NXP MC92460 Reference manual

NXP MC92460 Reference manual
Freescale Semiconductor, Inc.
Freescale Semiconductor, Inc...
MC92460UM/D
5/2002
REV 2.2
MC92460 Multichannel HDLC
User’s Manual
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Contents
Paragraph
Section
Number
Title
Page
Number
Freescale Semiconductor, Inc...
Chapter 1
Overview
1.1
1.2
1.3
1.3.1
1.3.2
1.4
1.5
1.5.1
1.5.2
1.5.3
Features ................................................................................................................ 1-2
Memory and Register Map .................................................................................. 1-3
Internal Memory Map ........................................................................................ 1-10
Internal Memory Map Register (IMMR)....................................................... 1-11
Process Revision Register (PRR)................................................................... 1-11
IEEE1149.1 (JTAG) Interface............................................................................ 1-12
Configurations of MC92460 with Compliant Devices ...................................... 1-12
MPC8260 with MC92460 Slaves .................................................................. 1-12
MPC8260 with MC92460 Master and MC92460 Slave................................ 1-14
MPC603e and MPC106 with MC92460s ...................................................... 1-15
Chapter 2
Signals
2.1
2.2
Signal Groups....................................................................................................... 2-1
Signal Descriptions .............................................................................................. 2-2
Chapter 3
System Control Unit
3.1
3.1.1
3.1.2
3.1.3
3.1.4
3.2
3.2.1
3.2.2
3.3
3.3.1
3.4
3.4.1
SCU Data Processing........................................................................................... 3-2
External Memory Receive ............................................................................... 3-2
External Memory Transmit.............................................................................. 3-4
SRAM Transmission Using MC92460 ............................................................ 3-5
SRAM Transmission Using MPC8260............................................................ 3-6
Interrupt Status..................................................................................................... 3-7
Interrupt Status Register 1 (INTS1)................................................................. 3-7
Interrupt Status Register 2 (INTS2)................................................................. 3-8
HDLC Channels................................................................................................... 3-8
Maximum HDLC Channel Register (MMCR) ................................................ 3-9
RxBD and TxBD Table Base Addresses.............................................................. 3-9
RxBD Table Base Address (RBASE) ............................................................ 3-10
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Contents
Paragraph
Number
3.4.2
3.5
Title
Page
Number
TxBD Table Base Address (TBASE)............................................................. 3-11
Communication Buffer (SRAM) ....................................................................... 3-11
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Chapter 4
High-level Data Link Controller (HDLC)
4.1
4.2
4.3
4.3.1
4.3.2
4.3.3
4.3.4
4.3.5
4.4
4.4.1
4.4.2
4.4.3
4.4.4
4.4.5
4.4.6
4.4.7
4.5
4.5.1
4.6
4.6.1
4.6.2
4.6.3
4.6.4
4.7
4.8
4.8.1
4.8.2
Introduction.......................................................................................................... 4-1
HDLC Features .................................................................................................... 4-2
HDLC Channel Frame Transmission................................................................... 4-3
Flag Sequence Field......................................................................................... 4-3
Address Field ................................................................................................... 4-3
Control Field .................................................................................................... 4-4
Information Field ............................................................................................. 4-5
Frame Check Sequence Field .......................................................................... 4-5
HDLC Buffer Descriptors (BDs) and Buffers ..................................................... 4-6
SRAM Buffers ................................................................................................. 4-7
Receive Buffer Descriptor (RxBD).................................................................. 4-7
Transmit Buffer Descriptor (TxBD) ................................................................ 4-9
Receiving Using RxBDs ................................................................................ 4-11
Transmitting Using TxBDs............................................................................ 4-12
HDLC Frame Transmission ........................................................................... 4-13
HDLC Frame Reception ................................................................................ 4-13
HDLC-Specific Parameter RAM ....................................................................... 4-14
HDLC Base Offset Address ........................................................................... 4-15
Error Handling by the HDLC Controller ........................................................... 4-16
HDLC Mode Register (MRA) ....................................................................... 4-17
HDLC Data Synchronization Register (DSR) ............................................... 4-19
HDLC Event Register/Mask Register (ER)/MR) .......................................... 4-19
HDLC Status Register (SR) ........................................................................... 4-20
HDLC Commands ............................................................................................. 4-21
Baud Rate Generator.......................................................................................... 4-22
BRG Configuration Registers (BRGCx)........................................................ 4-23
Baud Rate Examples...................................................................................... 4-23
Chapter 5
Master Interface Unit
5.1
5.2
5.2.1
5.2.2
5.2.3
System Mode ....................................................................................................... 5-2
Direct Memory Access (DMA)............................................................................ 5-2
Source Address (DMASA) .............................................................................. 5-3
Transfer Size (DMATS) ................................................................................... 5-3
Destination Address (DMADA) ...................................................................... 5-4
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Contents
Paragraph
Number
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5.2.4
5.2.5
5.2.6
5.3
5.3.1
5.3.2
5.4
Title
Page
Number
Mode Register (DMAMR)............................................................................... 5-5
Status Register (DMASR) ............................................................................... 5-6
DMA Error Address Register (DMAEA) ........................................................ 5-7
Arbiter .................................................................................................................. 5-7
Mode Register 0 (ARBM0) ............................................................................. 5-9
Mode Register 1 (ARBM1) ............................................................................. 5-9
Notes .................................................................................................................. 5-10
Chapter 6
IEEE 1149.1 Test Access Port
6.1
6.1.1
6.1.2
6.1.3
6.1.4
6.1.5
6.2
6.3
Functional Blocks ................................................................................................ 6-1
TAP Controller................................................................................................. 6-2
Instruction Register.......................................................................................... 6-3
Device Identification Register.......................................................................... 6-3
Bypass Register................................................................................................ 6-4
Boundary Scan Register................................................................................... 6-4
JTAG Instruction Support .................................................................................... 6-4
Boundary Scan Register Path............................................................................... 6-5
Chapter 7
Phase-Locked Loop
7.1
7.2
7.3
7.3.1
7.4
7.5
PLL1 .................................................................................................................... 7-1
PLL2 .................................................................................................................... 7-2
Programmer’s Model of PLL 1 and PLL2 ........................................................... 7-2
PLL Mode Register (PLL) ............................................................................... 7-2
Operation of PLL1 ............................................................................................... 7-3
Operation of PLL2 ............................................................................................... 7-3
Chapter 8
Reset
8.1
8.1.1
8.1.2
8.1.3
8.1.4
Reset Causes ........................................................................................................ 8-1
Reset Actions ................................................................................................... 8-1
Power-On Reset Sequence ............................................................................... 8-2
HRESET Sequence .......................................................................................... 8-2
TRST................................................................................................................ 8-2
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Contents
Paragraph
Number
Title
Page
Number
Appendix A
Transaction and Bandwidth Calculations
Memory Cycles................................................................................................... A-1
60x Bus Performance Consideration .................................................................. A-2
Total Theoretical Bus Bandwidth ....................................................................... A-6
Typical Bandwidth .............................................................................................. A-7
Maximum Throughput Measurement ................................................................. A-8
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A.1
A.2
A.3
A.4
A.5
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Figures
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Figure
Number
1-1
1-2
1-3
1-4
1-5
1-6
2-1
3-1
3-2
3-3
3-4
3-5
3-6
3-7
3-8
3-9
3-10
4-1
4-2
4-3
4-4
4-5
4-6
4-7
4-8
4-9
4-10
4-11
4-12
4-13
4-14
4-15
4-16
4-17
4-18
Title
Page
Number
MC92460 Block Diagram ........................................................................................... 1-1
Internal Memory Map Register (IMMR) .................................................................. 1-11
Process Revision Register (PRR).............................................................................. 1-11
MPC8260 and MC92460 System Using MPC8260 Arbiter ..................................... 1-13
MPC8260 and MC92460 System Using MC92460#0 As Arbiter ............................ 1-14
MPC603e, MPC106, and MC92460 System ............................................................ 1-16
MC92460 External Signals ......................................................................................... 2-1
SCU Block Diagram ................................................................................................... 3-1
External Memory Receive Sequence with RxBD ....................................................... 3-3
External Memory Transmit Sequence with TxBD...................................................... 3-4
Internal SRAM Transmit Sequence Using MC92460 DMA ...................................... 3-5
Internal SRAM Transmit Sequence Using MPC8260 ................................................ 3-6
Interrupt Status Register (INTS1) ............................................................................... 3-7
Interrupt Status Register 2 (INTS2) ............................................................................ 3-8
Max HDLC Channel Register (MMCR)..................................................................... 3-9
RBASE Register........................................................................................................ 3-10
TBASE Register ........................................................................................................ 3-11
HDLC Controller Block Diagram............................................................................... 4-2
HDLC Frame Structure ............................................................................................... 4-3
Frame Sequence Flag .................................................................................................. 4-3
FS Used As Closing and Opening Flag....................................................................... 4-3
Address........................................................................................................................ 4-4
Control Field ............................................................................................................... 4-4
Information Field ........................................................................................................ 4-5
Padding to Fill Out an Octet........................................................................................ 4-5
Frame Check ............................................................................................................... 4-5
Buffer Descriptors ....................................................................................................... 4-6
BD Table and Buffer Memory Structure..................................................................... 4-7
Receive Buffer Descriptor (RxBD)............................................................................. 4-8
Transmit Buffer Descriptor ......................................................................................... 4-9
HDLC Receiving Using RxBDs ............................................................................... 4-11
HDLC Transmitting Using TxBDs ........................................................................... 4-12
Data Synchronization Register (DSR) ...................................................................... 4-19
Event/Mask Register (ER/MR) ................................................................................. 4-19
HDLC Status Register (SR) ...................................................................................... 4-20
Figures
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Figures
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Figure
Number
4-19
4-20
4-21
5-1
5-2
5-3
5-4
5-5
5-6
5-7
5-8
5-9
5-10
5-11
6-1
6-2
7-1
7-2
7-3
8-1
A-1
A-2
A-3
Title
Page
Number
HDLC Command Register (CMR) ........................................................................... 4-21
Baud Rate Generator Block Diagram ....................................................................... 4-22
Baud Rate Generator Configuration Register (BRGCx)........................................... 4-23
Master Interface Unit Block Diagram......................................................................... 5-1
System Mode Register (SMR) .................................................................................... 5-2
DMA Source Address Register (DMASA) ................................................................. 5-3
DMA Transfer Size Register (DMATS)...................................................................... 5-4
Destination Address Register (DMADA) ................................................................... 5-4
DMA Mode Register (DMAMR)................................................................................ 5-5
DMA Status Register (DMASR) ................................................................................ 5-6
DMA Error Address Register (DMAEA) ................................................................... 5-7
Arbitration Between Two MC92460s ......................................................................... 5-8
Mode Register 0 (ARBM0)......................................................................................... 5-9
Mode Register 1 (ARMB1)......................................................................................... 5-9
JTAG Logic Block Diagram........................................................................................ 6-2
TAP Controller State Diagram .................................................................................... 6-3
PLL1 Block Diagram .................................................................................................. 7-1
PLL2 Block Diagram .................................................................................................. 7-2
PLL Mode Register (PLL) .......................................................................................... 7-3
Reset Flow................................................................................................................... 8-2
DMA Accesses: Two 4-Beat Burst Reads and One Write ......................................... A-2
60x Bus Behavior with PQII System ......................................................................... A-7
Throughput Increase per Number of Channels Used................................................. A-8
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Tables
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Table
Number
1-1
1-2
1-3
2-1
3-1
3-2
3-3
3-4
3-5
4-1
4-2
4-3
4-4
4-5
4-6
4-7
4-8
4-9
4-10
4-11
4-12
4-13
4-14
4-15
4-16
4-17
5-1
5-2
5-3
5-4
5-5
5-6
5-7
5-8
5-9
Title
Page
Number
Internal Memory Map ................................................................................................. 1-3
IMMR Field Description........................................................................................... 1-11
PRR Field Description .............................................................................................. 1-12
Signal Descriptions ..................................................................................................... 2-2
Interrupt Status Register Field Description................................................................. 3-8
Interrupt Status Register 2 Descriptions ..................................................................... 3-8
Maximum HDLC Channel Register Description........................................................ 3-9
Default Base Addresses for RxBD Table .................................................................. 3-10
Default Base Addresses for TxBD Table .................................................................. 3-11
Address Field .............................................................................................................. 4-4
Control Frame Classes ................................................................................................ 4-4
CRC Generator Polynomials....................................................................................... 4-5
Receive Buffer Descriptor Bit Functions .................................................................... 4-8
Transmit Buffer Descriptor Bit Functions................................................................... 4-9
Parameter RAM Map ................................................................................................ 4-14
HDLC Base Offset Addresses ................................................................................... 4-15
Transmit Errors ......................................................................................................... 4-16
Receive Errors ........................................................................................................... 4-16
Mode Register (MRA) .............................................................................................. 4-17
Mode Register Description ....................................................................................... 4-18
Data Synchronization Register Description .............................................................. 4-19
ER/MR Register Description .................................................................................... 4-19
SR Field Descriptions ............................................................................................... 4-20
HDLC Command Register Field Descriptions ......................................................... 4-21
BRGCx Register Description.................................................................................... 4-23
Baud Rate .................................................................................................................. 4-24
SMR Register Descriptions......................................................................................... 5-2
DMASA Register Description .................................................................................... 5-3
DMATS Register Description ..................................................................................... 5-4
DMADA Register Description.................................................................................... 5-4
DMAMR Register Descriptions.................................................................................. 5-5
DMASR Field Descriptions ........................................................................................ 5-6
DMAEA Register Field Description........................................................................... 5-7
ARBM0 Register Field Descriptions .......................................................................... 5-9
ARBM1 Register Field Description............................................................................ 5-9
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Tables
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Table
Number
6-1
6-2
7-1
7-2
8-1
8-2
A-1
A-2
A-3
A-4
A-5
Title
Page
Number
Device Identification Register ID Codes..................................................................... 6-3
Instruction Decoding................................................................................................... 6-5
PLL Mode Register Field Descriptions....................................................................... 7-3
Baud Rate Clock Output with 14.72 MHz EXCLK.................................................... 7-4
Reset Causes ............................................................................................................... 8-1
Reset Action for Each Reset Source ........................................................................... 8-2
Average Clock Cycles by External DMA .................................................................. A-1
External DMA Transactions–Read Sequence ............................................................ A-4
External DMA Transactions–Write Sequence ........................................................... A-5
Theoretical Maximum Data Transfer Rate................................................................. A-6
Maximum Throughput ............................................................................................... A-9
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Chapter 1
Overview
The MC92460 is a 40-channel high-level data link controller (HDLC) with an aggregate
throughput of up to 1919 Mbps across a synchronous optical network (SONET). It is a
peripheral device that connects to the 60x bus of microprocessors such as the MPC8260 or
the MPC603e. Figure 1-1 shows a block diagram of the MC92460.
X2
60x bus
64-bit 66.7 MHz 3.3V
Master Interface Unit
Bus Interface
DMA
Arbiter
MPC8260
Register interrupt
dual-port RAM
32 Kbyte
SCU
SRAM
32-byte x 80 FIFO
Communication
Buffer
(64-bit x 4kW)
64-bit
Rx FIFO
BIST
Tx FIFO
HDLC
PLLs
Two or more
MC92460s
Flag/Abort/Idle
0-Insert/Delete
16 / 32 CRC
JTAG
40 Channels
RxSD RxCK TxCK TxSD
MC92460
Figure 1-1. MC92460 Block Diagram
Chapter 1. Overview
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Features
1.1 Features
The following is an overview of the MC92460 feature set:
•
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•
•
•
•
•
Channels
— 40 full-duplex HDLC channels
— Programmable channel assignment (any logical channel to any signal)
— Each channel has a default of 64 buffer descriptors (Rx and Tx) but the number
of buffer descriptors per channel is configurable
Controllers
— Maximum throughput of 1919 Mbps; individual controllers operate up to 66.7
Mbps
— All communication controllers operate asynchronously
— Programmable frame size (maximum 65,535 bytes)
— Transparent memory access with internal memory controller
60x Bus
— MC92460 directly connects with a 64-bit data and 32-bit address 60x bus
— Supports 66.7 MHz 60x bus speed, with aggregate bandwidth of up to 1919
Mbps depending on the type of main memory used
— Up to four MC92460’s may be connected in parallel on the 60x bus
— Bus supports multiple master design
Communication Buffers
— Data Buffer
– 256 Kbits on-chip memory for data buffers
– 256 Kbit communication buffer can store up to 819 bytes per frame.
– 80 channel virtual DMA functionality executes between off-chip memory and
the communication buffer
— BD Buffer
– 32 Kbyte on-chip dual-port RAM for buffer descriptors
– A total of 4096 buffer descriptors (2048 TxBD and 2048 RxBD)
JTAG Support
— Supports the IEEE1149.1 JTAG controller standard
Power and Clocks
— Supports single-beat and burst accesses
— On-chip PLL for baud rate generator (maximum of 66.7 MHz)
— Separate power supplies for core internal logic (1.8V) and for I/O (3.3V)
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Memory and Register Map
•
Package
— 480 pin TPGA, 1.27 mm pitch
1.2 Memory and Register Map
The MC92460’s internal memory resources are within a contiguous block of memory. The
size of the internal space is 32 Kbytes. The location of this block within the global 4 Gbyte
real memory space is mapped to an implementation specific special register called the
internal memory map register (IMMR). Table 1-1 defines the internal memory map of the
MC92460.
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Table 1-1. Internal Memory Map
Internal Address
Abbreviation
0x0_0000 - 0x0_7fff
HDLCB
0x0_8000 - 0x4_ffff
Reserved
0x5_0000 –
0x5_00ff
0x5_0000 –
0x50007
Name
Size
Module
Internal RAM for HDLC Tx & Rx Buffer
32 Kbytes
SCU
RxBD0-0
HDLC0-0 Receive Buffer Descriptor
8 bytes
HDLC
0x50008 0x5000f
RxBD0-1
HDLC0-1 Receive Buffer Descriptor
8 bytes
0x50010 0x50017
RxBD0-2
HDLC0-2 Receive Buffer Descriptor
8 bytes
0x50018 0x5001f
RxBD0-3
HDLC0-3 Receive Buffer Descriptor
8 bytes
0x50020 0x50027
RxBD0-4
HDLC0-4 Receive Buffer Descriptor
8 bytes
0x50028 0x5002f
RxBD0-5
HDLC0-5 Receive Buffer Descriptor
8 bytes
0x50030 0x50037
RxBD0-6
HDLC0-6 Receive Buffer Descriptor
8 bytes
0x50038 0x5003f
RxBD0-7
HDLC0-7 Receive Buffer Descriptor
8 bytes
0x50040 0x5_00ff
RxBD0
HLDC0-8 to -31 Receive Buffer Descriptor
192 bytes
0x5_0100 0x5_01ff
RxBD1
HDLC1 Receive Buffer Descriptor Table
256 bytes
0x5_0200 0x5_02ff
RxBD2
HDLC2 Receive Buffer Descriptor Table
256 bytes
0x5_0300 0x5_03ff
RxBD3
HDLC3 Receive Buffer Descriptor Table
256 bytes
0x5_0400 0x5_04ff
RxBD4
HDLC4 Receive Buffer Descriptor Table
256 bytes
0x5_0500 0x5_05ff
RxBD5
HDLC5 Receive Buffer Descriptor Table
256 bytes
0x5_0600 0x5_06ff
RxBD6
HDLC6 Receive Buffer Descriptor Table
256 bytes
Chapter 1. Overview
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Memory and Register Map
Table 1-1. Internal Memory Map (Continued)
Freescale Semiconductor, Inc...
