AMCC S5935QF

Part Number S5935
Revision 1.02 – June 27, 2006
S5935
Data Book
PCI Product
S5935
PCI PRODUCT
DATA BOOK
AMCC Confidential and Proprietary
DS1527
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Revision 1.02 – June 27, 2006
S5935 – PCI Product
Data Book
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DS1527
AMCC Confidential and Proprietary
Part Number S5935
Revision 1.02 – June 27, 2006
S5935
Data Book
PCI Product
FEATURES
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DESCRIPTION
PCI 2.1 Compliant Master/Slave Device
Full 132 Mbytes/sec Transfer Rate
Supports new Intel 440BX/GX Chipsets
Supports new WinNT Service Pack 2 & 3
PCI Bus Operation DC to 33 MHz
8/16/32 Bit Add-On User Bus
Four Definable Pass-Thru Data Channels
Two 32 Byte Internal FIFOs w/DMA
Synchronous Add-On Bus Operation
Mail Box Registers w/Byte Level Status
Direct Mail Box Data Strobe/Interrupts
Direct PCI & Add-On Interrupt Pins
Optional Non-Volatile Memory Boot Loading
Optional Expansion BIOS/POST Code
The PCI Local bus concept was developed to break
the PC data I/O bottleneck and clearly opens the door
to increasing system speed and expansion capabilities. The PCI Local bus moves high speed peripherals
from the I/O bus and places them closer to the system’s processor bus, providing faster data transfers
between the processor and peripherals. The PCI Local
bus also addresses the industry’s need for a bus standard which is not directly dependent on the speed,
size and type of system processor. It represents the
first microprocessor independent bus offering performance more than adequate for the most demanding
applications such as full-motion video.
Applied Micro Circuits Corporation (AMCC), the premier supplier of single chip solutions, has developed
the S5935 to solve the problem of interfacing applications to the PCI Local bus while offering support for
newer PCI chipsets and operating systems. The
S5935 is a powerful and flexible PCI controller supporting several levels of interface sophistication. At the
lowest level, it can serve simply as a PCI bus Target
with modest transfer requirements. For high-performance applications, the S5935 can become a Bus
Master to attain the PCI Local bus peak transfer capability of 132 MBytes/sec. The S5935 PCI controller
also maintains dropin compatibility for upgrading many
existent S5933 designs requiring migration into new
motherboard architectures, PCI BIOSs and software
operating systems.
APPLICATIONS
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High Speed Networking
Digital Video Applications
I/O Communications Ports
High Speed Data Input/Output
Multimedia Communications
Memory Interfaces
High Speed Data Acquisition
Data Encryption/Decryption
Intel i960 Interface
General Purpose PCI Interfacing
Existent S5933 Design Upgrades
PCI Local Bus
Figure 1. S5935 Block Diagram
2.1 PCI Local Bus
Interface Logic
S5935
User
Application
Pass-Thru Data &
Address Registers
I/O Audio
Bus MasterTransfer
Count &Address
Registers
FIFOs
AMCC
Add-On
Local Bus
Interface Logic
Mailboxes
Mux/Demux
Configuration
Registers
Buffers
Mux/Demux
Buffers
Read/Write
Control
Status Registers
ISDN
FDDI
ATM
Graphics/
MPEG/
Grabber
Proprietary
Backplane
Satellite
Receiver/
Modem
Serial/Parallel nvRAM
Configuration Space
Expansion BIOS
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S5935 – PCI Product
Data Book
TABLE OF CONTENTS
FEATURES .............................................................................................................................................................. 3
APPLICATIONS ...................................................................................................................................................... 3
DESCRIPTION ........................................................................................................................................................ 3
TABLE OF CONTENTS .......................................................................................................................................... 4
LIST OF FIGURES .................................................................................................................................................. 9
LIST OF TABLES .................................................................................................................................................. 12
S5935 ARCHITECTURE ....................................................................................................................................... 14
S5935 Register Architecture ............................................................................................................................ 14
PCI Configuration Registers ............................................................................................................................ 15
PCI Operation Registers .................................................................................................................................. 15
Add-On Bus Operation Registers .................................................................................................................... 16
Non-Volatile Memory Interface ........................................................................................................................ 16
Mailbox Operation ........................................................................................................................................... 17
Pass-Thru Operation ....................................................................................................................................... 19
FIFO PCI Bus Mastering Operation ................................................................................................................. 19
Signal Type Definition ...................................................................................................................................... 23
NON-VOLATILE MEMORY INTERFACE SIGNALS ............................................................................................ 27
ADD-ON BUS INTERFACE SIGNALS .................................................................................................................. 28
PCI CONFIGURATION REGISTERS .................................................................................................................... 32
VENDOR IDENTIFICATION REGISTER (VID) ..................................................................................................... 34
DEVICE IDENTIFICATION REGISTER (DID) ....................................................................................................... 35
PCI COMMAND REGISTER (PCICMD) ................................................................................................................ 36
PCI STATUS REGISTER (PCISTS) ...................................................................................................................... 38
REVISION IDENTIFICATION REGISTER (RID) ................................................................................................... 40
CLASS CODE REGISTER (CLCD) ....................................................................................................................... 41
CACHE LINE SIZE REGISTER (CALN) ............................................................................................................... 45
LATENCY TIMER REGISTER (LAT) .................................................................................................................... 46
HEADER TYPE REGISTER (HDR) ....................................................................................................................... 47
BUILT-IN SELF-TEST REGISTER (BIST) ............................................................................................................ 48
BASE ADDRESS REGISTERS (BADR) ............................................................................................................... 49
Determining Base Address Size ...................................................................................................................... 49
Assigning the Base Address ............................................................................................................................ 49
EXPANSION ROM BASE ADDRESS REGISTER (XROM) ................................................................................. 53
INTERRUPT LINE REGISTER (INTLN) ................................................................................................................ 55
INTERRUPT PIN REGISTER (INTPIN) ................................................................................................................. 56
MINIMUM GRANT REGISTER (MINGNT) ............................................................................................................ 57
MAXIMUM LATENCY REGISTER (MAXLAT) ...................................................................................................... 58
OUTGOING MAILBOX REGISTERS (OMB) ........................................................................................................ 61
INCOMING MAILBOX REGISTERS (IMB) ........................................................................................................... 61
FIFO REGISTER PORT (FIFO) ............................................................................................................................. 61
PCI CONTROLLED BUS MASTER WRITE ADDRESS REGISTER (MWAR) ..................................................... 62
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PCI CONTROLLED BUS MASTER WRITE TRANSFER COUNT REGISTER (MWTC) ..................................... 63
PCI CONTROLLED BUS MASTER READ ADDRESS REGISTER (MRAR) ....................................................... 64
PCI CONTROLLED BUS MASTER READ TRANSFER COUNT REGISTER (MRTC) ........................................ 65
MAILBOX EMPTY FULL/STATUS REGISTER (MBEF) ....................................................................................... 66
INTERRUPT CONTROL/STATUS REGISTER (INTCSR) .................................................................................... 68
MASTER CONTROL/STATUS REGISTER (MCSR) ............................................................................................ 72
ADD-ON BUS OPERATION REGISTERS ............................................................................................................ 76
ADD-ON INCOMING MAILBOX REGISTERS (AIMBX) ....................................................................................... 77
ADD-ON OUTGOING MAILBOX REGISTERS (AOMBX) .................................................................................... 77
ADD-ON FIFO REGISTER PORT (AFIFO) ........................................................................................................... 77
ADD-ON CONTROLLED BUS MASTER WRITE ADDRESS REGISTER (MWAR) ............................................ 78
ADD-ON PASS-THRU ADDRESS REGISTER (APTA) ........................................................................................ 79
ADD-ON PASS-THRU DATA REGISTER (APTD) ............................................................................................... 79
ADD-ON CONTROLLED BUS MASTER READ ADDRESS REGISTER (MRAR) ............................................... 80
ADD-ON EMPTY/FULL STATUS REGISTER (AMBEF) ...................................................................................... 81
ADD-ON INTERRUPT CONTROL/STATUS REGISTER (AINT) .......................................................................... 83
ADD-ON GENERAL CONTROL/STATUS REGISTER (AGCSTS) ...................................................................... 86
ADD-ON CONTROLLED BUS MASTER WRITE TRANSFER COUNT REGISTER (MWTC) ............................. 89
ADD-ON CONTROLLED BUS MASTER READ TRANSFER COUNT REGISTER (MRTC) ............................... 90
INITIALIZATION .................................................................................................................................................... 92
PCI RESET ............................................................................................................................................................ 92
LOADING FROM BYTE-WIDE NV MEMORIES ................................................................................................... 92
PCI BUS CONFIGURATION CYCLES .................................................................................................................. 95
EXPANSION BIOS ROMS .................................................................................................................................... 97
PCI BUS INTERFACE ......................................................................................................................................... 100
PCI BUS TRANSACTIONS ................................................................................................................................. 100
PCI BURST TRANSFERS ................................................................................................................................... 102
PCI Read Transfers ....................................................................................................................................... 102
PCI Write Transfers ....................................................................................................................................... 104
Master-Initiated Termination .......................................................................................................................... 105
Normal Cycle Completion .............................................................................................................................. 105
Initiator Preemption ....................................................................................................................................... 106
Master Abort .................................................................................................................................................. 107
Target-Initiated Termination .......................................................................................................................... 107
Target Disconnects ........................................................................................................................................ 108
Target Requested Retries ............................................................................................................................. 109
Target Aborts ................................................................................................................................................. 109
PCI BUS MASTERSHIP ...................................................................................................................................... 111
Bus Mastership Latency Components ........................................................................................................... 111
Bus Arbitration ............................................................................................................................................... 111
Bus Acquisition .............................................................................................................................................. 112
Target Latency ............................................................................................................................................... 112
Target Locking ............................................................................................................................................... 112
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PCI BUS INTERRUPTS ...................................................................................................................................... 114
PCI BUS PARITY ERRORS ................................................................................................................................ 114
ADD-ON BUS INTERFACE ................................................................................................................................. 116
ADD-ON OPERATION REGISTER ACCESSES ................................................................................................ 116
Add-On Interface Signals .............................................................................................................................. 116
System Signals .............................................................................................................................................. 116
Register Access Signals ................................................................................................................................ 116
Asynchronous Register Accesses ................................................................................................................. 117
Synchronous FIFO and Pass-Thru Data Register Accesses ........................................................................ 117
nv Memory Accesses Through the Add-On General Control/Status Register ............................................... 117
MAILBOX BUS INTERFACE .............................................................................................................................. 117
Mailbox Interrupts .......................................................................................................................................... 120
FIFO BUS INTERFACE ....................................................................................................................................... 120
FIFO Direct Access Inputs ............................................................................................................................. 120
FIFO Status Signals ...................................................................................................................................... 120
FIFO Control Signals ..................................................................................................................................... 120
PASS-THRU BUS INTERFACE .......................................................................................................................... 120
Pass-Thru Status Indicators .......................................................................................................................... 120
Pass-Thru Control Inputs ............................................................................................................................... 120
NON-VOLATILE MEMORY INTERFACE ........................................................................................................... 121
Non-Volatile Memory Interface Signals ......................................................................................................... 121
Accessing Non-Volatile Memory .................................................................................................................... 121
nv Memory Device Timing Requirements ...................................................................................................... 124
MAILBOX OVERVIEW ........................................................................................................................................ 126
FUNCTIONAL DESCRIPTION ............................................................................................................................ 126
Mailbox Empty/Full Conditions ...................................................................................................................... 127
Mailbox Interrupts .......................................................................................................................................... 127
Add-On Outgoing Mailbox 4, Byte 3 Access ................................................................................................. 127
BUS INTERFACE ................................................................................................................................................ 128
PCI Bus Interface .......................................................................................................................................... 128
Add-On Bus Interface .................................................................................................................................... 128
8-Bit and 16-Bit Add-On Interfaces ................................................................................................................ 128
CONFIGURATION ............................................................................................................................................... 129
Mailbox Status ............................................................................................................................................... 129
Mailbox Interrupts .......................................................................................................................................... 130
FIFO OVERVIEW ................................................................................................................................................ 134
FUNCTIONAL DESCRIPTION ............................................................................................................................ 134
FIFO Buffer Management and Endian Conversion ....................................................................................... 134
FIFO Advance Conditions ............................................................................................................................. 134
Endian Conversion ........................................................................................................................................ 135
64-Bit Endian Conversion .............................................................................................................................. 136
Add-On FIFO Status Indicators ..................................................................................................................... 137
Add-On FIFO Control Signals ........................................................................................................................ 137
PCI Bus Mastering with the FIFO .................................................................................................................. 137
Add-On Initiated Bus Mastering ..................................................................................................................... 137
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PCI Initiated Bus Mastering ........................................................................................................................... 138
Address and Transfer Count Registers ......................................................................................................... 138
Bus Mastering FIFO Management Schemes ................................................................................................ 138
FIFO Bus Master Cycle Priority ..................................................................................................................... 139
FIFO Generated Bus Master Interrupts ......................................................................................................... 139
BUS INTERFACE ................................................................................................................................................ 139
FIFO PCI Interface (Target Mode) ................................................................................................................. 139
FIFO PCI Interface (Initiator Mode) ............................................................................................................... 140
FIFO PCI Bus Master Reads ......................................................................................................................... 142
FIFO PCI Bus Master Writes ......................................................................................................................... 142
Add-On Bus Interface .................................................................................................................................... 142
Add-On FIFO Register Accesses .................................................................................................................. 142
Add-On FIFO Direct Access Mode ................................................................................................................ 142
Additional Status/Control Signals for Add-On Initiated Bus Mastering .......................................................... 144
FIFO Generated Add-On Interrupts ............................................................................................................... 145
8-Bit and 16-Bit FIFO Add-On Interfaces ...................................................................................................... 145
CONFIGURATION ............................................................................................................................................... 146
FIFO Setup During Initialization ..................................................................................................................... 146
FIFO Status and Control Bits ......................................................................................................................... 146
PCI Initiated FIFO Bus Mastering Setup ....................................................................................................... 147
PASS-THRU OVERVIEW .................................................................................................................................... 149
FUNCTIONAL DESCRIPTION ............................................................................................................................ 149
Pass-Thru Transfers ...................................................................................................................................... 150
Pass-Thru Status/Control Signals ................................................................................................................. 151
Pass-Thru Add-On Data Bus Sizing .............................................................................................................. 151
BUS INTERFACE ................................................................................................................................................ 151
PCI Bus Interface .......................................................................................................................................... 151
PCI Pass-Thru Single Cycle Accesses .......................................................................................................... 151
PCI Pass-Thru Burst Accesses ..................................................................................................................... 152
PCI Retry Conditions ..................................................................................................................................... 152
PCI Write Retries ........................................................................................................................................... 152
PCI Read Retries ........................................................................................................................................... 153
Add-On Bus Interface .................................................................................................................................... 153
Single Cycle Pass-Thru Writes ...................................................................................................................... 153
Single Cycle Pass-Thru Reads ...................................................................................................................... 156
Pass-Thru Burst Writes ................................................................................................................................. 156
Pass-Thru Burst Reads ................................................................................................................................. 161
Add-On Pass-Thru Disconnect Operation ..................................................................................................... 165
8-Bit and 16-Bit Pass-Thru Add-On Bus Interface ......................................................................................... 166
CONFIGURATION ............................................................................................................................................... 170
S5935 Base Address Register Definition ...................................................................................................... 170
Creating a Pass-Thru Region ........................................................................................................................ 170
Accessing a Pass-Thru Region ..................................................................................................................... 171
ABSOLUTE MAXIMUM RATINGS ...................................................................................................................... 173
DC CHARACTERISTICS ..................................................................................................................................... 173
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PCI BUS SIGNALS ............................................................................................................................................. 174
