generate a short reset pulse of 1 XTAL cycle duration. On the falling edge of this pulse, the delay timer starts counting the Time-out period
tTOUT. Refer to page 23 for details on operation of the Watchdog.
AT90S1200
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AT90S1200
Figure 17. Watchdog Reset during Operation
Interrupt Handling
The AT90S1200 has two Interrupt Mask Control Registers: the GIMSK (General Interrupt Mask Register) at I/O space address $3B and the TIMSK (Timer/Counter Interrupt
Mask Register) at I/O address $39.
When an interrupt occurs, the Global Interrupt Enable I-bit is cleared (zero) and all interrupts are disabled. The user software can set (one) the I-bit to enable interrupts. The Ibit is set (one) when a Return from Interrupt instruction (RETI) is executed.
When the Program Counter is vectored to the actual interrupt vector in order to execute
the interrupt handling routine, hardware clears the corresponding flag that generated the
interrupt. Some of the interrupt flags can also be cleared by writing a logic one to the flag
bit position(s) to be cleared.
If an interrupt condition occurs when the corresponding interrupt enable bit is cleared
(zero), the interrupt flag will be set and remembered until the interrupt is enabled, or the
flag is cleared by software.
If one or more interrupt conditions occur when the global interrupt enable bit is cleared
(zero), the corresponding interrupt flag(s) will be set and remembered until the global
interrupt enable bit is set (one), and will be executed by order of priority.
Note that external level interrupt does not have a flag, and will only be remembered for
as long as the interrupt condition is active.
Note that the Status Register is not automatically stored when entering an interrupt routine and restored when returning from an interrupt routine. This must be handled by
software.
General Interrupt Mask
Register – GIMSK
Bit
7
6
5
4
3
2
1
$3B
-
INT0
-
-
-
-
-
0
-
Read/Write
R
R/W
R
R
R
R
R
R
Initial Value
0
0
0
0
0
0
0
0
GIMSK
• Bit 7 – Res: Reserved Bit
This bit is a reserved bit in the AT90S1200 and always reads as zero.
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• Bit 6 – INT0: External Interrupt Request 0 Enable
When the INT0 bit is set (one) and the I-bit in the Status Register (SREG) is set (one),
the external pin interrupt is enabled. The Interrupt Sense Control0 bit 1/0 (ISC01 and
ISC00) in the MCU general Control Register (MCUCR) defines whether the external
interrupt is activated on rising or falling edge of the INT0 pin or low level sensed. INT0
can be activated even if the pin is configured as an output. See also page 17.
• Bits 5..0 – Res: Reserved Bits
These bits are reserved bits in the AT90S1200 and always read as zero.
Timer/Counter Interrupt Mask
Register – TIMSK
Bit
7
6
5
4
3
2
1
$39
-
-
-
-
-
-
TOIE0
0
-
Read/Write
R
R
R
R
R
R
R/W
R
Initial Value
0
0
0
0
0
0
0
0
TIMSK
• Bits 7..2 – Res: Reserved Bits
These bits are reserved bits in the AT90S1200 and always read as zero.
• Bit 1 – TOIE0: Timer/Counter0 Overflow Interrupt Enable
When the TOIE0 bit is set (one) and the I-bit in the Status Register is set (one), the
Timer/Counter0 Overflow interrupt is enabled. The corresponding interrupt (at vector
$002) is executed if an overflow in Timer/Counter0 occurs, i.e., when the TOV0 bit is set
in the Timer/Counter Interrupt Flag Register (TIFR).
• Bit 0 – Res: Reserved Bit
This bit is a reserved bit in the AT90S1200 and always reads as zero.
Timer/Counter Interrupt FLAG
Register – TIFR
Bit
7
6
5
4
3
2
1
$38
-
-
-
-
-
-
TOV0
0
-
Read/Write
R
R
R
R
R
R
R/W
R
Initial Value
0
0
0
0
0
0
0
0
TIFR
• Bits 7..2 – Res: Reserved Bits
These bits are reserved bits in the AT90S1200 and always read as zero.
• Bit 1 – TOV0: Timer/Counter0 Overflow Flag
The bit TOV0 is set (one) when an overflow occurs in Timer/Counter0. TOV0 is cleared
by hardware when executing the corresponding interrupt handling vector. Alternatively,
TOV0 is cleared by writing a logic one to the flag. When the SREG I-bit, and TOIE0
(Timer/Counter0 O ver flow Interrupt Enable), and TOV0 ar e set ( one), the
Timer/Counter0 Overflow interrupt is executed.
• Bit 0 – Res: Reserved Bit
This bit is a reserved bit in the AT90S1200 and always reads as zero.
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AT90S1200
External Interrupts
The External Interrupt is triggered by the INT0 pin. The interrupt can trigger on rising
edge, falling edge or low level. This is set up as described in the specification for the
MCU Control Register (MCUCR). When INT0 is level triggered, the interrupt is pending
as long as INT0 is held low.
The interrupt is triggered even if INT0 is configured as an output. This provides a way to
generate a software interrupt.
The interrupt flag can not be directly accessed by the user. If an external edge-triggered
interrupt is suspected to be pending, the flag can be cleared as follows.
1. Disable the External Interrupt by clearing the INT0 flag in GIMSK.
2. Select level triggered interrupt.
3. Select desired interrupt edge.
4. Re-enable the external interrupt by setting INT0 in GIMSK.
Interrupt Response Time
The interrupt execution response for all the enabled AVR interrupts is four clock cycles
minimum. Four clock cycles after the interrupt flag has been set, the program vector
address for the actual interrupt handling routine is executed. During this 4-clock-cycle
period, the Program Counter (9 bits) is pushed onto the Stack. The vector is normally a
relative jump to the interrupt routine, and this jump takes two clock cycles. If an interrupt
occurs during execution of a multi-cycle instruction, this instruction is completed before
the interrupt is served.
A return from an interrupt handling routine takes four clock cycles. During these four
clock cycles, the Program Counter (9 bits) is popped back from the Stack and the I-flag
in SREG is set. When the AVR exits from an interrupt, it will always return to the main
program and execute one more instruction before any pending interrupt is served.
Note that the Subroutine and Interrupt Stack is a 3-level true hardware stack, and if
more than three nested subroutines and interrupts are executed, only the most recent
three return addresses are stored.
17
0838H–AVR–03/02
MCU Control Register –
MCUCR
The MCU Control Register contains general microcontroller control bits for general MCU
control functions.
Bit
7
6
5
4
3
2
1
0
$35
–
–
SE
SM
–
–
ISC01
ISC00
Read/Write
R
R
R/W
R/W
R
R
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
MCUCR
• Bits 7, 6 – Res: Reserved Bits
These bits are reserved bits in the AT90S1200 and always read as zero.
• Bit 5 – SE: Sleep Enable
The SE bit must be set (one) to make the MCU enter the Sleep mode when the SLEEP
instruction is executed. To avoid the MCU entering the Sleep mode unless it is the programmers purpose, it is recommended to set the Sleep Enable SE bit just before the
execution of the SLEEP instruction.
• Bit 4 – SM: Sleep Mode
This bit selects between the two available sleep modes. When SM is cleared (zero), Idle
mode is selected as sleep mode. When SM is set (one), Power-down mode is selected
as sleep mode. For details, refer to the paragraph “Sleep Modes” on the following page.
• Bits 3, 2 – Res: Reserved Bits
These bits are reserved bits in the AT90S1200 and always read as zero.
• Bits 1, 0 – ISC01, ISC00: Interrupt Sense Control 0 Bit 1 and Bit 0
The External Interrupt 0 is activated by the external pin INT0 if the SREG I-flag and the
corresponding interrupt mask in the GIMSK register is set. The level and edges on the
external INT0 pin that activate the interrupt are defined in Table 4.
Table 4. Interrupt 0 Sense Control
ISC01
ISC00
Description
0
0
The low level of INT0 generates an interrupt request.
0
1
Reserved
1
0
The falling edge of INT0 generates an interrupt request.
1
1
The rising edge of INT0 generates an interrupt request.
The value on the INT0 pin is sampled before detecting edges. If edge interrupt is
selected, pulses with a duration longer than one CPU clock period will generate an interrupt. Shorter pulses are not guaranteed to generate an interrupt. If low level interrupt is
selected, the low level must be held until the completion of the currently executing
instruction to generate an interrupt. If enabled, a level triggered interrupt will generate an
interrupt request as long as the pin is held low.
18
AT90S1200
0838H–AVR–03/02
AT90S1200
Sleep Modes
To enter the sleep modes, the SE bit in MCUCR must be set (one) and a SLEEP instruction must be executed. If an enabled interrupt occurs while the MCU is in a sleep mode,
the MCU awakes, executes the interrupt routine, and resumes execution from the
instruction following SLEEP. The contents of the register file and the I/O memory are
unaltered. If a Reset occurs during sleep mode, the MCU wakes up and executes from
the Reset Vector.
Idle Mode
When the SM bit is cleared (zero), the SLEEP instruction makes the MCU enter the Idle
mode, stopping the CPU but allowing Timer/Counters, Watchdog and the interrupt system to continue operating. This enables the MCU to wake up from external triggered
interrupts as well as internal ones like Timer Overflow interrupt and Watchdog Reset. If
wakeup from the Analog Comparator interrupt is not required, the Analog Comparator
can be powered down by setting the ACD-bit in the Analog Comparator Control and Status Register (ACSR). This will reduce power consumption in Idle mode. When the MCU
wakes up from Idle mode, the CPU starts program execution immediately.
Power-down Mode
When the SM bit is set (one), the SLEEP instruction makes the MCU enter Power-down
mode. In this mode, the External Oscillator is stopped while the External Interrupts and
the Watchdog (if enabled) continue operating. Only an External Reset, a Watchdog
Reset (if enabled), an external level interrupt on INT0 can wake up the MCU.
Note that when a level triggered interrupt is used for wake-up from Power-down, the low
level must be held for a time longer than the reset delay time-out period tTOUT. Otherwise, the device will not wake up.
19
0838H–AVR–03/02
Timer/Counter0
Th e A T90 S 12 00 pr o v id e s o ne ge ne r al pu r p os e 8 - bi t Ti m er / Co un te r . Th e
Timer/Counter0 gets the prescaled clock from the 10-bit prescaling timer. The
Timer/Counter0 can either be used as a Timer with an internal clock time base or as a
Counter with an external pin connection, which triggers the counting.
Timer/Counter0
Prescaler
Figure 18 shows the general Timer/Counter0 prescaler.
Figure 18. Timer/Counter0 Prescaler
T0
TCK0
The four different prescaled selections are: CK/8, CK/64, CK/256, and CK/1024 where
CK is the Oscillator Clock. For the Timer/Counter0, added selections as CK, external
clock source and stop, can be selected as clock sources. Figure 19 shows the block diagram for Timer/Counter0.
20
AT90S1200
0838H–AVR–03/02
AT90S1200
Figure 19. Timer/Counter0 Block Diagram
T0
The 8-bit Timer/Counter0 can select clock source from CK, prescaled CK or an external
pin. In addition it can be stopped as described in the specification for the
Timer/Counter0 Control Register (TCCR0). The overflow status flag is found in the
Timer/Counter Interrupt Flag Register (TIFR). Control signals are found in the
Timer/Counter0 Control Register (TCCR0). The interrupt enable/disable settings for
Timer/Counter0 are found in the Timer/Counter Interrupt Mask Register (TIMSK).