Internal Address
Abbreviation
Name
Size
0x5_0700 0x5_07ff
RxBD7
HDLC7 Receive Buffer Descriptor Table
256 bytes
0x5_0800 0x5_08ff
RxBD8
HDLC8 Receive Buffer Descriptor Table
256 bytes
0x5_0900 0x5_09ff
RxBD9
HDLC9 Receive Buffer Descriptor Table
256 bytes
0x5_0a00 0x5_0aff
RxBD10
HDLC10 Receive Buffer Descriptor Table
256 bytes
0x5_0b00 0x5_0bff
RxBD11
HDLC11 Receive Buffer Descriptor Table
256 bytes
0x5_0c00 0x5_0cff
RxBD12
HDLC12 Receive Buffer Descriptor Table
256 bytes
0x5_0d00 0x5_0dff
RxBD13
HDLC13 Receive Buffer Descriptor Table
256 bytes
0x5_0e00 0x5_0eff
RxBD14
HDLC14 Receive Buffer Descriptor Table
256 bytes
0x5_0f00 0x5_0fff
RxBD15
HDLC15 Receive Buffer Descriptor Table
256 bytes
0x5_1000 0x5_10ff
RxBD16
HDLC16 Receive Buffer Descriptor Table
256 bytes
0x5_1100 0x5_11ff
RxBD17
HDLC17 Receive Buffer Descriptor Table
256 bytes
0x5_1200 0x5_12ff
RxBD18
HDLC18 Receive Buffer Descriptor Table
256 bytes
0x5_1300 0x5_13ff
RxBD19
HDLC19 Receive Buffer Descriptor Table
256 bytes
0x5_1400 0x5_14ff
RxBD20
HDLC20 Receive Buffer Descriptor Table
256 bytes
0x5_1500 0x5_15ff
RxBD21
HDLC21 Receive Buffer Descriptor Table
256 bytes
0x5_1600 0x5_16ff
RxBD22
HDLC22 Receive Buffer Descriptor Table
256 bytes
0x5_1700 0x5_17ff
RxBD23
HDLC23 Receive Buffer Descriptor Table
256 bytes
0x5_1800 0x5_18ff
RxBD24
HDLC24 Receive Buffer Descriptor Table
256 bytes
0x5_1900 0x5_19ff
RxBD25
HDLC25 Receive Buffer Descriptor Table
256 bytes
0x5_1a00 0x5_1aff
RxBD26
HDLC26 Receive Buffer Descriptor Table
256 bytes
0x5_1b00 0x5_1bff
RxBD27
HDLC27 Receive Buffer Descriptor Table
256 bytes
0x5_1c00 0x5_1cff
RxBD28
HDLC28 Receive Buffer Descriptor Table
256 bytes
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Memory and Register Map
Table 1-1. Internal Memory Map (Continued)
Freescale Semiconductor, Inc...
Internal Address
Abbreviation
Name
Size
0x5_1d00 0x5_1dff
RxBD29
HDLC29 Receive Buffer Descriptor Table
256 bytes
0x5_1e00 0x5_1eff
RxBD30
HDLC30 Receive Buffer Descriptor Table
256 bytes
0x5_1f00 0x5_1fff
RxBD31
HDLC31 Receive Buffer Descriptor Table
256 bytes
0x5_2000 0x5_20ff
RxBD32
HDLC32 Receive Buffer Descriptor Table
256 bytes
0x5_2100 0x5_21ff
RxBD33
HDLC33 Receive Buffer Descriptor Table
256 bytes
0x5_2200 0x5_22ff
RxBD34
HDLC34 Receive Buffer Descriptor Table
256 bytes
0x5_2300 0x5_23ff
RxBD35
HDLC35 Receive Buffer Descriptor Table
256 bytes
0x5_2400 0x5_24ff
RxBD36
HDLC36 Receive Buffer Descriptor Table
256 bytes
0x5_2500 0x5_25ff
RxBD37
HDLC37 Receive Buffer Descriptor Table
256 bytes
0x5_2600 0x5_26ff
RxBD38
HDLC38 Receive Buffer Descriptor Table
256 bytes
0x5_2700 0x5_27ff
RxBD39
HDLC39 Receive Buffer Descriptor Table
256 bytes
0x5_2800 - 0x5_9fff
Reserved
0x5_a000 0x5_a0ff
0x5_a000 0x5_a007
TxBD0-0
HDLC0-0 Transmitter Buffer Descriptor
8 bytes
0x5_a008 0x5_a00f
TxBD0-1
HDLC0-1 Transmitter Buffer Descriptor
8 bytes
0x5_a010 0x5_a017
TxBD0-2
HDLC0-2 Transmitter Buffer Descriptor
8 bytes
0x5_a018 0x5_a01f
TxBD0-3
HDLC0-3 Transmitter Buffer Descriptor
8 bytes
0x5_a020 0x5_a027
TxBD0-4
HDLC0-4 Transmitter Buffer Descriptor
8 bytes
0x5_a028 0x5_a02f
TxBD0-5
HDLC0-5 Transmitter Buffer Descriptor
8 bytes
0x5_a030 0x5_a037
TxBD0-6
HDLC0-6 Transmitter Buffer Descriptor
8 bytes
0x5_a038 0x5_a03f
TxBD0-7
HDLC0-7 Transmitter Buffer Descriptor
8 bytes
0x5_a040 0x5_a0ff
TxBD0
HDLC0-8 – 31 Transmitter Buffer Descriptor
192 bytes
TxBD1
HDLC1 Transmitter Buffer Descriptor Table
256 bytes
0x5_a100 0x5_a1ff
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HDLC
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Memory and Register Map
Table 1-1. Internal Memory Map (Continued)
Freescale Semiconductor, Inc...
Internal Address
Abbreviation
Name
Size
0x5_a200 0x5_a2ff
TxBD2
HDLC2 Transmitter Buffer Descriptor Table
256 bytes
0x5_a300 0x5_a3ff
TxBD3
HDLC3 Transmitter Buffer Descriptor Table
256 bytes
0x5_a400 0x5_a4ff
TxBD4
HDLC4 Transmitter Buffer Descriptor Table
256 bytes
0x5_a500 0x5_a5ff
TxBD5
HDLC5 Transmitter Buffer Descriptor Table
256 bytes
0x5_a600 0x5_a6ff
TxBD6
HDLC6 Transmitter Buffer Descriptor Table
256 bytes
0x5_a700 0x5_a7ff
TxBD7
HDLC7 Transmitter Buffer Descriptor Table
256 bytes
0x5_a800 0x5_a8ff
TxBD8
HDLC8 Transmitter Buffer Descriptor Table
256 bytes
0x5_a900 0x5_a9ff
TxBD9
HDLC9 Transmitter Buffer Descriptor Table
256 bytes
0x5_aa00 0x5_aaff
TxBD10
HDLC10 Transmitter Buffer Descriptor Table
256 bytes
0x5_ab00 0x5_abff
TxBD11
HDLC11 Transmitter Buffer Descriptor Table
256 bytes
0x5_ac00 0x5_acff
TxBD12
HDLC12 Transmitter Buffer Descriptor Table
256 bytes
0x5_ad00 0x5_adff
TxBD13
HDLC13 Transmitter Buffer Descriptor Table
256 bytes
0x5_ae00 0x5_aeff
TxBD14
HDLC14 Transmitter Buffer Descriptor Table
256 bytes
0x5_af00 0x5_afff
TxBD15
HDLC15 Transmitter Buffer Descriptor Table
256 bytes
0x5_b000 0x5_b0ff
TxBD16
HDLC16 Transmitter Buffer Descriptor Table
256 bytes
0x5_b100 0x5_b1ff
TxBD17
HDLC17 Transmitter Buffer Descriptor Table
256 bytes
0x5_b200 0x5_b2ff
TxBD18
HDLC18 Transmitter Buffer Descriptor Table
256 bytes
0x5_b300 0x5_b3ff
TxBD19
HDLC19 Transmitter Buffer Descriptor Table
256 bytes
0x5_b400 0x5_b4ff
TxBD20
HDLC20 Transmitter Buffer Descriptor Table
256 bytes
0x5_b500 0x5_b5ff
TxBD21
HDLC21 Transmitter Buffer Descriptor Table
256 bytes
0x5_b600 0x5_b6ff
TxBD22
HDLC22 Transmitter Buffer Descriptor Table
256 bytes
0x5_b700 0x5_b7ff
TxBD23
HDLC23 Transmitter Buffer Descriptor Table
256 bytes
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Memory and Register Map
Table 1-1. Internal Memory Map (Continued)
Freescale Semiconductor, Inc...
Internal Address
Abbreviation
Name
Size
0x5_b800 0x5_b8ff
TxBD24
HDLC24 Transmitter Buffer Descriptor Table
256 bytes
0x5_b900 0x5_b9ff
TxBD25
HDLC25 Transmitter Buffer Descriptor Table
256 bytes
0x5_ba00 0x5_baff
TxBD26
HDLC26 Transmitter Buffer Descriptor Table
256 bytes
0x5_bb00 0x5_bbff
TxBD27
HDLC27 Transmitter Buffer Descriptor Table
256 bytes
0x5_bc00 0x5_bcff
TxBD28
HDLC28 Transmitter Buffer Descriptor Table
256 bytes
0x5_bd00 0x5_bdff
TxBD29
HDLC29 Transmitter Buffer Descriptor Table
256 bytes
0x5_be00 0x5_beff
TxBD30
HDLC30 Transmitter Buffer Descriptor Table
256 bytes
0x5_bf00 0x5_bfff
TxBD31
HDLC31 Transmitter Buffer Descriptor Table
256 bytes
0x5_c000 0x5_c0ff
TxBD32
HDLC32 Transmitter Buffer Descriptor Table
256 bytes
0x5_c100 0x5_c1ff
TxBD33
HDLC33 Transmitter Buffer Descriptor Table
256 bytes
0x5_c200 0x5_c2ff
TxBD33
HDLC34 Transmitter Buffer Descriptor Table
256 bytes
0x5_c300 0x5_c3ff
TxBD34
HDLC35 Transmitter Buffer Descriptor Table
256 bytes
0x5_c400 0x5_c4ff
TxBD36
HDLC36 Transmitter Buffer Descriptor Table
256 bytes
0x5_c500 0x5_c5ff
TxBD37
HDLC37 Transmitter Buffer Descriptor Table
256 bytes
0x5_c600 0x5_c6ff
TxBD38
HDLC38 Transmitter Buffer Descriptor Table
256 bytes
0x5_c700 0x5_c7ff
TxBD39
HDLC39 Transmitter Buffer Descriptor Table
256 bytes
0x5_c800 - 0x6_3fff
Reserved
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Module
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Memory and Register Map
Table 1-1. Internal Memory Map (Continued)
Internal Address
Abbreviation
Name
Size
Parameter RAM Area
Freescale Semiconductor, Inc...
0x6_4000 0x6_407c
0x6_4000
MRBLR
HDLC0 Channel Maximum Rx Buffer Length
2 bytes
0x6_4008
Reserved
4 bytes
0x6_4010
Reserved
4 bytes
0x6_4018
C_MASK
HDLC0 CRC Mask
4 bytes
0x6_4020
C_PRES
HDLC0 CRC Preset
4 bytes
0x6_4028
MFLR
HDLC0 Max Frame Length
2 bytes
0x6_4030
HMASK
HDLC0 Mask Register
2 bytes
0x6_4038
HADDR1
HDLC0 Address1
2 bytes
0x6_403c
Reserved
0x6_4040
HADDR2
HDLC0 Address2
2 bytes
0x6_4048
HADDR3
HDLC0 Address3
2 bytes
0x6_4050
HADDR4
HDLC0 Address4
2 bytes
0x6_4058
MRA
HDLC0 Mode Register
4 bytes
0x6_4060
DSR
HDLC0 Data Sychronization
2 bytes
0x6_4064
ER
HDLC0 Event Register
2 bytes
0x6_4068
MR
HDLC0 Mask Register
2 bytes
0x6_406c
SR
HDLC0 Status Register
1 byte
0x6_4070
BRG
HDLC0 Baud Rate Generator
2 bytes
0x6_4074
RBASE
HDLC0 RxBD Table Base Address
4 bytes
0x6_4078
CMR
HDLC0 Command Register
2 bytes
0x6_407c
TBASE
HDLC0 TxBD Table Base Address
4 bytes
0x6_4080
MRBLR
HDLC1 Channel Maximum Rx Buffer Length
128 bytes
0x6_4100
MRBLR
HDLC2 Channel
128 bytes
0x6_4180
MRBLR
HDLC3 Channel
128 bytes
0x6_4200
MRBLR
HDLC4 Channel
128 bytes
0x6_4280
MRBLR
HDLC5 Channel
128 bytes
0x6_4300
MRBLR
HDLC6 Channel
128 bytes
0x6_4380
MRBLR
HDLC7 Channel
128 bytes
0x6_4400
MRBLR
HDLC8 Channel
128 bytes
0x6_4480
MRBLR
HDLC9 Channel
128 bytes
0x6_4500
MRBLR
HDLC10 Channel
128 bytes
0x6_4580
MRBLR
HDLC11 Channel
128 bytes
0x6_4600
MRBLR
HDLC12 Channel
128 bytes
0x6_4680
MRBLR
HDLC13 Channel
128 bytes
0x6_4700
MRBLR
HDLC14 Channel
128 bytes
2 bytes
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Memory and Register Map
Table 1-1. Internal Memory Map (Continued)
Freescale Semiconductor, Inc...
Internal Address
Abbreviation
Name
Size
0x6_4780
MRBLR
HDLC15 Channel
128 bytes
0x6_4800
MRBLR
HDLC16 Channel
128 bytes
0x6_4880
MRBLR
HDLC17 Channel
128 bytes
0x6_4900
MRBLR
HDLC18 Channel
128 bytes
0x6_4980
MRBLR
HDLC19 Channel
128 bytes
0x6_4a00
MRBLR
HDLC20 Channel
128 bytes
0x6_4a80
MRBLR
HDLC21 Channel
128 bytes
0x6_4b00
MRBLR
HDLC22 Channel
128 bytes
0x6_4b80
MRBLR
HDLC23 Channel
128 bytes
0x6_4c00
MRBLR
HDLC24 Channel
128 bytes
0x6_4c80
MRBLR
HDLC25 Channel
128 bytes
0x6_4d00
MRBLR
HDLC26 Channel
128 bytes
0x6_4d80
MRBLR
HDLC27 Channel
128 bytes
0x6_4e00
MRBLR
HDLC28 Channel
128 bytes
0x6_4e80
MRBLR
HDLC29 Channel
128 bytes
0x6_4f00
MRBLR
HDLC30 Channel
128 bytes
0x6_4f80
MRBLR
HDLC31 Channel
128 bytes
0x6_5000
MRBLR
HDLC32 Channel
128 bytes
0x6_5080
MRBLR
HDLC33 Channel
128 bytes
0x6_5100
MRBLR
HDLC34 Channel
128 bytes
0x6_5180
MRBLR
HDLC35 Channel
128 bytes
0x6_5200
MRBLR
HDLC36 Channel
128 bytes
0x6_5280
MRBLR
HDLC37 Channel
128 bytes
0x6_5300
MRBLR
HDLC38 Channel
128 bytes
0x6_5380
MRBLR
HDLC39 Channel
128 bytes
0x6_5400
INTS
Interrupt Status Register
8 bytes
0x6_5408
Reserved
8 bytes
0x6_5410
Reserved
4 bytes
0x6_5414
Reserved
4 bytes
0x6_5418
Reserved
4 bytes
0x6_541c
Reserved
4 bytes
0x6_5420
Reserved
4 bytes
0x6_5424
Reserved
4 bytes
0x6_5428
Reserved
4 bytes
0x6_542c
Reserved
4 bytes
0x6_5430
Reserved
4 bytes
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Module
SCU
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Internal Memory Map
Table 1-1. Internal Memory Map (Continued)
Freescale Semiconductor, Inc...
Internal Address
Abbreviation
Name
Size
0x6_5434
Reserved
0x6_5438
MMCR
Max HDLC Channel
2 bytes
0x6_5440
IMMR
Internal Memory Map Register
2 bytes
0x6_5444
SMR
System Mode Register
2 bytes
0x6_5448
PLL
PLL Mode Register
4 bytes
0x6_544c
Reserved
4 bytes
0x6_5450
Reserved
4 bytes
0x6_5454
Reserved
4 bytes
0x6_5458
Reserved
4 bytes
0x6_545c
Reserved
4 bytes
0x6_5460
Reserved
158 bytes
0x6_5500
DMASA
Source Address of DMA
4 byte
0x6_5504
DMATS
Transfer Size of DMA
4 byte
0x6_5508
DMADA
Destination Address of DMA
4 bytes
0x6_550c
DMAMR
Mode Register of DMA
4 bytes
0x6_5510
DMASR
Status Register
4 bytes
0x6_5514
DMAEA
Error Address Register
4 bytes
0x6_5518
PRR
Process Revision Rregister
4 bytes
0x6_551c
Reserved
0x6_5520
ARBM0
Mode Register0
2 bytes
0x6_5524
ARBM1
Mode Register1
2 bytes
0x6_5526
Reserved
2 bytes
0x6_5528
Reserved
320 bytes
Module
4 bytes
MI
4 bytes
1.3 Internal Memory Map
The MC92460’s internal memory map is defined with IMMR[ISB] and IMMR[CS]. The
upper 9 bits (A[0:8]) are the ISB field that specify the internal space base, and the next 3
bits (A[9:11]) are the chip selects. The default base address 0xFD30_0000, for example,
has an ISB of 0xFDx and a CS of 0x0.
Although IMMR can be read many times, it can be written only once after a reset operation.
After a reset, a protection circuit is enabled allowing the IMMR to be written. After the first
write access to the IMMR, the circuit is disabled. This register cannot be written by byte
access.
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Internal Memory Map
1.3.1 Internal Memory Map Register (IMMR)
The internal memory map register (IMMR), shown in Table 1-2, identifies a specific device
as well as holds the base address for the internal memory map. Software can deduce the
availability and location of all on-chip system resources from the values in IMMR.
Freescale Semiconductor, Inc...
0
8
Field
ISB
Reset
At reset, bits 0–8 take the values of CSA[0:8]; the default
setting is 1111_1101_0
R/W
RW
9
11
12
15
CS0 CS1 CS2
X
X
X
–
R
Figure 1-2. Internal Memory Map Register (IMMR)
Table 1-2. IMMR Field Description
Bits
Field
Description
0-8
ISB
Internal space base. Defines the base address of the internal memory space. The value of
ISB is configured at reset to one of 32 addresses; it can then be changed to any value by the
software. The default is 0xFD, which maps to address 0xFDx0_0000.
As soon as ISB is written with a new base address, the IMMR base address is relocated
according to the just written ISB. ISB can be configured to one of several possible addresses
at reset to enable the configuration of multiple-MC92460 systems.
9-11
CS[0:2]
12-15
–
Chip select status. These bits indicate the state of the CS[0:2] signals at reset.
Reserved
1.3.2 Process Revision Register (PRR)
The process revision register (PRR) holds the code that identifies the revision number of
the MC92560.
0
15
Field
ID
Reset
0000_0000_0000_0000
R/W
R
16
31
Field
ID
Reset
0000_0000_0000_0010
R/W
R
Figure 1-3. Process Revision Register (PRR)
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IEEE1149.1 (JTAG) Interface
Table 1-3. PRR Field Description
Bits
Field
0-
ID
Description
The revision number
1.4 IEEE1149.1 (JTAG) Interface
MC92460 supports the IEEE1149.1 standard for facilitating board test and chip debug. The
IEEE1149.1 test interface is used for boundary-scan testing.
Freescale Semiconductor, Inc...
The JTAG user code is 0000_0010_1000_0000_1101_0000_0001_1101 (MSB to LSB).
1.5 Configurations of MC92460 with Compliant
Devices
The following figures demonstrate how the MC92460 connects with 60x compliant
devices.
1.5.1 MPC8260 with MC92460 Slaves
Figure 1-4 shows the configuration of an MPC8260 operating in 60x compatible bus mode
with arbitration being done by the MPC8260. MC92460 #0 and MC92460 #1 are both set
in slave mode and BR, BG, and DBG of the MC92460’s slave #0 and slave #1 are
connected in cascade. MC92460 slave #0’s BR, BG, and DBG, for example, are connected
to MPC8260’s BR, BG, and DBG. And slave #1’s BR, BG, and DBGs are connected to
slave #0’s SBR, SBG, and SDBG. If additional slaves are added, their BR, BG, and DBG
will be connected to the SBR, SBG, and SDBG of the slave before them. Note that this
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Configurations of MC92460 with Compliant Devices
configuration requires a 4-input AND gate off chip.
MPC8260
CS
SDRAS
SDCAS
SDWE
SDAMUX
ALE
Freescale Semiconductor, Inc...
ABB
TEA
DBB
ARTRY
AACK
TC[0:1]
A[0:31
D[0:63]
TT[0:4]
TS
TBST
TA
TSIZ[1:3]
DBG
BR
BG
IRQ1
PSDVAL
TSIZ0
CPU DBG
EXT_DBG2
EXT_DBG3
SDRAM
Multiplexer
Latch
MC92460
#0
(Slave)
MC92460
#1
(Slave)
ABB
TEA
DRTRY
DBB
ARTRY
AACK
TC[0:1]
A[0:31
D[0:63]
TT[0:4]
TS
TBST
TA
TSIZ[0:2]
DBG SDBG
BR
SBR
BG
SBG
INT
SIRQ
G_DBG
ABB
TEA
DRTRY
DBB
ARTRY
AACK
TC[0:1]
A[0:31
D[0:63]
TT[0:4]
TS
TBST
TA
TSIZ[0:2]
DBG SDBG
BR
SBR
BG
SBG
INT
SIRQ
G_DBG
MODE
CS0
CS1
CS2
AMODE
SMODE0
SMODE1
MODE
CS0
CS1
CS2
AMODE
SMODE0
SMODE1
Rx/Tx
Rx/Tx
Figure 1-4. MPC8260 and MC92460 System Using MPC8260 Arbiter
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Configurations of MC92460 with Compliant Devices
1.5.2 MPC8260 with MC92460 Master and MC92460 Slave
Figure 1-5 shows the configuration with the MPC8260 operating in 60x compatible bus
mode and external arbitration mode. The MC92460 can support two bus masters. The two
MC92460 devices are connected to a 60x bus with the MC92460 #0 in master mode and
doing the arbitration, and #1 set in slave mode. The SDRAM bank is controlled by an
SDRAM controller on the MPC8260.