ADD-ON BUS SIGNALS ..................................................................................................................................... 175
AC CHARACTERISTICS ..................................................................................................................................... 176
PCI Bus Timings ............................................................................................................................................ 176
ADD-ON BUS TIMINGS ...................................................................................................................................... 178
Synchronous RDFIFO# Timing ..................................................................................................................... 179
Synchronous WRFIFO# Timing ..................................................................................................................... 180
Asynchronous RD# Register Access Timing ................................................................................................. 181
Asynchronous WR# Register Access Timing ................................................................................................ 182
Synchronous RD# FIFO Timing .................................................................................................................... 183
Synchronous Multiple RD# FIFO Timing ....................................................................................................... 184
Synchronous WR# FIFO Timing .................................................................................................................... 185
Synchronous Multiple WR# FIFO Timing ...................................................................................................... 186
Target S5935 Pass-Thru Interface Timings ................................................................................................... 187
Target Byte-Wide nv Memory Interface Timings ........................................................................................... 189
Target Interrupt Timings ................................................................................................................................ 191
S5935 Pinout and Pin Assignment - 160 PQFP ............................................................................................ 193
S5935 Pinout and Pin Assignment - 208 TQFP ............................................................................................ 194
S5935 Numerical Pin Assignment - 160 PQFP ............................................................................................. 195
Package Physical Dimensions - 160 PQFP .................................................................................................. 197
DOCUMENT REVISION HISTORY ..................................................................................................................... 203
Ordering Information ...................................................................................................................................... 204
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Data Book
LIST OF FIGURES
Figure 1. S5935 Block Diagram ............................................................................................................................... 3
Figure 2. ................................................................................................................................................................ 14
Figure 3. ................................................................................................................................................................ 18
Figure 4. ................................................................................................................................................................ 19
Figure 5. ................................................................................................................................................................ 20
Figure 6. S5933 Pin Assignment ........................................................................................................................... 21
Figure 7. S5935 Signal Pins .................................................................................................................................. 23
Figure 8. Vendor Identification Register ................................................................................................................. 34
Figure 9. Device Identification Register ................................................................................................................. 35
Figure 10. PCI Command Register ........................................................................................................................ 36
Figure 11. PCI Status Register .............................................................................................................................. 38
Figure 12. Revision Identification Register ............................................................................................................ 40
Figure 13. .............................................................................................................................................................. 41
Figure 14. Cache Line Size Register ..................................................................................................................... 45
Figure 15. Latency Timer Register ......................................................................................................................... 46
Figure 16. Header Type Register ........................................................................................................................... 47
Figure 17. Built-In Self Test Register ..................................................................................................................... 48
Figure 18. Base Address Register — Memory ....................................................................................................... 49
Figure 19. Expansion ROM Base Address Register .............................................................................................. 53
Figure 20. Interrupt Line Register .......................................................................................................................... 55
Figure 21. Interrupt Pin Register ............................................................................................................................ 56
Figure 22. Minimum Grant Register ....................................................................................................................... 57
Figure 23. Maximum Latency Register .................................................................................................................. 58
Figure 24. PCI Controlled Bus Master Write Address Register ............................................................................. 62
Figure 25. PCI Controlled Bus Master Write Transfer Count Register ................................................................... 63
Figure 26. PCI Controlled Bus Master Read Address Register ............................................................................. 64
Figure 27. PCI Controlled Bus Master Read Transfer Count Register .................................................................. 65
Figure 28. Mailbox Empty/Full Status Register ...................................................................................................... 66
Figure 29. Interrupt Control/Status Register .......................................................................................................... 68
Figure 30. FIFO Management and Endian Control Byte ........................................................................................ 69
Figure 31. Bus Master Control/Status Register ..................................................................................................... 72
Figure 32. Add-On Controlled Bus Master Write Address Register ....................................................................... 78
Figure 33. Add-On Controlled Bus Master Read Address Register ....................................................................... 80
Figure 34. Add-On Mailbox Empty/Full Status Register ......................................................................................... 81
Figure 35. Add-On Interrupt Control/Status Register ............................................................................................. 83
Figure 36. Add-On General Control/Status Register ............................................................................................. 86
Figure 37. Add-On Controlled Bus Master Write Transfer Count Register ............................................................ 89
Figure 38. Add-On Controlled Bus Master Read Transfer Count Register ............................................................ 90
Figure 39. Serial Interface Definition of Start and Stop .......................................................................................... 94
Figure 40. Serial Interface Clock/Data Relationship .............................................................................................. 94
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Figure 41. Serial Interface Byte Access — Write ................................................................................................... 94
Figure 42. Serial Interface Byte Access — Read ................................................................................................... 94
Figure 43. PCI AD Bus Definition During a Type 0 Configuration Access ............................................................. 95
Figure 44. Type 0 Configuration Read Cycles ....................................................................................................... 96
Figure 45. Type 0 Configuration Write Cycles ....................................................................................................... 96
Figure 46. Zero Wait State Burst Read PCI Bus Transfer (S5935 as Initiator) .................................................... 102
Figure 47. Single Data Phase PCI Bus Read of S5935 Registers (S5935 as Target) ......................................... 103
Figure 48. Burst PCI Bus Read Attempt to S5935 Registers (S5935 as Target) ................................................. 103
Figure 49. Zero Wait State Burst Write PCI Bus Transfer (S5935 as Initiator) .................................................... 104
Figure 50. Single Data Phase PCI Bus Write of S5935 Registers (S5935 as Target) ......................................... 105
Figure 51. Master-Initiated, Normal Completion (S5935 as either Target or Initiator) ......................................... 105
Figure 52. Master Initiated Termination Due to Preemption and Latency Timer Active (S5935 as Master) ........ 106
Figure 53. Master Initiated Termination Due to Preemption and Latency Timer Expired (S5935 as Master) ...... 106
Figure 54. Master Abort, No Response ............................................................................................................... 107
Figure 55. Target Disconnect Example 1 (IRDY# deasserted) ............................................................................ 108
Figure 56. Target-Initiated Retry .......................................................................................................................... 109
Figure 57. Target Abort Example ......................................................................................................................... 110
Figure 58. PCI Bus Arbitration and S5935 Bus Ownership Example ................................................................... 110
Figure 59. PCI Bus Access Latency Components ............................................................................................... 111
Figure 60. Engaging the LOCK# Signal ............................................................................................................... 112
Figure 61. Access to a Locked Target by its Owner ............................................................................................ 113
Figure 62. Access Attempt to a Locked Target .................................................................................................... 113
Figure 63. Error Reporting Signals ...................................................................................................................... 115
Figure 64. Asynchronous Add-On Operation Register Read ............................................................................... 118
Figure 65. Asynchronous Add-On Operation Register Write ............................................................................... 118
Figure 66. Synchronous FIFO or Pass-Thru Data Register Read ....................................................................... 119
Figure 67. Synchronous FIFO or Pass-Thru Data Register Write ........................................................................ 119
Figure 68. nv Memory Read Operation ................................................................................................................ 124
Figure 69. nv Memory Write Operation ................................................................................................................ 125
Figure 70. Block Diagram - PCI to Add-On Mailbox Register .............................................................................. 126
Figure 71. Block Diagram - Add-On to PCI Mailbox Register .............................................................................. 126
Figure 72. INTCSR FIFO Advance and Endian Control Bits ................................................................................ 134
Figure 73. Figure 2a. 16-bit Endian Conversion .................................................................................................. 135
Figure 74. PCI Read from a Full S5935 FIFO ...................................................................................................... 140
Figure 75. PCI Read from an Empty S5935 FIFO (Target Disconnect) ............................................................... 140
Figure 76. PCI Write to an Empty S5935 FIFO .................................................................................................... 141
Figure 77. PCI Write to a Full S5935 FIFO (Target Disconnect) .......................................................................... 141
Figure 78. Synchronous FIFO Register Burst Read Access Example ................................................................. 143
Figure 79. Synchronous FIFO Register Burst RDFIFO# Access Example .......................................................... 144
Figure 80. Single Cycle Pass-Thru Write ............................................................................................................. 153
Figure 81. Single Cycle Pass-Thru Write with PTADR# ...................................................................................... 154
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Figure 82. Single Cycle Pass-Thru Read with PTADR# ...................................................................................... 158
Figure 83. Pass-Thru Burst Write ........................................................................................................................ 158
Figure 84. Pass-Thru Burst Writes Controlled by PTRDY# ................................................................................. 159
Figure 85. Pass-Thru Burst Read ........................................................................................................................ 161
Figure 86. PCI Burst Read Controlled by PTRDY# .............................................................................................. 163
Figure 87. Target Requested Retry on the First PCI Data Phase ........................................................................ 165
Figure 88. Target Requested Retry after the First Data Phase of a Burst Operation .......................................... 166
Figure 89. Pass-Thru Signals after a Target Requested Retry ............................................................................ 167
Figure 90. Pass-Thru Write to an 8-bit Add-On Device ........................................................................................ 169
Figure 91. PCI Clock Timing ................................................................................................................................ 176
Figure 92. PCI Output Timing .............................................................................................................................. 177
Figure 93. PCI Input Timing ................................................................................................................................. 177
Figure 94. Add-On Clock Timing .......................................................................................................................... 178
Figure 95. Pass-Thru Clock Relationship to PCI Clock ........................................................................................ 178
Figure 96. Synchronous RDFIFO# Timing ........................................................................................................... 179
Figure 97. Synchronous WRFIFO# Timing .......................................................................................................... 180
Figure 98. Asynchronous RD# FIFO Timing ........................................................................................................ 181
Figure 99. Asynchronous WR# FIFO Timing ....................................................................................................... 182
Figure 100. Synchronous RD# FIFO Timing ........................................................................................................ 183
Figure 101. Synchronous RD# FIFO Timing ........................................................................................................ 184
Figure 102. Synchronous WR# FIFO Timing ....................................................................................................... 185
Figure 103. Synchronous Multiple WR# FIFO Timing .......................................................................................... 186
Figure 104. Pass-Thru Data Register Read Timing ............................................................................................. 188
Figure 105. Pass-Thru Data Register Write Timing ............................................................................................. 188
Figure 106. Pass-Thru Status Indicator Timing ................................................................................................... 189
Figure 107. nv Memory Read Timing ................................................................................................................... 190
Figure 108. nv Memory Write Timing ................................................................................................................... 190
Figure 109. IRQ# Interrupt Output Timing ........................................................................................................... 191
Figure 110. Mailbox 4, Byte 3 Direct Input Timing ............................................................................................... 191
Figure 111. S5935 - 160 PQFP Package Drawing .............................................................................................. 197
Figure 112. S5935 - Marking Drawing ................................................................................................................. 198
Figure 113. Package Physical Dimension - 208 TQFP ........................................................................................ 202
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LIST OF TABLES
Table 1. PCI Configuration Registers .................................................................................................................... 15
Table 2. PCI Operation Registers .......................................................................................................................... 16
Table 3. Add-On Bus Operation Registers ............................................................................................................ 17
Table 4. Configuration Registers ........................................................................................................................... 32
Table 5. Vendor Identification Register .................................................................................................................. 34
Table 6. Device Identification Register .................................................................................................................. 35
Table 7. PCI Command Register ........................................................................................................................... 37
Table 8. PCI Status Register ................................................................................................................................. 39
Table 9. Revision Identification Register ................................................................................................................ 40
Table 10. Defined Base Class Codes .................................................................................................................... 41
Table 11. Base Class Code 00h: Early, Pre-2.0 Specification Devices ................................................................. 42
Table 12. Base Class Code 01h: Mass Storage Controllers .................................................................................. 42
Table 13. Base Class Code 02h: Network Controllers ........................................................................................... 42
Table 14. Base Class Code 03h: Display Controllers ............................................................................................ 42
Table 15. Base Class Code 04h: Multimedia Devices ........................................................................................... 42
Table 16. Base Class Code 05h: Memory Controllers ........................................................................................... 42
Table 17. Base Class Code 06h: Bridge Devices .................................................................................................. 43
Table 18. Base Class Code 07h: Simple Communications Controllers ................................................................. 43
Table 19. Base Class Code 08h: Base System Peripherals .................................................................................. 43
Table 20. Base Class Code 09h: Input Devices .................................................................................................... 43
Table 21. Base Class Code 0Ah: Docking Stations ............................................................................................... 44
Table 22. Base Class Code 0Bh: Processors ........................................................................................................ 44
Table 23. Base Class Code 0Ch: Serial Bus Controllers ....................................................................................... 44
Table 24. Built-In Self-Test Register ...................................................................................................................... 48
Table 25. Base Address Register — Memory (Bit 0 = 0) ....................................................................................... 50
Table 26. Read Response (Memory Assigned) to an All-Ones Write Operation to a Base Address Register ...... 51
Table 27. Read Response (I/O Assigned) to an All-Ones write Operation to a Base Address Register ............... 52
Table 28. Expansion ROM Base Address Register ............................................................................................... 53
Table 29. Read Response to Expansion ROM Base Address Register (after all-ones written) ............................. 54
Table 30. Operation Registers — PCI Bus ............................................................................................................ 60
Table 31. Mailbox Empty/Full Status Register ....................................................................................................... 67
Table 32. Interrupt Control/Status Register ........................................................................................................... 70
Table 33. Bus Master Control/Status Register ....................................................................................................... 73
Table 34. Operation Registers — Add-On Interface .............................................................................................. 76
Table 35. Add-On Mailbox Empty/Full Status Register .......................................................................................... 82
Table 36. Interrupt Control/Status Register ........................................................................................................... 84
Table 37. Add-On General Control/Status Register ............................................................................................... 87
Table 38. Valid External Boot Memory Contents ................................................................................................... 93
Table 39. PC Compatible Expansion ROM ............................................................................................................ 97
Table 40. PCI Data Structure ................................................................................................................................. 98
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Table 41. Supported PCI Bus Commands ........................................................................................................... 101
Table 42. Target Termination Types .................................................................................................................... 109
Table 43. Possible Combinations of FRAME# and IRDY# .................................................................................. 112
Table 44. Byte Lane Steering for Pass-Thru Data Register Read (PCI Write) .................................................... 168
Table 45. Byte Lane Steering for Pass-Thru Data Register Write (PCI Read) .................................................... 168
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The S5935 is an off-the-shelf, low-cost, standard product, which is PCI 2.1 compliant. And, since AMCC is a
member of the PCI Special Interest Group, the S5935
has been tested on various manufacturer’s PCI motherboards, chip sets, PCI BIOSs and operating
systems. This removes the burden of compliance and
compatibility testing from the designer and thus significantly reduces development time. Utilizing the S5935
allows the designer to focus on the actual application,
not debugging the PCI interface.
The S5935 allows special direct data accessing
between the PCI bus and the user application through
implementation of four definable Pass-Thru data channels. Each data channel is implemented by defining a
Host memory segment size and 8/16/32-bit user bus
width. The addition of two 32 byte FIFOs, also used in
S5935 Bus Mastering applications, provides further
versatility to data transfer capabilities. FIFO DMA
transfers are supported using Address and Transfer
Count Registers. Four 32-bit Mailbox Registers coupled with a Status Register and extensive interrupt
capabilities provide flexible user command or message transfers between the two buses. In addition, the
S5935 also allows use of an external serial, or bytewide non-volatile memory to perform any pre-boot initialization requirements and to provide custom
expansion BIOS or POST code capability.
S5935 ARCHITECTURE
The block diagram in Figure 1 above shows the major
functional elements within the S5935. The S5935 provides three physical bus interfaces: the PCI Local bus,
the user local bus referred to as the Add-On Local bus
and the optional serial and byte-wide non-volatile
memory buses. Data movement between buses can
take place through mailbox registers or the FIFO data
channel, or a user can define and enable one or more
of the four Pass-Thru data channels. S5935 Bus Master or DMA data transfers to and from the PCI Local
bus are performed through the FIFO data channel
under either Host or Add-On software control or AddOn hardware control using dedicated S5935 signal
pins.
The S5935 signal pins are shown in Figure 2. The PCI
Local Bus signals are detailed on the left side; Add-On
14
DS1527
Local Bus signal are detailed on the right side. All
additional S5935 device control signals are shown on
the lower right side.
The S5935 supports a two wire serial nvRAM bus and
a byte-wide EPROM/FLASH bus. This allows the
designer to customize the S5935 configuration by
loading setup information on system power-up.
Figure 2.
PCLK
INTA#
RST#
AD[31:0]
C/BE[3:0]#
PCI
Local
Bus
REQ#
GNT#
FRAME#
DEVSEL#
IRDY#
TRDY#
IDSEL#
STOP#
LOCK#
PAR
PERR#
SERR#
S5935
Control
MODE
SNV
S5935
BPCLK
IRQ#
SYSRST#
DQ[31:0]
Add-On Bus
Control
Add-On
Data Bus
SELECT#
ADR[6:2]
BE[3:0]#
RD#
WR#
S5933 Register
Access
PTATN#
PTBURST#
PTNUM[1:0]#
PTBE[3:0]#
PTADR#
PTWR
PTRDY#
Pass-Thru
Control/Access
RDFIFO#
WRFIFO#
RDEMPTY
WRFULL
Direct FIFO
Access
EA[15:0]
EQ[7:0]
Byte Wide
Config/BIOS Opt.