When Timer/Counter0 is externally clocked, the external signal is synchronized with the
oscillator frequency of the CPU. To assure proper sampling of the external clock, the
minimum time between two external clock transitions must be at least one internal CPU
clock period. The external clock signal is sampled on the rising edge of the internal CPU
clock.
The 8-bit Timer/Counter0 features both a high-resolution and a high-accuracy usage
with the lower prescaling opportunities. Similarly, the high prescaling opportunities make
the Timer/Counter0 useful for lower speed functions or exact timing functions with infrequent actions.
Timer/Counter0 Control
Register – TCCR0
Bit
7
6
5
4
3
2
1
0
$33
-
-
-
-
-
CS02
CS01
CS00
Read/Write
R
R
R
R
R
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
TCCR0
• Bits 7..3 – Res: Reserved Bits
These bits are reserved bits in the AT90S1200 and always read as zero.
21
0838H–AVR–03/02
• Bits 2, 1, 0 – CS02, CS01, CS00: Clock Select0, Bits 2, 1 and 0
The Clock Select0 bits 2, 1 and 0 define the prescaling source of Timer/Counter0.
Table 5. Clock 0 Prescale Select
CS02
CS01
CS00
Description
0
0
0
Stop, the Timer/Counter0 is stopped.
0
0
1
CK
0
1
0
CK/8
0
1
1
CK/64
1
0
0
CK/256
1
0
1
CK/1024
1
1
0
External Pin T0, falling edge
1
1
1
External Pin T0, rising edge
The Stop condition provides a Timer Enable/Disable function. The CK down divided
modes are scaled directly from the CK Oscillator clock. If the external pin modes are
used for Timer/Counter0, transitions on PD4/(T0) will clock the counter even if the pin is
configured as an output. This feature can give the user SW control of the counting.
Timer/Counter0 – TCNT0
Bit
7
$32
MSB
6
5
4
3
2
1
0
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
LSB
TCNT0
The Timer/Counter0 is realized as an up-counter with read and write access. If the
Timer/Counter0 is written and a clock source is present, the Timer/Counter0 continues
counting in the timer clock cycle following the write operation.
22
AT90S1200
0838H–AVR–03/02
AT90S1200
Watchdog Timer
The Watchdog Timer is clocked from a separate On-chip Oscillator that runs at 1 MHz.
This is the typical value at VCC = 5V. See characterization data for typical values at other
VCC levels. By controlling the Watchdog Timer prescaler, the Watchdog Reset interval
can be adjusted, see Table 6 for a detailed description. The WDR (Watchdog Reset)
instruction resets the Watchdog Timer. Eight different clock cycle periods can be
selected to determine the maximum period between two WDR instructions to prevent
the Watchdog Timer from resetting the MCU. If the reset period expires without another
WDR instruction, the AT90S1200 resets and executes from the Reset Vector. For timing
details on the Watchdog Reset, refer to page 14.
Figure 20. Watchdog Timer
Watchdog Timer Control
Register – WDTCR
Bit
7
6
5
4
3
2
1
0
$21
–
–
–
–
WDE
WDP2
WDP1
WDP0
Read/Write
R
R
R
R
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
WDTCR
• Bits 7..4 – Res: Reserved Bits
These bits are reserved bits in the AT90S1200 and will always read as zero.
• Bit 3 – WDE: Watchdog Enable
When the WDE is set (one) the Watchdog Timer is enabled, and if the WDE is cleared
(zero) the Watchdog Timer function is disabled.
• Bits 2..0 – WDP2..0: Watchdog Timer Prescaler 2, 1 and 0
The WDP2..0 determine the Watchdog Timer prescaling when the Watchdog Timer is
enabled. The different prescaling values and their corresponding timeout periods are
shown in Table 6.
23
0838H–AVR–03/02
Table 6. Watchdog Timer Prescale Select
Number of WDT
Oscillator Cycles
Typical Time-out
at VCC = 3.0V
Typical Time-out
at VCC = 5.0V
0
16K cycles
47 ms
15 ms
0
1
32K cycles
94 ms
30 ms
0
1
0
64K cycles
0.19 s
60 ms
0
1
1
128K cycles
0.38 s
0.12 s
1
0
0
256K cycles
0.75 s
0,24 s
1
0
1
512K cycles
1.5 s
0.49 s
1
1
0
1,024K cycles
3.0 s
0.97 s
1
1
1
2,048K cycles
6.0 s
1.9 s
WDP2
WDP1
WDP0
0
0
0
Note:
24
The frequency of the Watchdog Oscillator is voltage dependent as shown in “Typical
Characteristics” on page 51.
The WDR (Watchdog Reset) instruction should always be executed before the Watchdog
Timer is enabled. This ensures that the reset period will be in accordance with the
Watchdog Timer prescale settings. If the Watchdog Timer is enabled without Reset, the
Watchdog Timer may not start to count from zero.
To avoid unintentional MCU resets, the Watchdog Timer should be disabled or reset
before changing the Watchdog Timer Prescale Select.
AT90S1200
0838H–AVR–03/02
AT90S1200
EEPROM Read/Write
Access
The EEPROM access registers are accessible in the I/O space.
The write access time is in the range of 2.5 - 4 ms, depending on the VCC voltages. A
self-timing function, however, lets the user software detect when the next byte can be
written. If the user code contains code that writes the EEPROM, some precaution must
be taken. In heavily filtered power supplies, VCC is likely to rise or fall slowly on Powerup/down. This causes the device for some period of time to run at a voltage lower than
specified as minimum for the clock frequency used. CPU operation under these conditions is likely cause the program counter to perform unintentional jumps and eventually
execute the EEPROM write code. To secure EEPROM integrity, the user is advised to
use an external under-voltage reset circuit in this case.
In order to prevent unintentional EEPROM writes, a specific write procedure must be followed. Refer to “EEPROM Control Register – EECR” on page 25 for details on this.
When the EEPROM is read or written, the CPU is halted for two clock cycles before the
next instruction is executed.
EEPROM Address Register –
EEAR
Bit
7
6
5
4
3
2
1
0
$1E
–
–
EEAR5
EEAR4
EEAR3
EEAR2
EEAR1
EEAR0
Read/Write
R
R
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
EEAR
• Bit 7, 6 – Res: Reserved Bits
These bits are reserved bits in the AT90S1200 and will always read as zero.
• Bits 5..0 – EEAR5..0: EEPROM Address
The EEPROM Address Register (EEAR5..0) specifies the EEPROM address in the 64byte EEPROM space. The EEPROM data bytes are addressed linearly between 0 and
63.
EEPROM Data Register –
EEDR
Bit
7
6
5
4
3
2
1
0
$1D
MSB
LSB
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
EEDR
• Bits 7..0 – EEDR7..0: EEPROM Data
For the EEPROM write operation, the EEDR register contains the data to be written to
the EEPROM in the address given by the EEAR register. For the EEPROM read operation, the EEDR contains the data read out from the EEPROM at the address given by
EEAR.
EEPROM Control Register –
EECR
Bit
7
6
5
4
3
2
1
0
$1C
–
–
–
–
–
–
EEWE
EERE
Read/Write
R
R
R
R
R
R
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
EECR
• Bits 7..2 – Res: Reserved Bits
These bits are reserved bits in the AT90S1200 and will always be read as zero.
25
0838H–AVR–03/02
• Bit 1 – EEWE: EEPROM Write Enable
The EEPROM Write Enable Signal (EEWE) is the write strobe to the EEPROM. When
address and data are correctly set up, the EEWE bit must be set to write the value into
the EEPROM. When the write access time (typically 2.5 ms at VCC = 5V and 4 ms at
VCC = 2.7V) has elapsed, the EEWE bit is cleared (zero) by hardware. The user software can poll this bit and wait for a zero before writing the next byte. When EEWE has
been set, the CPU is halted for two cycles before the next instruction is executed.
• Bit 0 – EERE: EEPROM Read Enable
The EEPROM Read Enable Signal (EERE) is the read strobe to the EEPROM. When
the correct address is set up in the EEAR register, the EERE bit must be set. When the
EERE bit is cleared (zero) by hardware, requested data is found in the EEDR register.
The EEPROM read access takes one instruction and there is no need to poll the EERE
bit. When EERE has been set, the CPU is halted for four cycles before the next instruction is executed.
Caution: If an interrupt routine accessing the EEPROM is interrupting another EEPROM
access, the EEAR or EEDR register will be modified, causing the interrupted EEPROM
access to fail. It is recommended to have the global interrupt flag cleared during
EEPROM write operation to avoid these problems.
Prevent EEPROM
Corruption
During periods of low VCC, the EEPROM data can be corrupted because the supply voltage is too low for the CPU and the EEPROM to operate properly. These issues are the
same as for board-level systems using the EEPROM, and the same design solutions
should be applied.
An EEPROM data corruption can be caused by two situations when the voltage is too
low. First, a regular write sequence to the EEPROM requires a minimum voltage to
operate correctly. Secondly, the CPU itself can execute instructions incorrectly, if the
supply voltage for executing instructions is too low.
EEPROM data corruption can easily be avoided by following these design recommendations (one is sufficient):
1. Keep the AVR RESET active (low) during periods of insufficient power supply
voltage. This is best done by an external low VCC Reset Protection circuit, often
referred to as a Brown-out Detector (BOD). Please refer to application note AVR
180 for design considerations regarding power-on reset and low-voltage
detection.
2. Keep the AVR core in Power-down Sleep mode during periods of low VCC. This
will prevent the CPU from attempting to decode and execute instructions, effectively protecting the EEPROM registers from unintentional writes.
3. Store constants in Flash memory if the ability to change memory contents from
software is not required. Flash memory cannot be updated by the CPU, and will
not be subject to corruption.
26
AT90S1200
0838H–AVR–03/02
AT90S1200
Analog Comparator
The Analog Comparator compares the input values on the positive input PB0 (AIN0) and
the negative input PB1 (AIN1). When the voltage on the positive input PB0 (AIN0) is
higher than the voltage on the negative input PB1 (AIN1), the Analog Comparator Output (ACO) is set (one). The comparator’s output can be set to trigger the Analog
Comparator interrupt. The user can select interrupt triggering on comparator output rise,
fall or toggle. A block diagram of the comparator and its surrounding logic is shown in
Figure 21.
Figure 21. Analog Comparator Block Diagram
Analog Comparator Control
and Status Register – ACSR
Bit
7
6
5
4
3
2
1
0
$08
ACD
–
ACO
ACI
ACIE
–
ACIS1
ACIS0
Read/Write
R/W
R
R
R/W
R/W
R
R/W
R/W
Initial Value
0
0
N/A
0
0
0
0
0
ACSR
• Bit 7 – ACD: Analog Comparator Disable
When this bit is set (one), the power to the Analog Comparator is switched off. This bit
can be set at any time to turn off the analog comparator. This will reduce power consumption in Active and Idle modes. When changing the ACD bit, the Analog Comparator
Interrupt must be disabled by clearing the ACIE bit in ACSR. Otherwise, an interrupt can
occur when the bit is changed.
• Bit 6 – Res: Reserved Bit
This bit is a reserved bit in the AT90S1200 and will always read as zero.