.
MPC8260
Freescale Semiconductor, Inc...
CS
SDRAS
SDCAS
SDWE
SDAMUX
ALE
ABB
TEA
DBB
ARTRY
AACK
TC[0:1]
A[0:31
D[0:63]
TT[0:4]
TS
TBST
TA
TSIZ[1:3]
DBG
BR
BG
IRQ1
PSDVAL
TSIZ0
SDRAM
Multiplexer
Latch
MC92460
#0
(Slave)
MC92460
#1
(Slave)
ABB
TEA
DRTRY
DBB
ARTRY
AACK
TC[0:1]
A[0:31
D[0:63]
TT[0:4]
TS
TBST
TA
TSIZ[0:2]
DBG SDBG
BR
SBR
BG
SBG
INT
SIRQ
G_DBG
ABB
TEA
DRTRY
DBB
ARTRY
AACK
TC[0:1]
A[0:31
D[0:63]
TT[0:4]
TS
TBST
TA
TSIZ[0:2]
DBG SDBG
BR
SBR
BG
SBG
INT
SIRQ
G_DBG
MODE
CS0
CS1
CS2
AMODE
SMODE0
SMODE1
MODE
CS0
CS1
CS2
AMODE
SMODE0
SMODE1
Rx/Tx
Rx/Tx
Figure 1-5. MPC8260 and MC92460 System Using MC92460#0 As Arbiter
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Configurations of MC92460 with Compliant Devices
1.5.3 MPC603e and MPC106 with MC92460s
Freescale Semiconductor, Inc...
Figure 1-6 shows the configuration of the MPC603e and the MPC106 with MC92460s. The
MPC106 can handle four bus masters. In this configuration the MPC603e and the
MC92460 #0 are in bus master mode, and the arbitration is done by the MPC106. MC92460
#1 is a slave connected to MC92460 #0 in cascade. The LBCLAIM signal is enabled by
setting the PICRL1[CF_LBA_EN] bit of the MPC106.
Chapter 1. Overview
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Configurations of MC92460 with Compliant Devices
Note that this configuration requires one 2-input AND gate and one 5-input AND gate off
chip.
Freescale Semiconductor, Inc...
MPC603e
ABB
TEA
DRTRY
DBB
ARTRY
AACK
TC[0:1]
A[0:31
D[0:63]
TT[0:4]
TS
TBST
TA
TSIZ[1:2]
DBG
BR
BG
MPC106
TEA
ARTRY
AACK
A[0:31
D[0:63]
TT[0:4]
TS
TBST
TA
TSIZ[1:2]
DBG0 DBG1
BR0
BR1
BG0
BG1
DBG2
BR2
BG2
DBGL2
DBGLB
LBCLAIM
INT
MC92460
#0
MC92460
#1
ABB
TEA
DRTRY
DBB
ARTRY
AACK
TC[0:1]
A[0:31
D[0:63]
TT[0:4]
TS
TBST
TA
TSIZ[0:2]
DBG SDBG
BR
SBR
BG
SBG
G_DBG
ABB
TEA
DRTRY
DBB
ARTRY
AACK
TC[0:1]
A[0:31
D[0:63]
TT[0:4]
TS
TBST
TA
TSIZ[0:2]
SDBG
SBR
SBG
G_DBG
MODE
CS0
CS1
CS2
AMODE
SMODE0
SMODE1
MODE
CS0
CS1
CS2
AMODE
SMODE0
SMODE1
LBCLAIM
INT
SIRQ
INT
SIRQ
Rx/Tx
LBCLAIM
DBG
BR
BG
Rx/Tx
Figure 1-6. MPC603e, MPC106, and MC92460 System
MC92460 Multichannel HDLC User’s Manual
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Chapter 2
Signals
Freescale Semiconductor, Inc...
This chapter describes the MC92460 signals.
2.1 Signal Groups
Figure 2-1 shows the MC92460 external signals grouped by function.
RxCK[0:39]
40
TxCK[0:39]
40
RxSD[0:39]
40
TxSD[0:39]
40
HRESET
POR
SYSCLK
EXCLK
PLL1O
PLL2O
1
1
1
1
1
1
INT
BTO
1
1
TEST[0:3]
CS[0:2]
PCMD
MODE
SMODE[0:1]
AMODE
CSA[0:8]
4
3
1
1
2
1
9
ATPG
SEN
scan_out [a–l]
scan_in [j–k]
1
12
2
Slave
SBR
SBG
SDBG
SIRQ
1
1
1
1
HDLC
Reset and
Clock
Interrupt
Config
MC92460
1
1
1
1
32
4
1
5
1
3
1
1
1
1
2
1
1
1
1
1
32
32
8
1
1
1
1
1
BR
BG
ABB
TS
A[0:31]
AP[0:3]
APE
TT[0:4]
TBST
TSIZ[0:2]
GBL
CI
WT
G_DBG
TC[0:1]
AACK
ARTRY
DBG
DBWO
DBB
DH[0:31]
DL[0:31]
DP[0:7]
DPE
DBDIS
TA
DRTRY
TEA
1
LBCLAIM
1
1
1
1
1
TMS
TCK
TDI
TDO
TRST
Figure 2-1. MC92460 External Signals
Chapter 2. Signals
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60x Bus
Interface
JTAG
Freescale Semiconductor, Inc.
Signal Descriptions
2.2 Signal Descriptions
The MC92460 system bus, shown in Table 2-1, consists of all the signals that interface with
the external bus. Many of these signals perform different functions, depending on how the
user assigns them.
Table 2-1. Signal Descriptions
Signal
Description
I/O
Type
mA
BR
60x bus request—This signal is an output when an
external arbiter is used and an input when an internal
main arbiter is used. As an output, the MC92460
asserts BR to request ownership of the 60x bus in
slave mode. As an input, an external master should
assert BR to request 60x bus ownership from the
internal arbiter.
Input/
output
Three-state
10
BG
60x bus grant—This is an output signal when an
internal main arbiter is used and an input when an
external arbiter is used. As an output the MC92460
asserts BG to grant 60x bus ownership to an external
bus master. As an input the external arbiter should
assert BG to grant 60x bus ownership to the
MC92460.
Output/
input
Three-state
10
ABB
60x address bus busy—As an output the MC92460
asserts this signal for the duration of the address bus
tenure. Following an AACK, which terminates the
address bus tenure, the MC92460 negates ABB for a
fraction of a bus cycle and then stops driving this
signal. As an input, the MC92460 will not assume 60x
bus ownership as long as it senses this signal is
asserted by an external 60x bus master.
Input/
output
Three-state
10
TS
60x bus transfer start—Assertion of this signal
indicates the beginning of a new address bus tenure.
The MC92460 asserts TS when the DMA internal 60x
bus master begins an address tenure. When the
MC92460 senses TS being asserted by an external
60x bus master, it will respond to the address bus
tenure as required.
Input/
output
Three-state
10
A[0-31]
60x address bus—When the MC92460 is in external
master bus mode, these signals function as the 60x
address bus. The MC92460 drives the address of its
internal 60x bus masters and respond to addresses
generated by external 60x bus masters. When the
MC92460 is in internal master bus mode, A[0-31] are
used as address lines connected to memory devices
and controlled by the memory controller.
Input/
output
Three-state
10
AP[0-3]
Address parity —The 60x master that drives the
address bus also drives the address parity signals.
The value driven on the address parity signal should
give odd parity (odd number of bits) on the group of
signals that includes address parity 0 and A[0-7],
AP1 A[8-15], AP2 A[16-23], AP3 A[24-31]
Input/
output
Three-state
10
Freescale Semiconductor, Inc...
60x Bus Interface Signals
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Freescale Semiconductor, Inc.
Signal Descriptions
Table 2-1. Signal Descriptions (Continued)
Signal
I/O
Type
mA
Address parity error—This output signal will be
asserted when the MC92460 detects wrong parity
driven on its address parity signals by an external
master.
Output/
Input
Three-state
10
TT[0-4]
60x bus transfer type—The 60x bus master drives
TT[0-4] during the address tenure to specify the type
of the transaction.
Input/
output
Three-state
10
TBST
60x bus transfer burst—The 60x bus master asserts
TBST to indicate that the current transaction is a
burst transaction (transfers 4 double words).
Input/
output
Three-state
10
TSIZ[0-2]
60x transfer size—The 60x bus master drives these
signals with a value indicating the amount of bytes
transferred in the current transaction.
Input/
output
Three-state
10
AACK
60x address acknowledge—A 60x bus slave asserts
AACK to indicate that it identified the address tenure.
Assertion of this signal terminates the address
tenure. Negation of AACK must occur one bus clock
cycle after it is asserted.
Output/
input
Three-state
10
ARTRY
60x address retry—Assertion of ARTRY indicates
that the bus transaction should be retried by the 60x
bus master. The MC92460 never asserts this signal.
Input/
output
Three-state
10
DBG
60x data bus grant— In master mode the MC92460
asserts DBG to grant 60x data bus ownership to an
external bus master. In slave mode, DBG is a data
grant input signal. Note: see AMODE.
Output/
Input
Three-state
10
DBB
60x data bus busy—As an output the MC92460
asserts DBB for the duration of the data bus tenure.
Following a TA, which terminates the data bus tenure,
the MC92460 negates DBB for a fraction of a bus
cycle and then stops driving this signal. As an input,
the MC92460 does not assume 60x data bus
ownership as long as it senses DBB asserted by an
external 60x bus master. Note: see AMODE.
Input/
output
Three-state
10
DH[0-31]
DL[0-31]
60x data bus—These are input/output signals. In
write transactions, the 60x bus master drives the valid
data on this bus. In read transactions, the 60x slave
drives the valid data on this bus.
Input/
output
Three-state
10
DP[0-7]
60x data parity—(Input/output)The 60x agent that
drives the data bus drives also the data parity signals.
The value driven on the data parity signals should
give odd parity (odd number of bits) on the group of
signals that includes data parity 0 and D[0–7], 1 and
D[8-15], 2 and D[16-23], 3 and D[24-31], 4 and
D[32-39], 5 and D[40-47], 6 and D[48-55], 7 and
D[56-63].
Input/
output
Three-state
10
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APE
Description
Chapter 2. Signals
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PU/PD
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Signal Descriptions
Freescale Semiconductor, Inc...
Table 2-1. Signal Descriptions (Continued)
Signal
Description
I/O
Type
mA
TA
Transfer acknowledge—Indicates that a 60x data
beat is valid on the data bus. For 60x single beat
transfers, assertion of this signal indicates the
termination of the transfer. For 60x burst transfers, TA
is asserted four times to indicate the transfer of four
data beats with the last assertion indicating the
termination of the burst transfer. Negation must occur
after the one and half bus clock cycle after assertion
of TA.
Output/
input
Three-state
10
TEA
Transfer error acknowledge—Assertion of this signal
indicates a bus error. Any 60x masters within the
MC92460 monitor the state of this signal. The
MC92460’s internal bus monitor may assert this
signal in case it identifies a hung 60x bus transfer.
Input/
output
Three-state
10
GBL
Global—When an MC92460 master within the chip
initiates a bus transaction, it drives this signal.
Assertion of this signal indicates that the transfer is
global and it should be snooped by caches in the
system.
Output/
Input
Open Drain
10
CI
Cache inhibit—Used for L2 cache control. For each
MC92460 60x transaction initiated in the core, the
state of this signal indicates if this transaction should
be cached. Assertion of the CI signal indicates that
the transaction should not be cached. When the
MC92460 is in master mode, it always asserts this
signal.
Output
Open Drain
10
WT
Write-through—Used for L2 cache control. For each
core-initiated MC92460 60x transaction, the state of
this signal indicates if the transaction should be
cached using write-through or copy-back mode.
Assertion of WT indicates that the transaction should
be cached using the write- through mode. When a
MC92460 is in master mode, MC92460 always
negates this signal.
Output
Open Drain
10
G_DBG
Global DBG input/output
If MODE is 1, G_DBG becomes an input signal. One
DBG is ANDed with another DBG.
If MODE is 0, this signal becomes an output signal.
All DBGs are ANDed signal outputs.
Input/
Output
LBCLAIM
LBCLAIM output—Used with the MPC106 and
MPC107, this signal connects to the MPC106 &
MPC107 LBCLAIM input, and drives SMODE0 input
high.
Input/
Output
Three-state
10
Transfer Code—The transfer code output signals
supply information that can be useful for debug
purposes for each of the MC92460’s initiated bus
transactions.
Input/
Output
Three-state
10
TC[0-1]
5
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PU/PD
U1001
U1001
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Signal Descriptions
Table 2-1. Signal Descriptions (Continued)
Signal
Description
I/O
Type
mA
DBWO
Data bus write only—The processor can run the data
bus tenure for an outstanding write address even if a
read address is pipelined before the write address. If
write data is not available, the processor performs the
first pending read transfer. Hiz output only..
Input/
Output
Three-state
10
Data parity error—The processor detects incorrect
data bus parity on incoming read data.
Output/
Input
Three-state
10
DBDIS
Data bus disable—For a write transaction, the
processor must release the data bus and DP[07] to
high impedance in the next cycle. The data tenure
remains active, DBB remains driven, and the transfer
termination signals are still monitored by the
processor. The DBDIS signal is ignored for reads.
Input/
Output
Three-state
10
DRTRY
Data retry—The master must invalidate the data from
the previous read operation. DRTRY is ignored for
write transactions and is not defined for direct-store
transfers.
Output/
input
Three-state
10
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DPE
PU/PD
JTAG
TMS
JTAG Test Mode Status
Input
TCK
JTAG Test Clock
Input
TDI
JTAG Test Data Input
Input
TDO
JTAG Test Data Output
TRST
JTAG Test Reset
Output
U1001
U1001
Three-state
5
U1001
Input
HDLC Channels
RxCK[0-39]
Receive Clock
Input/
Output
Three-state
5
TxCK[0-39]
Transmit Clock
Input/
Output
Three-state
5
RxSD[0-39]
Receive Serial Data Input
Input/
Output
Three-state
5
TxSD[0-39]
Transmit Serial Data Output
Output/
Input
Three-state
5
INT
Interrupt output for level interrupt
Output
BTO
Bus time out; When TA does not assert within a 32
clock cycle, BTO goes high.
Input/
Output
Three-state
10
SBR
Bus request from slave device
Input/
Output
Three-state
5
SBG
Bus grant to slave device
Output
5
SDBG
Data bus grant to slave device
Output
5
SIRQ
Slave interrupt request input
Input/
Output
Interrupt
10
Slave
Three-state
Chapter 2. Signals
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5
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Signal Descriptions
Table 2-1. Signal Descriptions (Continued)
Signal
Description
I/O
Function test select signal. This is always set to 1010.
Input
Type
mA
PU/PD
Configuration
Freescale Semiconductor, Inc...
TEST[0-3]
CS[0-2]
Chip select signal
Input/
Output
5
CSA[0–8]
Chip select signal
Input
5
D1002=
CSA6
CSA8
U1001=
CSA[0:5]
CSA7
MODE
Select master or slave for the MC92460: Master
mode = 0; Slave mode = 1
Input/
Output
5
PCMD
CPU’s PLL configure mode. Low input at bus: core =
1:1, High input at other bus clocking.
Input/
Output
5
SMODE0
System Mode0—When the MC92460 is to be used
with the MPC106, set SMODE0 high ( = 1)
When the MC92460 is to be used with the MPC8260,
set SMODE0 low ( = 0)
Input
U1001
SMODE1
System Mode1—Not used: SMODE1 is connected to
VDD
Input
U1001
AMODE
Arbiter Mode- Select fast arbitration mode(AMODE =
1), or clocked arbitration mode(AMODE = 0).
• When AMODE is 0 or 1, so long as MODE is 1,
DBG is an input.
• When AMODE is 0 or 1, MODE is 0, and DBB is
negated, DBG will be asserted at the next cycle
of TS assertion.
• But when AMODE is 0, MODE is 0, and DBB is
asserted, DBG is asserted as soon as DBB is
negated
• And when AMODE is 1, MODE is 0, and DBB is
asserted, DBG is asserted one cycle after DBB is
negated
Input
D1002
Hard reset—When asserted, this line causes the
MC92460 to enter a hard reset state.
Input
Power on reset
Input
Clock in—This is the primary clock input.
Input
EXCLK
External baud rate clock input
Input
PLL1O
VCO1 output for test
Output
Analog
PLL2O
VCO2 output for test
Output
Analog
Reset and Clock
HRESET
POR
SYSCLK
Schmitt
ATPG (Scan test)
SEN
scan_in[j-k]
Scan test enable
• Low = scan test mode
• High = normal mode
Input
D1002
Scan mode test input signals
Input
D1002
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Signal Descriptions
Table 2-1. Signal Descriptions (Continued)
Signal
scan_out[a-l]
Description
Scan mode test output signals
I/O
Output
/Input
Power
1
GND for PLL1
ACoreVdd1
VDD for PLL1
ACoreGnd2
GND for PLL2
ACoreVdd2
VDD for PLL2
U100: internal pull-up 100K ohms
D100: internal pull-down 100K ohms
Freescale Semiconductor, Inc...
2
ACoreGnd1
Chapter 2. Signals
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Type
mA
PU/PD
5
D1002
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Freescale Semiconductor, Inc...
Signal Descriptions
MC92460 Multichannel HDLC User’s Manual
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Chapter 3
System Control Unit
The system control unit (SCU) of the MC92460 consists of several functions that control
internal memory, the high-level data link controllers (HDLCs), and the external system bus.
Key features of the SCU include the following:
•
•
•
•
System configuration and protection
Arbitration of the internal memory (SRAM) access between the HDLCs and the
external system bus
Flexible, high-performance memory controller arbitration of the 60x bus data
(coming through the bus interface) and the HDLC transmit and receive data to the
buffers
Storage of HDLC channel data in buffers by referencing 4096 buffer descriptors
(2048 TxBDs and 2048 RxBDs) that reside in dual-port RAM. Refer to Section 4.4,
“HDLC Buffer Descriptors (BDs) and Buffers.”
Figure 3-1 shows the SCU block diagram.
HDLC_Rx Control
RxBD Control
Main
Control
Memory
Controller
TxBD Control
HDLC_Tx Control
Figure 3-1. SCU Block Diagram
Chapter 3. System Control Unit
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SRAM
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SCU Data Processing
3.1 SCU Data Processing
Following are the data transmit and receive processes of the MC92460.
3.1.1 External Memory Receive
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When data arrives, the SCU performs required processing on the data and moves resultant
data to the buffer pointed to by the first BD; it continues until the buffer is full or an event,
such as an error or end-of-frame detection, occurs. The buffer is then closed; subsequent
data uses the next BD.
On the other hand, if the SCU tries to move data to a buffer that is not empty (E = 0), the
buffer will report a busy error. The SCU will not move from this current BD until E is set
to 1 (empty) by the core. The SCU waits until the core completes processing the BD. After
a buffer descriptor is used (is full), the SCU clears E, and the BD is not reused until it has
been processed by the core. However, in continuous mode (CM), E remains set to 1. When
the SCU discovers a buffer descriptor’s wrap (W) bit set (indicating it is the last BD in the
circular BD table), it returns to the beginning of the table when it is time to move to the next
buffer.
If BDs point to external memory, BDs access the 60x bus with burst beat access only. So a
low-order buffer pointer must be oriented on an address that is a multiple of 8. Buffer
descriptors transfer 32 bytes of data every time.
Figure 3-2 shows the sequence of data received with RxBD. In this case, the RxBD points
to external memory.
1. Assuming the RxBD is empty, the core sets E = 1.
2. The SCU checks the enable bit of the RxBD to make sure the buffer descriptor is
empty.
3. The core (application program) sets the enable bit.
4. Data is received by the HDLC .
5. Data is moved to the Rx FIFO.
6. A data transfer request from the arbiter is received by the SCU.
7. The DMA reads the Rx FIFO.
8. Data is transferred from the Rx FIFO to memory.
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SCU Data Processing
MPC8260
Application
program
External Memory
60x bus
1
Set E-bit
Bus Interface
RxBD
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Receive data is transferred
FIFO to external memory
8
DMA & Arbiter
6
Data transfer request
E-Bit
Dual-Port RAM
2
7
DMA read FIFO
Check E-bit
SCU
32Byte FIFO
3
set Enable
5
HDLC
Receive data
4
RxSD
Figure 3-2. External Memory Receive Sequence with RxBD
Chapter 3. System Control Unit
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SCU Data Processing
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3.1.2 External Memory Transmit
When the core sets the R bit to enable the transmit side of an HDLC, the SCU starts with
the first BD in that TxBD table. Once the SCU detects that the R bit is set in the TxBD, it
starts processing the buffer. The SCU detects that the BD is ready when it polls the R bit or
when the user writes to the TODR. After data from the BD is put in the Tx FIFO, if
necessary the SCU waits for the next descriptor’s R bit to be set before proceeding. Thus,
the SCU does no look-ahead descriptor processing and does not skip BDs that are not ready.