EWR#/SDA
ERD#/SCL
Serial Bus
Config/BIOS Opt.
S5935 Register Architecture
Control and configuration of the Add-On Local bus,
and the S5935 itself, is performed through three primary groups of registers. These groups consist of PCI
Configuration Registers, PCI Operation Registers and
Add-On Operation Registers. These registers are user
configurable through either their associated bus or
from an external non-volatile memory device. This
section will provide a brief overview of each of these
register groups and the optional non-volatile interface.
AMCC Confidential and Proprietary
Revision 1.02 – June 27, 2006
S5935 – PCI Product
Data Book
PCI Configuration Registers
All PCI compliant devices are required to provide a
group of Configuration Registers for the host system.
These registers are polled during power up initialization and contain specific device and add-in card
product information including Vendor ID, Device ID,
Revision and the amount of memory required for product operation. The S5935 can either load these
registers with default values or initialize them from an
external non-volatile memory area called ‘Configuration Space’. The S5935 can accommodate a total of
256 bytes of external memory for this purpose. The
first 64 bytes is reserved for user defined configuration
data which is loaded into the PCI Configuration Registers during power-up initialization. The remaining 192
bytes may be used to implement an Expansion BIOS
or contain add-in card POST code. Table 1 shows all
the S5935 PCI Configuration Registers.
Table 1. PCI Configuration Registers
Byte 3
AMCC Confidential and Proprietary
Byte 1
Byte 0
Address
Device ID
Vendor ID
00h
PCI Status
PCI Command
04h
Class Code
Revision ID
08h
Built-in
Self Test
PCI Operation Registers
The second group of registers are the PCI Operation
Registers shown in Table 2. This group consists of sixteen 32-bit (DWORD) registers accessible to the Host
processor from the PCI Local bus. These are the main
registers through which the PCI Host configures
S5935 operation and communicates with the Add-On
Local bus. These registers encompass the PCI bus
incoming and outgoing Mailboxes, FIFO data channel,
Bus Master Address and Count registers, Pass-Thru
data channel registers and S5935 device Status and
Control registers.
Byte 2
Max.
Latency
Header
Type
Latency
Timer
Cache
Line Size
0Ch
Base Address Register 0
10h
Base Address Register 1
14h
Base Address Register 2
18h
Base Address Register 3
1Ch
Base Address Register 4
20h
Reserved
24h
Reserved Space
28h
Reserved Space
2Ch
Expansion ROM Base Address
30h
Reserved Space
34h
Reserved Space
38h
Min. Grant
Interrupt
Pin
Interrupt
Line
3Ch
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Revision 1.02 – June 27, 2006
S5935 – PCI Product
Data Book
Add-On Bus Operation Registers
Table 2. PCI Operation Registers
The third and last register group consists of the AddOn Operation Registers, shown in Table 3. This group
of eighteen 32-bit (DWORD) registers is accessible to
the Add-On Local bus. These are the main registers
through which the Add-On logic configures S5935
operation and communicates with the PCI Local bus.
These registers encompass the Add-On bus Mailboxes, Add-On FIFO, DMA Address/Count Registers
(when Add-On initiated Bus Mastering), Pass-Thru
Registers and Status/Control registers.
Table 2. PCI Operation Registers
PCI Operation Registers
Address
Offset
Outgoing Mailbox Register 1 (OMB1)
00h
Outgoing Mailbox Register 2 (OMB2)
04h
Outgoing Mailbox Register 3 (OMB3)
08h
Outgoing Mailbox Register 4 (OMB4)
0Ch
Incoming Mailbox Register 1 (IMB1)
10h
Incoming Mailbox Register 2 (IMB2)
14h
Incoming Mailbox Register 3 (IMB3)
18h
16
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PCI Operation Registers
Address
Offset
Incoming Mailbox Register 4 (IMB4)
1Ch
FIFO Register Port (bidirectional) (FIFO)
20h
Master Write Address Register (MWAR)
24h
Master Write Transfer Count Register (MWTC)
28h
Master Read Address Register (MRAR)
2Ch
Master Read Transfer Count Register (MRTC)
30h
Mailbox Empty/Full Status Register (MBEF)
34h
Interrupt Control/Status Register (INTCSR)
38h
Bus Master Control/Status Register (MCSR)
3Ch
Non-Volatile Memory Interface
The S5935 contains a set of PCI Configuration Registers. These registers can be initialized with default
values or with designer specified values contained in
an external nvRAM. The nvRAM can be either a serial
(2 Kbytes, maximum) or a byte-wide device (64
Kbytes, maximum).
AMCC Confidential and Proprietary
Revision 1.02 – June 27, 2006
S5935 – PCI Product
Data Book
The optional nvRAM allows the Add-On card manufacturer to initialize the S5935 with his specific Vendor ID
and Device ID numbers along with desired S5935
operation characteristics. The non-volatile memory
feature also provides for the Expansion BIOS and
POST code (power-on-self-test) options on the PCI
bus.
Table 3. Add-On Bus Operation Registers
Add-On Bus Operation Registers
Address
Incoming Mailbox Register 1 (AIMB1)
00h
Incoming Mailbox Register 2 (AIMB2)
04h
Incoming Mailbox Register 3 (AIMB3)
08h
Incoming Mailbox Register 4 (AIMB4)
0Ch
Outgoing Mailbox Register 1 (AOMB1)
10h
Outgoing Mailbox Register 2 (AOMB2)
14h
Outgoing Mailbox Register 3 (AOMB3)
18h
Outgoing Mailbox Register 4 (AOMB4)
1Ch
FIFO Port (AFIFO)
20h
Bus Master Write Address Register (MWAR)
24h
Pass-Thru Address Register (APTA)
28h
Pass-Thru Data Register (APTD)
2Ch
Bus Master Read Address Register (MRAR)
30h
Mailbox Empty/Full Status Register (AMBEF)
34h
Interrupt Control/Status Register (AINT)
38h
General Control/Status Register (ARCR)
3Ch
Bus Master Write Transfer Count (MWTC)
58h
Bus Master Read Transfer Count (MRTC)
5Ch
AMCC Confidential and Proprietary
Mailbox Operation
The Mailbox Registers are divided into two four
DWORD sets. Each set is dedicated to one bus for
transferring data to the other bus. Figure 3 below
shows a block diagram of the mailbox section of the
S5935. The provision of Mailbox Registers provides
an easy path for the transfer of user information (command, status or parametric data) between the two
buses. An empty/full indication for each Mailbox Register, at the byte level, is determined by polling a
Status Register accessible to both the PCI and AddOn buses. Providing Mailbox byte level empty/full indications allows for greater flexibility in 8-, 16- or 32-bit
system interfaces. i.e., transferring a single byte to an
8-bit Add-On bus without requiring the assembling or
disassembling of 32-bit data.
The generation of interrupts from Mailbox Registers is
equivalent with the commonly known ‘DOORBELL’
interrupt technique. Bit locations configured within the
S5935’s Operation Registers select a Mailbox and
Mailbox byte which is to generate an interrupt when
full or touched. A mailbox interrupt control register is
then used to enable interrupt generation and to select
if the interrupt is to be generated on the PCI or Add-On
Local bus. PCI Local bus interrupts may also be generated from direct hardware interfacing due to a
unique AMCC feature. A dedicated Mailbox byte is
directly accessible via a set of hardware device signal
pins. A mailbox load signal pin latches Add-On bus
data directly into the Mailbox initiating a PCI bus interrupt if enabled. Mailbox data may also be read in a
similar manner. This option is shared with the byte
wide non-volatile memory signal pins. The S5935
must use the serial nvRAM for the direct mailbox
option signal pins to be available or they are assigned
to the byte wide at power up.
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S5935 – PCI Product
Data Book
Figure 3.
PCI MB1
Byte 0
PCI MB2
Byte 0
PCI MB3
Byte 0
PCI MB4
Byte 0
PCI MB1
Byte 1
PCI MB2
Byte 1
PCI MB3
Byte 1
PCI MB4
Byte 1
PCI MB1
Byte 2
PCI MB2
Byte 2
PCI MB3
Byte 2
PCI MB4
Byte 2
PCI MB1
Byte 3
PCI MB2
Byte 3
PCI MB3
Byte 3
PCI MB4
Byte 3
Add MB1
Byte 0
Add MB2
Byte 0
Add MB3
Byte 0
Add MB4
Byte 0
Add MB1
Byte 1
Add MB2
Byte 1
Add MB3
Byte 1
Add MB4
Byte 1
Add MB1
Byte 2
Add MB2
Byte 2
Add MB3
Byte 2
Add MB4
Byte 2
Add MB1
Byte 3
Add MB2
Byte 3
Add MB3
Byte 3
Add MB4
Byte 3
Add-On Local Bus
PCI Local Bus
S5935
Mailbox Status Register
18
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AMCC Confidential and Proprietary
Revision 1.02 – June 27, 2006
S5935 – PCI Product
Data Book
Pass-Thru Operation
FIFO PCI Bus Mastering Operation
Pass-Thru operation executes PCI bus cycles in real
time with the Add-On bus. This allows the PCI bus to
directly read or write to Add-On resources. The S5935
allows the designer to declare up to four individual
Pass-Thru Regions. Each region may be defined as 8,
16-, or 32-bits wide, mapped into host memory or I/O
space and may be up to 512MB bytes in size. Figure 4
right shows a block diagram of the S5935 Pass-Thru
architecture.
FIFO PCI Bus Master data transfers are processed by
one of two 8-DWORD FIFOs. The FIFO block diagram
is shown in Figure 5. The particular FIFO selected for
a data transfer is dependent only on the direction of
data flow and is completely transparent to the user.
Internal S5935 decode logic selects the FIFO that is
dedicated to transferring data to the other bus.
Pass-Thru operations are performed in PCI target only
mode, making this data channel useful for converting
existing ISA or EISA designs over to the fast PCI
architecture. The Pass-Thru data channel utilizes separate Add-On bus signal pins to reflect a PCI bus read
or write request. Add-On logic decodes these signals
to determine if it must read or write data to the S5935
to satisfy the request. Information decoded includes
PCI request occurring, the byte lanes involved, the
specific Pass-Thru region accessed and if the request
is a burst or single-cycle access. All requested PassThru address and data information is passed via AddOn Operation Registers.
Pass-Thru operation supports single PCI data cycles
and PCI data bursts. During PCI burst operations, the
S5935 is capable of transferring data at the full PCI
bandwidth. Should slower Add-On logic be implemented, the S5935 automatically issues PCI bus waits
or a Host retry indication until the requested transfer is
satisfied.
Figure 4.
PCI Local Bus
Address Latch
Add-On PassThru Address
Register
Add-On Pass-Thru W
rite Data
Add-On Pass-Thru Read Data
AMCC Confidential and Proprietary
Add-On Local Bus
S5935
The way data is transferred by a FIFO, is determined
by Operation and Configuration Registers contained
within the S5935. A FIFO may be configured for either
PCI or Add-On initiated Bus Mastering with programmable byte advance conditions, read vs. write
priorities and Add-On bus widths. Advance conditions
allow the FIFO to implement 8-, 16- or 32-bit bus
widths. Configuring the S5935 for Bus Master operation enables separate address and data count
registers, which are loaded with the PCI memory
address location and number of bytes to be read or
written. This is accomplished by either the Host CPU
or Add-On logic. Data can be transferred between the
two buses transparent to the PCI Host processor, however, the Add-On logic is required to service the S5935
Add-On Local bus. An indication of transfer completion
can be seen by polling a status register done bit or
S5935 signal pin or enabling a ‘transfer count = 0’
interrupt to either bus.
Further FIFO configuration bits select 16, 32, or 64 bit
Endian conversion options for incoming and outgoing
data. Endian conversion allows an Add-On processor
and the host to transfer data in their native Endian format. Other configuration bits determine if the Add-On
Local bus width is 8, 16 or 32 bits. 16-bit bus configurations internally steer FIFO data from the upper 16
bits of the DWORD and then to the lower 16-bits on
alternate accesses. FIFO pointers are then updated
when appropriate bytes are accessed. Other methods
are available for 8-bit or 16-bit Add-Ons.
Efficient FIFO management configuration schemes
unique to the AMCC S5935 specify how full or empty a
FIFO must be before it requests the PCI Local bus.
These criteria include bus requests when any of the 8
DWORDs are empty, or when four or more DWORDs
are empty. This allows the designer to control how
often the S5935 requests the bus. The S5935 always
attempts to perform burst operations to empty or fill the
FIFOs. Further FIFO capabilities over the standard
register access methods allow for direct hardware
FIFO access. This is provided through separate
access pins on the S5935. Other status output pins
allow for easily cascading external FIFOs to the AddOn design.
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Revision 1.02 – June 27, 2006
S5935 – PCI Product
Data Book
Figure 5.
PCI Local Bus
Endian
Converter
B0
B0
B0
B0
B0
B0
B0
B0
B1
B1
B1
B1
B1
B1
B1
B1
B2
B2
B2
B2
B2
B2
B2
B2
B3
B3
B3
B3
B3
B3
B3
B3
B0
B0
B0
B0
B0
B0
B0
B0
B1
B1
B1
B1
B1
B1
B1
B1
B2
B2
B2
B2
B2
B2
B2
B2
B3
B3
B3
B3
B3
B3
B3
B3
Endian
Converter
Add-On Local Bus
S5935
32-Bit Master Write Address Register
32-Bit Master ReadAddress Register
30-Bit Master Read Count Register
28-Bit Master Write Count Register
20
DS1527
AMCC Confidential and Proprietary
Revision 1.02 – June 27, 2006
S5935 – PCI Product
Data Book
Figure 6. S5933 Pin Assignment
DQ0 100
DQ1 99
56 AD0
55 AD1
54 AD2
52 AD3
48 AD4
47 AD5
46 AD6
44 AD7
DQ2
98
DQ3
96
DQ4
95
DQ5
94
DQ6
92
DQ7
88
DQ8
86
DQ9
84
42 AD8
40 AD9
DQ10
83
DQ11
82
39 AD10
38 AD11
DQ12
80
DQ13
79
DQ14
78
DQ15
76
36 AD12
35 AD13
34 AD14
32 AD15
14 AD16
12 AD17
8 AD18
7 AD19
6 AD20
4 AD21
3 AD22
2 AD23
158 AD24
156 AD25
155 AD26
154 AD27
PCI Local Bus
S5935 Matchmaker
152 AD28
148 AD29
147 AD30
146 AD31
43 C/BE0#
28 C/BE1#
15 C/BE2#
159 C/BE3#
DQ16 157
DQ17 145
DQ20 117
DQ21 105
DQ22
93
DQ23
85
DQ24
77
DQ25
65
DQ26
53
DQ27
45
DQ28
37
DQ29
25
DQ30
13
DQ31
BPCLK
16 FRAME#
20 DEVSEL#
18 IRDY#
19 TRDY#
160 IDSEL
22 STOP#
23 LOCK#
27 PAR
24 PERR#
26 SERR#
ADR2
68
ADR3
67
Power & Ground
64
ADR6
132
BE0#
87
BE1#
63
BE#2
62
BE3#/ADR1
60
SELECT#
75
WR#
74
RD#
72
PTBE0#
116
PTBE1#
118
PTBE2#
119
PTBE3#
120
10
Vss
30
Vss
50
Vss
70
Vss
ADD-ON Local Bus Register Controls
PTNUM0 123
PTNUM1 122
58 INTA#
MODE
138 RSVD
135 SNV
ADD-ON Local Bus Controls
66
ADR5
142 CLK
139 RST#
59
Device Controls
5
140
IRQ# 124
SYSRST# 126
ADR4
144 REQ#
143 GNT#
ADD-ON Local Bus
DQ18 133
DQ19 125
Pass-Thru Data Controls
PTATN# 114
PTBURST# 112
PTADR#
107
PTWR
108
PTRDY#
115
WRFULL
103
WRFIFO#
102
RDEMPTY 106
RDFIFO# 104
90 Vss
110 Vss
130 Vss
EA0
57
EA1
61
EA2
69
150 Vss
EA3
73
EA4
81
FIFO Data Controls
89
11
Vdd
EA5
31
Vdd
EA6
97
51
Vdd
EA7
101
71
Vdd
EA8
109
91 Vdd
111 Vdd
131 Vdd
EA9
113
EA10
121
EA11
129
151 Vdd
EA12
137
EA13
141
FWE/EA14
149
Byte Wide NVRAM Data
FRF/EA15 153
EQ0
AMCC Confidential and Proprietary
1
EQ1
9
EQ2
17
EQ3
21
FWC#/EQ4
29
FRC#/EQ5
33
AMREN/EQ6
41
AMWEN/EQ7
49
EWR#/SDA
127
ERD#/SCL
128
NVRAM Data Bus
DS1527
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S5935 – PCI Product
Data Book
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22
DS1527
AMCC Confidential and Proprietary
Revision 1.02 – June 27, 2006
S5935 – PCI Product
Data Book
Signal Type Definition
The following signal type definitions [in, out, t/s, s/t/s and o/d] are taken from Revision 2.1 of the PCI local bus
specification.
in
Input is a standard input-only signal.
out
Totem Pole Output is a standard active driver.
t/s
Tri-State ® is a bidirectional, tristate input/output pin.
s/t/s
Sustained Tri-State is an active low tristate signal owned and driven by one and only one agent at a time. The agent
that drives an s/t/s pin low must drive it high for at least one clock before letting it float. A new agent cannot start driving a s/t/s signal any sooner than one clock after the previous owner tri-states it. A pullup is required to sustain the
inactive state until another agent drives it, and must be provided by the central source.
o/d
Open Drain allows multiple devices to share as a wire-OR.