• Bit 5 – ACO: Analog Comparator Output
ACO is directly connected to the comparator output.
• Bit 4 – ACI: Analog Comparator Interrupt Flag
This bit is set (one) when a comparator output event triggers the interrupt mode defined
by ACIS1 and ACIS0. The Analog Comparator Interrupt routine is executed if the ACIE
bit is set (one) and the I-bit in SREG is set (one). ACI is cleared by hardware when executing the corresponding interrupt handling vector. Alternatively, ACI is cleared by
writing a logic one to the flag. Observe however, that if another bit in this register is modified using the SBI or CBI instruction, ACI will be cleared if it has become set before the
operation.
27
0838H–AVR–03/02
• Bit 3 – ACIE: Analog Comparator Interrupt Enable
When the ACIE bit is set (one) and the I-bit in the Status Register is set (one), the Analog Comparator Interrupt is activated. When cleared (zero), the interrupt is disabled.
• Bit 2 – Res: Reserved Bit
This bit is a reserved bit in the AT90S1200 and will always read as zero.
• Bits 1, 0 – ACIS1, ACIS0: Analog Comparator Interrupt Mode Select
These bits determine which comparator events trigger the Analog Comparator Interrupt.
The different settings are shown in Table 7.
Table 7. ACIS1/ACIS0 Settings
ACIS1
ACIS0
0
0
Comparator Interrupt on Output Toggle
0
1
Reserved
1
0
Comparator Interrupt on Falling Output Edge
1
Comparator Interrupt on Rising Output Edge
1
Note:
28
Interrupt Mode
When changing the ACIS1/ACIS0 bits, the Analog Comparator Interrupt must be disabled by clearing its Interrupt Enable bit in the ACSR register. Otherwise, an interrupt
can occur when the bits are changed.
AT90S1200
0838H–AVR–03/02
AT90S1200
I/O Ports
All AVR ports have true Read-Modify-Write functionality when used as general digital
I/O ports. This means that the direction of one port pin can be changed without unintentionally changing the direction of any other pin with the SBI and CBI instructions. The
same applies for changing drive value (if configured as output) or enabling/disabling of
pull-up resistors (if configured as input).
Port B
Port B is an 8-bit bi-directional I/O port.
Three I/O memory address locations are allocated for the Port B, one each for the Data
Register – PORTB ($18), Data Direction Register – DDRB ($17), and the Port B Input
Pins – PINB ($16). The Port B Input Pins address is read-only, while the Data Register
and the Data Direction Register are read/write.
All port pins have individually selectable pull-up resistors. The Port B output buffers can
sink 20 mA and thus drive LED displays directly. When pins PB0 to PB7 are used as
inputs and are externally pulled low, they will source current if the internal pull-up resistors are activated.
The Port B pins with alternate functions are shown in Table 8.
Table 8. Port B Pin Alternate Functions
Port Pin
Alternate Functions
PB0
AIN0 (Analog Comparator positive input)
PB1
AIN1 (Analog Comparator negative input)
PB5
MOSI (Data Input line for memory downloading)
PB6
MISO (Data Output line for memory uploading)
PB7
SCK (Serial Clock input)
When the pins are used for the alternate function, the DDRB and PORTB register has to
be set according to the alternate function description.
Port B Data Register – PORTB
Port B Data Direction Register
– DDRB
Port B Input Pin Address –
PINB
Bit
7
6
5
4
3
2
1
0
$18
PORTB7
PORTB6
PORTB5
PORTB4
PORTB3
PORTB2
PORTB1
PORTB0
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
$17
DDB7
DDB6
DDB5
DDB4
DDB3
DDB2
DDB1
DDB0
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
$16
PINB7
PINB6
PINB5
PINB4
PINB3
PINB2
PINB1
PINB0
Read/Write
R
R
R
R
R
R
R
R
Initial Value
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
PORTB
DDRB
PINB
The Port B Input Pins address (PINB) is not a register, and this address enables access
to the physical value on each Port B pin. When reading PORTB, the Port B Data Latch
is read, and when reading PINB, the logical values present on the pins are read.
29
0838H–AVR–03/02
Port B as General Digital I/O
All eight pins in Port B have equal functionality when used as digital I/O pins.
PBn, General I/O pin: The DDBn bit in the DDRB Register selects the direction of this
pin, if DDBn is set (one), PBn is configured as an output pin. If DDBn is cleared (zero),
PBn is configured as an input pin. If PORTBn is set (one) and the pin is configured as an
input pin, the MOS pull-up resistor is activated. To switch the pull-up resistor off,
PORTBn has to be cleared (zero) or the pin has to be configured as an output pin. The
Port B pins are tri-stated when a reset condition becomes active, even if the clock is not
active.
Table 9. DDBn Effect on Port B Pins
DDBn
PORTBn
I/O
Pull-up
0
0
Input
No
Tri-state (High-Z)
0
1
Input
Yes
PBn will source current if ext. pulled low.
1
0
Output
No
Push-pull Zero Output
1
Output
No
Push-pull One Output
1
Note:
Alternate Functions of Port B
Comment
n: 7,6...0, pin number.
The alternate pin functions of Port B are:
• SCK – Port B, Bit 7
SCK, Clock Input pin for memory up/downloading.
• MISO – Port B, Bit 6
MISO, Data Output pin for memory uploading.
• MOSI – Port B, Bit 5
MOSI, Data Input pin for memory downloading.
• AIN1 – Port B, Bit 1
AIN1, Analog Comparator Negative Input. When configured as an input (DDB1 is
cleared [zero]) and with the internal MOS pull-up resistor switched off (PB1 is cleared
[zero]), this pin also serves as the negative input of the On-chip Analog Comparator.
• AIN0 – Port B, Bit 0
AIN0, Analog Comparator Positive Input. When configured as an input (DDB0 is cleared
[zero]) and with the internal MOS pull-up resistor switched off (PB0 is cleared [zero]),
this pin also serves as the positive input of the On-chip Analog Comparator.
30
AT90S1200
0838H–AVR–03/02
AT90S1200
Port B Schematics
Note that all port pins are synchronized. The synchronization latches are, however, not
shown in the figures.
Figure 22. Port B Schematic Diagram (Pins PB0 and PB1)
31
0838H–AVR–03/02
Figure 23. Port B Schematic Diagram (Pins PB2, PB3, and PB4)
2,
Figure 24. Port B Schematic Diagram (Pin PB5)
32
AT90S1200
0838H–AVR–03/02
AT90S1200
Figure 25. Port B Schematic Diagram (Pin PB6)
Figure 26. Port B Schematic Diagram (Pin PB7)
33
0838H–AVR–03/02
Port D
Three I/O memory address locations are allocated for Port D, one each for the Data
Register – PORTD ($12), Data Direction Register – DDRD ($11), and the Port D Input
Pins – PIND ($10). The Port D Input Pins address is read-only, while the Data Register
and the Data Direction Register are read/write.
Port D has seven bi-directional I/O pins with internal pull-up resistors, PD6..PD0. The
Port D output buffers can sink 20 mA. As inputs, Port D pins that are externally pulled
low will source current if the pull-up resistors are activated.
Some Port D pins have alternate functions as shown in Table 10.
Table 10. Port D Pin Alternate Functions
Port Pin
Alternate Function
PD2
INT0 (External Interrupt 0 input)
PD4
T0 (Timer/Counter 0 external input)
Port D Data Register – PORTD
Port D Data Direction Register
– DDRD
Port D Input Pins Address –
PIND
Bit
7
6
5
4
3
2
1
0
$12
–
PORTD6
PORTD5
PORTD4
PORTD3
PORTD2
PORTD1
PORTD0
Read/Write
R
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
$11
–
DDD6
DDD5
DDD4
DDD3
DDD2
DDD1
DDD0
Read/Write
R
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
$10
–
PIND6
PIND5
PIND4
PIND3
PIND2
PIND1
PIND0
Read/Write
R
R
R
R
R
R
R
R
Initial Value
0
N/A
N/A
N/A
N/A
N/A
N/A
N/A
PORTD
DDRD
PIND
The Port D Input Pins address (PIND) is not a register, and this address enables access
to the physical value on each Port D pin. When reading PORTD, the Port D Data Latch
is read; and when reading PIND, the logical values present on the pins are read.
Port D as General Digital I/O
34
PDn, general I/O pin: The DDDn bit in the DDRD Register selects the direction of this
pin. If DDDn is set (one), PDn is configured as an output pin. If DDDn is cleared (zero),
PDn is configured as an input pin. If PORTDn is set (one) when DDDn is configured as
an input pin, the MOS pull-up resistor is activated. To switch the pull-up resistor off, the
PORTDn bit has to be cleared (zero) or the pin has to be configured as an output pin.
The Port D pins are tri-stated when a reset condition becomes active, even if the clock is
not active.
AT90S1200
0838H–AVR–03/02
AT90S1200
Table 11. DDDn Bits’ Effect on Port D Pins
DDDn
PORTDn
I/O
Pull-up
0
0
Input
No
Tri-state (High-Z)
0
1
Input
Yes
PDn will source current if ext. pulled low.
1
0
Output
No
Push-pull Zero Output
1
1
Output
No
Push-pull One Output
Note:
Alternate Functions for Port D
Comment
n: 6…0, pin number.
The alternate functions of Port D are:
• T0 – Port D, Bit 4
T0, Timer/Counter0 clock source. See the timer description for further details.
• INT0 – Port D, Bit 2
INT0, External Interrupt source 0. See the interrupt description for further details.
Port D Schematics
Note that all port pins are synchronized. The synchronization latches are, however, not
shown in the figures.
Figure 27. Port D Schematic Diagram (Pins PD0, PD1, PD3, PD5, and PD6)
35
0838H–AVR–03/02
Figure 28. Port D Schematic Diagram (Pin PD2)
Figure 29. Port D Schematic Diagram (Pin PD4)
RD
MOS
PULLUP
RESET
Q
R
D
DDD4
C
DATA BUS
WD
RESET
R
Q
D
PORTD4
PD4
C
RL
WP
RP
WP:
WD:
RL:
RP:
RD:
WRITE PORTD
WRITE DDRD
READ PORTD LATCH
READ PORTD PIN
READ DDRD
SENSE CONTROL
CS02
36
CS01
TIMER0 CLOCK
SOURCE MUX
CS00
AT90S1200
0838H–AVR–03/02
AT90S1200
Memory
Programming
Program and Data
Memory Lock Bits
The AT90S1200 MCU provides two Lock bits that can be left unprogrammed (“1”) or can
be programmed (“0”) to obtain the additional features listed in Table 12. The Lock bits
can only be erased with the Chip Erase command.
Table 12. Lock Bit Protection Modes
Memory Lock Bits
Mode
LB1
LB2
1
1
1
No memory lock features enabled.
2
0
1
Further programming of the Flash and EEPROM is disabled.(1)
3
0
0
Same as mode 2, and verify is also disabled.
Note:
Fuse Bits
Signature Bytes
Protection Type
1. In Parallel mode, further programming of the Fuse bits are also disabled. Program
the Fuse bits before programming the Lock bits.
The AT90S1200 has two Fuse bits: SPIEN and RCEN.
•
When the SPIEN Fuse bit is programmed (“0”), Serial Program Downloading is
enabled. Default value is programmed (“0”).