When the SCU sees a buffer descriptor’s W bit set, it returns to the start of the BD table
after this last BD of the table is processed. The SCU clears R (not ready) after using a
TxBD, which keeps it from being retransmitted before it is confirmed by the core. However,
some protocols support a continuous mode (CM), for which R is not cleared (signifying that
it is always ready).
Figure 3-3 shows the sequence of data transmitted with TxBD. TxBD points to external
memory.
MPC8260
Application
program
External Memory
5
60x bus
Transmit data is transferred from
external memory to FIFO
1
Set R-bit
Bus Interface
TxBD
DMA & Arbiter
Dual-Port RAM
2
6
DMA write FIFO
4
Data transfer request
R-Bit
Check R-bit
SCU
32Byte FIFO
3 Enable
set
HDLC
7
Transmit data
8
TxSD
Figure 3-3. External Memory Transmit Sequence with TxBD
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SCU Data Processing
3.1.3 SRAM Transmission Using MC92460
Shown in Figure 3-4 is the data transmission sequence from external memory to internal
SRAM of the MC92460 using a DMA write, and from there to the HDLC. The sequence
of RxBDs is the same as the sequence of TxBDs.
MPC8260
Application
program
External Memory
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60x bus
1 DMA
Start bit set
4
Set R-bit
Bus Interface
2
Transmit data is transferred from
external memory to internal SRAM
DMA & Arbiter
3 DMA writes to buffer
TxBD
SRAM
64bits x 5Kw
R-Bit
Dual-Port RAM
5
Check R-bit
Transmit buffer
SCU
6
set Enable
7
Transmit data
HDLC
8
TxSD
Figure 3-4. Internal SRAM Transmit Sequence Using MC92460 DMA
Chapter 3. System Control Unit
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SCU Data Processing
3.1.4 SRAM Transmission Using MPC8260
Shown in Figure 3-5 is the data transmission sequence from external memory to internal
SRAM arbitrated by the MPC8260. The sequence of RxBDs is the same as the sequence of
TxBDs.
MPC8260
Application
program
Memory
60x bus
Freescale Semiconductor, Inc...
2
Set R-bit
Transmit data is transferred from
external memory to
internal SRAM with MPC8260
1
Bus Interface
TxBD
SRAM
64bits x 5Kw
R-Bit
Dual-Port RAM
3 Check R-bit
Transmit buffer
SCU
4
set Enable
5
Transmit data
HDLC
6
TxSD
Figure 3-5. Internal SRAM Transmit Sequence Using MPC8260
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Interrupt Status
3.2 Interrupt Status
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Follow these steps to handle an HDLC interrupt:
1. When an interrupt occurs, read the event register (ER) of the HDLC to determine the
interrupt sources and clear those ER bits (in most cases).
2. Process the TxBDs to reuse them if ER[TXB] or ER[TXE] = 1. If the transmit speed
is fast or the interrupt delay is long, the HDLC may have sent more than one Tx BD.
Thus, it is important to check more than one TxBD during interrupt handling. A
common practice is to process all TxBDs in the handler until one is found with its R
bit set.
3. Extract data from the RxBD if ER[RX], ER[RXB], or ER[RXF] is set. As with
transmit buffers, if the receive speed is fast or the interrupt delay is long, the HDLC
may have received more than one buffer and the handler should check more than one
RxBD. A common practice is to process all RxBDs in the interrupt handler until one
is found with its E bit set. This 40-bit, read-only INT1 and INT2 register allows
monitoring of the real-time status.
NOTE:
The MC92460 supports level interrupts only.
3.2.1 Interrupt Status Register 1 (INTS1)
The INTS1 register is used to report events recognized by the 32 HDLC channels and to
generate interrupts. INTS1 can be read at any time. Bits are cleared by writing a 1 to the ER
of each HDLC; writing zeros does not affect bit values.
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Field HDLC HDLC HDLC HDLC HDLC HDLC HDLC HDLC HDLC HDLC HDLC HDLC HDLC HDLC HDLC HDLC
0
1
2
3
4
5
Reset
6
7
8
9
10
11
12
13
14
15
26
27
28
29
30
31
0000_0000_0000_0000
R/W
R
16
17
18
19
20
21
22
23
24
25
Field HDLC HDLC HDLC HDLC HDLC HDLC HDLC HDLC HDLC HDLC HDLC HDLC HDLC HDLC HDLC HDLC
16
Reset
R/W
17
18
19
20
21
22
23
24
25
26
27
00000_0000_0000_0000
R
Figure 3-6. Interrupt Status Register (INTS1)
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28
29
30
31
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HDLC Channels
Table 3-1. Interrupt Status Register Field Description
Field
Description
HDLC[0-31]
HDLCx generate interrupt request
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3.2.2 Interrupt Status Register 2 (INTS2)
The INTS2 register is used to report events recognized by the 8 HDLC channels, the
DMASR, SIRQ, and to generate interrupts. INTS2 can be read at any time. Bits 0-7 of
INTS2 are cleared by writing a one to the ER of each HDLC. Bit 15 is cleared by writing
ones to DMASR, bit 16 is cleared by ones to the ER of all HDLCs, and bit 17 is cleared by
writing ones to the ER of all HDLCs and to the DMASR of all slave MC92460s; writing
zeros does not affect bit values.
0
1
2
3
4
5
6
7
8
Field HDLC32 HDLC33 HDLC34 HDLC35 HDLC36 HDLC37 HDLC38 HDLC39
Reset
—
15
DMA
0000_0000_0000_0000
R/W
Field
14
R
16
17
INT
EXT
18
31
—
Reset
0000_0000_0000_0000
R/W
R
Figure 3-7. Interrupt Status Register 2 (INTS2)
Table 3-2. Interrupt Status Register 2 Descriptions
Bits
Field
Description
0–7
HDLC [32-39]
8–14
—
15
DMA
16
INT
HDLC0 to HDLC39 or DMA generate interrupt request
17
EXT
Slave devices drive SIRQ signal
18–31
—
HDLCx generate interrupt request
Reserved
DMA generate interrupt request
Reserved
3.3 HDLC Channels
The SCU can support a maximum of 40 HDLC channels at the low baud rate. All HDLC
channels can be programmed by the SCU.
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RxBD and TxBD Table Base Addresses
3.3.1 Maximum HDLC Channel Register (MMCR)
The MMCR sets the maximum number of HDLC channels that can be programmed. The
number can be up to 40.
The configuration in Table 3-8 should be chosen when 40 HDLC channels are needed.
MMCR does not support dynamic reassigns, so before changing the MMCR, all HDLC
channels should be disabled by setting MRA[ENT] and MRA[ENR] to zero.
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0
1
2
7
8
15
Field
—
MHC
—
Reset
00
10_1000
0000_0000
R/W
R
R/W
R
Figure 3-8. Max HDLC Channel Register (MMCR)
Table 3-3. Maximum HDLC Channel Register Description
Bits
Field
0–1
—
2–7
MHC
8–15
—
Description
Reserved. Writing a 1 to this register can cause boundedly undefined results.
Program Max HDLC channel.
Example1: 0x28 SCU supports HDLC0 to HDLC39
Example2: 0x08 SCU supports HDLC0 to HDLC7
Reserved. Writing a 1 to this register can cause boundedly undefined results.
3.4 RxBD and TxBD Table Base Addresses
Each of the 40 channels has an RxBD and TxBD table in dual-port RAM that holds the
buffer descriptors for that channel. The default number of BDs for each channel is 64, of
which 32 are RxBDs and 32 are TxBDs.The base addresses of these RxBD and TxBD
tables is defined by the RBASE and TBASE registers.
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RxBD and TxBD Table Base Addresses
3.4.1 RxBD Table Base Address (RBASE)
The RBASE register defines the base address of each channel’s RxBD table. RBASE
should be 8 byte aligned.
0
13
15
Field
—
Upper value
Reset
0000_0000_0000_00
Table 3-4
R
R/W
R/W
16
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14
28
29
31
Field
Lower value
—
Reset
Table 3-4
000
R/W
R
R/W
Figure 3-9. RBASE Register
The default base addresses of the RxBD table shown in Table 3-4 allocate 32 buffer
descriptors for each of the 40 channels. Dual-port RAM, however, holds up to 2048 Rx
buffer descriptors that can be distributed among the 40 RxBD tables. Thus it is possible to
place all Rx buffer descriptors in one RxBD table and none in the other tables.
To reconfigure the number of buffer descriptors in each channel, change the RBASE
addresses in parameter RAM.
Table 3-4. Default Base Addresses for RxBD Table
Name
Address
Name
Address
Name
Address
Name
Address
RBASE0
0x10000
RBASE1
0x10100
RBASE2
0x10200
RBASE3
0x10300
RBASE4
0x10400
RBASE5
0x10500
RBASE6
0x10600
RBASE7
0x10700
RBASE8
0x10800
RBASE9
0x10900
RBASE10
0x10a00
RBASE11
0x10b00
RBASE12
0x10c00
RBASE13
0x10d00
RBASE14
0x10e00
RBASE15
0x10f00
RBASE16
0x11000
RBASE17
0x11100
RBASE18
0x11200
RBASE19
0x11300
RBASE20
0x11400
RBASE21
0x11500
RBASE22
0x11600
RBASE23
0x11700
RBASE24
0x11800
RBASE25
0x11900
RBASE26
0x11a00
RBASE27
0x11b00
RBASE28
0x11c00
RBASE29
0x11d00
RBASE30
0x11e00
RBASE31
0x11f00
RBASE32
0x12000
RBASE33
0x12100
RBASE34
0x12200
RBASE35
0x12300
RBASE36
0x12400
RBASE37
0x12500
RBASE38
0x12600
RBASE39
0x12700
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Communication Buffer (SRAM)
3.4.2 TxBD Table Base Address (TBASE)
The TBASE register defines the base address of each channel’s TxBD table. TBASE should
be 8 byte aligned.
0
13
15
Field
—
Upper value
Reset
0000_0000_0000_00
Table 3-5
R
R/W
R/W
16
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14
28
29
31
Field
Lower value
—
Reset
Table 3-5
000
R/W
R
R/W
Figure 3-10. TBASE Register
The default base addresses of the TxBD table shown in Table 3-5 allocate 32 buffer
descriptors for each of the 40 channels. Dual-port RAM, however, holds up to 2048 Tx
buffer descriptors that can be distributed among the 40 TxBD tables. Thus it is possible to
place all Tx buffer descriptors in one TxBD table and none in the other tables.
To reconfigure the number of buffer descriptors in each channel, change the TBASE
addresses in parameter RAM.
Table 3-5. Default Base Addresses for TxBD Table
Name
Address
Name
Address
Name
Address
Name
Address
TBASE0
0x1a000
TBASE1
0x1a100
TBASE2
0x1a200
TBASE3
0x1a300
TBASE4
0x1a400
TBASE5
0x1a500
TBASE6
0x1a600
TBASE7
0x1a700
TBASE8
0x1a800
TBASE9
0x1a900
TBASE10
0x1aa00
TBASE11
0x1ab00
TBASE12
0x1ac00
TBASE13
0x1ad00
TBASE14
0x1ae000
TBASE15
0x1af00
TBASE16
0x1b000
TBASE17
0x1b100
TBASE18
0x1b200
TBASE19
0x1b300
TBASE20
0x1b400
TBASE21
0x1b500
TBASE22
0x1b600
TBASE23
0x1b700
TBASE24
0x1b800
TBASE25
0x1b900
TBASE26
0x1ba00
TBASE27
0x1bb00
TBASE28
0x1bc00
TBASE29
0x1bd00
TBASE30
0x1be00
TBASE31
0x1bf00
TBASE32
0x1c000
TBASE33
0x1c100
TBASE34
0x1c200
TBASE35
0x1c300
TBASE36
0x1c400
TBASE37
0x1c500
TBASE38
0x1c600
TBASE39
0x1c700
3.5 Communication Buffer (SRAM)
The MC92460 has a 64-bit X 5 Kword SRAM that can be used to hold the transmit and
receive buffer data pointed to by TxBD and RxBD. The bus master (MPC8260, MPC603e,
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Communication Buffer (SRAM)
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and DMA devices) can be accessed as memory.
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Chapter 4
High-level Data Link Controller (HDLC)
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4.1 Introduction
High-level data link control (HDLC) is one of the most common protocols in the data link
layer, layer 2 of the OSI model. Many other common layer 2 protocols, such as synchronous
data link control (SDLC), link access protocol-balanced (LAPB), and link access protocol
for the D channel (LAPD), are based on HDLC and its framing structure in particular.
Figure 4-2 shows the HDLC frame structure. HDLC uses a zero insertion/deletion process
(bit-stuffing) to ensure that a data bit pattern matching the delimiter flag does not occur in
a field between flags. The HDLC frame is synchronous and relies on the physical layer for
clocking and synchronization of the transmitter/receiver. An address field is needed to carry
the frame’s destination address because the layer 2 frame can be sent over point-to-point
links, broadcast networks, packet-switched, or circuit-switched systems.
An address field is commonly 0, 8, or 16 bits, depending on the data link layer protocol.
SDLC and LAPB use an 8-bit address. LAPD divides its 16-bit address into different fields
to specify various access points within one device. LAPD also defines a broadcast address.
Some HDLC-type protocols permit addressing beyond 16 bits.
The 8- or 16-bit control field provides a flow control number and defines the frame type
(control or data). The exact use and structure of this field depends on the protocol using the
frame. The length of the data in the data field depends on the frame protocol. Layer 3 frames
are carried in this data field.
Error control is implemented by appending a cyclic redundancy check (CRC) to the frame,
which in most protocols is 16 bits long but can be as long as 32 bits. In HDLC, the least
significant bit of each octet is sent first; the most significant bit of the CRC is sent first. In
a nonmultiplexed modem interface, HDLC outputs connect directly to external pins.
An MC92460 HDLC controller consists of separate transmit and receive sections whose
operations are asynchronous with respect to other HDLCs. Independent baud rate
generators allow flexible clocking for each HDLC channel.
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HDLC Features
Figure 4-1 shows a block diagram of a HDLC.
Tx
FIFO
Parallel to
Serial
conversion
Data length
counter
Mux
CRC
ALU
Tx Block
Internal
bus
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HDLC Controller
Rx
FIFO
Serial to
parallel
conversion
Zero
insertion
TxSD
Flag
idle
transmit
Baud Rate
Generator
Data length
counter
Flag
Detector
Address
compare
Abort
Detector
CRC
ALU and
compare
Zero
suppress
TxCK
RxCK
RxSD
64bits
PLLs
Rx Block
Figure 4-1. HDLC Controller Block Diagram
4.2 HDLC Features
The following are features of the HDLC controllers:
•
•
•
•
•
•
•
•
•
•
•
•
Support for a maximum of 66.7 Mbps in each HDLC channel
Flexible buffers with multiple buffers per frame
Separate interrupts for frames and buffers (Rx and Tx)
Received-frames threshold to reduce interrupt overhead
Flag/abort/idle generation and detection
Zero insertion and deletion
16- or 32-bit CRC-CCITT generation and checking
Detection of non-octet aligned frames
Detection of frames that are too long
Programmable flags (0-15) between successive frames
Echo and local loopback mode for testing
Independent baud rate generators providing clocks for the HDLC channels.
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HDLC Channel Frame Transmission
4.3 HDLC Channel Frame Transmission
HDLC protocol uses frames to send data. A frame is a packed bit stream of transmitted data.
The HDLC frame has the following fields, explained in these sections:
•
•
•
•
•
Section 4.3.1, “Flag Sequence Field”
Section 4.3.2, “Address Field”
Section 4.3.3, “Control Field”
Section 4.3.4, “Information Field”
Section 4.3.5, “Frame Check Sequence Field”
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Figure 4-2 shows the HDLC frame structure.
FS (Flag sequence)
A (Address)
C (Control)
8/16
I (Information)
8
FCS (Frame Check Sequence)
8n
FS
16/32
Figure 4-2. HDLC Frame Structure
4.3.1 Flag Sequence Field
All frames start and end with the flag sequence (FS) field that contains the sequence pattern
0x7E (0111_1110). All data stations that are attached to the data link continuously hunt for
this sequence to distinguish the beginning and ending of frames. The flag shown in
Figure 4-3 is used for frame synchronization.
FS
A
C
I
FCS
FS
Figure 4-3. Frame Sequence Flag
A single shared flag is used as both the opening and closing FS fields of a frame, as shown
in Figure 4-4.
FS
A
C
I
FCS
FS
A
C
I
FCS
FS
Figure 4-4. FS Used As Closing and Opening Flag
4.3.2 Address Field
In command frames, the address identifies the data station for which the command is
intended. In response frames, the address identifies the data station from which the response
originated.
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HDLC Channel Frame Transmission
Figure 4-5 shows the address field configuration.
FS
A
C
I
FCS
FS
8/16
Figure 4-5. Address
The address field is 1 or 2 octets wide. Also the internal address register is a prepared16-bit
length for a width of 2 octets. When the field needs only one octet, the HDLC controller
recognizes the 8-bit field by the address mask register.
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Table 4-1. Address Field
1 octet
2 octets
Description
0x00
0x0000
0x1A–0xFE
0x001A–0xFFFE
0xFF
0xFFFF
No-station address (TEST Address)
This value must not be received by any receivers.
Address value.
254 addresses for 1 octet, 65534 addresses for 2 octets
Global address
This value must be received by all receivers.
4.3.3 Control Field
The control field indicates the class of commands or responses to be carried out by the
frame, and contains sequence numbers that specify any sequence that the command must
follow. The control field conveys a command to perform a particular operation to the data
station to which the command is addressed, or conveys a response to such a command from
the addressed data station. The MC92460 should not recognize any data elements in the
control field, as they are defined in the application.
FS
A
C
I
FCS
FS
8
Figure 4-6. Control Field
Table 4-2 shows the three classes of HDLC control frames recognized by the HDLC
controller used in the MC92460.
.
Table 4-2. Control Frame Classes
Control Frame
Class
Description
I
Conveys not only information but also commands to operate transmission.
S
Conveys a command and response to supervise a data link.ApplIcation programs define
the S class.
U
Conveys a command and response for an operation mode setting. In some cases, the U
class has no information field
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HDLC Channel Frame Transmission
4.3.4 Information Field
Information or data can be formatted in any sequence of bits and is stored in the information
field that follows the control field, as seen in Figure 4-7.
FS
A
C
I
FCS
FS
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Figure 4-7. Information Field
In most cases, it will be linked to a convenient character structure (octets, for example) but
if required, it may be an unspecified number of bits and unrelated to a character structure.
For start/stop transmission, eight information bits exist between the start element and the
stop element. If the information field is other than a multiple of 8 bits, the remaining bits
are padded to complete the octet.
Original data
I#0
I#1
pad
I#2
1 octet
Figure 4-8. Padding to Fill Out an Octet
4.3.5 Frame Check Sequence Field
Two CRC-CCITT frame checking sequences are specified, a 16-bit frame checking
sequence and a 32-bit sequence. The generator polynomials for each check sequence are
described below in Figure 4-9.
FS
A
C
I
FCS
FS
Figure 4-9. Frame Check
Table 4-3. CRC Generator Polynomials
Name
Generator Polynomial
CRC-CCITT16
X16+X12+X5+1
CRC-CCITT32
X32+X26+X23+X22+X16+X12+X11+X10+X8+X7+X5+X4+X2+X1+1
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HDLC Buffer Descriptors (BDs) and Buffers
4.4 HDLC Buffer Descriptors (BDs) and Buffers
The system control unit (SCU) stores the data associated with each HDLC channel in
buffers (such as in SRAM), and each buffer is referenced by an 8-byte buffer descriptor
(BD) that can reside anywhere in dual-port RAM. The MC92460 has 4096 BDs (2048
RxBDs and 2048 TxBDs).The total number of BDs is limited only by the size of the
32-Kbyte dual-port RAM. Each 64-bit BD has the following structure:
•
The half word at offset + 0x0 contains status and control bits that control and report
on the data transfer. These bits vary from protocol to protocol. The HDLC updates
the status bits after the buffer is sent or received.
The half word at offset + 0x2 (data length) holds the number of bytes sent or
received.
— For an RxBD, this is the number of bytes the controller writes into the buffer. The
HDLC writes the length after received data is placed into the associated buffer
and the buffer closed.
In frame-based protocols such as is used by the MC92460, this field contains the
total frame length, including CRC bytes. Also, if a received frame’s length,
including CRC, is an exact multiple of MRBLR, the last BD holds no actual data
but does contain the total frame length.