Note that a # symbol at the end of a signal name denotes that the active state occurs when the signal is at a low voltage. When no # symbol is
present, the signal is active high.
Figure 7. S5935 Signal Pins
S5935
PCI 2.1 Local Bus
PCLK
BPCLK
INTA#
IRQ#
RST#
SYSRST
AD[31:0]
DQ[31:0]
C/BE[3:0]#
SELECT#
ADR[6:2]
REQ#
BE[3:0]#
GNT#
RD#
FRAME#
WR#
Add-On Bus
Control
Add-On Data Bus
S5933
Register
Access
DEVSEL#
IRDY#
TRDY#
IDSEL
PTATN#
PTBURST#
PTNUM[1:0]
PTBE[3:0]#
STOP#
LOCK#
PTADR#
Pass-Thru
Control/
Access
PTWR
PTRDY#
PAR#
PERR#
RDFIFO#
SERR#
WRFIFO#
RDEMPTY
WRFULL
EA[15:0]
EQ[7:0]
S5935
Control
AMCC Confidential and Proprietary
Direct
FIFO
Access
Byte Wide
Config/BIOS Opt.
MODE
RSVD
SNV
EWR#/SDA
ERD#/SCL
Serial
Config/BIOS Opt.
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Revision 1.02 – June 27, 2006
S5935 – PCI Product
Data Book
Address and Data Pins — PCI Local Bus
Signal
Type
Description
AD[31:00]
t/s
Local Bus Address/Data lines. Address and data are multiplexed on the same pins. Each bus operation consists of an address phase followed by one or more data phases. Address phases are identified
when the control signal, FRAME#, is asserted. Data transfers occur during those clock cycles in which
control signals IRDY# and TRDY# are both asserted.
C/BE[3:0]#
t/s
Bus Command and Byte Enables. These are multiplexed on the same pins. During the address phase
of a bus operation, these pins identify the bus command, as shown in the table below. During the data
phase of a bus operation, these pins are used as Byte Enables, with C/BE[0]# enabling byte 0 (least
significant byte) and C/BE[3]# enabling byte 3 (most significant byte).
C/BE[3:0]#
PAR
24
DS1527
t/s
Description (during address phase)
0
0
0
0
Interrupt Acknowledge
0
0
0
1
Special Cycle
0
0
1
0
I/O READ
0
0
1
1
I/O WRITE
0
1
0
0
Reserved
0
1
0
1
Reserved
0
1
1
0
Memory Read
0
1
1
1
Memory Write
1
0
0
0
Reserved
1
0
0
1
Reserved
1
0
1
0
Configuration Read
1
0
1
1
Configuration Write
1
1
0
0
MEMORY READ - Multiple
1
1
0
1
Dual Address Cycle
1
1
1
0
Memory Read Line
1
1
1
1
Memory Write and Invalidate
Parity. This signal is even parity across the entire AD[31:00] field along with the C/BE[3:0]# field. The
parity is stable in the clock following the address phase and is sourced by the master. During the data
phase for write operations, the bus master sources this signal on the clock following IRDY# active;
during the data phase for read operations, this signal is sourced by the target and is valid on the clock
following TRDY# active. The PAR signal therefore has the same timing as AD[31:00}, delayed by one
clock.
AMCC Confidential and Proprietary
Revision 1.02 – June 27, 2006
S5935 – PCI Product
Data Book
System Pins — PCI Local Bus
Signal
Type
Description
CLK
in
Clock. The rising edge of this signal is the reference upon which all other signals are based, with the
exception of RST# and the interrupt (IRQA#-). The maximum frequency for this signal is 33 MHz and the
minimum is DC (0 Hz).
RST#
in
Reset. This signal is used to bring all other signals within this device to a known, consistent state. All PCI
bus interface output signals are not driven (tri-stated), and open drain signals such as SERR# are floated.
Interface Control Pins — PCI Bus Signal
Signal
Type
Description
FRAME#
s/t/s
Frame. This signal is driven by the current bus master and identifies both the beginning and duration of
a bus operation. When FRAME# is first asserted, it indicates that a bus transaction is beginning and
that valid addresses and a corresponding bus command are present on the AD[31:00] and C/BE[3:0]
lines. FRAME# remains asserted during the data transfer portion of a bus operation and is deasserted
to signify the final data phase.
IRDY#
s/t/s
Initiator Ready. This signal is sourced by the bus master and indicates that the bus master is able to
complete the current data phase of a bus transaction. For write operations, it indicates that valid data is
on the AD[31:00] pins. Wait states occur until both TRDY# and IRDY# are asserted together.
TRDY#
s/t/s
Target Ready. This signal is sourced by the selected target and indicates that the target is able to complete the current data phase of a bus transaction. For read operations, it indicates that the target is providing valid data on the AD[31:00] pins. Wait states occur until both TRDY# and IRDY# are asserted
together.
STOP#
s/t/s
Stop. The Stop signal is sourced by the selected target and conveys a request to the bus master to stop
the current transaction.
LOCK#
in
Lock. The lock signal provides for the exclusive use of a resource. The S5935 may be locked as a target by one master at a time. The S5935 cannot lock a target when it is a master.
IDSEL
in
Initialization Device Select. This pin is used as a chip select during configuration read or write operations.
DEVSEL#
s/t/s
Device Select. This signal is sourced by an active target upon decoding that its address and bus commands are valid. For bus masters, it indicates whether any device has decoded the current bus cycle.
Arbitration Pins (Bus Masters Only) — PCI Local Bus
Signal
Type
Description
REQ#
out
Request. This signal is sourced by an agent wishing to become the bus master. It is a point-to-point signal
and each master has its own REQ#.
GNT#
in
Grant. The GNT# signal is a dedicated, point-to-point signal provided to each potential bus master and signifies that access to the bus has been granted.
Error Reporting Pins — PCI Local Bus
Signal
Type
Description
PERR#
s/t/s
Parity Error. This pin is used for reporting parity errors during the data portion of a bus transaction for all
cycles except a Special Cycle. It is sourced by the agent receiving data and driven active two clocks following the detection of the error. This signal is driven inactive (high) for one clock cycle prior to returning to
the tri-state condition.
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Error Reporting Pins — PCI Local Bus
Signal
Type
Description
SERR#
o/d
System Error. This pin is used for reporting address parity errors, data parity errors on Special Cycle commands, or any error condition having a catastrophic system impact.
Interrupt Pin — PCI Local Bus
Signal
Type
Description
INTA#
o/d
Interrupt A. This pin is a level sensitive, low active interrupt to the host. The INTA# interrupt must be used
for any single function device requiring an interrupt capability.
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NON-VOLATILE MEMORY INTERFACE
SIGNALS
This signal grouping provides for connection to external non-volatile memories. Either a serial or byte-wide
device may be used.
The serial interface shares the read and write control
pins used for interfacing with byte-wide memory
devices. Since it is intended that only one (serial or
byte wide) configuration be used in any given implementation, separate descriptions are provided for
each. The S5935 provides the pins necessary to interface to a byte wide non-volatile memory. When they
are connected to a properly configured serial memory,
these byte wide interface pins assume alternate functions. These alternate functions include added
external FIFO status flags, FIFO reset control, Add-On
control for bus mastering and a hardware interface
mailbox port.
Serial nv Devices
Signal
Type
Description
SCL
t/s
Serial Clock. This output is intended to drive a two-wire Serial Interface and functions as the bus’s master.
It is intended that this signal be directly connected to one or more inexpensive serial non-volatile RAMs or
EEPROMs. This pin is shared with the byte wide interface signal, ERD#.
SDA
t/s
Serial Data/Address. This bidirectional pin is used to transfer addresses and data to or from a serial
nvRAM or EEPROM. It is an open drain output and intended to be wire-ORed with all other devices on the
serial bus using a 4.7K external pull-up resistor. This pin is shared with the byte wide interface signal,
EWR#.
SNV
in
Serial Non-Volatile Device. This input, when high, indicates a serial boot device or no boot device is
present. When this pin is low, a byte-wide boot device is present.
Note: SCL and SDA are not controlled by FLT#.
Byte-Wide nv Devices
Signal
Type
Description
EA[15:00]
t/s
External nv memory address. These signals connect directly to the external BIOS (or EEPROM) or
EPROM address pins EA0 through EA15. The PCI interface controller assembles 32-bit-wide accesses
through multiple read cycles of the 8-bit device. The address space from 0040h through 007Fh is used
to preload and initialize the PCI configuration registers. Should an external nv memory be used, the
minimum size required is 128 bytes and the maximum is 64K bytes. When a serial memory is connected to the S5935, the pins EA[7:0] are reconfigured to become a hardware Add-On to PCI mailbox
register with the EA8 pin as the mailbox load clock. Also, the EA15 signal pin will provide an indication
that the PCI to Add-On FIFO is full (FRF#), and the EA14 signal pin will indicate whether the Add-On to
PCI FIFO is empty (FWE#).
ERD#
out
External nv memory read control. This pin is asserted during read operations involving the external
non-volatile memory. Data is transferred into the S5935 during the low to high transition of ERD#. This
pin is shared with the serial external memory interface signal, SCL.
EWR#
t/s
External nv memory write control. This pin is asserted during write operations involving the external
non-volatile memory. Data is presented on pins EQ[7:0] along with its address on pins EA[15:0]
throughout the entire assertion of EWR#. This pin is shared with the serial external memory interface
signal, SDA.
EQ[7:0]
t/s
External memory data bus. These pins are used to directly connect with the data pins of an external
non-volatile memory. When a serial memory is connected to the S5935, the pins EQ4, EQ5, EQ6 and
EQ7 become reconfigured to provide signal pins for bus mastering control from the Add-On interface.
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ADD-ON BUS INTERFACE SIGNALS
The following sets of signals represent the interface
pins available for the Add-On function. There are four
groups: Register access, FIFO access, Pass-Thru
mode pins, and general system pins.
Register Access Pins
Signal
Type
Description
DQ[31:00]
t/s
Datapath DQ0–DQ31. These pins represent the datapath for the Add-On peripheral’s data bus. They
provide the interface to the controller’s FIFO and other registers. When MODE=V CC, only DQ[15:00]
are used. DQ[31:0] have internal pull-up resistors.
ADR[6:2]
in
Add-On Addresses. These signals are the address lines to select which of the 16 DWORD registers
within the controller is desired for a given read or write cycle, as shown in the table below.
ADR[6:2]
28
Register Name
0
0
0
0
0
Add-On Incoming Mailbox Reg. 1
0
0
0
0
1
Add-On Incoming Mailbox Reg. 2
0
0
0
1
0
Add-On Incoming Mailbox Reg. 3
0
0
0
1
1
Add-On Incoming Mailbox Reg. 4
0
0
1
0
0
Add-On Outgoing Mailbox Reg. 1
0
0
1
0
1
Add-On Outgoing Mailbox Reg. 2
0
0
1
1
0
Add-On Outgoing Mailbox Reg. 3
0
0
1
1
1
Add-On Outgoing Mailbox Reg. 4
0
1
0
0
0
Add-On FIFO Port
0
1
0
0
1
Bus Master Write Address Register
0
1
0
1
0
Add-On Pass-Thru Address
0
1
0
1
1
Add-On Pass-Thru Data
0
1
1
0
0
Bus Master Read Address Register
0
1
1
0
1
Add-On Mailbox Empty/Full Status
0
1
1
1
0
Add-On Interrupt Control
0
1
1
1
1
Add-On General Control/Status Register
1
0
1
1
0
Bus Master Write Transfer Count
1
0
1
1
1
Bus Master Read Transfer Count
BE3# or
ADR1
in
Byte Enable 3 (32-bit mode) or ADR1 (16 bit mode). This pin is used in conjunction with the read or
write strobes (RD# or WR#) and the Add-On select signal, SELECT#. As a Byte Enable, it is necessary to have this pin asserted to perform write operations to the register identified by ADR[6:2] bit locations d24 through d31; for read operations it controls the DQ[31:24] output drive.
BE[2:0]#
in
Byte Enable 2 through 0. These pins provide for individual byte control during register read or write
operations. BE2# controls activity over DQ[23:DQ16], BE1# controls DQ[15:8], and BE0# controls
DQ[7:0]. During read operations they control the output drive for each of their respective byte lanes;
for write operations they serve as a required enable to perform the modification of each byte lane.
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Register Access Pins (Continued)
Signal
Type
Description
SELECT#
in
Select for the Add-On interface. This signal must be driven low for any write or read access to the AddOn interface registers. This signal must be stable during the assertion of command signals WR# or
RD#.
WR#
in
Write strobe. This pin, when asserted in conjunction with the SELECT# pin, causes the writing of one
of the internal registers. The specific register and operand size are identified through address pins
ADR[6:2] and the byte enables, BE[3:0]#.
RD#
in
Read strobe. This pin, when asserted in conjunction with the SELECT# pin, causes the reading of one
of the internal registers. The specific register and operand size are identified through address pins
ADR[6:2] and the byte enables BE[3:0]#.
MODE
in
This pin control whether the S5935 data accesses on the DQ bus are to be 32-bits wide (MODE = low)
or 16-bits wide (MODE = high). When in the 16 bit mode, the signal BE3# is reassigned as the address
signal ADR1.
FIFO Access Pins
Signal
Type
Description
WRFIFO#
in
Write FIFO. This signal provides a method to directly write the FIFO without having to generate the
SELECT# signal or the ADR[6:2] value of [01000b] to access the FIFO. Access width is either 32 bits
or 16 bits depending on the data bus size available. This signal is intended for implementing PCI DMA
transfers with the Add-On system.
RDFIFO#
in
Read FIFO. This signal provides a method to directly read the FIFO without having to generate the
SELECT# signal or the ADR[6:2] value of [01000b] to access the FIFO. Access width is either 32 bits
or 16 bits, depending on the data bus size defined by the MODE pin. This signal is intended for implementing PCI DMA transfers with the Add-On system. WRFULL out Write FIFO full. This pin indicates
whether the Add-On-to-PCI bus FIFO is able to accept more data. This pin is intended to be used to
implement DMA hardware on the Add-On system bus. A logic low output from this pin can be used to
represent a DMA write (Add-On to-PCI FIFO) request.
RDEMPTY
out
Read FIFO Empty. This pin indicates whether the read FIFO (PCI-to-Add-On FIFO) contains data.
This pin is intended to be used by the Add-On system to control DMA transfers from the PCI bus to the
Add-On system bus. A logic low from this pin can be used to represent a DMA (PCI-to-Add-On FIFO)
request.