•
When the RCEN Fuse bit is programmed (“0”), MCU clocking from the Internal RC
Oscillator is selected. Default value is erased (“1”). Parts with this bit preprogrammed (“0”) can be delivered on demand.
•
The Fuse bits are not accessible in Serial Programming mode. The status of the
Fuse bits is not affected by Chip Erase.
All Atmel microcontrollers have a 3-byte signature code that identifies the device. This
code can be read in both Serial and Parallel modes. The three bytes reside in a separate address space.
For the AT90S1200 they are:
1. $00: $1E (indicates manufactured by Atmel)
2. $01: $90 (indicates 1 Kb Flash memory)
3. $02: $01 (indicates AT90S1200 device when $01 is $90)
Note:
Programming the Flash
and EEPROM
When both Lock bits are programmed (lock mode 3), the signature bytes cannot be read
in Serial mode. Reading the signature bytes will return: $00, $01 and $02.
Atmel’s AT90S1200 offers 1K byte of in-System Reprogrammable Flash program memory and 64 bytes of EEPROM data memory.
The AT90S1200 is normally shipped with the On-chip Flash program memory and
EEPROM data memory arrays in the erased state (i.e., contents = $FF) and ready to be
programmed. This device supports a High-voltage (12V) Parallel Programming mode
and a Low-voltage Serial Programming mode. The +12V is used for programming
enable only, and no current of significance is drawn by this pin. The Serial Programming
mode provides a convenient way to download program and data into the AT90S1200
inside the user’s system.
The program and data memory arrays on the AT90S1200 are programmed byte-by-byte
in either programming mode. For the EEPROM, an auto-erase cycle is provided within
37
0838H–AVR–03/02
the self-timed write instruction in the Serial Programming mode. During programming,
the supply voltage must be in accordance with Table 13.
Table 13. Supply Voltage during Programming
Parallel Programming
Part
Serial Programming
Parallel Programming
AT90S1200
2.7 - 6.0V
4.5 - 5.5V
This section describes how to parallel program and verify Flash program memory,
EEPROM data memory, Lock bits and Fuse bits in the AT90S1200.
Figure 30. Parallel Programming
Signal Names
In this section, some pins of the AT90S1200 are referenced by signal names describing
their function during parallel programming rather than their pin names, see Figure 30
and Table 14. Pins not described in Table 14 are referenced by pin names.
The XA1/XA0 pins determines the action executed when the XTAL1 pin is given a positive pulse. The coding is shown in Table 15.
When pulsing WR or OE, the command loaded determines the action executed. The
command is a byte where the different bits are assigned functions as shown in Table 16.
Table 14. Pin Name Mapping
38
Signal Name in
Programming Mode
Pin Name
I/O
Function
RDY/BSY
PD1
O
0: Device is busy programming, 1: Device is ready
for new command
OE
PD2
I
Output Enable (Active low)
WR
PD3
I
Write Pulse (Active low)
BS
PD4
I
Byte Select (“0” selects low byte, “1” selects high
byte)
XA0
PD5
I
XTAL Action Bit 0
XA1
PD6
I
XTAL Action Bit 1
DATA
PB0-7
I/O
Bi-directional Data Bus (Output when OE is low)
AT90S1200
0838H–AVR–03/02
AT90S1200
.
Table 15. XA1 and XA0 Coding
XA1
XA0
Action when XTAL1 is Pulsed
0
0
Load Flash or EEPROM Address (High or low address byte for Flash
determined by BS).
0
1
Load Data (High or low data byte for Flash determined by BS).
1
0
Load Command
1
1
No Action, Idle
Table 16. Command Byte Coding
Command Byte
Enter Programming Mode
Command Executed
1000 0000
Chip Erase
0100 0000
Write Fuse Bits
0010 0000
Write Lock Bits
0001 0000
Write Flash
0001 0001
Write EEPROM
0000 1000
Read Signature Bytes
0000 0100
Read Fuse and Lock Bits
0000 0010
Read Flash
0000 0011
Read EEPROM
The following algorithm puts the device in Parallel Programming mode:
1. Apply supply voltage according to Table 13, between VCC and GND.
2. Set the RESET and BS pin to “0” and wait at least 100 ns.
3. Apply 11.5 - 12.5V to RESET. Any activity on BS within 100 ns after +12V has
been applied to RESET, will cause the device to fail entering Programming
mode.
Chip Erase
The Chip Erase command will erase the Flash and EEPROM memories, and the Lock
bits. The Lock bits are not Reset until the Flash and EEPROM have been completely
erased. The Fuse bits are not changed. Chip Erase must be performed before the Flash
or EEPROM is reprogrammed.
Load Command “Chip Erase”
1. Set XA1, XA0 to “10”. This enables command loading.
2. Set BS to “0”.
3. Set DATA to “1000 0000”. This is the command for Chip Erase.
4. Give XTAL1 a positive pulse. This loads the command.
5. Give WR a tWLWH_CE wide negative pulse to execute Chip Erase, tWLWH_CE is found
in Table 17. Chip Erase does not generate any activity on the RDY/BSY pin.
Programming the Flash
A: Load Command “Write Flash”
1. Set XA1, XA0 to “10”. This enables command loading.
2. Set BS to “0”.
3. Set DATA to “0001 0000”. This is the command for Write Flash.
39
0838H–AVR–03/02
4. Give XTAL1 a positive pulse. This loads the command.
B: Load Address High Byte
1. Set XA1, XA0 to “00”. This enables address loading.
2. Set BS to “1”. This selects high byte.
3. Set DATA = Address high byte ($00 - $01).
4. Give XTAL1 a positive pulse. This loads the address high byte.
C: Load Address Low Byte
1. Set XA1, XA0 to “00”. This enables address loading.
2. Set BS to “0”. This selects low byte.
3. Set DATA = Address low byte ($00 - $FF).
4. Give XTAL1 a positive pulse. This loads the address low byte.
D: Load Data Low Byte
1. Set XA1, XA0 to “01”. This enables data loading.
2. Set DATA = Data low byte ($00 - $FF).
3. Give XTAL1 a positive pulse. This loads the data low byte.
E: Write Data Low Byte
1. Set BS to “0”. This selects low data.
2. Give WR a negative pulse. This starts programming of the data byte. RDY/BSY
goes low.
3. Wait until RDY/BSY goes high to program the next byte.
(See Figure 31 for signal waveforms.)
F: Load Data High Byte
1. Set XA1, XA0 to “01”. This enables data loading.
2. Set DATA = Data high byte ($00 - $FF).
3. Give XTAL1 a positive pulse. This loads the data high byte.
G: Write Data High Byte
1. Set BS to “1”. This selects high data.
2. Give WR a negative pulse. This starts programming of the data byte. RDY/BSY
goes low.
3. Wait until RDY/BSY goes high to program the next byte.
(See Figure 32 for signal waveforms.)
The loaded command and address are retained in the device during programming. For
efficient programming, the following should be considered:
•
The command needs only be loaded once when writing or reading multiple memory
locations.
•
Address high byte needs only be loaded before programming a new 256-word page
in the Flash.
•
Skip writing the data value $FF; that is, the contents of the entire Flash and
EEPROM after a Chip Erase.
These considerations also apply to EEPROM programming and Flash, EEPROM and
signature byte reading.
40
AT90S1200
0838H–AVR–03/02
AT90S1200
Figure 31. Programming the Flash Waveforms
DATA
$10
ADDR. HIGH
ADDR.LOW
DATA LOW
XA1
XA0
BS
XTAL1
WR
RDY/BSY
RESET
12V
OE
Figure 32. Programming the Flash Waveforms (Continued)
DATA
DATA HIGH
XA1
XA0
BS
XTAL1
WR
RDY/BSY
RESET
+12V
OE
Reading the Flash
The algorithm for reading the Flash memory is as follows (refer to “Programming the
Flash” for details on command and address loading):
1. A: Load Command “0000 0010”.
2. B: Load Address High Byte ($00 - $01).
3. C: Load Address Low Byte ($00 - $FF).
4. Set OE to “0”, and BS to “0”. The Flash word low byte can now be read at DATA.
5. Set BS to “1”. The Flash word high byte can now be read from DATA.
6. Set OE to “1”.
41
0838H–AVR–03/02
Programming the EEPROM
The programming algorithm for the EEPROM data memory is as follows (refer to “Programming the Flash” for details on command, address and data loading):
1. A: Load Command “0001 0001”.
2. C: Load Address Low Byte ($00 - $3F).
3. D: Load Data Low Byte ($00 - $FF).
4. E: Write Data Low Byte.
Reading the EEPROM
The algorithm for reading the EEPROM memory is as follows (refer to “Programming the
Flash” for details on command and address loading):
1. A: Load Command “0000 0011”.
2. C: Load Address Low Byte ($00 - $3F).
3. Set OE to “0”, and BS to “0”. The EEPROM data byte can now be read at DATA.
4. Set OE to “1”.
Programming the Fuse Bits
The algorithm for programming the Fuse bits is as follows (refer to “Programming the
Flash” for details on command and data loading):
1. A: Load Command “0100 0000”.
2. D: Load Data Low Byte. Bit n = “0” programs and bit n = “1” erases the Fuse bit.
Bit 5 = SPIEN Fuse
Bit 0 = RCEN Fuse
Bit 7 - 6, 4 - 1 = “1”. These bits are reserved and should be left unprogrammed (“1”).
3. Give WR a tWLWH_PFB wide negative pulse to execute the programming; tWLWH_PFB
is found in Table 17. Programming the Fuse bits does not generate any activity
on the RDY/BSY pin.
Programming the Lock Bits
The algorithm for programming the Lock bits is as follows (refer to “Programming the
Flash” for details on command and data loading):
1. A: Load Command “0010 0000”.
2. D: Load Data Low Byte. Bit n = “0” programs the Lock bit.
Bit 2 = Lock Bit2
Bit 1 = Lock Bit1
Bit 7 - 3, 0 = “1”. These bits are reserved and should be left unprogrammed (“1”).
3. E: Write Data Low Byte.
The Lock bits can only be cleared by executing Chip Erase.
Reading the Fuse and Lock
Bits
The algorithm for reading the Fuse and Lock bits is as follows (refer to “Programming
the Flash” on page 39 for details on command loading):
1. A: Load Command “0000 0100”.
2. Set OE to “0”, and BS to “1”. The status of Fuse and Lock bits can now be read
at DATA (“0” means programmed).
Bit 7 = Lock Bit1
Bit 6 = Lock Bit2
Bit 5 = SPIEN Fuse
Bit 0 = RCEN Fuse
3. Set OE to “1”.
Observe especially that BS needs to be set to “1”.
42
AT90S1200
0838H–AVR–03/02
AT90S1200
Reading the Signature Bytes
The algorithm for reading the signature bytes is as follows (refer to “Programming the
Flash” on page 39 for details on command and address loading):
1. A: Load Command “0000 1000”.
2. C: Load Address Low Byte ($00 - $02).
Set OE to “0”, and BS to “0”. The selected signature byte can now be read at DATA.
Set OE to “1”.