— For a TxBD, this is the number of bytes the controller should send from its buffer.
Normally, this value should be greater than zero. The HDLC never modifies this
field.
The word at offset + 0x4 (buffer pointer) points to the beginning of the buffer in
memory (internal or external). Both Rx and Tx buffer pointers can be even or odd in
external memory. Because Rx and Tx buffers are 32 byte-aligned, the pointers at
offset + 0x4 must be a multiple of 8 (8 byte-aligned).
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•
•
Writes to buffer descriptors should be 32-/64-bit single beat or burst writes. Reads are
described in Section 4.4.2, “Receive Buffer Descriptor (RxBD)” and Section 4.4.3,
“Transmit Buffer Descriptor (TxBD).”
Shown in Figure 4-10, the format of Tx and Rx BDs is the same in each HDLC.
Bit
0
15
Offset + 0
Status and Command
Offset + 2
Data Length
Offset + 4
High-Order Buffer Pointer
Offset + 6
Low-Order Buffer Pointer
Figure 4-10. Buffer Descriptors
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HDLC Buffer Descriptors (BDs) and Buffers
4.4.1 SRAM Buffers
The MC92460’s Rx and Tx buffers are stored in a 64-bit x 4K word SRAM. Both Rx and
Tx buffers are 32-byte aligned.
For frame-oriented protocols, a message can reside in as many buffers as necessary. Each
buffer has a maximum length of 65,535 bytes. The SCU does not assume that all buffers of
a single frame are currently linked to the BD table. The SCU does assume, however, that
the unlinked buffers are provided by the core in time to be sent or received; otherwise, an
error condition reports an underrun when sending and a busy when receiving.
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Figure 4-11 shows the SCU BD table and buffer structure.
External or Internal Memory
Dual-Port RAM
Buffer Descriptors
HDLC Channel x
RxBD table
Status & Command
Buffer Length
Buffer Pointer
HDLC Channel x
TxBD table
Rx Buffer
Buffer Descriptors
Status & Command
Buffer Length
Buffer Pointer
Tx Buffer
Figure 4-11. BD Table and Buffer Memory Structure
In all protocols, BDs can point to buffers in the internal RAM. However, because internal
RAM is used for descriptors, buffers are usually put in external RAM, especially if they are
large.
4.4.2 Receive Buffer Descriptor (RxBD)
Figure 4-12 shows the receive buffer descriptor (RxBD) format.
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HDLC Buffer Descriptors (BDs) and Buffers
BIT
0
1
2
3
4
5
6
7
Offset + 0
E
X
W
I
L
F
CM
9
—
10
11
12
13
14
15
LG
NO
AB
CR
OV
BE
Data length
Offset + 2
Offset + 4
Rx buffer pointer
Offset + 6
Figure 4-12. Receive Buffer Descriptor (RxBD)
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Note that offsets + 0 through + 2 are accessed by half-words, whereas offsets +4 and +6 are
accessed by words and half-words. The data length is not allowed to be zero.
Table 4-4 shows the function of each receive buffer descriptor bit.
Table 4-4. Receive Buffer Descriptor Bit Functions
Bit
Name
Description
0
E
Empty.
0 The buffer is full or reception stopped because of an error. The core can read or write
to any fields of this RxBD. The SCU does not use this BD while E = 0.
1 The buffer is not full. The SCU controls the BD and buffer. The core should not update
the BD.
1
X
External buffer.
0 This RxBD access the internal SRAM
1 This RxBD access the external memory
2
W
Wrap (last BD in the RxBD table).
0 Not the last BD in the table.
1 Last BD in the table. After this buffer is used, the SCU receives incoming data using
the BD pointed to by RBASE. The number of BDs in this table are programmable and
determined only by RxBD[W] and overall space constraints of the dual-port RAM.
3
I
Interrupt.
0 ER[RXB] is not set after this buffer is used; ER[RXF] is unaffected.
1 ER[RXB] or ER[RXF] is set when the HDLC uses this buffer.
4
L
Last buffer in frame.
0 Not the last buffer in frame.
1 Last buffer in frame. Indicates reception of a closing flag or an error, in which case
one or more of the OV, AB, and LG bits are set. The HDLC writes the number of frame
octets to the data length field.
5
F
First in frame.
0 Not the first buffer in a frame.
1 First buffer in a frame.
6
CM
Continuous mode. Note that RxBD[E] is cleared if an error occurs during reception,
regardless of CM.
0 Normal operation.
1 RxBD[E] is not cleared by the HDLC after this BD is closed, allowing the associated
buffer to be overwritten next time the HDLC accesses it
7-9
—
Reserved
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HDLC Buffer Descriptors (BDs) and Buffers
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Table 4-4. Receive Buffer Descriptor Bit Functions (Continued)
Bit
Name
Description
10
LG
Rx frame length violation. Set when a frame larger than the maximum defined for this
channel is recognized. Only the maximum-allowed number of bytes (MFLR) is written to
the buffer. This event is not reported until the buffer is closed, ER[RXF] is set, and the
closing flag is received. The total number of bytes received between flags is still written
to the data length field.
11
NO
Rx non-octet aligned frame. Set when a received frame contains a number of bits not
divisible by eight.
12
AB
Rx abort sequence. Set when at least seven consecutive ones are received during
frame reception.
13
CR
Rx CRC error. Set when a frame contains a CRC error. CRC bytes received are always
written to the Rx buffer.
14
OV
Overrun. Set when a receiver overrun occurs during frame reception.
15
BE
Bus transfer error. Set when a bus transfer error occurs.
4.4.3 Transmit Buffer Descriptor (TxBD)
Figure 4-13 shows the transmit buffer descriptor (TxBD) format.
Bits
0
1
2
3
4
5
6
7
Offset + 0
R
X
W
I
L
TC
CM
13
Reserved
14
15
UN
BE
Data Length
Offset + 2
Offset + 4
Tx Buffer Pointer
Offset + 6
Figure 4-13. Transmit Buffer Descriptor
Offsets + 0 and + 2 are accessed by half-word access, and offsets + 4 and +6 are accessed
through word access. The data length is not allowed to be zero.
Table 4-5 shows the transmit buffer descriptor (Tx BD) bit functions.
Table 4-5. Transmit Buffer Descriptor Bit Functions
Bit
Name
Description
0
R
Ready.
0 The buffer is not ready for transmission. Both the buffer and the BD can be updated. The
SCU clears R after the buffer is sent or an error is encountered.
1 The buffer has not been sent or is being sent and the BD cannot be updated.
1
X
External buffer.
0 This TxBD access the internal SRAM
1 This TxBD access the external memory
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Table 4-5. Transmit Buffer Descriptor Bit Functions (Continued)
Bit
Name
Description
2
W
3
I
Interrupt.
0 No interrupt is generated after this buffer is processed.
1 ER[TXB] or ER[TXE] is set when this buffer is processed, causing interrupts if not
masked.
4
L
Last.
0 Not the last buffer in the frame
1 Last buffer in the frame
5
TC
Tx CRC valid only when TxBD[L]=1. Otherwise, it is ignored.
0 Transmit the closing flag after the last data byte. This setting can be used to send a bad
CRC after the data for testing purposes.
1 Transmit the CRC sequence after the last data byte.
6
CM
Continuous mode.
0 Normal operation.
1 The SCU does not clear TxBD[R] after this BD is closed allowing the buffer to be resent
the next time the SCU accesses this BD. However, TxBD[R] is cleared if an error occurs
during transmission, regardless of CM.
7-13
—
Reserved
14
UN
Underrun. Set after the HDLC sends a buffer and a transmitter underrun occurred.
15
BE
Bus transfer error. Set When a bus transfer error occurs.
Wrap (last BD in TxBD table).
0 Not the last BD in the table.
1 Last BD in the BD table. After this buffer is used, the SCU sends data using the BD
pointed to by TBASE. The number of TxBDs in this table is determined by TxBD[W] and
the space constraints of the dual-port RAM.
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HDLC Buffer Descriptors (BDs) and Buffers
4.4.4 Receiving Using RxBDs
Figure 4-14 shows an example of how RxBDs are used in receiving.
Stored in Rx Buffer
F
A
A
C
I
I
I
I
I
Stored in
Rx Buffer
Idle
I FCS FCS F
F
A
A
C
Abort/Idle
...
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Unexpected abort occurs
before closing flag
Rx BD 0
E
L
F
status
0
0
Address 1
1
Address 2
frame
length
0x0008
Control
pointer
32-bit
buffer pointer
Rx BD 1
Buffer full
Information
5 octets
E
L
F
Information(6)
0
1
0
CRC 1
frame
length
0x000B
CRC 2
pointer
32-bit
buffer pointer
status
Rx BD 2
status
F
AB
Address!
0
1
1
1
Address 2
pointer
32-bit
buffer pointer
status
8 bytes
Empty
L
0x0003
Rx BD 3
Buffer closed
when closing
flag received
E
frame
length
8 bytes
Control
Abort: was
received after
control field
8 bytes
Empty
E
1
frame
length
0xXXXX
pointer
32-bit
buffer pointer
Empty
Buffer still empty
*MRBLR = 8 bytes
Figure 4-14. HDLC Receiving Using RxBDs
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8 bytes
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HDLC Buffer Descriptors (BDs) and Buffers
4.4.5 Transmitting Using TxBDs
Figure 4-15 shows an example of how TxBDs are used in transmitting.
Data sent from Tx Buffer
F
A
A
C
I
I
I
I
I
Data sent from
Tx Buffer
Idle
I FCS FCS F
F
A
A
C
Abort/Idle
...
Unexpected abort occurs
before closing flag
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Tx BD 0
Address 1
R
L
status 1
0
number of
bytes to send
pointer
Tx BD 1
Address 2
0x0008
Control
Read buffer
32-bit
buffer pointer
R
L
status 1
1
number of
bytes to send
8 bytes
Information
5 octets
Information
1 octet
1 byte
0x0001
pointer
32-bit
buffer pointer
Buffer closed
when L (last)
flag received
Tx BD 2
Address 1
R
L
status 1
1
number of
bytes to send
pointer
Address 2
UN
0x0003
32-bit
buffer pointer
3 bytes
Control
Abort:
transmitter
underrun
occurred
Tx BD 3
R
status 0
number of
bytes to send
pointer
Empty
0xXXXX
Buffer still empty
32-bit
buffer pointer
Figure 4-15. HDLC Transmitting Using TxBDs
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HDLC Buffer Descriptors (BDs) and Buffers
4.4.6 HDLC Frame Transmission
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The HDLC transmitter is designed to work with little or no core intervention. Once enabled
by the core, a transmitter starts sending flags or idles as programmed in the HDLC mode
register. The HDLC polls the first BD in the TxBD table. When there is a frame to transmit,
the HDLC fetches the data from memory and starts sending the frame after sending the
minimum number of flags specified between frames. When the end of the current buffer is
reached and TxBD[L] (the last buffer in the frame) is set, the CRC and the closing flag are
appended. The lsb of each octet and the msb of the CRC are sent first.
After a closing flag is sent, the HDLC updates the frame status bits of the BD and clears
TxBD[R] (buffer ready). At the end of the current buffer, if TxBD[L] is not set (multiple
buffers per frame), only TxBD[R] is cleared. Before the HDLC proceeds to the next TxBD
in the table, an interrupt can be issued if TxBD[I] is set. This interrupt programmability
allows the core to intervene after each buffer, after a specific buffer, or after each frame.
4.4.7 HDLC Frame Reception
The HDLC receiver is designed to work with little or no core intervention to perform
address recognition, CRC checking, and maximum frame length checking. Received
frames can be used to implement any HDLC-based protocol. Once enabled by the core, the
receiver waits for an opening flag character. When it detects the first byte of the frame, the
HDLC compares the frame address with four user-programmable, 16-bit address registers
and an address mask. The HDLC compares the received address field with the user-defined
values after masking with the address mask. To detect broadcast (all ones) address frames,
one address register must be written with all ones.
If an address match is detected, the HDLC fetches the next BD and starts transferring the
incoming frame to the buffer if it is empty. When the buffer is full, the HDLC clears
RxBD[E] and generates a maskable interrupt if RxBD[I] is set. If the incoming frame is
larger than the current buffer, the HDLC continues receiving using the next BD in the table.
During reception, the HDLC checks for frames that are too long (using the max frame
length register, MFLR). When the frame ends, the CRC field is checked against the
recalculated value and written to the buffer.
The data length of the last RxBD in the HDLC frame contains the entire frame length. This
also enables software to identify the frames in which maximum frame length violations
occur. The HDLC sets RxBD[L] (last buffer in frame), writes the frame status bits, and
clears RxBD[E]. It then generates a maskable event (ER[RXF]; see Table 4-17) to indicate
a frame was received. The HDLC then waits for a new frame.
Back-to-back frames can be received with only one shared flag between frames. The
received frames threshold parameter (RFTH) can be used to postpone interrupts until a
specified number of frames is received. This function can be combined with a timer to
implement a time-out if fewer than the specified number of threshold frames is received.
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HDLC-Specific Parameter RAM
HDLC mode, or any other synchronous mode, must receive a minimum of eight clocks
after the last bit arrives to account for Rx FIFO delay.
4.5 HDLC-Specific Parameter RAM
The SCU maintains a section of RAM called the parameter RAM, which contains many
parameters for the operation of the HDLC channels. Each channel has 128 bytes of
parameter RAM space whose starting address is an offset of the HDLC base offset address.
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The parameter RAM includes features such as a maximum receive buffer length, CRC
preset and mask, protocol conditions, and so forth, that are common to all HDLC protocols.
Table 4-6 shows these common parameters.
Some parameter RAM values must be initialized before the HDLC can be enabled. Other
values are initialized or written by the HDLC. Once initialized, most parameter RAM
values do not need to be accessed because most activity centers around the descriptors
rather than the parameter RAM. However, if the parameter RAM is accessed, note the
following:
•
•
Parameter RAM can be read at any time.
Tx parameter RAM can be written only when the transmitter is disabled.
NOTE:
Boldfaced entries in the parameter RAM table must be
initialized by the user.
Table 4-6. Parameter RAM Map
Offset1 RAM Area
Width
Description
0x00
MRBLR
Half-word Maximum receive buffer length. Defines the maximum number of bytes the MPU
writes to a receive buffer before it goes to the next buffer. The MPU can write
fewer bytes than MRBLR if a condition such as an error or end-of-frame occurs. It
never writes more bytes than the MRBLR value. Therefore, user-supplied buffers
should be no smaller than MRBLR. MRBLR should be greater than 8 for all
modes. It should be a multiple of 8 for HDLC modes, and in totally transparent
mode unless the Rx FIFO is 8-bits wide. Note that although MRBLR is not
intended to be changed while the HDLC is operating, it can be changed
dynamically. Changing MRBLR has no immediate effect. To guarantee the exact
Rx BD on which the change occurs, change MRBLR only while the receiver is
disabled. Transmit buffer length is programmed in TxBD [Data Length] and is not
affected by MRBLR.
0x02
-0x17
—
0x18
C_MASK
Word
CRC mask. For the 16-bit CRC-CCITT, initialize with 0x0000_F0B8; for 32-bit
CRC-CCITT, initialize with 0xDEBB_20E3.
0x20
C_PRES
Word
CRC preset. For the 16-bit CRC-CCITT, initialize with 0x0000_FFFF; for 32-bit
CRC-CCITT, initialize with 0xFFFF_FFFF.
Reserved
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HDLC-Specific Parameter RAM
Table 4-6. Parameter RAM Map (Continued)
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Offset1 RAM Area
1
Width
Description
0x28
MFLR
Half-word Max frame length register. The HDLC compares the incoming HDLC frame’s
length with the user-defined limit in MFLR. If the limit is exceeded, the rest of the
frame is discarded and RxBD[LG] is set in the last BD of that frame. At the end of
the frame the HDLC reports frame status and frame length in the last RxBD. The
MFLR is defined as all in-frame bytes between the opening and closing flags.
0x30
HMASK
0x38
HADDR1
0x40
HADDR2
0x48
HADDR3
0x50
HADDR4
Half-word Mask register (HMASK) and four address registers (HADDRn) for address
recognition. The HDLC reads the frame address from the HDLC receiver,
Half-word
compares it with the HADDRs, and masks the result with HMASK. Setting an
Half-word HMASK bit enables the corresponding comparison bit, clearing a bit masks it.
When a match occurs, the frame address and data are written to the buffers.
Half-word When no match occurs and a frame is error-free, the nonmatching address
Half-word received counter is incremented. The eight low-order bits of HADDRn should
contain the first address byte after the opening flag. For example, to recognize a
frame that begins 0x7E (flag), 0x68, 0xAA, using 16-bit address recognition,
HADDRn should contain 0xAA68 and HMASK should contain 0xFFFF. For 8-bit
addresses, clear the eight high-order HMASK bits.
0x58
MRA
0x60
DSR
0x64
ER
Half-word Event register
0x68
MR
Half-word Mask register
0x6c
SR
0x70
BRG
0x74
RBASE
0x78
CMR
0x7c
TBASE
Word
Mode register
Half-word Data sync register
Byte
Status register
Half-word Baud rate generator configuration register
Word
RBASE Table register
Half-word HDLC command register
Word
TBASE table register
Offset from HDLC Base (IMMR + 0x64000 + HDLC base offset address)
4.5.1 HDLC Base Offset Address
This section describes the address offsets for the 40 HDLC channels. The HDLC base offset
addresses are offsets of IMMR + 0x64000.
The MC92460 supports HDLC mode only.
Table 4-7. HDLC Base Offset Addresses
Page
Offset
Address1
Peripheral
Size (bytes)
Page
Offset
Address1
Peripheral
Size (bytes)
0
0x000
HDLC0
128
20
0xa00
HDLC20
128
1
0x080
HDLC1
128
21
0xa80
HDLC21
128
2
0x100
HDLC2
128
22
0xb00
HDLC22
128
3
0x180
HDLC3
128
23
0xb80
HDLC23
128
4
0x200
HDLC4
128
24
0xc00
HDLC24
128
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Table 4-7. HDLC Base Offset Addresses (Continued)
1
Page
Offset
Address1
Peripheral
Size (bytes)
Page
Offset
Address1
Peripheral
Size (bytes)
5
0x280
HDLC5
128
25
0xc80
HDLC25
128
6
0x300
HDLC6
128
26
0xd00
HDLC26
128
7
0x380
HDLC7
128
27
0xd80
HDLC27
128
8
0x400
HDLC8
128
28
0xe00
HDLC28
128
9
0x480
HDLC9
128
29
0xe80
HDLC29
128
10
0x500
HDLC10
128
30
0xf00
HDLC30
128
11
0x580
HDLC11
128
31
0xf80
HDLC31
128
12
0x600
HDLC12
128
32
0x1000
HDLC32
128
13
0x680
HDLC13
128
33
0x1080
HDLC33
128
14
0x700
HDLC14
128
34
0x1100
HDLC34
128
15
0x780
HDLC15
128
35
0x1180
HDLC35
128
16
0x800
HDLC16
128
36
0x1200
HDLC36
128
17
0x880
HDLC17
128
37
0x1280
HDLC37
128
18
0x900
HDLC18
128
38
0x1300
HDLC38
128
19
0x980
HDLC19
128
39
0x1380
HDLC39
128
Offset from IMMR + 0x64000
4.6 Error Handling by the HDLC Controller
The HDLC controller reports frame reception and transmission errors using BDs and the
event register (ER). The transmission error is shown in Table 4-8.
Table 4-8. Transmit Errors
Error
Description
Transmitter Underrun The channel stops transmitting, closes the buffer, sets TxBD[UN],
and generates a TXE interrupt if not masked.
Receiving errors are shown in Table 4-9.
Table 4-9. Receive Errors
Error
Description
Overrun
Each HDLC maintains an internal FIFO for receiving data. When an Rx FIFO
overrun occurs, the previous byte is overwritten by the next byte. The previous
data byte and the frame status are lost. The channel closes the buffer with
RxBD[OV] set and generates an RXF interrupt if not masked. The receiver then
enters hunt mode. Even if an overrun occurs during a frame whose address is not
recognized, an RxBD with data length 2 is opened to report the overrun and the
interrupt is generated.
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Error Handling by the HDLC Controller
Table 4-9. Receive Errors (Continued)
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Error
Description
Abort
Sequence
Occurs when seven or more consecutive ones are received. When this occurs
while receiving a frame, the channel closes the buffer, sets RxBD[AB] and
generates a maskable RXF interrupt. The CRC and non connected error status
conditions are not checked on aborted frames. The receiver then enters hunt
mode.
CRC
The channel writes the received CRC to the buffer, closes the buffer, sets
RxBD[CR], generates a maskable RXF interrupt. After receiving a frame with a
CRC error, the receiver enters hunt mode. An immediate back-to-back frame is
still received. CRC checking cannot be disabled, but the CRC error can be
ignored if checking is not required.