Pass-Thru Interface Pins
Signal
Type
Description
PTATN#
out
Pass-Thru Attention. This signal identifies that an active PCI bus cycle has been decoded and data
must be read from or written to the Pass-Thru Data Register.
PTBURST#
out
Pass-Thru Burst. This signal identifies PCI bus operations involving the current Pass-Thru cycle as
requesting burst access.
PTRDY#
in
PTNUM[1:0]
out
Pass-Thru Number. These signals identify which of the four base address registers decoded a PassThru bus activity. These bits are only meaningful when signal PTATN# is active. A value of 00 corresponds to Base Address Register 1, a value of 01 for Base Address Register 2, and so on.
PTBE[3:0]#
out
Pass-Thru Byte Enables. These signals indicate which bytes are requested for a given Pass-Thru
operation. They are valid during the presence of signal PTATN# active.
Pass-Thru Ready. This input indicates when Add-On logic has completed a Pass-Thru cycle and
another may be initiated.
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Pass-Thru Interface Pins
Signal
Type
Description
PTADR#
in
Pass-Thru Address. This signal causes the actual Pass-Thru requested address to be presented as
outputs on the DQ pins DQ[31:0] for Add-Ons with 32-bit buses, or the low-order 16 bits for Add-Ons
with 16-bit buses. It is necessary that all other bus control signals be in their inactive state during the
assertion of PTADR#. The purpose of this signal is to provide the direct addressing of external AddOn peripherals through use of the PTNUM[1:0] and the low-order address bits presented on the DQ
bus with this pin active.
PTWR
out
Pass-Thru Write. This signal identifies whether a Pass-Thru operation is a read or write cycle. This
signal is valid only when PTATN# is active.
System Pins
Signal
Type
SYSRST#
out
System Reset. This low active output is a buffered form of the PCI bus reset, RST#. It is not synchronized to any clock within the PCI interface controller. Additionally, this signal can be invoked through
software from the PCI host interface.
BPCLK
out
Buffered PCI Clock. This output is a buffered form of the PCI bus clock and, as such, has all of the
behavioral characteristics of the PCI clock (i.e., DC-to-33 MHz capability).
IRQ#
out
Interrupt. This pin is used to signal the Add-On system that a significant event has occurred as a result
of activity within the PCI controller.
RSVD
in
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Reserved. This pin must be left open at all times.
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PCI CONFIGURATION REGISTERS
Each PCI bus device contains a unique 256-byte
region called its configuration header space. Portions
of this configuration header are mandatory in order for
a PCI agent to be in full compliance with the PCI spec-
ification. This section describes each of the
configuration space fields—its address, default values,
initialization options, and bit definitions—and also provides an explanation of its intended usage.
Table 4. Configuration Registers
Configuration Address Offset
Abbreviation
Register Name
00h–01h
VID
Vendor Identification
02h–03h
DID
Device Identification
04h–05h
PCICMD
PCI Command Register
06h–07h
PCISTS
PCI Status Register
08h
RID
Revision Identification Register
09h–0Bh
CLCD
Class Code Register
0Ch
CALN
Cache Line Size Register
0Dh
LAT
Master Latency Timer
0Eh
HDR
Header Type
0Fh
BIST
Built-in Self-test
10h–27h
BADR0-BADR5
Base Address Registers (0-5)
28h–2Fh
—
Reserved
30h
EXROM
Expansion ROM Base Address
34h–3Bh
—
Reserved
3Ch
INTLN
Interrupt Line
3Dh
INTPIN
Interrupt Pin
3Eh
MINGNT
Minimum Grant
3Fh
MAXLAT
Maximum Latency
40h–FFh
—
Not used
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PCI Configuration Space Header
31
24 23
DEVICE ID
STATUS
16 15
CLASS CODE
HEADER TYPE = 0
BIST
8 7
VENDOR ID
COMMAND
00
REV ID
LATENCY TIMER
CACHE LINE SIZE
BASE ADDRESS REGISTER #0
BASE ADDRESS REGISTER #1
BASE ADDRESS REGISTER #2
BASE ADDRESS REGISTER #3
BASE ADDRESS REGISTER #4
BASE ADDRESS REGISTER #5
RESERVED = 0's
RESERVED = 0's
EXPANSION ROM BASE ADDRESS
MAX_LAT
RESERVED = 0's
RESERVED = 0's
MIN_GNT
INTERRUPT PIN
INTERRUPT LINE
00
04
08
0C
10
14
18
1C
20
24
28
2C
30
34
38
3C
LEGEND
EPROM IS DATA SOURCE (READ ONLY)
CONTROL FUNCTION
EPROM INITIALIZED RAM (CAN BE ALTERED FROM PCI PORT)
EPROM INITIALIZED RAM (CAN BE ALTERED FROM ADD-ON PORT)
HARD-WIRED TO ZEROES
Note:
Some registers are a combination of the above. See individual sections
for full description.
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VENDOR IDENTIFICATION REGISTER
(VID)
Register Name
Vendor Identification
Address Offset
00h-01h
Power-up value
10E8h (AMCC, Applied Micro Circuits Corp.)
Boot-load
External nvRAM offset 040h-41h
Attribute
Read Only (RO)
Size
16 bits
The VID register contains the vendor identification
number. This number is assigned by the PCI Special
Interest Group and is intended to uniquely identify any
PCI device. Write operations from the PCI interface
have no effect on this register. After reset is removed,
this field can be boot-loaded from the external non-volatile device (if present and valid) so that other
legitimate PCI SIG members can substitute their vendor identification number for this field.
Figure 8. Vendor Identification Register
15
0
10E8h
Vendor Identification Register (RO)
Table 5. Vendor Identification Register
Bit
15:0
34
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Description
Vendor Identification Number: This is a 16 bit-value assigned to AMCC.
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DEVICE IDENTIFICATION REGISTER (DID)
Register Name
Device Identification
Address Offset
02h-03h
Power-up value
4750h (ASCII hex for ‘GP’, General
Purpose)
Boot-load
External nvRAM offset 042h-43h
Attribute
Read Only
Size
16 bits
The DID register contains the vendor-assigned device
identification number. This number is generated by
AMCC in compliance with the conditions of the PCI
specification. Write operations from the PCI interface
have no effect on this register. After reset is removed,
this field can be boot-loaded from the external non-volatile device (if present and valid) so that other
legitimate PCI SIG members can substitute their own
device identification number for this field.
Figure 9. Device Identification Register
0
15
4750h
Device Identification Register (RO)
Table 6. Device Identification Register
Bit
Description
15:0
Device Identification Number: This is a 16-bit value initially assigned by AMCC for applications
using the AMCC Vendor ID.
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PCI COMMAND REGISTER (PCICMD)
Register Name
PCI Command
Address Offset
04h-05h
Power-up value
0000h
Boot-load
not used
Attribute
Read/Write (R/W on 6 bits, Read
Only for all others)
Size
16 bits
This 16-bit register contains the PCI Command. The
function of this register is defined by the PCI specification and its implementation is required of all PCI
devices. Only six of the ten fields are used by this
device; those which are not used are hardwired to 0.
The definitions for all fields are provided here for
completeness.
Figure 10. PCI Command Register
15
Reserved = 00's
9
8
0X
X0
7
6
5
4
3
2
1
0
0
0
0
X
X
X
Fast Back-to-Back
SERRE
Wait Cycle Enable
Parity Error Enable
Palette Snoop Enable
Memory Write and Invalidate Enable
Special Cycle Enable
Bus Master Enable
Memory Access Enable
I/O Access Enable
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Table 7. PCI Command Register
Bit
15:10
Description
Reserved. Equals all 0’s.
9
Fast Back-to-Back Enable. The S5935 does not support this function. This bit must be set to zero. This bit is cleared
to a 0 upon RESET#.
8
System Error Enable. When this bit is set to 1, it permits the S5935 controller to drive the open drain output pin,
SERR#. This bit is cleared to 0 upon RESET#. The SERR# pin driven active normally signifies a parity error on the
address/control bus.
7
Wait Cycle Enable. This bit controls whether this device does address/data stepping. Since the S5935 controller
never uses stepping, it is hardwired to 0.
6
Parity Error Enable. This bit, when set to a one, allows this controller to check for parity errors. When a parity error is
detected, the PCI bus signal PERR# is asserted. This bit is cleared (parity testing disabled) upon the assertion of
RESET#.
5
Palette Snoop Enable. This bit is not supported by the S5935 controller and is hardwired to 0. This feature is used
solely for PCI-based VGA devices.
4
Memory Write and Invalidate Enable. This bit allows certain Bus Master devices to use the Memory Write and Invalidate PCI bus command when set to 1. When set to 0, masters must use the Memory Write command instead. The
S5935 controller does not support this command when operated as a master and therefore it is hardwired to 0.
3
Special Cycle Enable. Devices which are capable of monitoring special cycles can do so when this bit is set to 1.
The S5935 controller does not monitor (or generate) special cycles and this bit is hardwired to 0.
2
Bus Master Enable. This bit, when set to a one, allows the S5935 controller to function as a bus master. This bit is
initialized to 0 upon the assertion of signal pin RESET#.
1
Memory Space Enable. This bit allows the S5935 controller to decode and respond as a target for memory regions
that may be defined in one of the five base address registers. This bit is initialized to 0 upon the assertion of signal
pin RESET#.
0 I/O
Space Enable. This bit allows the S5935 controller to decode and respond as a target to I/O cycles which are to
regions defined by any one of the five base address registers. This bit is initialized to 0 upon the assertion of signal
pin RESET#.
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PCI STATUS REGISTER (PCISTS)
Register Name
PCI Status
Address Offset
06h-07h
Power-up value
0080h
Boot-load
not used
Attribute
Read Only (RO), Read/Write Clear
(R/WC)
Size
16 bits
This 16-bit register contains the PCI status information. The function of this register is defined by the PCI
specification and its implementation is required of all
PCI devices. Only some of the bits are used by this
device; those which are not used are hardwired to 0.
Most status bits within this register are designated as
“write clear,” meaning that in order to clear a given bit,
the bit must be written as a 1. All bits written with a 0
are left unchanged. These bits are identified in Figure
4 as (R/WC). Those which are Read Only are shown
as (RO) in Figure 4.
Figure 11. PCI Status Register
15
14
13
12
11
10
9
8
70 6
X
X
X
X
X
0
0
X
0
Reserved (RO) = 00's
Reserved (RO)
Fast Back-to-Back (RO)
Data Parity Reported (R/WC)
DEVSEL# Timing Status (RO)
0 0 = Fast (S5933)
0 1 = Medium
1 0 = Slow
1 1 = Reserved
Signaled Target Abort (R/WC)
Received Target Abort (R/WC)
Received Master Abort (R/WC)
Signaled System Error (R/WC)
Detected Parity Error (R/WC)
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Table 8. PCI Status Register
Bit
Description
15
Detected Parity Error. This bit is set whenever a parity error is detected. It functions independently from the state of
Command Register Bit 6. This bit may be cleared by writing a 1 to this location.
14
Signaled System Error. This bit is set whenever the device asserts the signal SERR#. This bit can be reset by writing
a 1 to this location.
13
Received Master Abort. This bit is set whenever a bus master abort occurs. This bit can be reset by writing a 1 to this
location.
12
Received Target Abort. This bit is set whenever this device has one of its own initiated cycles terminated by the currently addressed target. This bit can be reset by writing a 1 to this location.
11
Signaled Target Abort. This bit is set whenever this device aborts a cycle when addressed as a target. This bit can be
reset by writing a 1 to this location.
10:9
Device Select Timing. These bits are read-only and define the signal behavior of DEVSEL# from this device when
accessed as a target.
8
Data Parity Reported. This bit is set upon the detection of a data parity error for a transfer involving the S5935 device
as the master. The Parity Error Enable bit (D6 of the Command Register) must be set in order for this bit to be set.
Once set, it can only be cleared by either writing a 1 to this location or by the assertion of the signal RESET#.
7
Fast Back-to-back Capable. When equal to 1, this indicates that the device can accept fast back-to-back cycles as a
target.
6:0
Reserved. Equal all 0’s.
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REVISION IDENTIFICATION REGISTER
(RID)
Register Name
Revision Identification
Address Offset
08h
Power-up value
00h
Boot-load
External nvRAM/EPROM offset 048h
Attribute
Read Only
Size
8 bits
The RID register contains the revision identification
number. This field is initially cleared. Write operations
from the PCI interface have no effect on this register.
After reset is removed, this field can be boot-loaded
from the external non-volatile device (if present and
valid) so that another value may be used.
Figure 12. Revision Identification Register
7
0
00h
Revision Identification Number (RO)
Table 9. Revision Identification Register
Bit
Description
7:0
Revision Identification Number. Initialized to zeros, this register may be loaded to the value in non-volatile memory at
offset 048h.
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CLASS CODE REGISTER (CLCD)
Register Name
Class Code
Address Offset
09h-0Bh
Power-up value
FF0000h
Boot-load
External nvRAM offset 049h-4Bh
Attribute
Read Only
Size
24 bits
This 24-bit, read-only register is divided into three onebyte fields: the base class resides at location 0Bh, the
sub-class at 0Ah, and the programming interface at
09h. The default setting for the base class is all ones
(FFh), which indicates that the device does not fit into
the thirteen base classes defined in the PCI Local Bus
Specification. It is possible, however, through use of
the external non-volatile memory, to implement one of
the defined class codes described in Table 7 below.
For devices that fall within the seven defined class
codes, sub-classes are also assigned. Tables 8
through 20 describe each of the sub-class codes for
base codes 00h through 0Ch, respectively.
Figure 13.
@0Bh
@0Ah
7
0
7
Base Class
@09h
0
7
Sub-Class
(Offset)
0 (Bit)
Prog I/F
Table 10. Defined Base Class Codes
Base-Class
Description
00h
Early, pre-2.0 PCI specification devices
01h
Mass storage controller
02h
Network controller
03h
Display controller
04h
Multimedia device
05h
Memory controller
06h
Bridge device
07h
Simple communication controller
08h
Base system peripherals
09h
Input devices
0Ah
Docking stations
0Bh
Processors
0Ch
Serial bus controllers
0D-FEh
FFh
Reserved
Device does not fit defined class codes (default)
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Table 11. Base Class Code 00h: Early, Pre-2.0 Specification Devices
Sub-Class
Prog I/F
00h
01h
00h
00h
Description
All devices other than VGA
VGA-compatible device
Table 12. Base Class Code 01h: Mass Storage Controllers
Sub-Class
Prog I/F
00h
01h
02h
03h
04h
80h
00h
xxh
00h
00h
00h
00h
Description
SCSI controller
IDE controller
Floppy disk controller
IPI controller
RAID controller
Other mass storage controller
Table 13. Base Class Code 02h: Network Controllers
Sub-Class
Prog I/F
00h
01h
02h
03h
80h
00h
00h
00h
00h
00h
Description
Ethernet controller
Token ring controller
FDDI controller
ATM controller
Other network controller
Table 14. Base Class Code 03h: Display Controllers
Sub-Class
Prog I/F
00h
00h
01h
80h
00h
01h
00h
00h
Description
VGA-compatible controller
8514 compatible controller
XGA controller
Other display controller
Table 15. Base Class Code 04h: Multimedia Devices
Sub-Class
Prog I/F
00h
01h
80h
00h
00h
00h
Description
Video device
Audio device
Other multimedia device
Table 16. Base Class Code 05h: Memory Controllers
42
Sub-Class
Prog I/F
00h
01h
80h
00h
00h
00h
DS1527
Description
RAM memory controller
Flash memory controller
Other memory controller
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Table 17. Base Class Code 06h: Bridge Devices
Sub-Class
Prog I/F
00h
01h
02h
03h
04h
05h
06h
07h
80h
00h
00h
00h
00h
00h
00h
00h
00h
00h
Description
Host/PCI bridge
PCI/ISA bridge
PCI/EISA bridge
PCI/Micro Channel bridge
PCI/PCI bridge
PCI/PCMCIA bridge
NuBus bridge
CardBus bridge
Other bridge type
Table 18. Base Class Code 07h: Simple Communications Controllers
Sub-Class
Prog I/F
Description
00h
00h
01h
02h
Generic XT compatible serial controller
16450 compatible serial controller
16550 compatible serial controller
01h
00h
01h
02h
Parallel port
Bidirectional parallel port
ECP 1.X compliant parallel port
80h
00h
Other communications device
Table 19. Base Class Code 08h: Base System Peripherals
Sub-Class
Prog I/F
Description
00h
00h
01h
02h
Generic 8259 PIC
ISA PIC
EISA PIC
01h
00h
01h
02h
Generic 8237 DMA controller
ISA DMA controller
EISA DMA controller
02h
00h
01h
02h
Generic 8254 system timer
ISA system timer
EISA system timers (2 timers)
03h
00h
01h
Generic RTC controller
ISA RTC controller
80h
00h
Other system peripheral
Table 20. Base Class Code 09h: Input Devices
Sub-Class
Prog I/F
00h
01h
02h
80h
00h
00h
00h
00h
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Description
Keyboard controller
Digitizer (Pen)
Mouse controller
Other input controller
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Table 21. Base Class Code 0Ah: Docking Stations
Sub-Class
Prog I/F
00h
80h
00h
00h
Description
Generic docking station
Other type of docking station
Table 22. Base Class Code 0Bh: Processors
Sub-Class
Prog I/F
00h
01h
02h
10h
40h
00h
00h
00h
00h
00h
Description
Intel386™
Intel486™
Pentium™
Alpha™
Co-processor
Table 23. Base Class Code 0Ch: Serial Bus Controllers
44
Sub-Class
Prog I/F
00
01h
02h
00h
00h
00h
DS1527
Description
FireWire™ (IEEE 1394)
ACCESS.bus
SSA
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CACHE LINE SIZE REGISTER (CALN)
Register Name
Cache Line Size
Address Offset
0Ch
Power-up value
00h, hardwired
Boot-load
not used
Attribute
Read Only
Size
8 bits
This register is hardwired to 0. The cache line configuration register is used by the system to define the
cache line size in doubleword (64-bit) increments. This
controller does not use the “Memory Write and Invalidate” PCI bus cycle commands when operating in the
bus master mode, and therefore does not internally
require this register. When operating in the target
mode, this controller does not have the connections
necessary to “snoop” the PCI bus and accordingly
cannot employ this register in the detection of burst
transfers that cross a line boundary.