Parallel Programming
Characteristics
Figure 33. Parallel Programming Timing
tXLWL
tXHXL
XTAL1
tDVXH
tXLDX tBVWL
Data & Contol
(DATA, XA0/1, BS)
Write
tWLWH
WR
tRHBX
tWHRL
RDY/BSY
tWLRH
tXLOL
tOHDZ
tOLDV
Read
OE
DATA
Table 17. Parallel Programming Characteristics, TA = 25°C ± 10%, VCC = 5V ± 10%
Symbol
Parameter
Min
VPP
Programming Enable Voltage
11.5
IPP
Programming Enable Current
tDVXH
Data and Control Setup before XTAL1 High
67.0
ns
tXHXL
XTAL1 Pulse Width High
67.0
ns
tXLDX
Data and Control Hold after XTAL1 Low
67.0
ns
tXLWL
XTAL1 Low to WR Low
67.0
ns
tBVWL
BS Valid to WR Low
67.0
ns
tRHBX
BS Hold after RDY/BSY High
67.0
ns
tWLWH
WR Pulse Width Low(1)
67.0
ns
tWHRL
WR High to RDY/BSY Low(2)
tWLRH
WR Low to RDY/BSY High
(2)
tXLOL
XTAL1 Low to OE Low
tOLDV
OE Low to DATA Valid
tOHDZ
OE High to DATA Tri-stated
tWLWH_CE
WR Pulse Width Low for Chip Erase
5.0
tWLWH_PFB
WR Pulse Width Low for Programming the Fuse
Bits
1.0
Notes:
Typ
Max
Units
12.5
V
250.0
µA
20.0
0.5
0.7
ns
0.9
67.0
ms
ns
20.0
ns
20.0
ns
10.0
15.0
ms
1.5
1.8
ms
1. Use tWLWH_CE for chip erase and tWLWH_PFB for programming the Fuse bits.
2. If tWLWH is held longer than tWLRH, no RDY/BSY pulse will be seen.
43
0838H–AVR–03/02
Serial Downloading
Both the program and data memory arrays can be programmed using the SPI bus while
RESET is pulled to GND. The serial interface consists of pins SCK, MOSI (input) and
MISO (output) (see Figure 34). After RESET is set low, the Programming Enable
instruction needs to be executed first before program/erase instructions can be
executed.
Figure 34. Serial Programming and Verify
2.7 - 6.0V
AT90S1200
GND
RESET
VCC
PB7
PB6
PB5
CLOCK INPUT
SCK
MISO
MOSI
XTAL1
GND
Note:
If the device is clocked by the Internal Oscillator, it is no need to connect a clock source
to the XTAL1 pin
For the EEPROM, an auto-erase cycle is provided within the self-timed write instruction
and there is no need to first execute the Chip Erase instruction. The Chip Erase instruction turns the content of every memory location in both the Program and EEPROM
arrays into $FF.
The program and EEPROM memory arrays have separate address spaces: $0000 to
$01FF for Flash program memory and $000 to $03F for EEPROM data memory.
Either an external system clock is supplied at pin XTAL1 or a crystal needs to be connected across pins XTAL1 and XTAL2. The minimum low and high periods for the Serial
Clock (SCK) input are defined as follows:
Low: > 1 XTAL1 clock cycle
High: > 4 XTAL1 clock cycles
Serial Programming
Algorithm
When writing serial data to the AT90S1200, data is clocked on the rising edge of SCK.
When reading data from the AT90S1200, data is clocked on the falling edge of SCK.
See Figure 35 and Table 20 for timing details.
To program and verify the AT90S1200 in the Serial Programming mode, the following
sequence is recommended (See 4-byte instruction formats in Table 17):
1. Power-up sequence:
Apply power between VCC and GND while RESET and SCK are set to “0”. If a crystal is not connected across pins XTAL1 and XTAL2 or the device is not running from
the Internal RC Oscillator, apply a clock signal to the XTAL1 pin. If the programmer
can not guarantee that SCK is held low during power-up, RESET must be given a
positive pulse after SCK has been set to “0”.
2. Wait for at least 20 ms and enable serial programming by sending the Programming Enable serial instruction to the MOSI (PB5) pin.
44
AT90S1200
0838H–AVR–03/02
AT90S1200
3. If a Chip Erase is performed (must be done to erase the Flash), wait tWD_ERASE
after the instruction, give RESET a positive pulse, and start over from step 2.
See Table 21 on page 47 for tWD_ERASE value.
4. The Flash or EEPROM array is programmed one byte at a time by supplying the
address and data together with the appropriate Write instruction. An EEPROM
memory location is first automatically erased before new data is written. Wait
tWD_PROG after transmitting the instruction. In an erased device, no $FFs in the
data file(s) needs to be programmed. See Table 22 on page 47 for tWD_PROG
value.
5. Any memory location can be verified by using the Read instruction which returns
the content at the selected address at the serial output MISO (PB6) pin.
At the end of the programming session, RESET can be set high to commence normal operation.
6. Power-off sequence (if needed):
Set XTAL1 to “0” (if a crystal is not used or the device is running from the Internal
RC Oscillator).
Set RESET to “1”.
Turn VCC power off.
Data Polling EEPROM
When a byte is being programmed into the EEPROM, reading the address location
being programmed will give the value P1 until the auto-erase is finished, and then the
value P2. See Table 18 for P1 and P2 values.
At the time the device is ready for a new EEPROM byte, the programmed value will read
correctly. This is used to determine when the next byte can be written. This will not work
for the values P1 and P2, so when programming these values, the user will have to wait
for at least the prescribed time tWD_PROG before programming the next byte. See Table 22
for tWD_PROG value. As a chip-erased device contains $FF in all locations, programming of
addresses that are meant to contain $FF can be skipped. This does not apply if the
EEPROM is reprogrammed without first chip-erasing the device.
Table 18. Read Back Value during EEPROM Polling
Data Polling Flash
Part
P1
P2
AT90S1200
$00
$FF
When a byte is being programmed into the Flash, reading the address location being
programmed will give the value $FF. At the time the device is ready for a new byte, the
programmed value will read correctly. This is used to determine when the next byte can
be written. This will not work for the value $FF, so when programming this value, the
user will have to wait for at least tWD_PROG before programming the next byte. As a chiperased device contains $FF in all locations, programming of addresses that are meant
to contain $FF, can be skipped.
45
0838H–AVR–03/02
Figure 35. Serial Programming Waveforms
Table 19. Serial Programming Instruction Set for AT90S1200
Instruction Format
Instruction
Byte 1
Byte 2
Byte 3
Byte4
Operation
Programming
Enable
1010 1100
0101 0011
xxxx xxxx
xxxx xxxx
Enable serial programming while RESET is low.
Chip Erase
1010 1100
100x xxxx
xxxx xxxx
xxxx xxxx
Chip erase both Flash and EEPROM memory
arrays.
Read Program
Memory
0010 H000
0000 000a
bbbb bbbb
oooo oooo
Read H (high or low) byte o from program memory at
word address a:b.
Write Program
Memory
0100 H000
0000 000a
bbbb bbbb
iiii iiii
Write H (high or low) byte i to program memory at
word address a:b.
Read EEPROM
Memory
1010 0000
0000 0000
00bb bbbb
oooo oooo
Read data o from EEPROM memory at address b.
Write EEPROM
Memory
1100 0000
0000 0000
00bb bbbb
iiii iiii
Write data i to EEPROM memory at address b.
Write Lock Bits
1010 1100
1111 1211
xxxx xxxx
xxxx xxxx
Write Lock bits. Set bits 1,2 = “0” to program Lock
bits.
Read Signature 0011 0000 xxxx xxxx xxxx xxbb oooo oooo Read signature byte o from address b.(1)
Byte
Note:
a = address high bits, b = address low bits, H = 0 – Low byte, 1 – High byte, o = data out, i = data in, x = don’t care, 1 = Lock
Bit 1, 2 = Lock Bit 2
Note:
46
1. The signature bytes are not readable in lock mode 3 (i.e., both Lock bits programmed).
AT90S1200
0838H–AVR–03/02
AT90S1200
Serial Programming
Characteristics
Figure 36. Serial Programming Timing
MOSI
tOVSH
SCK
tSLSH
tSHOX
tSHSL
MISO
tSLIV
Table 20. Serial Programming Characteristics, TA = -40°C to 85°C, VCC = 2.7 - 6.0V
(unless otherwise noted)
Symbol
Parameter
Min
1/tCLCL
Oscillator Frequency (VCC = 2.7 - 4.0V)
tCLCL
Oscillator Period (VCC = 2.7 - 4.0V)
1/tCLCL
Oscillator Frequency (VCC = 4.0 - 6.0V)
tCLCL
Oscillator Period (VCC = 4.0 - 6.0V)
tSHSL
Typ
0
Max
Units
4.0
MHz
250.0
ns
0
12.0
MHz
83.3
ns
SCK Pulse Width High
4.0 tCLCL
ns
tSLSH
SCK Pulse Width Low
tCLCL
ns
tOVSH
MOSI Setup to SCK High
1.25 tCLCL
ns
tSHOX
MOSI Hold after SCK High
2.5 tCLCL
ns
tSLIV
SCK Low to MISO Valid
10.0
16.0
32.0
ns
Table 21. Minimum Wait Delay after the Chip Erase Instruction
Symbol
3.2V
3.6V
4.0V
5.0V
tWD_ERASE
18 ms
14 ms
12 ms
8 ms
Table 22. Minimum Wait Delay after Writing a Flash or EEPROM Location
Symbol
3.2V
3.6V
4.0V
5.0V
tWD_PROG
9 ms
7 ms
6 ms
4 ms
47
0838H–AVR–03/02
Electrical Characteristics
Absolute Maximum Ratings*
Operating Temperature.................................. -55°C to +125°C
*NOTICE:
Stresses beyond those listed under “Absolute
Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and
functional operation of the device at these or
other conditions beyond those indicated in the
operational sections of this specification is not
implied. Exposure to absolute maximum rating
conditions for extended periods may affect
device reliability.
Storage Temperature ..................................... -65°C to +150°C
Voltage on Any Pin Except RESET
with Respect to Ground ...............................-1.0V to VCC+0.5V
Voltage on RESET with Respect to Ground ....-1.0V to +13.0V
Maximum Operating Voltage ............................................ 6.6V
DC Current per I/O Pin ............................................... 40.0 mA
DC Current VCC and GND Pins................................ 200.0 mA
DC Characteristics
TA = -40×C to 85×C, VCC = 2.7V to 6.0V (unless otherwise noted)
Symbol
Parameter
Condition
Min
Typ
Max
Units
(1)
V
VIL
Input Low Voltage
(Except XTAL1)
-0.5
0.3 VCC
VIL1
Input Low Voltage
(XTAL1)
-0.5
0.3 VCC(1)
V
0.6 VCC
(2)
VCC + 0.5
V
0.7 VCC
(2)
VCC + 0.5
V
VCC + 0.5
V
0.6
0.5
V
V
VIH
VIH1
Input High Voltage
(Except XTAL1, RESET)
Input High Voltage
(XTAL1)
VCC(2)
VIH2
Input High Voltage
(RESET)
VOL
Output Low Voltage(3)
(Ports B, D)
IOL = 20 mA, VCC = 5V
IOL = 10 mA, VCC = 3V
VOH
Output High Voltage(4)
(Ports B, D)
IOH = -3 mA, VCC = 5V
IOH = -1.5 mA, VCC = 3V
IIL
Input Leakage
Current I/O pin
VCC = 6V, pin low
(absolute value)
8.0
µA
IIH
Input Leakage
Current I/O pin
VCC = 6V, pin high
(absolute value)
980.0
nA
RRST
Reset Pull-up Resistor
100.0
500.0
kΩ
RI/O
I/O Pin Pull-up Resistor
35.0
120.0
kΩ
ICC
Power Supply Current
Active Mode, VCC = 3V,
4 MHz
3.0
mA
Idle Mode VCC = 3V, 4 MHz
1.0
mA
ICC
48
(5)
Power-down mode
0.85
4.3
2.3
V
V
WDT enabled, VCC = 3V
9.0
15.0
µA
WDT disabled, VCC = 3V
<1.0
2.0
µA
AT90S1200
0838H–AVR–03/02
AT90S1200
DC Characteristics
TA = -40×C to 85×C, VCC = 2.7V to 6.0V (unless otherwise noted) (Continued)
Symbol
Parameter
Condition
VACIO
Analog Comparator
Input Offset Voltage
VCC = 5V
Vin = VCC/ 2
IACLK
Analog Comparator
Input Leakage Current
VCC = 5V
Vin = VCC/ 2
tACPD
Notes:
1.