Nonoctet-Aligned
Frame
The channel writes the received data to the buffer, closes the buffer, sets
RxBD[NO], and generates a maskable RXF interrupt. CRC error status should be
disregarded on nonoctet frames.
An immediate back-to-back frame is still received. The nonoctet data may be
derived from the last word in the buffer as follows:
msb
lsb
—
1
0
0
Valid Data
Nonvalid Data
4.6.1 HDLC Mode Register (MRA)
Each HDLC channel has the protocol-specific mode register (MRA), shown in Table 4-10.
No bits (except ENT and ENR) can be modified while the receiver and transmitter are
enabled.
Table 4-10. Mode Register (MRA)
0
Field
3
NOF
4
5
CRC
6
7
8
9
—
FLG
—
DRT
Reset
10
12
13
14
15
—
DIAG0 DIAG1 DIAG2
R
R/W
0000_0000_0000_0000
R/W
R/W
16
Field ENT
17
18
—
ENR
Reset
R/W R/W
19
21
—
0000_0000
R
R/W
R
R
R/W
R
22
23
24
IRCK
ITCK
R/W
31
RFTH
0000_1000
R/W
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Error Handling by the HDLC Controller
Table 4-11 shows the descriptions of each mode register field.
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Table 4-11. Mode Register Description
Bit
Field
0–3
NOF
Number of flags. Minimum number of flags between or before frames. If NOF = 0b0000, no
flags are inserted between frames and the closing flag of one frame is followed by the
opening flag of the next frame in the case of back-to-back frames. NOF can be modified on
the fly.
4–5
CRC
00 16-bit CCITT-CRC (HDLC). X16 + X12 + X5 + 1. This field defines the protocol format.
01 Reserved.
11 Reserved.
10 32-bit CCITT-CRC (Ethernet and HDLC). X32 + X26 + X23 + X22 + X16 + X12 + X11 +
X10 + X8+ X7 + X5 + X4 + X2 + X1 +1
6
—
7
FLG
8
—
9
DRT
10–12
—
13–15
Description
Reserved.
Send flag or IDLE during frame
0 Send IDLE
1 Send flag
Reserved.
Disable receiver while transmitting.
0 Normal operation.
1 As the HDLC sends data, the receiver is disabled and gated by the internal RTS. This
helps if the HDLC channel is on a multidrop line and the HDLC does not need to receive its
own transmission.
Reserved.
DIAG[0–2] Diagnosis mode
000 Normal operation
001 Loop back mode TxSD high
010 Auto Echo mode TxSD through
011 Reserved
100 Normal
101 Loop back mode TxSD data out
110 Auto Echo mode re-synchronize TxSD with RxCK
111 Reserved
16
ENT
Enable transmitter
0 Disable
1 Enable
17
—
18
ENR
19–21
—
22
IRCK
Invert RxCK
0 Not invert RxCK
1 Invert RxCK
23
ITCK
Invert TxCK
0 Not invert TxCK
1 Invert TxCK
24–31
RFTH
Receive frame threshold parameter
Number of receive frames that generate RXF interrupt
Reserved.
Enable receiver
0 Disable
1 Enable
Reserved.
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Error Handling by the HDLC Controller
4.6.2 HDLC Data Synchronization Register (DSR)
Each HDLC channel has a data synchronization register (DSR) that specifies the pattern
used for frame synchronization. The pattern that each SYN1 and SYN2 flag specifies is
0x7E and, because this is the default sequence, it does not need to be written.
0
7
8
15
Field
SYN2
SYN1
Reset
0x7E
0x7E
R/W
R
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Figure 4-16. Data Synchronization Register (DSR)
Table 4-12. Data Synchronization Register Description
Bit
Field
Description
0-7
SYN2
Defaults and fixes to 0x7E for HDLC flag sequence pattern
8-15
SYN1
Defaults and fixes to 0x7E for HDLC flag sequence pattern
4.6.3 HDLC Event Register/Mask Register (ER)/MR)
The HDLC event register (ER) is used to report events recognized by the HDLC channel
and to generate interrupts. When an event is recognized, the HDLC controller sets the
corresponding ER bit. Interrupts generated through ER can be masked in the HDLC mask
register (MR) which has the same bit format as the ER. Setting an MR bit enables the
corresponding interrupt; clearing a bit masks it. ER bits are cleared by writing ones; writing
zeros has no effect. All unmasked bits must be cleared before the HDLC controller clears
the internal interrupt request. Table 4-17 shows the ER/MR register for HDLC operation.
0
Field
5
—
Reset
6
7
FLG
IDL
8
10
—
11
12
13
14
TXE RXF BSY TXB
15
RXB
0000_0000_0000_0000
R/W
R
RW
R
RW
Figure 4-17. Event/Mask Register (ER/MR)
Table 4-13. ER/MR Register Description
Bit
Field
Description
0–5
—
6
FLG
Flag status. Set when the HDLC channel stops or starts receiving HDLC flags. Real-time status
can be read in SR[FG].
7
IDL
Idle sequence status changed. Set when HDLC line status changes. Real-time status of the
line can be read in SR[ID].
8–10
—
Reserved.
Reserved.
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Table 4-13. ER/MR Register Description (Continued)
Bit
Field
Description
11
TXE
Tx error. Indicates an error has occurred on the transmitter channel.
12
RXF
Rx frame. Set when the number of receive frames specified in RFTH are received on the HDLC
channel. It is set no sooner than two clocks after the last bit of the closing flag is received. This
event is not maskable via the RxBD[I] bit.
13
BSY
Busy condition. Indicates a frame arrived but was discarded due to a lack of buffers.
14
TXB
Transmit buffer. Enabled by setting TxBD[I]. TXB is set when a buffer is sent on the HDLC
channel. For the last buffer in the frame, TXB is not set before the last bit of the closing flag
begins its transmission.
15
RXB
Receive buffer. Enabled by setting RxBD[I]. RXB is set when the HDLC channel receives a
buffer(MRBLR) that is not the last in a frame.
4.6.4 HDLC Status Register (SR)
The HDLC status register (SR), shown in Table 4-18, permits monitoring of real-time status
conditions on RxD.
0
Field
3
—
5
BSYSR FG
6
7
—
ID
R
RW
0000_0000
Reset
R/W
4
R
RW
Figure 4-18. HDLC Status Register (SR)
Table 4-14. SR Field Descriptions
Bit
Field
Description
0–3
—
4
BSYSR
5
FG
Flags. The line is checked after the data has been decoded.
0 HDLC flags are not being received. The most recently received 8 bits are examined every
bit time to see if a flag is present.
1 HDLC flags are being received. FG is set as soon as an HDLC flag (0x7E) is received on
the line.
Once it is set, FG remains set at least eight bit times and the next eight received bits are
examined. If another flag occurs, FG stays set for at least another eight bits. If not, it is
cleared and the search begins again.
6
—
Reserved.
7
ID
Idle status.
0 The line is busy.
1 Set when RXD is a logic 1 (idle) for 15 or more consecutive bit times. It is cleared after a
single logic 0 is received.
Reserved.
Busy condition. This bit is set when a frame is received.
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HDLC Commands
4.7 HDLC Commands
The transmit and receive commands are issued to the command register (CMR).
0
Field
1
2
CMM
6
—
Reset
R/W
7
8
FLG
15
—
0000_0000_0000_0000
RW
R
Address
RW
R
—
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Figure 4-19. HDLC Command Register (CMR)
Table 4-15. HDLC Command Register Field Descriptions
Bit
Field
Description
0–1
CMM
CMM = 00 (Stop Transmit). After a hardware or software reset and a channel is enabled,
the transmitter starts polling the first BD and begins sending data if TxBD[R] is set. If the
HDLC receives the STOP TRANSMIT command while not transmitting, the transmitter
stops polling the BDs. If the HDLC receives the command during transmission,
transmission is aborted after a maximum of 64 additional bits, the Tx FIFO is flushed, and
the current BD pointer is not advanced (no new BD is accessed). The transmitter then
sends an abort sequence (0x7F) and stops polling the BDs.
When not transmitting, the channel sends flags or idles as programmed in the MRA.
CMM = 01 (Restart Transmit) Enables frames to be sent on the transmit channel. The
HDLC controller expects this command after a STOP TRANSMIT is issued. The
transmitter resumes from the current BD.
CMM = 10 (Enter Hunt Mode). After a hardware or software reset, once an HDLC is
enabled, the receiver is automatically enabled and uses the first BD in the RxBD table.
While the HDLC is looking for the beginning of a frame, that HDLC is in hunt mode. The
ENTER HUNT MODE command is used to force the HDLC receiver to stop receiving the
current frame and enter hunt mode, in which the HDLC continually scans the input data
stream for a g sequence. After receiving the command, the buffer is closed and the CRC is
reset. Further frame reception uses the next BD
CMM = 11 Received
2–6
—
7
FLG
8–15
—
Reserved.
Set by the MPU and cleared by the HDLC
0 The HDLC is ready to receive a new command
1 The HDLC is currently processing. The HDLA clear this bit at the end of a command.
Reserved.
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Baud Rate Generator
4.8 Baud Rate Generator
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The MC92460 contains an independent baud rate generator (BRG) for each of the 40
HDLCs. Inputs to the BRGs come from the PLLs. The clocks produced by the BRGs are
sent to each HDLC. In addition, the output of a BRG can be routed to TxCKn and RxCKn
to be used externally. The following is a list of the main features of the MC92460 baud rate
generators:
•
•
•
•
•
40 independent and identical baud rate generators
On-the-fly changes allowed
Input is from the PLLs
A 16x divider option allows slow baud rates at high system frequencies
BRGO output can be routed to a pin (TxCKn and RxCKn)
Figure 4-20 shows a baud rate generator.
TxCK
Internal
System
Clock
Baud
Rate
Clock
Clock
Source
Select
Prescaler
1/1 or 1/16
Clock Divider
1/1 to 1/4096
Tx
Clock
Selector
TxCK
Out
Rx
Clock
Selector
RxCK
Out
BRGO
RxCK
Figure 4-20. Baud Rate Generator Block Diagram
Whether the internal system clock or the baud rate clock is used as the BRG clock source
depends on BRGCx [EXTC]). The internal system clock is generated in PLL1 and the baud
rate clock is generated by PLL2 as source clocks especially for the BRGs, see Chapter 7,
“Phase-Locked Loop.” These source options allow flexible baud rate frequency generation,
independent of the system frequency. The clock signals are not synchronized internally
before being used by the BRG.
The BRG provides a divide-by-16 prescaler option (BRGCx [DIV16]) and a 12-bit clock
divider (BRGCx[CD]) to divide the source clock frequency. The combined source-clock
divide factor can be changed on the fly; however, two changes should not occur within two
clock source periods. If the BRG divides the clock by an even value, the transitions of
BRGOn always occur on the falling edge of the source clock. If the divide factor is an odd
value, the transitions alternate between the falling and rising edges of the source clock.
The baud rate that is generated by PLL2 may be passed through an HDLC baud rate
generator with no change from its entry rate if zero values are selected for the prescaler and
the clock divider. Table 4-17 shows the various baud rates that can be generated from a 66
MHz baud rate clock input given specific DIV16 and CD values. If the baud rate clock input
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Baud Rate Generator
is other than 66 MHz, however, other baud rates than those shown in the table will be
generated from the BRGs.
4.8.1 BRG Configuration Registers (BRGCx)
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The baud rate generator configuration registers (BRGCx) are shown in Table 4-21. A reset
disables the BRG and drives the baud rate generator output (BRGO) clock high. The BRGC
can be written at any time with no need to disable the HDLCs or external devices that are
connected to the BRGO. Configuration changes occur at the end of the next BRG clock
cycle (no spikes occur on the BRGO output clock). The BRGC can be changed on the fly;
however, two changes should not occur within two clock source periods.
0
Field EXTC
Reset
0
1
2
3
4
TCS
RCS
DIV16
CD
1
1
0
0000_0000_0000
R/W
15
RW
Figure 4-21. Baud Rate Generator Configuration Register (BRGCx)
Table 4-16. BRGCx Register Description
Bit
Field
Description
0
EXTC
1
TCS
Select transmitter clock source
0 Internal baud rate generator output
1 TxCKn
2
RCS
Select receiver clock source
0 Internal baud rate generator output
1 RxCKn
3
DIV16
Prescaler: selects a divide-by-1 or divide-by-16 prescaler before reaching the clock divider.
0 Divide by 1
1 Divide by 16
4–15
CD
Clock divider. CD presets an internal 12-bit counter that is decremented at the DIV16 output
rate. When the counter reaches zero, it is reloaded with CD.
If CD = 0xFFF the minimum clock rate for BGRO (divide by 4096)is generated
If CD = 0x000 the maximum rate (divide by 1) is generated.
External clock source. Selects the BRG input clock.
0 The BRG input clock comes from the internal system clock (may be 66MHz)
1 The BRG input clock comes from the baud rate clock
4.8.2 Baud Rate Examples
This formula is used to calculate a baud rate for each channel:
Baud rate = main clock (internal system clock or baud rate clock) / (1 or 16 according to
BRGCx[DIV16]) ∗ (BRGCx[CD] + 1)
Table 4-17 shows the baud rate generated from a 66-MHz main clock.
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Baud Rate Generator
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Table 4-17. Baud Rate
DIV16
(Prescaler)
CD
(Clock
Divider)
Baud Rate (Actual
Frequency)
0
0
66 MHz
0
1
33 MHz
0
2
22 MHz
0
3
16.5 MHz
0
4095
16113.28 Hz
1
0
4.125 MHz
1
1
2.0625 MHz
1
2
1.375 MHz
1
3
1.03125 MHz
1
4095
1007.08 Hz
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Chapter 5
Master Interface Unit
The master interface unit (MIU) supports the 60x bus. This module is connected through
the 60x-compatible bus mode of the MPC8260. Key features of the MIU include the
following:
•
•
•
•
•
•
Direct connection with 64-bit data and 32-bit address 60x bus
Virtual DMA supports an 80 channel HDLC master (40 Tx, 40 Rx)
Virtual DMA functionality executing off-chip memory to internal memory
Supports single-beat and burst access
Either the MC92460 master or the MC92460 slave can be the 60x bus master
Supports 66 MHz 60x bus speed
Figure 5-1 shows the MIU block diagram.
Master Interface Unit
60x
Bus
Arbiter
BR & BG
DMA
Transfer
address
Bus
bridge
Address
data
control
Figure 5-1. Master Interface Unit Block Diagram
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System Mode
5.1
System Mode
The system mode is implemented by the system mode register (SMR), shown in Figure 5-2.
This register defines the 60x bus mode and the internal RAM wait cycle.
0
1
Field DPE APE
2
3
AAE
FAAC
Reset
4
14
—
15
RAMW
0000_0000_0000_0000
R/W
R/W
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Figure 5-2. System Mode Register (SMR)
Table 5-1. SMR Register Descriptions
Bits
Field
0
DPE
Data parity error signal control
0 Data parity error signal output disable
1 Data parity error signal output enable
1
APE
Address parity error signal control
0 Address parity error signal output disable
1 Address parity error signal output enable
2
AAE
Address ACK enable at address only access
0 AACK is asserted at address only access on Master mode
1 AACK is NOT asserted at address only access on Master mode
3
FAAC
AACK select
0 MPC8260 pipeline-1 mode
1 Fast AACK mode; support 60x bus fastest AACK
4–14
—
15
5.2
Description
Reserved
RAMW Internal RAM wait cycle select
0 0x0 to 0x63fff is two wait access
1 0x0 to 0x63fff is one wait access
Direct Memory Access (DMA)
The modules that are required to perform DMA transfers arbitrate for the system master bus
(external 60x bus). These DMA modules are referred to as master modules. If such a
module also has registers accessible to the processor core, then the module also will
connect to the system slave bus. The detailed specification of the master bus is dependent
on the type of processor core being used.
The DMA has two modes, external and direct. These are selected by DMAMR[EXT].
Ordinarily the external mode should be selected, because this mode generates and enables
80 DMA channels of HDLC. When the MC92460 has no need to perform HDLC data
transfers, the DMA module can be used as a generic DMA module by selecting direct
mode.
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Direct Memory Access (DMA)
A user can transfer data among all the memories on the 60x bus, among all of the
MC92460’s memories, or between the memories on the 60x bus and the MC92460. Direct
mode supports only data that is aligned on 8 byte boundaries and of a minimum 8 byte data
size. Thus, values written to the lower 3 bits of DMASA, DMADA, and DMATS are
ignored and have no meaning.
5.2.1
Source Address (DMASA)
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The DMA source address register (DMASA) holds the starting address of internal memory
source data. The DMA reads the data from the internal memory source address and then
transfers the data to the destination address.
0
15
Field
Upper 16-bit Source Address
Reset
0000_0000_0000_0000
R/W
R/W
16
Field
28
29
31
Lower 16-bit Source Address
Reset
R/W
0000_0000_0000_0
000
R/W
R
Figure 5-3. DMA Source Address Register (DMASA)
Table 5-2. DMASA Register Description
Field
Description
Source Address
5.2.2
DMA transfer source address.
This value is used in DIRECT MODE only
Transfer Size (DMATS)
The DMA transfer size register (DMATS) determines the maximum allowed byte size of
reads and writes to the source and destination registers.
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Direct Memory Access (DMA)
0
15
Field
Upper 16-bit Transfer Size
Reset
0000_0000_0000_0000
R/W
R/W
16
Field
29
31
Lower 16-bit Transfer Size
Reset
R/W
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28
0000_0000_0000_0
000
R/W
R
Figure 5-4. DMA Transfer Size Register (DMATS)
Table 5-3. DMATS Register Description
Field
Description
Transfer Size
5.2.3
DMA transfer byte count.
This value is used in DIRECT MODE only. A data length of zero is not allowed.
Destination Address (DMADA)
The DMA destination address register (DMADA) indicates the start of the MC92460’s
internal memory destination address. The DMA reads the data from the internal memory
source address and then transfers the data to the destination address.
0
15
Field
Upper 16-bit Destination Address
Reset
0000_0000_0000_0000
R/W
R/W
16
31
Field
Lower 16-bit Destination Address
Reset
0000_0000_0000_0000
R/W
R/W
R
Figure 5-5. Destination Address Register (DMADA)
Table 5-4. DMADA Register Description
Field
Destination
Address
Description
DMA transfer destination address.
This value is used in DIRECT MODE only.
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Direct Memory Access (DMA)
5.2.4
Mode Register (DMAMR)
The DMA mode register (DMAMR) defines the MC92460’s DMA parameters; refer to
Table 5-5. Parameters except STRT should be modified only while the EN bit is 0 (the
DMA is disabled).
Field
0
1
2
3
EN
EXT
EOTIE
ERIE SNP
Reset
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5
7
8
—
10
11
TSIZ
13
14
15
—
DAL SAL
R
R/W
0100_0000_0000_0000
R/W
R/W
16
R
R/W
17
31
Field STRT
—
Reset
R/W
4
0000_0000_0000_0000
R/W
R
Figure 5-6. DMA Mode Register (DMAMR)
Table 5-5. DMAMR Register Descriptions
Bits
Field
Description
0
EN
DMA enable/disable
0 Disable
1 Enable
1
EXT
External Mode
1 External mode. DMA uses the value that is provided by the transfer requesting
device/module(I/O) through the interface signals.
0 Direct mode. DMA uses the source/destination registers, in which the transfer information is
described, for the data transfer.
2
EOTIE
3
ERIE
Transfer error interrupt enable
0 If there is an error during a DMA transfer, an interrupt will be generated.
1 No interrupt will be generated when a transfer error occurs.
4
SNP
Transfer is snoopable.
0 Access is non-global.
1 Access is global.
5-7
—
8-10
TSIZ
11-13
—
End-of-transfer interrupt enable/disable
0 No interrupt will be generated at the end-of-transfer.
1 If the current DMA transfer is finished an interrupt will be generated.
Reserved.
Source transfer size. The value in this field is valid. These values must be set.
000 8-byte for the burst read/write
001 1-byte
010 2-byte
011 3-byte
NOTE: MC92460 supports 000 (burst read/write) only
Reserved.
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Direct Memory Access (DMA)
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Table 5-5. DMAMR Register Descriptions (Continued)
Bits
Field
14
DAL
Destination address location.
0 Destination address is located in the MC92460 internal SRAM memory space (0x0~0x7fff)
1 Destination address is located in the external memory space on 60x bus.
15
SAL
Source address location.
0 Source address is located in the MC92460 internal SRAM memory space (0x0~0x7fff)
1 Source address is located in the external memory space on 60x bus.
16
STRT
17–31
—
5.2.5
Description
DMA Transfer start
1 When BUSY is negated and write 1 allows to start the DMA transfer. If BUSY is asserted and
write 1, it will not affect to the current DMA process.
0 Always 0 when this bit is read
Reserved.
Status Register (DMASR)
The DMA status register reports the status of DMA transfer events.