Figure 14. Cache Line Size Register
7
0
00h
Cache Line Size (RO)
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LATENCY TIMER REGISTER (LAT)
The latency timer register has meaning only when this
controller is used as a bus master and pertains to the
number of PCI bus clocks that this master will be guaranteed. The nonzero value for this register is internally
decremented after this device has been granted the
bus and has begun to assert FRAME#. Prior to this
latency timer count reaching zero, this device can
ignore the removal of the bus grant and may continue
the use of the bus for data transfers.
Register Name
Latency Timer
Address Offset
0Dh
Power-up value
00h
Boot-load
External nvRAM offset 04Dh
Attribute
Read/Write, bits 7:3; Read Only bits
2:0
Size
8 bits
Figure 15. Latency Timer Register
7
6
5
4
3
2
1
0
Bit
X
X
X
X
X
0
0
0
Value
Latency Timer value (R/W)
# of clocks x 8
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HEADER TYPE REGISTER (HDR)
Register Name
Header Type
Address Offset
0Eh
Power-up value
00h
Boot-load
External nvRAM offset 04Eh
Attribute
Read Only
Size
8 bits
This register consists of two fields: Bits 6:0 define the
format for bytes 10h through 3Fh of the device configuration header, and bit 7 establishes whether this
device represents a single function (bit 7 = 0) or a multifunction (bit 7 = 1) PCI bus agent. The S5935 is a
single function PCI device.
Figure 16. Header Type Register
7
6
X
5
3
4
2
1
00h
0
Bit
Value
Format field (Read Only)
Single/Multi-function device (Read Only)
0 = single function
1 = multi-function
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BUILT-IN SELF-TEST REGISTER (BIST)
Register Name
Built-in Self-Test
Address Offset
0Fh
Power-up value
00h
Boot-load
External nvRAM/EPROM offset 04Fh
Attribute
D7, D5-0 Read Only, D6 as PCI bus
write only
Size
8 bits
The Built-In Self-Test (BIST) register permits the
implementation of custom, user-specific diagnostics.
This register has four fields as depicted in Figure 10.
Bit 7, when set signifies that this device supports a
built-in self test. When bit 7 is set, writing a 1 to bit 6
will commence the self test. In actuality, writing a 1 to
bit 6 produces an interrupt to the Add-On interface. Bit
6 will remain set until cleared by a write operation to
this register from the Add-On bus interface. When bit 6
is reset it is interpreted as completion of the self-test
and an error is indicated by a non-zero value for the
completion code (bits 3:0).
Figure 17. Built-In Self Test Register
7
6
5
4
3
2
1
0
Bit
X
0
0
0
X
X
X
X
Value
User defined
Completion Code (RO)
Reserved (RO)
Start BIST (WO)
BIST Capable (RO)
Table 24. Built-In Self-Test Register
Bit
Description
7
BIST Capable. This bit indicates that the Add-On device supports a built-in self-test when a one is returned. A zero
should be returned if this self test feature is not desired. This field is read only from the PCI interface.
6
Start BIST. Writing a 1 to this bit indicates that the self-test should commence. This bit can only be written when bit 7 is
a 1. When bit 6 becomes set, an interrupt is issued to the Add-On interface. Other than through the reset pin, Bit 6 can
only be cleared by a write to this element from the Add-On bus interface as outlined in Section 6.5. The PCI bus specification requires that this bit be cleared within 2 seconds after being set, or the device will be failed.
5:4
Reserved. These bits are reserved. This field will always return zeros.
3:0
Completion Code. This field provides a method for detailing a device-specific error. It is considered valid when the Start
BIST field (bit 6) changes from 1 to 0. An all-zero value for the completion code indicates successful completion.
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BASE ADDRESS REGISTERS (BADR)
BADR5 register is not implemented and will return all
0’s.
Determining Base Address Size
Register Name
Base Address
Address Offset
10h, 14h, 18h, 1Ch, 20h, 24h
Power-up value
FFFFFFC1h for offset 10h;
00000000h for all others
Boot-load
External nvRAM offset 050h, 54h,
58h, 5Ch, 60h (BADR0-4)
Attribute
high bits Read/Write; low bits Read
Only
Size
32 bits
The base address registers provide a mechanism for
assigning memory or I/O space for the Add-On function. The actual location(s) the Add-On function is to
respond to is determined by first interrogating these
registers to ascertain the size or space desired, and
then writing the high-order field of each register to
place it physically in the system’s address space. Bit
zero of each field is used to select whether the space
required is to be decoded as memory (bit 0 = 0) or I/O
(bit 0 = 1). Since this PCI controller has 16 DWORDs
of internal operating registers, the Base Address Register at offset 10h is assigned to them. The remaining
five base address registers can only be used by bootloading them from the external nvRAM interface.
The address space defined by a given base address
register is determined by writing all 1s to a given base
address register from the PCI bus and then reading
that register back. The number of 0s returned starting
from D4 for memory space and D2 for I/O space
toward the high-order bits reveals the amount of
address space desired. Tables 23 and 24 list the possible returned values and their corresponding size for
both memory and I/O, respectively. Included in the
table are the nvRAM/EPROM boot values which correspond to a given assigned size. A register returning all
zeros is disabled.
Assigning the Base Address
After a base address has been sized as described in
the preceding paragraph, the region associated with
that base address register (the high order one bits)
can physically locate it in memory (or I/O) space. For
example, the first base address register returns
FFFFFFC1h indicating an I/O space (D0=1) and is
then written with the value 00000300h. This means
that the controller’s internal registers can be selected
for I/O addresses between 00000300h through
0000033Fh, in this example. The base address value
must be on a natural binary boundary for the required
size (example 300h, 340h, 380h etc.; 338h would not
be allowable).
Figure 18. Base Address Register — Memory
31 30 29
4
3
2
1
0
Bit
X
X
X
X
Value
}
Memory Space0 = Memory
Indicator (RO) 1 = I/O
See page 3-157
Type (RO)
00-locate anywhere (32)
01-below 1 MB
10-locate anywhere (64)
11-reserved
Prefetchable (RO)
Programmable (R/W)
Base Address Register — I/O
31
2
1
0
Bit
0
X
Value
I/O Space
Indicator (RO)
Reserved (RO)
Programmable (R/W)
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Table 25. Base Address Register — Memory (Bit 0 = 0)
Bit
Description
31:4
Base Address Location. These bits are used to position the decoded region in memory space. Only bits which return
a 1 after being written as 1 are usable for this purpose. Except for Base Address Register 0, these bits are individually
enabled by the contents sourced from the external boot memory.
3
Prefetchable. When set as a 1, this bit signifies that this region of memory can be cached. Cachable regions can only
be located within the region altered through PCI bus memory writes. This bit, when set, also implies that all read
operations will return the data associated for all bytes regardless of the Byte Enables. Memory space which cannot
support this behavior should leave this bit in the zero state. For Base Addresses 1 through 4, this bit is set by the
Reset pin and later initialized by the external boot memory (if present). Base Address Register 0 always has this bit
set to 0. This bit is read only from the PCI interface.
2:1
Memory Type. These two bits identify whether the memory space is 32 or 64 bits wide and if the space location is
restricted to be within the first megabyte of memory space. The table below describes the encoding:
Bits
Description
21
00
Region is 32 bits wide and can be located anywhere in 32 bit memory space.
01
Region is 32 bits wide and must be mapped below the first MByte of memory space.
10
Region is 64 bits wide and can be mapped anywhere within 64 bit memory space. (Not supported by this controller.)
11
Reserved. (Not supported by this controller.)
1
The 64-bit memory space is not supported by this controller, so bit 2 should not be set. The only meaningful option is
whether it is desired to position memory space anywhere within 32-bit memory space or restrain it to the first megabyte. For Base Addresses 1 through 5, this bit is set by the reset pin and later initialized by the external boot memory
(if present).
0
Space Indicator = 0. When set to 0, this bit identifies a base address region as a memory space and the remaining
bits in the base address register are defined as shown in Table 22a.
Base Address Register — I/O (Bit 0 = 1)
Bit
Description
31:2
Base Address Location. These bits are used to position the decoded region in I/O space. Only bits which return a “1”
after being written as “1” are usable for this purpose. Except for Base Address 0, these bits are individually enabled
by the contents sourced from the external boot memory (EPROM or nvRAM).
1
Reserved. This bit should be zero. (Note: disabled Base Address Registers will return all zeros for the entire register
location, bits 31 through 0).
0
Space Indicator = 1. When one this bit identifies a base address region as an I/O space and the remaining bits in the
base address register have the definition as shown in Table 11b.
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Table 26. Read Response (Memory Assigned) to an All-Ones Write Operation to a Base Address Register
Response
[EPROM boot value]1
Size in bytes
00000000h
none - disabled
00000000h or BIOS missing2,3
FFFFFFF0h
16 bytes (4 DWORDs)
FFFFFFF0h
FFFFFFE0h
32 bytes (8 DWORDs)
FFFFFFE0h
FFFFFFC0h
64 bytes (16 DWORDs)
FFFFFFC0h
FFFFFF80h
128 bytes (32 DWORDs)
FFFFFF80h
FFFFFF00h
256 bytes (64 DWORDs)
FFFFFF00h
FFFFFE00h
512 bytes (128 DWORDs)
FFFFFE00h
FFFFFC00h
1K bytes (256 DWORDs)
FFFFFC00h
FFFFF800h
2K bytes (512 DWORDs)
FFFFF800h
FFFFF000h
4K bytes (1K DWORDs)
FFFFF000h
FFFFE000h
8K bytes (2K DWORDs)
FFFFE000h
FFFFC000h
16K bytes (4K DWORDs)
FFFFC000h
FFFF8000h
32K bytes (8K DWORDs)
FFFF8000h
FFFF0000h
64K bytes (16K DWORDs)
FFFF0000h
FFFE0000h
128K bytes (32K DWORDs)
FFFE0000h
FFFC0000h
256K bytes (64K DWORDs)
FFFC0000h
FFF80000h
512K bytes (128K DWORDs)
FFF80000h
FFF00000h
1M bytes (256K DWORDs)
FFF00000h
FFE00000h
2M bytes (512K DWORDs)
FFE00000h
FFC00000h
4M bytes (1M DWORDs)
FFC00000h
FF800000h
8M bytes (2M DWORDs)
FF800000h
FF000000h
16M bytes (4M DWORDs)
FF000000h
FE000000h
32M bytes (8M DWORDs)
FE000000h
FC000000h
64M bytes (16M DWORDs)
FC000000h
F8000000h
128M bytes (32M DWORDs)
F8000000h
F0000000h
256M bytes (64M DWORDs)
F0000000h
E0000000h
512M bytes (128M DWORDs)
E0000000h
1. The two most significant bits define bus width for BADR1:4 in Pass-Thru operation).
2. Bits D3, D2 and D1 may be set to indicate other attributes for the memory space. See text for details.
3. BADR5 register is not implemented and will return all 0’s.
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Table 27. Read Response (I/O Assigned) to an All-Ones write Operation to a Base Address Register
Response
Size in bytes
[EPROM boot value]
00000000h
none - disabled
00000000h or BIOS missing1
FFFFFFFDh
4 bytes (1 DWORDs)
FFFFFFFDh
FFFFFFF9h
8 bytes (2 DWORDs)
FFFFFFF9h
FFFFFFF1h
16 bytes (4 DWORDs)
FFFFFFF1h
FFFFFFE1h
32 bytes (8 DWORDs)
FFFFFFE1h
FFFFFFC1h
64 bytes (16 DWORDs)
FFFFFFC1h2
FFFFFF81h
128 bytes (32 DWORDs)
FFFFFF81h
FFFFFF01h
256 bytes (64 DWORDs)
FFFFFF01h
1. BADR5 register is not implemented and will return all 0’s.
2. Base Address Register 0 (at offset) 10h powers up as FFFFFFC1h. This default assignment allows usage without an external boot memory.
Should an EPROM or nvRAM be used, the base address can be boot loaded to become a memory space (FFFFFFC0h or FFFFFFC2h).
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EXPANSION ROM BASE ADDRESS
REGISTER (XROM)
Register Name
Expansion ROM Base Address
Address Offset
30h
Power-up value
00000000h
Boot-load
External nvRAM offset 70h
Attribute
bits 31:11, bit 0 Read/Write; bits 10:1
Read Only
Size
32 bits
The expansion base address ROM register provides a
mechanism for assigning a space within physical
memory for an expansion ROM. Access from the PCI
bus to the memory space defined by this register will
cause one or more accesses to the S5935 controllers’
external BIOS ROM (or nvRAM) interface. Since PCI
bus accesses to the ROM may be 32 bits wide,
repeated operations to the ROM are generated by the
S5935 and the wider data is assembled internal to the
S5935 controller and then transferred to the PCI bus
by the S5935.
Figure 19. Expansion ROM Base Address Register
31
11 10
1
0
0
Bit
0
Value
Address Decode
Enable (RW)
0=Disabled
1=Enabled
Reserved (RO)
Programmable (R/W)
Table 28. Expansion ROM Base Address Register
Bit
Description
31:11
Expansion ROM Base Address Location. These bits are used to position the decoded region in memory space. Only
bits which return a 1 after being written as 1 are usable for this purpose. These bits are individually enabled by the
contents sourced from the external boot memory (EPROM or nvRAM). The desired size for the ROM memory is
determined by writing all ones to this register and then reading back the contents. The number of bits returned as
zeros, in order from least significant to most significant bit, indicates the size of the expansion ROM. This controller
limits the expansion ROM area to 64K bytes. The allowable returned values after all ones are written to this register
are shown in Table 26.
10:1
Reserved. All zeros.
0
Address Decode Enable. The Expansion ROM address decoder is enabled or disabled with this bit. When this bit is
set, the decoder is enabled; when this bit is zero, the decoder is disabled. It is required that the PCI command register also have the memory decode enabled for this bit to have an effect.