2.
3.
4.
5.
Min
-50.0
Typ
Max
Units
40.0
mV
50.0
nA
750.0
ns
Analog Comparator
VCC = 2.7V
500.0
Propagation Delay
VCC = 4.0V
“Max” means the highest value where the pin is guaranteed to be read as low.
“Min” means the lowest value where the pin is guaranteed to be read as high.
Although each I/O port can sink more than the test conditions (20 mA at VCC = 5V, 10 mA at VCC = 3V) under steady state
conditions (non-transient), the following must be observed:
1] The sum of all IOL, for all ports, should not exceed 200 mA.
2] The sum of all IOL, for port D0 - D5 and XTAL2, should not exceed 100 mA.
3] The sum of all IOL, for ports B0 - B7 and D6, should not exceed 100 mA.
If IOL exceeds the test condition, VOL may exceed the related specification. Pins are not guaranteed to sink current greater
than the listed test condition.
Although each I/O port can source more than the test conditions (3 mA at VCC = 5V, 1.5 mA at VCC = 3V) under steady state
conditions (non-transient), the following must be observed:
1] The sum of all IOH, for all ports, should not exceed 200 mA.
2] The sum of all IOH, for port D0 - D5 and XTAL2, should not exceed 100 mA.
3] The sum of all IOH, for ports B0 - B7 and D6, should not exceed 100 mA.
If IOH exceeds the test condition, VOH may exceed the related specification. Pins are not guaranteed to source current
greater than the listed test condition.
Minimum VCC for power-down is 2V.
49
0838H–AVR–03/02
External Clock Drive
Waveforms
Figure 37. External Clock Drive
VIH1
VIL1
External Clock Drive
Table 23. External Clock Drive
VCC = 2.7V to 4.0V
50
VCC = 4.0V to 6.0V
Min
Max
Min
Max
Units
0
4.0
0
12.0
MHz
Symbol
Parameter
1/tCLCL
Oscillator Frequency
tCLCL
Clock Period
250.0
83.3
ns
tCHCX
High Time
100.0
33.3
ns
tCLCX
Low Time
100.0
33.3
ns
tCLCH
Rise Time
1.6
0.5
µs
tCHCL
Fall Time
1.6
0.5
µs
AT90S1200
0838H–AVR–03/02
AT90S1200
Typical
Characteristics
The following charts show typical behavior. These figures are not tested during manufacturing. All current consumption measurements are performed with all I/O pins
configured as inputs and with internal pull-ups enabled. A sine wave generator with railto-rail output is used as clock source.
The power consumption in Power-down mode is independent of clock selection.
The current consumption is a function of several factors such as: operating voltage,
operating frequency, loading of I/O pins, switching rate of I/O pins, code executed and
ambient temperature. The dominating factors are operating voltage and frequency.
The current drawn from capacitive loaded pins may be estimated (for one pin) as
CL • V CC • f where C L = load capacitance, VCC = operating voltage and f = average
switching frequency of I/O pin.
The parts are characterized at frequencies higher than test limits. Parts are not guaranteed to function properly at frequencies higher than the ordering code indicates.
The difference between current consumption in Power-down mode with Watchdog
Timer enabled and Power-down mode with Watchdog Timer disabled represents the differential current drawn by the Watchdog Timer.
Figure 38. Active Supply Current vs. Frequency
ACTIVE SUPPLY CURRENT vs. FREQUENCY
TA= 25˚C
I cc(mA)
18
16
Vcc= 6V
14
Vcc= 5.5V
12
Vcc= 5V
10
Vcc= 4.5V
Vcc= 4V
8
Vcc= 3.6V
6
Vcc= 3.3V
Vcc= 3.0V
4
Vcc= 2.7V
2
0
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Frequency (MHz)
51
0838H–AVR–03/02
Figure 39. Active Supply Current vs. VCC
ACTIVE SUPPLY CURRENT vs. Vcc
FREQUENCY = 4 MHz
10
TA = -40˚C
9
TA = 25˚C
8
7
I cc(mA)
TA = 85˚C
6
5
4
3
2
1
0
2
2.5
3
3.5
4
4.5
5
5.5
6
Vcc(V)
Figure 40. Active Supply Current vs. VCC, Device Clocked by Internal Oscillator
ACTIVE SUPPLY CURRENT vs. Vcc
DEVICE CLOCKED BY INTERNAL RC OSCILLATOR
7
6
TA = 25˚C
5
I cc(mA)
TA = 85˚C
4
3
2
1
0
2
2.5
3
3.5
4
4.5
5
5.5
6
Vcc(V)
52
AT90S1200
0838H–AVR–03/02
AT90S1200
Figure 41. Idle Supply Current vs. Frequency
IDLE SUPPLY CURRENT vs. FREQUENCY
TA= 25˚C
4.5
Vcc= 6V
4
3.5
Vcc= 5.5V
I cc(mA)
3
Vcc= 5V
2.5
Vcc= 4.5V
2
Vcc= 4V
Vcc= 3.6V
Vcc= 3.3V
Vcc= 3.0V
1.5
1
Vcc= 2.7V
0.5
0
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Frequency (MHz)
Figure 42. Idle Supply Current vs. VCC
IDLE SUPPLY CURRENT vs. Vcc
FREQUENCY = 4 MHz
2.5
TA = -40˚C
TA = 25˚C
2
I cc(mA)
1.5
TA = 85˚C
1
0.5
0
2
2.5
3
3.5
4
4.5
5
5.5
6
Vcc(V)
53
0838H–AVR–03/02
Figure 43. Idle Supply Current vs. VCC, Device Clocked by Internal Oscillator
IDLE SUPPLY CURRENT vs. Vcc
DEVICE CLOCKED BY INTERNAL RC OSCILLATOR
0.4
TA = 25˚C
0.35
0.3
TA = 85˚C
I cc(mA)
0.25
0.2
0.15
0.1
0.05
0
2
2.5
3
3.5
4
4.5
5
5.5
6
Vcc(V)
Figure 44. Power-down Supply Current vs. VCC, Watchdog Timer Disabled
POWER DOWN SUPPLY CURRENT vs. Vcc
WATCHDOG TIMER DISABLED
1.8
TA = 85˚C
1.6
I cc(µΑ)
1.4
1.2
1
TA = 70˚C
0.8
0.6
0.4
TA = 45˚C
0.2
TA = 25˚C
0
2
2.5
3
3.5
4
4.5
5
5.5
6
Vcc(V)
54
AT90S1200
0838H–AVR–03/02
AT90S1200
Figure 45. Power-down Supply Current vs. VCC, Watchdog Timer Enabled
POWER DOWN SUPPLY CURRENT vs. Vcc
WATCHDOG TIMER ENABLED
140
TA = 25˚C
120
TA = 85˚C
I cc(µΑ)
100
80
60
40
20
0
2
2.5
3
3.5
4
4.5
5
5.5
6
Vcc(V)
Figure 46. Internal RC Oscillator Frequency vs. VCC
INTERNAL RC OSCILLATOR FREQUENCY vs. Vcc
1600
TA = 25˚C
1400
TA = 85˚C
F RC (KHz)
1200
1000
800
600
400
200
0
2
2.5
3
3.5
4
4.5
5
5.5
6
Vcc (V)
55
0838H–AVR–03/02
Figure 47. Analog Comparator Current vs. VCC
ANALOG COMPARATOR CURRENT vs. Vcc
1.2
1
TA = -40˚C
TA = 25˚C
I cc(mA)
0.8
0.6
TA = 85˚C
0.4
0.2
0
2
2.5
3
3.5
4
4.5
5
5.5
6
Vcc(V)
Note:
Analog comparator offset voltage is measured as absolute offset.
Figure 48. Analog Comparator Offset Voltage vs. Common Mode Voltage
ANALOG COMPARATOR OFFSET VOLTAGE vs.
COMMON MODE VOLTAGE
Vcc = 5V
18
16
TA = 25˚C
Offset Voltage (mV)
14
12
TA = 85˚C
10
8
6
4
2
0
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
Common Mode Voltage (V)
56
AT90S1200
0838H–AVR–03/02
AT90S1200
Figure 49. Analog Comparator Offset Voltage vs. Common Mode Voltage
ANALOG COMPARATOR OFFSET VOLTAGE vs.
COMMON MODE VOLTAGE
Vcc = 2.7V
10
TA = 25˚C
Offset Voltage (mV)
8
6
TA = 85˚C
4
2
0
0
0.5
1
1.5
2
2.5
3
Common Mode Voltage (V)
Figure 50. Analog Comparator Input Leakage Current
ANALOG COMPARATOR INPUT LEAKAGE CURRENT
VCC = 6V
TA = 25˚C
60
50
30
I
ACLK
(nA)
40
20
10
0
-10
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
5.5
6
6.5
7
VIN (V)
57
0838H–AVR–03/02
Note:
Sink and source capabilities of I/O ports are measured on one pin at a time.
Figure 51. Pull-up Resistor Current vs. Input Voltage
PULL-UP RESISTOR CURRENT vs. INPUT VOLTAGE
Vcc = 5V
120
TA = 25˚C
100
TA = 85˚C
I
OP (µA)
80
60
40
20
0
0
0.5
1
1.5
2
2.5
VOP (V)
3
3.5
4
4.5
5
Figure 52. Pull-up Resistor Current vs. Input Voltage
PULL-UP RESISTOR CURRENT vs. INPUT VOLTAGE
Vcc = 2.7V
30
TA = 25˚C
25
TA = 85˚C
15
I
OP (µA)
20
10
5
0
0
0.5
1
1.5
2
2.5
3
VOP (V)
58
AT90S1200
0838H–AVR–03/02
AT90S1200
Figure 53. I/O Pin Sink Current vs. Output Voltage
I/O PIN SINK CURRENT vs. OUTPUT VOLTAGE
Vcc = 5V
70
TA = 25˚C
60
TA = 85˚C
50
30
I
OL (mA)
40
20
10
0
0
0.5
1
1.5
2
2.5
3
VOL (V)
Figure 54. I/O Pin Source Current vs. Output Voltage
I/O PIN SOURCE CURRENT vs. OUTPUT VOLTAGE
Vcc = 5V
20
TA = 25˚C
18
16
TA = 85˚C
14
I
OH (mA)
12
10
8
6
4
2
0
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
VOH (V)
59
0838H–AVR–03/02
Figure 55. I/O Pin Sink Current vs. Output Voltage
I/O PIN SINK CURRENT vs. OUTPUT VOLTAGE
Vcc = 2.7V
25
TA = 25˚C
20
TA = 85˚C
10
I
OL (mA)
15
5
0
0
0.5
1
1.5
2
VOL (V)
Figure 56. I/O Pin Source Current vs. Output Voltage
I/O PIN SOURCE CURRENT vs. OUTPUT VOLTAGE
Vcc = 2.7V
6
TA = 25˚C
5
TA = 85˚C
3
I
OH (mA)
4
2
1
0
0
0.5
1
1.5
2
2.5
3
VOH (V)
60
AT90S1200
0838H–AVR–03/02
AT90S1200
Note:
Input threshold is measured at the center point of the hysteresis.