0
Field BUSY
1
2
3
EOTI
ERI
4
5
DMATT
Reset
R/W
15
—
0000_0000_0000_0000
R
R/W
R/W
R
—
Figure 5-7. DMA Status Register (DMASR)
Table 5-6. DMASR Field Descriptions
Bits
Field
0
BUSY
DMA transfer busy
0 - No DMA transfer.
1 - DMA transfer is in progress.
1
EOTI
DMA end-of-transfer interrupt status
0 - No EOT interrupt occurs.
1 - EOT interrupt occurs. Writing 1 clears this bit.
2
ERI
3–4
5–15
Description
DMA Transfer error interrupt status
0 - No Transfer Error interrupt occurs.
1 - Transfer Error interrupt occurs. If write 1, this bit is cleared.
DMATT DMA transfer type status. This status field indicates the data transfer direction of the current DMA
transfer.
00 - Memory to Memory transfer
01 - Memory to I/O transfer
10 - I/O to Memory transfer
11 - Reserved
—
Reserved
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Arbiter
5.2.6
DMA Error Address Register (DMAEA)
The DMA error address register holds the system address accessed during a transfer error
on the host bus.
0
15
Field
EA High
Reset
0000_0000_0000_0000
R/W
R
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16
31
Field
EA Low
Reset
0000_0000_0000_0000
R/W
R
Figure 5-8. DMA Error Address Register (DMAEA)
Table 5-7. DMAEA Register Field Description
Bits
Field
Description
0–15
EA
DMA transfer error address. When transfer error occurs, the address value on the host bus will
be saved in this field.
5.3
Arbiter
The system bus arbiter of the master interface unit (MIU) is responsible for allocating both
the internal master bus and the 60x external bus whenever the MPU core (Power PC
architecture core, MPC603e, or MPC8260) relinquishes bus control. This arbiter manages
the internal master bus and the 60x external bus for the DMA module
The system bus arbiter supports one internal master device (the MIU) and one external
device, another MC92460 for example, which can be either a master or a slave. Refer to
Figure 5-9. The external master supported does not include the MPU core.
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Arbiter
MC92460 #0
64-bit 66 MHz 3.3v
60x External Bus
Master Interface Unit
Bus Interface
MPU Core
Register Interrupt
Dual Port Ram
64bits X 2048
DMA
System
Bus
Arbiter
SCU
32-byte X 80 FIFO
Communication
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64 Bit Internal Master Bus
Buffer
SRAM
(64bit X 5kw)
Rx FIFO
Tx FIFO
------BIST
HDLC
PLL
Flag / Abort / Idle
------0-insert / Delete
16 / 32 CRC
RxSD RxCK TxCK TxSD
40 Channels
JTAG
MC92460 #1
60x External Bus
Master Interface Unit
Bus Interface
DMA
System
Bus
Arbiter
Figure 5-9. Arbitration Between Two MC92460s
The arbitration scheme enables DMA master modules to access other internal modules
including the SCU (system integration module), chip selects, and so forth. Because most
external master devices will not have all the required master bus signals available as
external signals, they cannot arbitrate for the internal master bus directly; they can only
arbitrate for the external bus.
When an external alternate master is granted control of the external bus, the external device
drives its signals and the system bus arbiter drives the internal master bus signals. The
arbiter controls priority automatically. The MPU is the highest priority after a system reset.
But if the arbiter is enabled, the MPU will be the lowest priority.
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Arbiter
5.3.1
Mode Register 0 (ARBM0)
The mode register 0 (ARBM0) defines the system bus arbiter parameters for a channel that
connects to an MC92460 master.
0
1
14
Field EN
—
Reset
PRI
0000_0000_0000_000
R/W R/W
15
1
R/W
R
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Figure 5-10. Mode Register 0 (ARBM0)
Table 5-8. ARBM0 Register Field Descriptions
Bits
Field
0
EN
Arbiter for internal master Enable/Disable
0 Disable.
1 Enable.
1–14
—
Reserved.
15
PRI
5.3.2
Description
Priority
0 Slave MC92460 is higher priority than Master MC92460
1 Master MC92460 is higher priority than Slave MC92460
Mode Register 1 (ARBM1)
The mode register 1 (ARBM1) defines the system bus arbiter parameters for a channel that
connects to an MC92460 slave.
0
1
15
Field EN
—
Reset
0000_0000_0000_0000
R/W RW
R
Figure 5-11. Mode Register 1 (ARMB1)
Table 5-9. ARBM1 Register Field Description
Bit
Field
Description
0
EN
Arbiter for internal master Enable/Disable
0 Disable.
1 Enable.
1–15
—
Reserved.
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Notes
5.4
•
In an MPC8260 SDRAM system with an attached MC92460, if the arbiter is
enabled (by pulling MODE low), the clocked mode of the arbiter cannot be used.
Pulling AMODE high to enable clocking of the enabled arbiter is not supported.
Assigning L2 cache space to the MC92460 address area is not supported.
The AMODE of an MC92460 slave should be set to the same value as the AMODE
of an MC92460 master.
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•
•
Notes
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Chapter 6
IEEE 1149.1 Test Access Port
The MC92460 provides a test access port (TAP) that is compatible with the IEEE 1149.1
standard test access port and boundary scan architecture. This implementation of IEEE
1149.1 allows boundary scan compatibility with other JTAG components in a circuit-board.
A boundary scan description language (BSDL) file for this device is provided in another
text file located on Motorola’s MC92460 product web site.
The TAP includes five dedicated signal pins, a 16-state TAP controller, a bypass register, an
instruction register, and a device identification (ID) register. The ID register contains the
specific JTAG ID code. A boundary scan register links all device I/O signal pins into a
shift-register chain around the periphery of the device. This path is provided with serial
input and output signal pins and is controlled by appropriate clock and control signals.
The JTAG test logic is independent of the device system logic. The JTAG implementation
on the MC92460 provides for the following capabilities:
•
•
•
•
•
•
•
6.1
Boundary scan operations
BYPASS mode, which bypasses the MC92460 boundary scan chain
Sampling system data from I/O signals (for inputs) and core system data (for
outputs) and shifting out the result through the boundary scan register
Test of component interconnect with EXTEST mode. This instruction updates
I/O and system logic with data that is shifted in serially. Output pins are driven with
the updated values, and input pins have the updated values driven into the core logic.
CLAMP mode, which drives as in EXTEST mode, but puts boundary scan chain in
BYPASS mode
IDCODE mode allows the ID code to be shifted from the ID register.
HIGHZ mode tristates all system outputs and bi-directionals for component
isolation.
Functional Blocks
The MC92460 implementation of the IEEE 1149.1 standard includes a TAP controller, an
instruction register, a bypass register, an ID code register, and the I/O boundary scan
register. The associated signal pins for the JTAG logic are:
•
TCK—Test clock input for the JTAG test logic
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Functional Blocks
•
TMS—Test mode select input used to sequence the TAP controller’s state machine,
sampled on the rising edge of TCK
TDI—Test data input sampled on the rising edge of TCK
TDO—Test data output active during the Shift-DR and Shift-IR controller states
TRST—Asynchronous test reset signal that initializes the TAP controller and other
JTAG logic, active low
•
•
•
A block diagram is shown in Figure 6-1.
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Boundary scan register
Bypass register
MUX
TDI
Identification register
MUX
TDO
Decoder
Instruction register
TMS
TCK
TAP
controller
TRST
Figure 6-1. JTAG Logic Block Diagram
6.1.1
TAP Controller
The TAP controller is a synchronous, 16-state machine that controls and manages the mode
of operation for the test circuitry. The controller interprets the sequence of logical values
on the TMS signal. The TAP controller states are explained in the IEEE 1149.1 document.
The state diagram for the controller is shown in Figure 6-2.
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Functional Blocks
1
Test Logic Reset
F
1
0
0
Run-Test/Idle
C
Select-DR-Scan
7
1
6
1
Select-IR-Scan
0
4
1
Capture-DR
0
0
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D = ‘D’ State of
TAP Controller
2
0 = Logic State of
TMS
‘0’ = Off/Low
‘1’ = On/High
1
5
0
0
1
A
1
0
Exit1-IR
0
1
Exit2-DR
1
Update-DR
0
0
9
Pause-DR
0
1
Capture-IR
Shift-IR
1
Exit1-DR
3
0
0
E
Shift-DR
1
1
0
Pause-IR
B
0
8
1
1
Exit2-IR
1
Update-IR
D
0
Figure 6-2. TAP Controller State Diagram
6.1.2
Instruction Register
The 4-bit instruction register holds various instructions that define which test registers are
to be used and the serial test data register path between TDI and TDO signals. The
instructions are described in Section 6.2 JTAG Instruction Support.
6.1.3
Device Identification Register
The device identification register is a 32-bit register that holds the manufacturer’s identity
code, sequence number (equivalent to a part number), and version code. The bit assignment
for the ID code is shown in Table 6-1. The ID code data is shifted out with the least
significant bit (0) shifted out first.
Table 6-1. Device Identification Register ID Codes
ID CODE (32bits)
BIN
(MSB) 0000 0010 1000 0000 1101 0000 0001 1101(LSB)
HEX
0280D01D
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JTAG Instruction Support
6.1.4
Bypass Register
The 1-bit bypass register is connected between TDI and TDO when either the BYPASS
instruction or the CLAMP instruction is active. This allows for bypassing the boundary
scan register while other components on a board are being tested. When the bypass register
is selected by the current instruction, the data that is shifted out on the first clock edge is
the previously latched data.
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6.1.5
Boundary Scan Register
The boundary scan register allows testing of circuitry external to the MC92460. It also
allows the signals flowing through the system pins to sampled and examined without
interfering with the operation of the MC92460. The boundary scan register includes all the
functional pins of the MC92460 and additional stages that control the direction and driving
state of some of the pins.
6.2
JTAG Instruction Support
The following instructions are supported by the MC92460:
•
•
•
•
•
SAMPLE—The SAMPLE instruction captures the input or output data from the I/O
pads. The data is captured on the rising edge of TCK when the TAP controller is in
the capture-DR state, and can be observed when shifted out through the boundary
scan register. This instruction does not update the core logic or the I/O pads. This
makes it useful for preloading the boundary scan register with known data when
entering the EXTEST instruction.
BYPASS—The BYPASS instruction selects the bypass register for serial access
between TDI and TDO. This instruction does not update the core logic or the I/O
pads.
EXTEST—The EXTEST instruction selects the boundary scan register. When the
EXTEST instruction is active, the output pins and the internal core input signals are
updated with test data that has been previously shifted into the boundary scan
register. Also, the state of all input ports of the chip core are defined by the data
shifted into the boundary scan register, and are updated on the falling edge of TCK
in the update-DR controller state. Refer to the IEEE 1149.1 document for more
details on the function and use of EXTEST.
IDCODE—The MC92460 includes a device identification register. The IDCODE
instruction selects only the device identification register to be connected for serial
access between TDI and TDO in the shift-DR controller state. When the IDCODE
instruction is selected, the vendor identification code is loaded into the ID register in
the capture-DR state.
CLAMP—The CLAMP instruction selects the bypass register for serial access
between TDI and TDO. The CLAMP instruction drives the core data and the chip
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Boundary Scan Register Path
•
I/O signals in the same manner as EXTEST, while the bypass register is selected as
the serial TDI/TDO path.
HIGHZ—The HIGHZ instruction selects the bypass register for serial access
between TDI and TDO. This instruction also puts all system logic output pins
(including bi-directional pins) in their inactive drive state. This instruction is
provided to help isolate the component during circuit board testing.
Table 6-2 shows the coding of the instructions supported by the MC92460. Bit 0 is the first
bit shifted in from TDI and the first bit shifted out through TDO. The shaded rows of the
table indicate the code point that is defined in the BSDL file for each instruction. The other
values are provided for completeness, but are not expected to be used.
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Table 6-2. Instruction Decoding
Code
Instruction
6.3
Bit3
Bit2
Bit1
Bit0
0
0
0
0
EXTEST
0
0
0
1
IDCODE
0
0
1
0
SAMPLE
0
0
1
1
RESERVED
0
1
0
0
RESERVED
0
1
0
1
RESERVED
0
1
1
0
RESERVED
0
1
1
1
PRIVATE
1
0
0
0
PRIVATE
1
0
0
1
HIGHZ
1
0
1
0
PRIVATE
1
0
1
1
PRIVATE
1
1
0
0
CLAMP
1
1
0
1
PRIVATE
1
1
1
0
PRIVATE
1
1
1
1
BYPASS
Boundary Scan Register Path
The MC92460 boundary scan register path is defined in another text file located on the
Motorola product web site in Boundary Scan Description Language (BSDL) format.
Chapter 6. IEEE 1149.1 Test Access Port
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Boundary Scan Register Path
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Chapter 7
Phase-Locked Loop
The MC92460 has two phase-locked loops, PLL1 and PLL2. Phase-locked loop 1 (PLL1)
generates all internal clocks for the MC92460. Using the SYSCLK external reference,
PLL1 as seen in Figure 7-1 generates a master clock as a reference for a bus clock and an
internal system clock that can be used by the baud rate generator in each HDLC controller.
Phase-locked loop 2 (PLL2) shown in Figure 7-2 receives the EXCLK to generate a baud
rate clock that also can be used by the baud rate generator in each HDLC controller. See
Chapter 4, “High-level Data Link Controller (HDLC)” for an explanation of the MC92460
baud rate generators.
7.1 PLL1
Phase-locked loop 1 divides SYSCLK to provide the system and bus clock for the
MC92460. VCO1 test output is provided by PLL1O.
VCO1
PLL1O
SYSCLK
÷2
Master
Clock
Phase-Locked
Loop 1
P Counter
MUX
Internal
System
Clock
MUX
Bus Clock
÷2
M Counter
÷2
Lock 1
Data Interface
Figure 7-1. PLL1 Block Diagram
Chapter 7. Phase-Locked Loop
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PLL Enable
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PLL2
7.2 PLL2
The phase-locked loop 2 (PLL2) EXCLK is divided by the values loaded into the P and M
counters from the PLL mode register to generate various frequencies for the baud rate
clock. VCO2 test output is provided by PLL2O.
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EXCLK
VCO2
Phase-Locked
Loop 2
PLL2O
Master Clock
(REFCLK)
P Counter
(÷ P)
M Counter
(÷ M)
MUX
Baud Rate
Clock
Lock 2
PLL Enable
Data Interface
Figure 7-2. PLL2 Block Diagram
7.3 Programmer’s Model of PLL 1 and PLL2
PLL1 has an M and a P counter with hardwired values that manipulate SYSCLK to
generate an internal system clock and a bus clock. The PLL2 has an M and a P counter,
which are programmable and divide EXCLK for setting the baud rate:
•
•
P Counter: Divides VCO output frequency and feeds it back to the PLL phase
comparator for comparison with the reference clocks SYSCLK or EXCLK.
M Counter: This is a PLL post-divider that divides VCO.
•
Baud rate = REFCLK X P value ÷ M value.
7.3.1 PLL Mode Register (PLL)
The PLL mode register controls PLL operation for the MC92460. By setting PLLEN, the
PLLs are enabled which generate a master clock used for an internal system clock, a bus
clock, and a baud rate clock. PLL2 uses the values written into PLL[P] and PLL[M] to
generate the desired baud rate clock. PLL1 uses P and M counter values that are hardwired
into the PLL1 to generate a 66 MHz internal clock and bus clock, given a 66 MHz
SYSCLK. PLL1 does not use writable PLL[P] or PLL[M].
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Operation of PLL1
When the PLLs are turned off, EXCLK goes directly to baud rate clock out, and SYSCLK
is used for the internal system clock and the bus clock. The lock bits are PLL status bits.
0
5
Field
6
11
P
—
0000_0000_0000_0000
R/W
R/W
16
Field
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15
M
Reset
17
18
22
—
—
Reset
R/W
12
23
24
PLLEN
29
—
30
31
LOCK1 LOCK2
0000_0000_0000_0000
R/W
R
R/W
R
R
R
Figure 7-3. PLL Mode Register (PLL)
Table 7-1. PLL Mode Register Field Descriptions
Bit
Field
Description
0–5
P
P-counters value. Only used in PLL2. Refer to Table 7-2.
6–11
M
M-counters value. Only used in PLL2. Refer to Table 7-2.
12-17
—
Reserved
18-22
—
Reserved.
23
PLLEN
24–29
—
30
Lock1
SYSCLK PLL1 lock/unlock status (read only)
0: PLL1 unlocked
1: PLL1 locked
31
Lock2
Baud rate PLL2 lock/unlock status (read only)
0: PLL2 unlocked
1: PLL2 locked
The PLLs can be enabled with this bit. When the PLLs are on, the internal master clock is
used. When the PLLs are turned off, the external SYSCLK and EXCLK are used.
0: PLLs Off
1: PLLs On
Reserved.
7.4 Operation of PLL1
PLL1 is enabled by setting PLLEN, and generates an internal system clock and a bus clock
at the same frequency as SYSCLK.
7.5 Operation of PLL2
This section describes the operation and preferred sequence for controlling phase-locked
loop 2. To generate a specific baud rate clock from PLL2, follow these steps:
Chapter 7. Phase-Locked Loop
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Operation of PLL2
•
•
•
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•
Set PLLEN, thereby turning on PLL operation
Write PLL[P] and PLL[M] register values into the PLL mode register. Refer to the
P and M register values of Table 7-2 to see the values needed.
These register values are bit reversed and loaded into the respective P and M
counters. Thus, if the hex value 0x0a, for example, is written into the register’s
six-bit P field with the binary value 0b001010, this binary value is bit reversed and
loaded into the P Counter with 0b010100, which has the decimal value of 20.
Wait for the Lock1 and Lock2 bits to be set to 1 (showing PLL1 and PLL2 are
locked).
Table 7-2 shows the baud rate clock frequencies with a 14.72 MHz EXCLK. The formula
used to calculate the baud rate clock is the following:
Baud rate clock = EXCLK * P / M
Table 7-2. Baud Rate Clock Output with 14.72 MHz EXCLK
P
Baud Rate (MHz)
M
PLLEN
Value
Register
Value1
Counter
Value2
Register
Value1
Counter
Value2
EXCLK
X
X
X
X
0
7.350
0x0a
20
0x05
40
1
14.720
0x0a
20
0x0a
20
1
22.080
0x06
24
0x02
16
1
29.440
0x06
24
0x0c
12
1
36.800
0x0a
20
0x04
8
1
44.160
0x06
24
0x04
8
1
51.520
0x0e
28
0x04
8
1
58.880
0x01
32
0x04
8
1
66.240
0x09
36
0x04
8
1
73.600
0x0a
20
0x08
4
1
80.960
0x1a
22
0x08
4
1
88.320
0x06
24
0x08
4
1
95.680
0x16
26
0x08
4
1
103.040
0x0e
28
0x08
4
1
110.400
0x1e
30
0x08
4
1
117.760
0x01
32
0x08
4
1
125.120
0x11
34
0x08
4
1
132.480
0x09
36
0x08
4
1
139.840
0x19
38
0x08
4
1
147.200
0x0a
20
0x10
2
1
154.560
0x2a
21
0x10
2
1
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Operation of PLL2
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Table 7-2. Baud Rate Clock Output with 14.72 MHz EXCLK (Continued)
161.920
0x1a
22
0x10
2
1
169.280
0x3a
23
0x10
2
1
176.640
0x06
24
0x10
2
1
184.000
0x26
25
0x10
2
1
191.360
0x16
26
0x10
2
1
198.720
0x36
27
0x10
2
1
206.080
0x0e
28
0x10
2
1
213.440
0x2e
29
0x10
2
1
220.800
0x1e
30
0x10
2
1
228.160
0x3e
31
0x10
2
1
235.520
0x01
32
0x10
2
1
242.880
0x21
33
0x10
2
1
250.240
0x11
34
0x10
2
1
257.600
0x31
35
0x10
2
1
264.960
0x09
36
0x10
2
1
272.320
0x29
37
0x10
2
1
279.680
0x19
38
0x10
2
1
287.040
0x39
39
0x10
2
1
294.400
0x05
40
0x10
2
1
294.400
0x0a
20
0x10
1
1
1
This is the hex value of the register field. Convert this hex value into a
binary value and enter into the register.
2 The register’s binary value is bit reversed and loaded into the counter.
This table show the decimal of the counter binary number.
Chapter 7. Phase-Locked Loop
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Operation of PLL2
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Chapter 8
Reset
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The MC92460 has several inputs to the reset logic:
•
•
•
Power-on reset (POR)
External hard reset (HRESET)
JTAG reset (TRST)
All of these reset sources are fed into the reset controller and, depending on the source of
the reset, different actions are taken.
8.1
Reset Causes
Table 8-1 describes reset causes.
Table 8-1. Reset Causes
Name
POR
HRESET
TRST
8.1.1
Description
Input pin. Asserting this pin initiates the power-on reset
sequence that resets both PLLs.
Input pin. Asserting this pin initiates the hard reset sequence
that resets all of the chip except the PLL and JTAG blocks.