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Table 29. Read Response to Expansion ROM Base Address Register (after all-ones written)
Response
Size in bytes
[EPROM boot value]
00000000h
none - disabled
00000000h or BIOS missing
FFFFF801h
2K bytes (512 DWORDs)
FFFFF801h
FFFFF001h
4K bytes (1K DWORDs)
FFFFF001h
FFFFE001h
8K bytes (2K DWORDs)
FFFFE001h
FFFFC001h
16K bytes (4K DWORDs)
FFFFC001h
FFFF8001h
32K bytes (8K DWORDs)
FFFF8001h
FFFF0001h
64K bytes (16K DWORDs)
FFFF0001h
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INTERRUPT LINE REGISTER (INTLN)
Register Name
Interrupt Line
Address Offset
3Ch
Power-up value
FFh
Boot-load
External nvRAM offset 7Ch
Attribute
Read/Write
Size
8 bit
This register indicates the interrupt routing for the
S5935 controller. The ultimate value for this register is
system-architecture specific. For x86 based PCs, the
values in this register correspond with the established
interrupt numbers associated with the dual 8259 controllers used in those machines. In x86-based PC
systems, the values of 0 to 15 correspond with the IRQ
numbers 0 through 15, and the values from 16 to 254
are reserved. The value of 255 (the controller’s default
power-up value) signifies either “unknown” or “no connection” for the system interrupt. This register is bootloaded from the external boot memory, if present, and
may be written by the PCI interface.
Figure 20. Interrupt Line Register
7
6
5
42
3
FFh
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0
Bit
Value
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INTERRUPT PIN REGISTER (INTPIN)
Register Name
Interrupt Pin
Address Offset
3Dh
Power-up value
01h
Boot-load
External nvRAM offset 7Dh
Attribute
Read Only
Size
8 bits
This register identifies which PCI interrupt, if any, is
connected to the controller’s PCI interrupt pins. The
allowable values are 0 (no interrupts), 1 (INTA#), 2
(INTB#), 3 (INTC#), and 4 (INTD#). The default powerup value assumes INTA#.
Figure 21. Interrupt Pin Register
7
6
5
42
3
0
0
0
0
0
X
1
0
Bit
X
X
Value
Pin Number
0 0 0 None
0 0 1 INTA#
0 1 0 INTB#
0 1 1 INTC#
1 0 0 INTD#
1 0 1 Reserved
1 1 X Reserved
Reserved
(all zeroes-RO)
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MINIMUM GRANT REGISTER (MINGNT)
Register Name
Minimum Grant
Address Offset
3Eh
Power-up value
00h
Boot-load
External nvRAM offset 7Eh
Attribute
Read Only
Size
8 bits
This register may be optionally used by bus masters to
specify how long a burst period the device needs. A
value of zero indicates that the bus master has no
stringent requirement. The units defined by the least
significant bit are in 250-ns increments. This register is
treated as “information only” and has no further implementation within this device. Values other than zero
are possible when an external boot memory is used.
Figure 22. Minimum Grant Register
7
6
0
00
5
4
3
2
1
0
bit
0
0
0
0
0
value
Value x 250ns (RO)
00-no requirement
01-FFh
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MAXIMUM LATENCY REGISTER
(MAXLAT)
This register may be optionally used by bus masters to
specify how often this device needs PCI bus access. A
value of zero indicates that the bus master has no
stringent requirement. The units defined by the least
significant bit are in 250-ns increments. This register is
treated as “information only” and has no further implementation within this device. Values other than zero
are possible when an external boot memory is used.
Register Name
Maximum Latency
Address Offset
3Fh
Power-up value
00h
Boot-load
External nvRAM offset 7Fh
Attribute
Read Only
Size
8 bits
Figure 23. Maximum Latency Register
7
6
0
00
5
4
3
2
1
0
bit
0
0
0
0
0
value
Value x 250ns (RO)
00-no requirement
01-FFh
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The PCI bus operation registers are mapped as 16
consecutive DWORD registers located at the address
space (I/O or memory) specified by the Base Address
Register 0. These locations are the primary method of
communication between the PCI and Add-On buses.
Data, software-defined commands and command
parameters can be either exchanged through the mailboxes, transferred through the FIFO in blocks under
program control, or transferred using the FIFOs under
Bus Master control. Table 1 lists the PCI Bus Operation Registers.
Table 30. Operation Registers — PCI Bus
60
Address Offset
Abbreviation
00h
OMB1
Outgoing Mailbox Register 1
04h
OMB2
Outgoing Mailbox Register 2
08h
OMB3
Outgoing Mailbox Register 3
0Ch
OMB4
Outgoing Mailbox Register 4
10h
IMB1
Incoming Mailbox Register 1
14h
IMB2
Incoming Mailbox Register 2
18h
IMB3
Incoming Mailbox Register 3
1Ch
IMB4
Incoming Mailbox Register 4
20h
FIFO
FIFO Register port (bidirectional)
24h
MWAR
Master Write Address Register
28h
MWTC
Master Write Transfer Count Register
2Ch
MRAR
Master Read Address Register
30h
MRTC
Master Read Transfer Count Register
34h
MBEF
Mailbox Empty/Full Status
38h
INTCSR
3Ch
MCSR
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Register Name
Interrupt Control/Status Register
Bus Master Control/Status Register
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OUTGOING MAILBOX REGISTERS (OMB)
Register Names
Outgoing Mailboxes 1-4
PCI Address Offset
00h, 04h, 08h, 0Ch
Power-up value
XXXXXXXXh
Attribute
Read/Write
Size
32 bits
These four DWORD registers provide a method for sending command or
parameter data to the Add-On system. PCI bus operations to these registers may be in any width (byte, word, or DWORD). Writing to these registers can be a source for Add-On bus interrupts (if desired) by enabling
their interrupt generation through the use of the Add-On’s interrupt control/status register.
INCOMING MAILBOX REGISTERS (IMB)
Register Names
Incoming Mailboxes 1-4
PCI Address Offset
10h, 14h, 18h, 1Ch
Power-up value
XXXXXXXXh
Attribute
Read Only
Size
32 bits
These four DWORD registers provide a method for receiving user defined
data from the Add-On system. PCI bus read operations to these registers
may be in any width (byte, word, or DWORD). Only read operations are
supported. Reading from these registers can optionally cause an Add-On
bus interrupt (if desired) by enabling their interrupt generation through the
use of the Add-On’s interrupt control/status register. Mailbox 4, byte 3 only
exists as device pins on the S5935 devices when used with a serial nonvolatile memory.
FIFO REGISTER PORT (FIFO)
Register Name
FIFO Port
PCI Address Offset
20h
Power-up value
XXXXXXXXh
Attribute
Read/Write
Size
32 bits
AMCC Confidential and Proprietary
This location provides access to the bidirectional FIFO. Separate registers
are used when reading from or writing to the FIFO. Accordingly, it is not
possible to read what was written to this location. The FIFO registers are
implicitly involved in all bus master operations and, as such, should not be
accessed during active bus master transfers. When operating upon the
FIFOs with software program transfers involving word or byte operations,
the endian sequence of the FIFO should be established as described
under FIFO Endian Conversion Management in order to preserve the
internal FIFO data ordering and flag management. The FIFO’s fullness
may be observed by reading the master control-status register or MCSR
register.
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PCI CONTROLLED BUS MASTER WRITE
ADDRESS REGISTER (MWAR)
Register Name
Master Write Address
PCI Address Offset
24h
Power-up value
00000000h
Attribute
Read/Write
Size
32 bits
This register is used to establish the PCI address for
data moving from the Add-On bus to the PCI bus during PCI bus memory write operations. It consists of a
30-bit counter with the low-order two bits hardwired as
zeros. Transfers may be any non-zero byte length as
defined by the transfer count register, MWTC, and
must begin on a DWORD boundary. This DWORD
boundary starting constraint is placed upon this controller’s PCI bus master transfers so that byte lane
alignment can be maintained between the S5935 controller’s internal FIFO data path, the Add-On interface,
and the PCI bus.
Note: Applications which require a non-DWORD starting boundary will need to move the first few bytes
under software program control (and without using the
FIFO) to establish a DWORD boundary. After the
DWORD boundary is established the S5935 can begin
the task of PCI bus master data transfers.
The Master Write Address Register is continually
updated during the transfer process and will always be
pointing to the next unwritten location. Reading of this
register during a transfer process (done when the
S5935 controller is functioning as a target, i.e. not a
bus master) is permitted and may be used to monitor
the progress of the transfer. During the address phase
for bus master write transfers, the two least significant
bits presented on the PCI bus pins AD[31:0] will
always be zero. This identifies to the target memory
that the burst address sequence will be in a linear
order rather than in an Intel 486 or Pentium™ cache
line fill sequence. Also, the PCI bus address bit A1 will
always be zero when this controller is the bus master.
This signifies to the target that the S5935 controller is
burst capable and that the target should not arbitrarily
disconnect after the first data phase of this operation.
Under certain circumstances, MWAR can be accessed
from the Add-On bus instead of the PCI bus. See AddOn Initiated Bus Mastering.
Figure 24. PCI Controlled Bus Master Write Address Register
31
2
1
0
Bit
0
0
Value
DWORD Address (RO)
Write Transfer Address (R/W)
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PCI CONTROLLED BUS MASTER WRITE
TRANSFER COUNT REGISTER (MWTC)
Register Name
Master Write Transfer Count
PCI Address Offset
28h
Power-up value
00000000h
Attribute
Read/Write
Size
32 bits
The master write transfer count register is used to convey to the S5935 controller the actual number of bytes
that are to be transferred. The value in this register is
decremented with each bus master PCI write operation until the transfer count reaches zero.
Upon reaching zero, the transfer operation ceases and
an interrupt may be optionally generated to either the
PCI or Add-On bus interface. Transfers which are not
whole multiples of DWORDs in size result in a partial
word ending cycle. This partial word ending cycle is
possible since all bus master transfers for this controller are required to begin on a DWORD boundary.
Under certain circumstances, MWTC can be accessed
from the Add-On bus instead of the PCI bus. See AddOn Initiated Bus Mastering.
Figure 25. PCI Controlled Bus Master Write Transfer Count Register
31
26
00
25
0
Bit
Value
Transfer Count
in Bytes (R/W)
Reserved = O's (RO)
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PCI CONTROLLED BUS MASTER READ
ADDRESS REGISTER (MRAR)
Register Name
Master Read Address
PCI Address Offset
2Ch
Power-up value
00000000h
Attribute
Read/Write
Size
32 bits
This register is used to establish the PCI address for
data moving to the Add-On bus from the PCI bus during PCI bus memory read operations. It consists of a
30-bit counter with the low-order two bits hardwired as
zeros. Transfers may be any non-zero byte length as
defined by the transfer count register, MRTC (Section
5.7) and must begin on a DWORD boundary. This
DWORD boundary starting constraint is placed upon
this controller’s PCI bus master transfers so that byte
lane alignment can be maintained between the S5935
controller’s internal FIFO data path, the Add-On interface and the PCI bus.
Note: Applications which require a non-DWORD starting boundary will need to move the first few bytes
under software program control (and without using the
FIFO) to establish a DWORD boundary. After the
DWORD boundary is established the S5935 can begin
the task of PCI bus master data transfers.
The Master Read Address Register is continually
updated during the transfer process and will always be
pointing to the next unread location. Reading of this
register during a transfer process (done when the
S5935 controller is functioning as a target—i.e., not a
bus master) is permitted and may be used to monitor
the progress of the transfer. During the address phase
for bus master read transfers, the two least significant
bits presented on the PCI bus AD[31:0] will always be
zero. This identifies to the target memory that the burst
address sequence will be in a linear order rather than
in an Intel 486 or Pentium™ cache line fill sequence.
Also, the PCI bus address bit A1 will always be zero
when this controller is the bus master. This signifies to
the target that the controller is burst capable and that
the target should not arbitrarily disconnect after the
first data phase of this operation.
Under certain circumstances, MRAR can be accessed
from the Add-On bus instead of the PCI bus.
Figure 26. PCI Controlled Bus Master Read Address Register
2
31
1
0
Bit
0
0
Value
DWORD Address (RO)
Read Transfer Address (R/W)
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PCI CONTROLLED BUS MASTER READ
TRANSFER COUNT REGISTER (MRTC)
Register Name
Master Read Transfer Count
PCI Address Offset
30h
Power-up value
00000000h
Attribute
Read/Write
Size
32 bits
The master read transfer count register is used to convey to the PCI controller the actual number of bytes
that are to be transferred. The value in this register is
decremented with each bus master PCI read operation until the transfer count reaches zero. Upon
reaching zero, the transfer operation ceases and an
interrupt may be optionally generated to either the PCI
or Add-On bus interface. Transfers which are not
whole multiples of DWORDs in size result in a partial
word ending cycle. This partial word ending cycle is
possible since all bus master transfers for this controller are required to begin on a DWORD boundary.
Under certain circumstances, MRTC can be accessed
from the Add-On bus instead of the PCI bus.
Figure 27. PCI Controlled Bus Master Read Transfer Count Register
31
26 25
00
0 Bit
Value
Transfer Count
in Bytes (R/W)
Reserved = 0's (RO)
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MAILBOX EMPTY FULL/STATUS REGISTER (MBEF)
Register Name
Mailbox Empty/Full Status
PCI Address Offset
34h
Power-up value
00000000h
Attribute
Read Only
Size
32 bits
This register provides empty/full visibility of each byte
within the mailboxes. The empty/full status for the Outgoing mailboxes is displayed on the low-order 16 bits
and the empty/full status for the Incoming mailboxes is
presented on the high-order 16 bits. A value of 1 signifies that a given mailbox has been written by one bus
interface but has not yet been read by the corresponding destination interface. A PCI bus incoming mailbox
is defined as one in which data travels from the AddOn bus into the PCI bus, and an outgoing mailbox is
defined as one where data travels out from the PCI
bus to the Add-On interface.
Figure 28. Mailbox Empty/Full Status Register
31
16 15
0 Bit
Value
Outgoing Mailbox
Status (RO)
Incoming Mailbox
Status (RO)
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Table 31. Mailbox Empty/Full Status Register
Bit
Description
31:16
Incoming Mailbox Status. This field indicates which incoming mailbox registers have been written by the Add-On
interface but have not yet been read by the PCI bus. Each bit location corresponds to a specific byte within one of
the four incoming mailboxes. A value of one for each bit signifies that the specified mailbox byte is full, and a value
of zero signifies empty. The mapping of these status bits to bytes within each mailbox is as follows:
Bit 31 = Incoming mailbox 4 byte 3
Bit 30 = Incoming mailbox 4 byte 2
Bit 29 = Incoming mailbox 4 byte 1
Bit 28 = Incoming mailbox 4 byte 0
Bit 27 = Incoming mailbox 3 byte 3
Bit 26 = Incoming mailbox 3 byte 2
Bit 25 = Incoming mailbox 3 byte 1
Bit 24 = Incoming mailbox 3 byte 0
Bit 23 = Incoming mailbox 2 byte 3
Bit 22 = Incoming mailbox 2 byte 2
Bit 21 = Incoming mailbox 2 byte 1
Bit 20 = Incoming mailbox 2 byte 0
Bit 19 = Incoming mailbox 1 byte 3
Bit 18 = Incoming mailbox 1 byte 2
Bit 17 = Incoming mailbox 1 byte 1
Bit 16 = Incoming mailbox 1 byte 0
15:00
Outgoing Mailbox Status. This field indicates which out going mail box registers have been written by the PCI bus
interface but have not yet been read by the Add-On bus. Each bit location corresponds to a specific byte within one
of the four outgoing mailboxes. A value of one for each bit signifies that the specified mailbox byte is full, and a value
of zero signifies empty. The mapping of these status bits to bytes within each mailbox is as follows:
Bit 15 = Outgoing mailbox 4 byte 3
Bit 14 = Outgoing mailbox 4 byte 2
Bit 13 = Outgoing mailbox 4 byte 1
Bit 12 = Outgoing mailbox 4 byte 0
Bit 11 = Outgoing mailbox 3 byte 3
Bit 10 = Outgoing mailbox 3 byte 2
Bit 09 = Outgoing mailbox 3 byte 1
Bit 08 = Outgoing mailbox 3 byte 0
Bit 07 = Outgoing mailbox 2 byte 3
Bit 06 = Outgoing mailbox 2 byte 2
Bit 05 = Outgoing mailbox 2 byte 1
Bit 04 = Outgoing Mailbox 2 byte 0
Bit 03 = Outgoing Mailbox 1 byte 3
Bit 02 = Outgoing Mailbox 1 byte 2
Bit 01 = Outgoing Mailbox 1 byte 1
Bit 00 = Outgoing Mailbox 1 byte 0
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INTERRUPT CONTROL/STATUS REGISTER (INTCSR)
Register Name
Interrupt Control and Status
PCI Address
Offset
38h
Power-up value
00000000h
Attribute
Read/Write (R/W), Read/
Write_One_Clear (R/WC)
Size
32 bits
This register provides the method for choosing which
conditions are to produce an interrupt on the PCI bus
interface, a method for viewing the cause of the interrupt, and a method for acknowledging (removing) the
interrupt’s assertion.