Figure 57. I/O Pin Input Threshold Voltage vs. VCC
I/O PIN INPUT THRESHOLD VOLTAGE vs. Vcc
TA = 25˚C
2.5
Threshold Voltage (V)
2
1.5
1
0.5
0
2.7
4.0
5.0
Vcc
Figure 58. I/O Pin Input Hysteresis vs. VCC
I/O PIN INPUT HYSTERESIS vs. Vcc
TA = 25˚C
0.18
0.16
Input hysteresis (V)
0.14
0.12
0.1
0.08
0.06
0.04
0.02
0
2.7
4.0
5.0
Vcc
61
0838H–AVR–03/02
AT90S1200 Register Summary
Address
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Page
$3F
SREG
I
T
H
S
V
N
Z
C
page 11
-
INT0
-
-
-
-
-
-
page 15
Notes:
62
$3E
Reserved
$3D
Reserved
$3C
Reserved
$3B
GIMSK
$3A
Reserved
$39
TIMSK
-
-
-
-
-
-
TOIE0
-
page 16
$38
TIFR
-
-
-
-
-
-
TOV0
-
page 16
$37
Reserved
$36
Reserved
-
-
SE
SM
-
-
ISC01
ISC00
page 18
-
-
-
-
-
CS02
CS01
CS00
$35
MCUCR
$34
Reserved
$33
TCCR0
$32
TCNT0
$31
Reserved
$30
Reserved
$2F
Reserved
$2E
Reserved
$2D
Reserved
$2C
Reserved
$2B
Reserved
$2A
Reserved
$29
Reserved
$28
Reserved
$27
Reserved
$26
Reserved
$25
Reserved
$24
Reserved
$23
Reserved
$22
Reserved
$21
WDTCR
$20
Reserved
$1F
Reserved
$1E
EEAR
$1D
EEDR
$1C
EECR
$1B
Reserved
$1A
Reserved
$19
Reserved
$18
$17
Timer/Counter0 (8 Bits)
-
-
-
-
-
WDE
page 21
page 22
WDP2
WDP1
WDP0
EEPROM Address Register
page 23
page 25
EEPROM Data Register
page 25
-
-
-
-
-
-
EEWE
EERE
page 25
PORTB
PORTB7
PORTB6
PORTB5
PORTB4
PORTB3
PORTB2
PORTB1
PORTB0
page 29
DDRB
DDB7
DDB6
DDB5
DDB4
DDB3
DDB2
DDB1
DDB0
page 29
$16
PINB
PINB7
PINB6
PINB5
PINB4
PINB3
PINB2
PINB1
PINB0
page 29
$15
Reserved
$14
Reserved
$13
Reserved
$12
PORTD
-
PORTD6
PORTD5
PORTD4
PORTD3
PORTD2
PORTD1
PORTD0
page 34
$11
DDRD
-
DDD6
DDD5
DDD4
DDD3
DDD2
DDD1
DDD0
page 34
$10
PIND
-
PIND6
PIND5
PIND4
PIND3
PIND2
PIND1
PIND0
page 34
$0F
Reserved
ACD
-
ACO
ACI
ACIE
-
ACIS1
ACIS0
page 27
...
Reserved
$09
Reserved
$08
ACSR
…
Reserved
$00
Reserved
1. For compatibility with future devices, reserved bits should be written to zero if accessed. Reserved I/O memory addresses
should never be written.
2. Some of the status flags are cleared by writing a logical “1” to them. Note that the CBI and SBI instructions will operate on all
bits in the I/O register, writing a “1” back into any flag read as set, thus clearing the flag. The CBI and SBI instructions work
with registers $00 to $1F only.
AT90S1200
0838H–AVR–03/02
AT90S1200
Instruction Set Summary
Mnemonic
Operands
Description
ARITHMETIC AND LOGIC INSTRUCTIONS
ADD
Rd, Rr
Add Two Registers
ADC
Rd, Rr
Add with Carry Two Registers
SUB
Rd, Rr
Subtract Two Registers
SUBI
Rd, K
Subtract Constant from Register
SBC
Rd, Rr
Subtract with Carry Two Registers
SBCI
Rd, K
Subtract with Carry Constant from Reg.
AND
Rd, Rr
Logical AND Registers
ANDI
Rd, K
Logical AND Register and Constant
OR
Rd, Rr
Logical OR Registers
ORI
Rd, K
Logical OR Register and Constant
EOR
Rd, Rr
Exclusive OR Registers
COM
Rd
One’s Complement
NEG
Rd
Two’s Complement
SBR
Rd, K
Set Bit(s) in Register
CBR
Rd, K
Clear Bit(s) in Register
INC
Rd
Increment
DEC
Rd
Decrement
TST
Rd
Test for Zero or Minus
CLR
Rd
Clear Register
SER
Rd
Set Register
BRANCH INSTRUCTIONS
RJMP
k
Relative Jump
RCALL
k
Relative Subroutine Call
RET
Subroutine Return
RETI
Interrupt Return
CPSE
Rd, Rr
Compare, Skip if Equal
CP
Rd, Rr
Compare
CPC
Rd, Rr
Compare with Carry
CPI
Rd, K
Compare Register with Immediate
SBRC
Rr, b
Skip if Bit in Register Cleared
SBRS
Rr, b
Skip if Bit in Register is Set
SBIC
P, b
Skip if Bit in I/O Register Cleared
SBIS
P, b
Skip if Bit in I/O Register is Set
BRBS
s, k
Branch if Status Flag Set
BRBC
s, k
Branch if Status Flag Cleared
BREQ
k
Branch if Equal
BRNE
k
Branch if Not Equal
BRCS
k
Branch if Carry Set
BRCC
k
Branch if Carry Cleared
BRSH
k
Branch if Same or Higher
BRLO
k
Branch if Lower
BRMI
k
Branch if Minus
BRPL
k
Branch if Plus
BRGE
k
Branch if Greater or Equal, Signed
BRLT
k
Branch if Less than Zero, Signed
BRHS
k
Branch if Half-carry Flag Set
BRHC
k
Branch if Half-carry Flag Cleared
BRTS
k
Branch if T-Flag Set
BRTC
k
Branch if T-Flag Cleared
BRVS
k
Branch if Overflow Flag is Set
BRVC
k
Branch if Overflow Flag is Cleared
BRIE
k
Branch if Interrupt Enabled
BRID
k
Branch if Interrupt Disabled
DATA TRANSFER INSTRUCTIONS
LD
Rd, Z
Load Register Indirect
ST
Z, Rr
Store Register Indirect
MOV
Rd, Rr
Move between Registers
LDI
Rd, K
Load Immediate
IN
Rd, P
In Port
OUT
P, Rr
Out Port
Operation
Flags
# Clocks
Rd ← Rd + Rr
Rd ← Rd + Rr + C
Rd ← Rd - Rr
Rd ← Rd - K
Rd ← Rd - Rr - C
Rd ← Rd - K - C
Rd ← Rd • Rr
Rd ← Rd • K
Rd ← Rd v Rr
Rd ← Rd v K
Rd ← Rd ⊕ Rr
Rd ← $FF - Rd
Rd ← $00 - Rd
Rd ← Rd v K
Rd ← Rd • (FFh - K)
Rd ← Rd + 1
Rd ← Rd - 1
Rd ← Rd • Rd
Rd ← Rd ⊕ Rd
Rd ← $FF
Z,C,N,V,H
Z,C,N,V,H
Z,C,N,V,H
Z,C,N,V,H
Z,C,N,V,H
Z,C,N,V,H
Z,N,V
Z,N,V
Z,N,V
Z,N,V
Z,N,V
Z,C,N,V
Z,C,N,V,H
Z,N,V
Z,N,V
Z,N,V
Z,N,V
Z,N,V
Z,N,V
None
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
PC ← PC + k + 1
PC ← PC + k + 1
PC ← STACK
PC ← STACK
if (Rd = Rr) PC ← PC + 2 or 3
Rd - Rr
Rd - Rr - C
Rd - K
if (Rr(b) = 0) PC ← PC + 2 or 3
if (Rr(b) = 1) PC ← PC + 2 or 3
if (P(b)= 0) PC ← PC + 2 or 3
if (P(b) = 1) PC ← PC + 2 or 3
if (SREG(s) = 1) then PC ← PC + k + 1
if (SREG(s) = 0) then PC ← PC + k + 1
if (Z = 1) then PC ← PC + k + 1
if (Z = 0) then PC ← PC + k + 1
if (C = 1) then PC ← PC + k + 1
if (C = 0) then PC ← PC + k + 1
if (C = 0) then PC ← PC + k + 1
if (C = 1) then PC ← PC + k + 1
if (N = 1) then PC ← PC + k + 1
if (N = 0) then PC ← PC + k + 1
if (N ⊕ V = 0) then PC ← PC + k + 1
if (N ⊕ V = 1) then PC ← PC + k + 1
if (H = 1) then PC ← PC + k + 1
if (H = 0) then PC ← PC + k + 1
if (T = 1) then PC ← PC + k + 1
if (T = 0) then PC ← PC + k + 1
if (V = 1) then PC ← PC + k + 1
if (V = 0) then PC ← PC + k + 1
if (I = 1) then PC ← PC + k + 1
if (I = 0) then PC ← PC + k + 1
None
None
None
I
None
Z,N,V,C,H
Z,N,V,C,H
Z,N,V,C,H
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
2
3
4
4
1/2
1
1
1
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
Rd ← (Z)
(Z) ← Rr
Rd ← Rr
Rd ← K
Rd ← P
P ← Rr
None
None
None
None
None
None
2
2
1
1
1
1
63
0838H–AVR–03/02
Instruction Set Summary (Continued)
Mnemonic
Operands
Description
BIT AND BIT-TEST INSTRUCTIONS
SBI
P, b
Set Bit in I/O Register
CBI
P, b
Clear Bit in I/O Register
LSL
Rd
Logical Shift Left
LSR
Rd
Logical Shift Right
ROL
Rd
Rotate Left through Carry
ROR
Rd
Rotate Right through Carry
ASR
Rd
Arithmetic Shift Right
SWAP
Rd
Swap Nibbles
BSET
s
Flag Set
BCLR
s
Flag Clear
BST
Rr, b
Bit Store from Register to T
BLD
Rd, b
Bit Load from T to Register
SEC
Set Carry
CLC
Clear Carry
SEN
Set Negative Flag
CLN
Clear Negative Flag
SEZ
Set Zero Flag
CLZ
Clear Zero Flag
SEI
Global Interrupt Enable
CLI
Global Interrupt Disable
SES
Set Signed Test Flag
CLS
Clear Signed Test Flag
SEV
Set Two’s Complement Overflow
CLV
Clear Two’s Complement Overflow
SET
Set T in SREG
CLT
Clear T in SREG
SEH
Set Half-carry Flag in SREG
CLH
Clear Half-carry Flag in SREG
NOP
No Operation
SLEEP
Sleep
WDR
Watchdog Reset
64
Operation
Flags
I/O(P,b) ← 1
I/O(P,b) ← 0
Rd(n+1) ← Rd(n), Rd(0) ← 0
Rd(n) ← Rd(n+1), Rd(7) ← 0
Rd(0) ← C,Rd(n+1) ← Rd(n),C ← Rd(7)
Rd(7) ← C,Rd(n) ← Rd(n+1),C ← Rd(0)
Rd(n) ← Rd(n+1), n = 0..6
Rd(3..0) ← Rd(7..4),Rd(7..4) ← Rd(3..0)
SREG(s) ← 1
SREG(s) ← 0
T ← Rr(b)
Rd(b) ← T
C←1
C←0
N←1
N←0
Z←1
Z←0
I←1
I←0
S←1
S←0
V← 1
V←0
T← 1
T ←0
H←1
H←0
None
None
Z,C,N,V
Z,C,N,V
Z,C,N,V
Z,C,N,V
Z,C,N,V
None
SREG(s)
SREG(s)
T
None
C
C
N
N
Z
Z
I
I
S
S
V
V
T
T
H
H
None
None
None
(see specific descr. for Sleep function)
(see specific descr. for WDR/timer)
# Clocks
2
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
AT90S1200
0838H–AVR–03/02
AT90S1200
Ordering Information(1)
Speed (MHz)
Power Supply
Ordering Code
Package
4
2.7 - 6.0V
AT90S1200-4PC
AT90S1200-4SC
AT90S1200-4YC
20P3
20S
20Y
Commercial
(0°C to 70°C)
AT90S1200-4PI
AT90S1200-4SI
AT90S1200-4YI
20P3
20S
20Y
Industrial
(-40°C to 85°C)
AT90S1200-12PC
AT90S1200-12SC
AT90S1200-12YC
20P3
20S
20Y
Commercial
(0°C to 70°C)
AT90S1200-12PI
AT90S1200-12SI
AT90S1200-12YI
20P3
20S
20Y
Industrial
(-40°C to 85°C)
12
Note:
4.0 - 6.0V
Operation Range
1. Order AT90S1200A-XXX for devices with the RCEN Fuse programmed.
Package Type
20P3
20-lead, 0.300" Wide, Plastic Dual Inline Package (PDIP)
20S
20-lead, 0.300" Wide, Plastic Gull Wing Small Outline (SOIC)
20Y
20-lead, 5.3 mm Wide, Plastic Shrink Small Outline Package (SSOP)
65
0838H–AVR–03/02
Packaging Information
20P3
D
PIN
1
E1
A
SEATING PLANE
A1
L
B
B1
e
E
COMMON DIMENSIONS
(Unit of Measure = mm)
C
eC
eB
Notes:
1. This package conforms to JEDEC reference MS-001, Variation AD.
2. Dimensions D and E1 do not include mold Flash or Protrusion.
Mold Flash or Protrusion shall not exceed 0.25 mm (0.010").
SYMBOL
MIN
NOM
MAX
A
–
–
5.334
A1
0.381
–
–
D
25.984
–
E
7.620
–
8.255
E1
6.096
–
7.112
B
0.356
–
0.559
B1
1.270
–
1.551
L
2.921
–
3.810
C
0.203
–
0.356
eB
–
–
10.922
eC
0.000
–
1.524
e
NOTE
25.493 Note 2
Note 2
2.540 TYP
09/28/01
R
66
2325 Orchard Parkway
San Jose, CA 95131
TITLE
20P3, 20-lead (0.300"/7.62 mm Wide) Plastic Dual
Inline Package (PDIP)
DRAWING NO.
20P3
REV.
B
AT90S1200
0838H–AVR–03/02
AT90S1200
20S
20S, 20-lead, Plastic Gull Wing Small
Outline (SOIC), 0.300" body.
Dimensions in Millineters and (Inches)*
JEDEC STANDARD MS-013
0.51(0.020)
0.33(0.013)
7.60 (0.2992) 10.65 (0.419)
7.40 (0.2914) 10.00 (0.394)
PIN 1 ID
PIN 1
1.27 (0.050) BSC
13.00 (0.5118)
12.60 (0.4961)
2.65 (0.1043)
2.35 (0.0926)
0.30(0.0118)
0.10 (0.0040)
0.32 (0.0125)
0.23 (0.0091)
0º ~ 8º
1.27 (0.050)
0.40 (0.016)
*Controlling dimension: Inches
REV. A
04/11/2001
67
0838H–AVR–03/02
20Y
20Y, 20-lead Plastic Shrink Small
Outline (SSOP), 5.3mm body Width.
Dimensions in Millimeters and (inches)*
0.38 (0.015)
0.25 (0.010)
5.38 (0.212) 7.90 (0.311)
5.20 (0.205) 7.65 (0.301)
PIN 1 ID
PIN 1
0.65 (0.0256) BSC
7.33 (0.289)
7.07 (0.278)
1.99 (0.078)
1.73 (0.068)
0.21 (0.008)
0.05 (0.002)
0.20 (0.008)
0.09 (0.004)
0º ~ 8º
0.95 (0.037)
0.63 (0.025)
*Controlling dimension: millimeters
REV. A
68
04/11/2001
AT90S1200
0838H–AVR–03/02
AT90S1200
Table of Contents
Features................................................................................................. 1
Pin Configuration.................................................................................. 1
Description ............................................................................................ 2
Block Diagram ......................................................................................................
Pin Descriptions....................................................................................................
Crystal Oscillator...................................................................................................
On-chip RC Oscillator ...........................................................................................
2
3
3
4
Architectural Overview......................................................................... 5
General Purpose Register File ............................................................................. 6
ALU – Arithmetic Logic Unit.................................................................................. 6
In-System Programmable Flash Program Memory .............................................. 6
Program and Data Addressing Modes.................................................................. 7
Subroutine and Interrupt Hardware Stack ............................................................ 8
EEPROM Data Memory........................................................................................ 9
Instruction Execution Timing................................................................................. 9
I/O Memory ......................................................................................................... 10
Reset and Interrupt Handling.............................................................................. 12
Sleep Modes....................................................................................................... 19
Timer/Counter0 ................................................................................... 20
Timer/Counter0 Prescaler................................................................................... 20
Watchdog Timer.................................................................................. 23
EEPROM Read/Write Access............................................................. 25
Prevent EEPROM Corruption ............................................................................. 26
Analog Comparator ............................................................................ 27
I/O Ports............................................................................................... 29
Port B.................................................................................................................. 29
Port D.................................................................................................................. 34
Memory Programming........................................................................ 37
Program and Data Memory Lock Bits.................................................................
Fuse Bits.............................................................................................................
Signature Bytes ..................................................................................................
Programming the Flash and EEPROM...............................................................
Parallel Programming .........................................................................................
Parallel Programming Characteristics ................................................................
Serial Downloading.............................................................................................
Serial Programming Characteristics ...................................................................
37
37
37
37
38
43
44
47
i
0838H–AVR–03/02
Electrical Characteristics................................................................... 48
Absolute Maximum Ratings*...............................................................................
DC Characteristics..............................................................................................
External Clock Drive Waveforms ........................................................................
External Clock Drive ...........................................................................................
48
48
50
50
Typical Characteristics ...................................................................... 51
AT90S1200 Register Summary.......................................................... 62
Instruction Set Summary ................................................................... 63
Ordering Information(1) ....................................................................... 65
Packaging Information ....................................................................... 66
20P3 ................................................................................................................... 66
20S ..................................................................................................................... 67
20Y ..................................................................................................................... 68
Table of Contents .................................................................................. i
ii
AT90S1200
0838H–AVR–03/02
Atmel Headquarters
Atmel Operations
Corporate Headquarters
Memory
2325 Orchard Parkway
San Jose, CA 95131
TEL 1(408) 441-0311
FAX 1(408) 487-2600
Europe
Atmel SarL
Route des Arsenaux 41
Casa Postale 80
CH-1705 Fribourg
Switzerland
TEL (41) 26-426-5555
FAX (41) 26-426-5500
Asia
Atmel Asia, Ltd.
Room 1219
Chinachem Golden Plaza
77 Mody Road Tsimhatsui
East Kowloon
Hong Kong
TEL (852) 2721-9778
FAX (852) 2722-1369
Japan
Atmel Japan K.K.
9F, Tonetsu Shinkawa Bldg.
1-24-8 Shinkawa
Chuo-ku, Tokyo 104-0033
Japan
TEL (81) 3-3523-3551
FAX (81) 3-3523-7581
Atmel Corporate
2325 Orchard Parkway
San Jose, CA 95131
TEL 1(408) 436-4270
FAX 1(408) 436-4314
Microcontrollers
Atmel Corporate
2325 Orchard Parkway
San Jose, CA 95131
TEL 1(408) 436-4270
FAX 1(408) 436-4314
Atmel Nantes
La Chantrerie
BP 70602
44306 Nantes Cedex 3, France
TEL (33) 2-40-18-18-18
FAX (33) 2-40-18-19-60
ASIC/ASSP/Smart Cards
Atmel Rousset
Zone Industrielle
13106 Rousset Cedex, France
TEL (33) 4-42-53-60-00
FAX (33) 4-42-53-60-01
RF/Automotive
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Theresienstrasse 2
Postfach 3535
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TEL (49) 71-31-67-0
FAX (49) 71-31-67-2340
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TEL 1(719) 576-3300
FAX 1(719) 540-1759
Biometrics/Imaging/Hi-Rel MPU/
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TEL (33) 4-76-58-30-00
FAX (33) 4-76-58-34-80
Atmel Colorado Springs
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Colorado Springs, CO 80906
TEL 1(719) 576-3300
FAX 1(719) 540-1759
Atmel Smart Card ICs
Scottish Enterprise Technology Park
Maxwell Building
East Kilbride G75 0QR, Scotland
TEL (44) 1355-803-000
FAX (44) 1355-242-743
e-mail
[email protected]
Web Site
http://www.atmel.com
© Atmel Corporation 2002.
Atmel Corporation makes no warranty for the use of its products, other than those expressly contained in the Company’s standard warranty
which is detailed in Atmel’s Terms and Conditions located on the Company’s web site. The Company assumes no responsibility for any errors
which may appear in this document, reserves the right to change devices or specifications detailed herein at any time without notice, and does
not make any commitment to update the information contained herein. No licenses to patents or other intellectual property of Atmel are granted
by the Company in connection with the sale of Atmel products, expressly or by implication. Atmel’s products are not authorized for use as critical
components in life support devices or systems.
ATMEL ® and AVR ® are the registered trademarks of Atmel.
Other terms and product names may be the trademarks of others.
Printed on recycled paper.
0838H–AVR–03/02
0M
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