When JTAG logic asserts the JTAG soft reset signal, an internal
soft reset sequence is generated.
Reset Actions
The reset block has reset control logic that determines the cause of reset, synchronizes it if
necessary, and resets the appropriate logic modules. The system control unit, HDLC
controller, master interface, register and I/O pins are initialized only on hard reset.
Chapter 8. Reset
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Reset Causes
Table 8-2 identifies reset actions for each reset source.
Table 8-2. Reset Action for Each Reset Source
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8.1.2
Name
Resets
Logic
Resets
PLL
Resets
JTAG
POR
No
Yes
No
HRESET
Yes
No
No
TRST
No
No
Yes
Power-On Reset Sequence
Assertion of the POR, TRST, and HRESET external signals initiates the power-on reset
sequence (reset flow). POR and TRST should be asserted externally for at least two input
clock cycles after external power to the chip reaches at least 2/3 Vcc (the CORE and I/O
supply voltages). PLL1 will be locked after the POR is negated and then will count 4096
SYSCLK cycles. When the PLL1 is locked, the clock block starts distributing clock signals
in the chip.
SYSCLK
POR
TRST
LOCK (Internal)
> 4096
HRESET
Figure 8-1. Reset Flow
8.1.3
HRESET Sequence
The HRESET sequence may be initiated externally by asserting HRESET for at least 4096
input clock cycles after POR is negated. Refer to Figure 8-1.
8.1.4
TRST
The test reset signal (TRST) is an asynchronous reset with an internal pull-up resister that
provides initialization of the TAP controller and other logic required by the IEEE1149.1
standard.
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Appendix A
Transaction and Bandwidth Calculations
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for the MC92460
This appendix specifies the number of access cycles the MC92460 requires to process
transactions, and provides information on improving 60x bus performance of HDLC data
transfers through using the MC92460’s external DMA mode.
A.1
Memory Cycles
Table A-1 shows the average number of clock cycles for DMA transactions. This cycle
count is for the whole period of a transaction, from preparation, bus grant, bus transfer,
through closing the transaction. The number of clock cycles for a transaction depends on
various factors including memory specifications, the last address or data tenure, the number
of wait cycles defined by a memory controller or a bus arbiter, whether a bottleneck exists
on the bus, and the pipeline-status at the transaction start.
NOTE
Table A-1 shows average clock cycles and is not related to
Figure A-1, which is an example of pipelined 4-beat burst
accesses.
Table A-1. Average Clock Cycles by External DMA
Single Beat
4-Beat Burst
Two 4-Beat Bursts
Type of Main Memory
READ
WRITE
READ
WRITE
READ
WRITE
SDRAM
(cas latency=2)
7+1
5+1
13 + 1
11 + 1
19 + 1
15 + 1
SyncBurstSRAM
(pipelined)
5+1
4+1
8+1
7+1
16 + 1
14 + 1
In this Table, (+1) is a minimum idle cycle and is inserted before each transaction.
Appendix A. Transaction and Bandwidth Calculations
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60x Bus Performance Consideration
Figure A-1 shows wave forms during a DMA access of two continuous 4-beat bursts. The
first read access to radr1 (memory address) is counted 9+1 for a 4-beat burst, and the
second 4-beat burst access radr2 is counted 16+1.
0 1 2 3 4 5 6 7 8 9 10................16
SYSCLK
A[0:31]
radr1
radr2
wadr1
ABB
D[0:63]
rd1
rd2
wd1
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TA
TT
0A
0A
06
TBST
Figure A-1. DMA Accesses: Two 4-Beat Burst Reads and One Write
A.2
60x Bus Performance Consideration
The MC92460’s buffer descriptor transmits data to and receives data from the DMA
module in a maximum 32 byte data size. The MC92460’s DMA module divides or
combines the data to adhere to a 32-byte alignment.
Table A-2 shows the transactions generated by a DMA read. In the table, “single” refers to
a single beat and “burst” means a 4-beat burst.
Table A-3 shows single-beat transactions generated by a DMA write. In the table,
7+8+8+8+1 means a single beat of 7 bytes, three beats of 8 bytes, and a single beat of 1
byte.
From these tables the data transfer speed can be calculated when the data is aligned along
a burst boundary. If the data’s destination or source address is burst aligned, it will take 1
burst access of 4 beats for a 32-byte read data event and two continuous burst accesses of 4
beats for a 32-byte write data event.
However, in the case of non-burst-aligned write data, it can take 5 write cycles for a 32-byte
data transfer. In addition, write cases such as an irregular start address or small data size
cause low bus performance (see the shading cells in Table A-3). In most cases cycle latency
will be lowest by aligning data on burst boundaries.
These considerations apply only to MC92460’s external DMA mode. The direct DMA
mode of the MC92460 accepts data only when the data is 8-byte aligned and in minimum
8-byte data units.
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60x Bus Performance Consideration
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In Table A-2, the rows are the data transfer size per set of external DMA read sequences,
and the columns are the lower start address of source memory by the same sequence. This
table shows the transactions that will be generated by the DMA in all cases.
Appendix A. Transaction and Bandwidth Calculations
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60x Bus Performance Consideration
Table A-2. External DMA Transactions–Read Sequence
Lower 5 Bits of DMA Start Address (Hex)
0
1
2
3
4
5
6
7
8
9
a
b
c
d
e
f
10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e
1
2
Single
3
4
5
6
Single
+ Single
8
9
a
b
c
d
Burst
Transfer size (hex bytes)
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7
e
f
10
11
12
13
14
15
16
17
Burst
+ Single
Single
+ Burst
18
19
1a
1b
1c
1d
Burst
+ Burst
1e
1f
20
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1f
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60x Bus Performance Consideration
In Table A-3, the rows are labeled data transfer size by one set of external DMA write
sequence, and the columns are labeled lower start address of destination memory by the
sequence. This table shows single-beat transactions that will be generated by the DMA
write in all cases.
Table A-3. External DMA Transactions–Write Sequence
Lower 3 Bits of Start Address
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Size
0
1
2
3
4
5
6
7
1
1
1
1
1
1
1
1
1
2
2
2
2
1-1
2
2
2
1-1
3
3
3
2-1
1-2
3
3
2-1
1-2
4
4
3-1
2-2
1-3
4
3-1
2-2
1-3
5
5
3-2
2-3
5
4-1
3-2
2-3
1-4
6
6
3-3
6
5-1
4-2
3-3
2-4
1-5
7
7
7
6-1
5-2
4-3
3-4
2-5
1-6
8
8
7-1
6-2
5-3
4-4
3-5
2-6
1-7
9
8-1
7-2
6-3
5-4
4-5
3-6
2-7
1-8
a
8-2
7-3
6-4
5-5
4-6
3-7
2-8
1-8-1
b
8-3
7-4
6-5
5-6
4-7
3-8
2-8-1
1-8-2
c
8-4
7-5
6-6
5-7
4-8
3-8-1
2-8-2
1-8-3
d
8-5
7-6
6-7
5-8
4-8-1
3-8-2
2-8-3
1-8-4
e
8-6
7-7
6-8
5-8-1
4-8-2
3-8-3
2-8-4
1-8-5
f
8-7
7-8
6-8-1
5-8-2
4-8-3
3-8-4
2-8-5
1-8-6
10
8-8
7-8-1
6-8-2
5-8-3
4-8-4
3-8-5
2-8-6
1-8-7
11
8-8-1
7-8-2
6-8-3
5-8-4
4-8-5
3-8-6
2-8-7
1-8-8
12
8-8-2
7-8-3
6-8-4
5-8-5
4-8-6
3-8-7
2-8-8
1-8-8-1
13
8-8-3
7-8-4
6-8-5
5-8-6
4-8-7
3-8-8
2-8-8-1
1-8-8-2
14
8-8-4
7-8-5
6-8-6
5-8-7
4-8-8
3-8-8-1
2-8-8-2
1-8-8-3
15
8-8-5
7-8-6
6-8-7
5-8-8
4-8-8-1
3-8-8-2
2-8-8-3
1-8-8-4
16
8-8-6
7-8-7
6-8-8
5-8-8-1
4-8-8-2
3-8-8-3
2-8-8-4
1-8-8-5
17
8-8-7
7-8-8
6-8-8-1
5-8-8-2
4-8-8-3
3-8-8-4
2-8-8-5
1-8-8-6
18
8-8-8
7-8-8-1
6-8-8-2
5-8-8-3
4-8-8-4
3-8-8-5
2-8-8-6
1-8-8-7
19
8-8-8-1
7-8-8-2
6-8-8-3
5-8-8-4
4-8-8-5
3-8-8-6
2-8-8-7
1-8-8-8
1a
8-8-8-2
7-8-8-3
6-8-8-4
5-8-8-5
4-8-8-6
3-8-8-7
2-8-8-8
1-8-8-8-1
1b
8-8-8-3
7-8-8-4
6-8-8-5
5-8-8-6
4-8-8-7
3-8-8-8
2-8-8-8-1
1-8-8-8-2
1c
8-8-8-4
7-8-8-5
6-8-8-6
5-8-8-7
4-8-8-8
3-8-8-8-1
2-8-8-8-2
1-8-8-8-3
Appendix A. Transaction and Bandwidth Calculations
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Total Theoretical Bus Bandwidth
Table A-3. External DMA Transactions–Write Sequence (Continued)
Lower 3 Bits of Start Address
1d
8-8-8-5
7-8-8-6
6-8-8-7
5-8-8-8
4-8-8-8-1
3-8-8-8-2
2-8-8-8-3
1-8-8-8-4
1e
8-8-8-6
7-8-8-7
6-8-8-8
5-8-8-8-1
4-8-8-8-2
3-8-8-8-3
2-8-8-8-4
1-8-8-8-5
1f
8-8-8-7
7-8-8-8
6-8-8-8-1
5-8-8-8-2
4-8-8-8-3
3-8-8-8-4
2-8-8-8-5
1-8-8-8-6
20
8-8-8-8 *1
7-8-8-8-1
6-8-8-8-2
5-8-8-8-3
4-8-8-8-4
3-8-8-8-5
2-8-8-8-6
1-8-8-8-7
Note: If the lower 4 bits of the starting address is 2’b_0000, this transaction is a 4-beat burst transaction.
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A.3
Total Theoretical Bus Bandwidth
The MC92460’s total bus bandwidth, or throughput (Tdt), is calculated by multiplying the
speed of the bus by its width by the number of beats per bus cycle. The formula for the
current version of the MC92460 is as follows:
Tdt (Mbps) = 66.7 MHz * 64 bits * 4 beats / N bus clocks)
In most cases, the theoretical maximum data transfer speed is defined by the number of
cycles required to access memory.
If, for example, one burst write cycle takes 7 clocks, and one burst read cycle takes 8clocks,
the average memory access cycle time N will be (8+1 +7+1)/2 = 8.5 clocks. In this case, the
theoretical maximum data transfer rate (Tdt) is as shown below:
Tdt (Mbps) = 64 bits x 4 beat x 66.7 (MHz) / (N=8.5 cycles) = 2000 Mbps*
*This is the theoretical data transfer value and ignores any memory service time (such as refresh time)
Table A-4. Theoretical Maximum Data Transfer Rate
Type of Main Memory
Typical Cycle Count for
4-Beat Burst
N
( Average Number
of Cycles)
Tdt
(Mbps)
READ
WRITE
SDRAM
(cas latency=2)
13 + 1
11 + 1
13
1300
SyncBurst SRAM
(pipelined)
8+1
7+1
8.5
1987
The cycle count (clock count during address issue and TA negation) is + 1.
The above value is calculated with ideal bus transactions, thus in the ideal environment,
read (or write) burst transactions are performed continuously, and only the MC92460 will
be granted the 60x bus.
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Typical Bandwidth
A.4
Typical Bandwidth
In real applications, it is impossible for the MC92460 to ensure the Tdt value, because there
are so many cases in which the bus grant might be issued to another master. Additionally,
the total data transfer speed of the HDLCs is different from the speed on the 60x bus over
a short time period. The following, therefore, should be used to calculate the realistic data
transfer speed.
Rbg = Estimated occupation rate of 60x bus by the MC92460’s external DMA
transactions (depends on the arbiter, firmware, HDLC channel usage)
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Thus, the Td may be as shown below in the application.
Td = Rbg x Tdt
Figure A-2 shows a example of 60x bus behavior with a PQII. In this example, instructions
are located in a SDRAM, the instruction cache is disabled, and the instruction has access
to an HDLC register. The approximate data transfer speed in the system can be estimated
as Td = 0.62 x 1300 = 800 Mbps. In most cases, overhead cycles from each bus-master
change can be ignored because of bus pipelining.
(Clock Cycles)
7+1
13+1
7+1
11+1
Instruction
Fetch
External DMA
Instruction
4-beat burst read
Execution
External DMA
4-beat burst write
Cm1 = Average clock cycles of PQII occupation = 7+1 = 8
N = Average clock cycles of MC92460 occupation = (13+1 +11 +1)/2 = 13
Rbg= N / (Cm1 + N) = 0.62
*The value is without any memory service time (for example refresh time)
*This figure is modeled to calculate the Rbg value, the real bus behavior is pipelined
Figure A-2. 60x Bus Behavior with PQII System
Note that single beat transactions may cause low bus performance. See Section A.2 .
Although the throughput of one HDLC channel can be 133 Mbps, the maximum throughput
of all channels is not a simple extrapolation of 40 X 133. Throughput approaches the
maximum 1919 Mbps linearly as illustrated in Figure A-3. The primary bottleneck on
throughput is that the maximum data tranfer speed for each of the transmission paths (Rx
and Tx) is 960 Mbps.
Appendix A. Transaction and Bandwidth Calculations
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Maximum Throughput Measurement
1900
Tx/Rx CK= 66.7MHz
1500
33.3MHz
1200
16.7MHz
Mbps
900
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600
300
133
66
33
1
5
10
15
20
25
30
35
40
Number of channels
Figure A-3. Throughput Increase per Number of Channels Used
Finally, it is important to note that when the MC92460’s own communication buffers are
used, the maximum data transfer speed may be faster. An example of this is a configuration
using the MC92460’s communication buffer as the transmit buffer and accessing external
memory through a DMA transaction for the receive buffer.
A.5
Maximum Throughput Measurement
Table A-5 shows the MC92460’s performance data measured from a real application.
All the HDLCs are assigned loop-back mode to measure the strict maximum performance
of the device. All 80 channels (40 Rx and 40 Tx) are enabled, and each channel uses a
default BD. All TxBDs indicate the same address as their Tx buffer memory, each RxBD
indicates the independent (unique) memory address as their Rx buffer memory. All TxBDs
and RxBDs are configured in "continuous mode," thus each channel continues to
transmit/receive frames during the test. Because some BDs are closed by overrun or
underrun status, the maximum data throughput can be measured by counting the number of
these error BDs.
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Maximum Throughput Measurement
Table A-5. Maximum Throughput
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Tx Buffer
Rx Buffer
Tx/Rx CLK
Frequency
Number of channels
Tx
Rx
Transferred Data
Size
TT (Mbps)
Actual
Throughput
AT (Mbps)
SPRAM
SPRAM
33.3MHz
29ch
29ch
1933
1919
SDRAM
SDRAM
16.7MHz
40ch
39ch
1317
1297
SPRAM
none
33.3MHz
29ch
-
967
960
none
SPRAM
33.3MHz
-
29ch
967
960
SDRAM
SPRAM
33.3MHz
22ch
22ch
1466
1443
SDRAM
none
22.2MHz
33ch
-
733
722
none
SDRAM
22.2MHz
-
35ch
778
766
Shows the
source buffer
location for the
transmit
Shows the
destination
buffer location
for the reception.
Shows the data
throughput.
Shows the actual
data throughput
excluding flags.
Shows the maximum
number of channels
which succeed to transfer data without overrun/underrun.
SPRAM : communication buffer 0x0~0x7FFF.
AT = TT x ( PD / AD)
PD : Pure data size excluding start/end flag.
AD : Full data size which is transferred.
The size of a frame is 128 or 288 bytes.
Appendix A. Transaction and Bandwidth Calculations
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Maximum Throughput Measurement
MC92460 Multichannel HDLC User’s Manual
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Index
Numerics
setting parameters, 4-14
Clocks
baud rate, 7-2
internal bus, 7-1
Command register (CMR), 4-21
Communication buffer (SRAM), 3-11
Continuous mode (CM), 3-2
Control field, 4-4
60x bus performance consideration, A-2
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A
Access cycles, A-1
Address field, 4-3
AMODE, 2-6, 5-10
Arbiter
general, 5-7
modes, 5-10
system bus, 5-7
D
Data synchronization register (DSR), 4-19
Data transfer rates, A-6
Destination address (DMADA), 5-4
Device identification register, 6-3
Direct memory access (DMA), 5-2
DMA
mode register (DMAMR), 5-5
modules, 5-2
transaction cycles, A-1
B
Bandwidth
calculations, A-1, A-6
typical, A-7
Base offset address, 4-15
Baud rate
calculation, 4-23
generation, 7-3
generator, 4-22
BD, 4-6
Block diagram
component, 1-1
HDLC, 4-2
PLLs, 7-1
signals, 2-1
Boundary scan
operations, 6-1
register, 6-4
BRG configuration registers (BRGCx), 4-23
Buffer descriptors
general, 4-6
table, 4-7
Bypass register, 6-4
E
Error control, 4-1
Error handling, 4-16
Event register/mask register (ER)/(MR), 4-19
EXCLK
PLL2, 7-2
External memory receive, 3-2
External memory transit, 3-4
F
Features overview, 1-2
Flag sequence field, 4-3
Frame check sequence field, 4-5
Frame structure, 4-3
H
C
HDLC
block diagram, 4-2
channels, 3-8
commands, 4-21
error control, 4-1
features, 4-2
Channel frame transmission, 4-3
Channels
HDLC, 3-8
reconfiguring Rx, 3-10
reconfiguring Tx, 3-11
Index
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frame structure, 4-3
interrupt, 3-7
HRESET, 8-2
PLL2, 7-2, 7-3
POR, 8-2
Power-on reset sequence, 8-2
Process revision register (PRR), 1-11
I
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Information field, 4-5
Instruction register, 6-3
Internal memory map register (IMMR), 1-11
Interrupt status register 1 (INTS1), 3-7
Interrupt status register 2 (INTS2), 3-8
Interrupts
HDLC, 3-7
status register, 3-7
J
JTAG
instruction support, 6-4
user code, 1-12
M
Master interface unit (MIU), 5-1
Maximum HDLC channel register (MMCR), 3-9
Maximum throughput measurement, A-8
MC92460
configurations
MPC603e, 1-15
MPC8260 with MC92460 master and MC92460
slave, 1-14
MPC8260 with MC92460 slaves, 1-12
features, 1-2
Memory
cycles, A-1
direct access, 5-2
external receive, 3-2
external transmit, 3-4
Memory maps
HDLC channels, 4-15
internal, 1-10
internal and register, 1-3
Mode register (MRA), 4-17
Mode register 0 (ARBM0), 5-9
Mode register 1 (ARBM1), 5-9
Mode signal, 2-6, 5-10
MPC106, 1-15
MRBLR, 4-6
P
Parameter RAM, 4-14
Performance, A-1
Pin assignment, 2-2
PLL1, 7-1, 7-3
R
RAM parameter, 4-14
Receive buffer descriptor, 3-2, 4-6
Receiving flow diagram, 4-11
Registers
ARBM0, 5-9
ARBM1, 5-9
boundary scan, 6-4
BRGC, 4-23
bypass, 6-4
CMR, 4-21
device identification, 6-3
DMADA, 5-4
DMAEA, 5-7
DMAMR, 5-5
DMASA, 5-3
DMASR, 5-6
DMATS, 5-3
DSR, 4-19
ER, 4-19
IMMR, 1-11
INTS1, 3-7
INTS2, 3-8
MMCR, 3-9
MR, 4-19
MRA, 4-17
PLL, 7-2
PRR, 1-11
RBASE, 3-10
RxBD, 4-8
SMR, 5-2
SR, 4-20
TBASE, 3-11
test instruction, 6-3
TxBD, 4-9
Reset
actions, 8-1
causes, 8-1
flow, 8-2
RxBD
diagram, 4-11
structure, 4-6
table base address (RBASE) register, 3-10
table base addresses, 3-9
S
Signals
external diagram, 2-1
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mode, 2-6
Source address (DMASA), 5-3
SRAM
buffers, 4-7
using as buffer, 3-5, 3-6, 3-11
Status register (SR), 4-20
System control unit (SCU), 3-1
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T
TAP controller, 6-2
Theoretical bus bandwidth, A-6
Transfer size (DMATS), 5-3
Transmit buffer descriptor, 3-4, 4-6
Transmitting flow diagram, 4-12
TRST, 8-2
TxBD
data sequence, 3-4
example, 4-12
structure, 4-6
table base address (TBASE) register, 3-11
table base addresses, 3-9
Index
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