Interrupt sources:
•
•
•
•
•
•
Write Transfer Terminal Count = zero
Read Transfer Terminal Count = zero
One of the Outgoing mailboxes (1,2,3 or 4)
becomes empty
One of the Incoming mailboxes (1,2,3 or 4)
becomes full.
Target Abort
Master Abort
Figure 29. Interrupt Control/Status Register
Actual Interrupt
24 23 21
31
FIFO and Endian Control 0
Interrupt Selection
16 15 14
12
0
8
4
0
Bit
Value
0 0 0
Interrupt Asserted (RO)
Interrupt Source (R/W)
Enable & Selection
Target Abort (R/WC)
D4-D0 Outgoing Mailbox
(Goes empty)
Master Abort (R/WC)
D4=Enable Interrrupt
Read Transfer
Complete (R/WC)
D3-D2=Mailbox #
Write Transfer
Complete (R/WC)
0
0
1
1
Incoming Mailbox
Interrupt (R/WC)
Outgoing Mailbox
Interrupt (R/WC)
0=Mailbox
1=Mailbox
0=Mailbox
1=Mailbox
1
2
3
4
D1-D0=Byte #
0
0
1
1
0=Byte 0
1=Byte 1
0=Byte 2
1=Byte 3
D12-D8 Incoming Mailbox (R/W)
(Becomes full)
D12=Enable Interrupt
D11-D10=Mailbox
0
0
1
1
0=Mailbox
1=Mailbox
0=Mailbox
1=Mailbox
1
2
3
4
D9-D8=Byte #
0 0=Byte 0
0 1=Byte 1
1 0=Byte 2
1 1=Byte 3
Interrupt on Write
Transfer Complete
Interrupt on Read
Transfer Complete
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Figure 30. FIFO Management and Endian Control Byte
31 30 29
OUTBOUND FIFO
PCI ADD-ON DWORD
TOGGLE
0 = BYTES 0-3 (DEFAULT)
1 = BYTE 4-7 (NOTE1)
INBOUND FIFO
ADD-ON PCI
DWORD
TOGGLE
0 = BYTES 0-3 (DEFAULT)
1 = BYTE 4-7 1
28 27
26 25
24
0
0
1
1
0
1
0
1
NO CONVERSION (DEFAULT)
16 BIT ENDIAN CONV.
32 BIT ENDIAN CONV.
64 BIT ENDIAN CONV
FIFO ADVANCE CONTROL
PCI INTERFACE
0 0 BYTE 0 (DEFAULT)
0 1 BYTE 1
1 0 BYTE 2
1 1 BYTE 3
FIFO ADVANCE CONTROL
ADD-ON INTERFACE
0 0 BYTE 0 (DEFAULT)
0 1 BYTE 1
1 0 BYTE 2
1 1 BYTE 3
NOTE 1: D24 and D25 MUST BE ALSO "1"
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Table 32. Interrupt Control/Status Register
Bit
Description
31:24
FIFO and Endian Control.
23
Interrupt asserted. This read only status bit indicates that one or more of the four possible interrupt conditions is
present. This bit is nothing more than the ORing of the interrupt conditions described by bits 19 through 16 of this
register.
22
Reserved. Always zero.
21
Target Abort. This bit signifies that an interrupt has been generated due to the S5935 encountering a target abort
during a PCI bus cycle while the S5935 was the current bus master. This bit operates as read or write one clear. A
write to this bit with the data of “one” will cause this bit to be reset, a write to this bit with the data of “zero” will not
change the state of this bit.
20
Master Abort. This bit signifies that an interrupt has been generated due to the S5935 encountering a Master Abort
on the PCI bus. A master abort occurs when there is no target response to a PCI bus cycle. This bit operates as
read or write one clear. A write to this bit with the data of “one” will cause this bit be reset, a write to this bit with the
data of “zero” will not change the state of this bit.
19
Read Transfer Complete. This bit signifies that an interrupt has been generated due to the completion of a PCI bus
master operation involving the transfer of data from the PCI bus to the Add-On. This interrupt will occur when the
Master Read Transfer Count register reaches zero. This bit operates as read or write one clear. A write to this bit
with the data of “one” will cause this bit to be reset; a write to this bit with the data of “zero” will not change the state
of this bit.
18
Write Transfer Complete. This bit signifies that an interrupt has been generated due to the completion of a PCI bus
master operation involving the transfer of data to the PCI bus from the Add-On. This interrupt will occur when the
Master Write Transfer Count register reaches zero. This bit operates as read or write one clear. A write to this bit
with the data of “one” will cause this bit to be reset; a write to this bit with the data of “zero” will not change the state
of this bit.
17
Incoming Mailbox Interrupt. This bit is set when the mailbox selected by bits 12 through 8 of this register are written
by the Add-On interface. This bit operates as read or write one clear. A write to this bit with the data of “one” will
cause this bit to be reset; a write to this bit with the data as “zero” will not change the state of this bit.
16
Outgoing Mailbox Interrupt. This bit is set when the mailbox selected by bits 4 through 0 of this register is read by the
Add-On interface. This bit operates as read or write one clear. A write to this bit with the data of “one” will cause this
bit to be reset; a write to this bit with the data of “zero” will not change the state of this bit.
15
Interrupt on Read Transfer Complete. This bit enables the occurrence of an interrupt when the read transfer count
reaches zero. This bit is read/write.
14
Interrupt on Write Transfer Complete. This bit enables the occurrence of an interrupt when the write transfer count
reaches zero. This bit is read/write.
13
Reserved. Always zero.
12
Enable incoming mailbox interrupt. This bit allows a write from the incoming mailbox register identified by bits 11
through 8 to produce a PCI interface interrupt. This bit is read/write.
11:10
Incoming Mailbox Interrupt Select. This field selects which of the four incoming mailboxes is to be the source for
causing an incoming mailbox interrupt. [00]b selects mailbox 1, [01]b selects mailbox 2, [10]b selects mailbox 3 and
[11]b selects mailbox 4. This field is read/write.
9:8
Incoming Mailbox Byte Interrupt select. This field selects which byte of the mailbox selected by bits 10 and 11 above
is to actually cause the interrupt. [00]b selects byte 0, [01]b selects byte 1, [10]b selects byte 2, and [11]b selects
byte 3. This field is read/write.
7:5
Reserved, Always zero.
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Table 32. Interrupt Control/Status Register (Continued)
Bit
Description
4
Enable outgoing mailbox interrupt. This bit allows a read by the Add-On of the outgoing mailbox register identified by
bits 3 through 0 to produce a PCI interface interrupt. This bit is read/write.
3:2
Outgoing Mailbox Interrupt Select. This field selects which of the four outgoing mailboxes is to be the source for
causing an outgoing mailbox interrupt. [00]b selects mailbox 1, [01]b selects mailbox 2, [10]b selects mailbox 3 and
[11]b selects mailbox 4. This field is read/write.
1:0
Outgoing Mailbox Byte Interrupt select. This field selects which byte of the mailbox selected by bits 3 and 2 above is
to actually cause the interrupt. [00]b selects byte 0, [01]b selects byte 1, [10]b selects byte 2, and [11]b selects byte
3. This field is read/write.
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MASTER CONTROL/STATUS REGISTER
(MCSR)
Register Name
Master Control/Status
PCI Address
Offset
3Ch
Power-up value
000000E6h
Attribute
Read/Write, Read Only, Write
Only
The following PCI bus controls are available:
•
•
•
•
•
•
•
•
•
•
•
Size32 bits
This register provides for overall control of this device.
It is used to enable bus mastering for both data directions as well as providing a method to perform
software resets.
Write Priority over Read
Read Priority over Write
Write Transfer Enable
Write master requests on 4 or more FIFO
words available (full)
Read transfer enable
Read master requests on 4 or more FIFO available (empty)
Assert reset to Add-On
Reset Add-On to PCI FIFO flags
Reset PCI to Add-On FIFO flags
Reset mailbox empty full status flags
Write external non-volatile memory
The following PCI interface status flags are provided:
•
•
•
•
•
•
•
•
PCI to Add-On FIFO FULL
PCI to Add-On FIFO has four or more empty
locations
PCI to Add-On FIFO EMPTY
Add-On to PCI FIFO FULL
Add-On to PCI FIFO has four or more words
loaded
Add-On to PCI FIFO EMPTY
PCI to Add-On Transfer Count = Zero
Add-On to PCI Transfer Count = Zero
Figure 31. Bus Master Control/Status Register
Control
31
29
27
0
nvRAM Access Ctrl
Reset Controls (R/WC)
D27=Mailbox Flags Reset
D26=Add-on to PCI FIFO
Status Flags Reset
D25=PCI to Add-on FIFO
Status Flags Reset
D24=Add-On Reset
nv operation
address/data
Memory Read Multiple
Enable = 1
Disable = 0
Read Transfer Control (R/W)
(PCI memory reads)
D14=Read Transfer Enable
D13=FIFO Management Scheme
D12=Read vs. Write Priority
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Status
16 15 14
0
12
10
0
87
65
0 Bit
Value
FIFO STATUS (RO)
D5=Add-on to PCI FIFO Empty
D4=Add-on to PCI FIFO 4+ Words
D3=Add-on to PCI FIFO Full
D2=PCI to Add-on FIFO Empty
D1=PCI to Add-on FIFO 4+Spaces
D0=PCI to Add-on FIFO Full
D7=Add-on to PCI Transfer Count
equals zero (R0)
D6=PCI to Add-on Transfer Count
equals zero (R0)
Write Transfer Control (R/W)
(PCI memory writes)
D10=Write Transfer Enable
D9=FIFO Management Scheme
D8=Write vs Read Priority
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Table 33. Bus Master Control/Status Register
Bit
Description
31:29
nvRAM Access Control. This field provides a method for access to the optional external non-volatile memory. Write
operations are achieved by a sequence of byte operations involving these bits and the 8-bit field of bits 23 through
16. The sequence requires that the low-order address, high order address, and then a data byte are loaded in order.
Bit 31 of this field acts as a combined enable and ready for the access to the external memory. D31 must be written
to a 1 before an access can begin, and subsequent accesses must wait for bit D31 to become zero (ready).
D31
D30
D29
W/R
0
X
X
W
Inactive
1
0
0
W
Load low address byte
1
0
1
W
Load high address byte
1
1
0
W
Begin write
1
1
1
W
Begin read
0
X
X
R
Ready
1
X
X
R
Busy
Cautionary note: The nonvolatile memory interface is also available for access by the Add-On interface. Accesses
by both the Add-On and PCI bus to the nv memory are not directly supported by the S5935 device. Software must
be designed to prevent the simultaneous access of nv memory to prevent data corruption within the memory and
provide for accurate data retrieval.
28
FIFO loop back mode.
27
Mailbox Flag Reset. Writing a one to this bit causes all mailbox status flags to become reset (EMPTY). It is not necessary to write this bit as zero because it is used internally to produce a reset pulse. Since reading of this bit will
always produce zeros, this bit is write only.
26
Add-On to PCI FIFO Status Reset. Writing a one to this bit causes the Add-On to PCI (Bus master memory writes)
FIFO empty flag to set indicating empty and the FIFO FULL flag to reset and the FIFO Four Plus word flag to reset.
It is not necessary to write this bit as zero because it is used internally to produce a reset pulse. Since reading of this
bit will always produce zeros, this bit is write only.
25
PCI to Add-On FIFO Status Reset. Writing a one to this bit causes the PCI to Add-On (Bus master memory reads)
FIFO empty flag to set indicating empty and the FIFO FULL flag to reset and the FIFO Four Plus words available
flag to set. It is not necessary to write this bit as zero because it is used internally to produce a reset pulse. Since
reading of this bit will always produce zeros, this bit is write only.
24
Add-On pin reset. Writing a one to this bit causes the reset output pin to become active. Writing a zero to this pin is
necessary to remove the assertion of reset. This register bit is read/write.
23:16
Non-volatile memory address/data port. This 8-bit field is used in conjunction with bit 31, 30 and 29 of this register to
access the external non-volatile memory. The contents written are either low address, high address, or data as
defined by bits 30 and 29. This register will contain the external non-volatile memory data when the proper read
sequence for bits 31 through 29 is performed.
15
Enable memory read multiple during S5935 bus mastering mode.
14
Read Transfer Enable. This bit must be set to a one for S5935 PCI bus master read transfers to take place. Writing
a zero to this location will suspend an active transfer. An active transfer is one in which the transfer count is not zero.
13
Read FIFO management scheme. When set to a 1, this bit causes the controller to refrain from requesting the PCI
bus unless it has four or more vacant FIFO locations to fill. Once the controller is granted the PCI bus or is in possession of the bus due to the write channel, this constraint is not meaningful. When this bit is zero the controller will
request the PCI bus if it has at least one vacant FIFO word.
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Table 33. Bus Master Control/Status Register
74
Bit
Description
12
Read versus Write priority. This bit controls the priority of read transfers over write transfers. When set to a 1 with bit
D8 as zero this indicates that read transfers always have priority over write transfers; when set to a one with D8 as
one, this indicates that transfer priorities will alternate equally between read and writes.
11
Reserved. Always zero.
10
Write Transfer Enable. This bit must be set to a one for PCI bus master write transfers to take place. Writing a zero
to this location will suspend an active transfer. An active transfer is one in which the transfer count is not zero.
9
Write FIFO management scheme. When set to a one this bit causes the controller to refrain from requesting the PCI
bus unless it has four or more FIFO locations filled. Once the S5935 controller is granted the PCI bus or is in possession of the bus due to the write channel, this constraint is not meaningful. When this bit is zero the controller will
request the PCI bus if it has at least one valid FIFO word.
8
Write versus Read priority. This bit controls the priority of write transfers over read transfers. When set to a one with
bit D12 as zero this indicates that write transfers always have priority over read transfers. This combination is not
allowed, data integrity may be compromised. When set to a one with D12 as one, this indicates that transfer priorities will alternate equally between writes and reads.
7
Add-On to PCI Transfer Count Equal Zero (RO). This bit is a one to signify that the write transfer count is all zeros.
6
PCI to Add-On Transfer Count Equals Zero (RO). This bit is a one to signify that the read transfer count is all zeros.
5
Add-On to PCI FIFO Empty. This bit is a one when the Add-On to PCI bus FIFO is completely empty.
4
Add-On to PCI 4+ words. This bit is a one when there are four or more FIFO words valid within the Add-On to PCI
bus FIFO.
3
Add-On to PCI FIFO Full. This bit is a one when the Add-On to PCI bus FIFO is completely full.
2
PCI to Add-On FIFO Empty. This bit is a one when the PCI bus to Add-On FIFO is completely empty.
1
PCI to Add-On FIFO 4+ spaces. This bit signifies that there are at least four empty words within the PCI to Add-On
FIFO.
0
PCI to Add-On FIFO Full. This bit is a one when the PCI bus to Add-On FIFO is completely full.
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ADD-ON BUS OPERATION REGISTERS
The Add-On bus interface provides access to 18
DWORDs (72 bytes) of data, control and status information. All of these locations are accessed by
asserting the Add-On bus chip select pin (SELECT#)
in conjunction with either the read or write control
strobes (signal pin RD# or WR#). Access to the FIFO
can also be achieved through use of the dedicated
pins, RDFIFO# and WRFIFO#. The dedicated pins for
control of the FIFO are provided to optionally implement Direct Memory Access (DMA) on the Add-On
bus, or to connect with an external FIFO.
as viewed by the Add-On. The flexibility of this
arrangement allows a number of user-defined software protocols to be built. For example, data, software
assigned commands, and command parameters can
be exchanged between the PCI and Add-On buses
using either the mailboxes or FIFOs with or without
handshaking interrupts. The register structure is very
similar to that of the PCI operation register set. The
major difference between the PCI bus and Add-On
bus register complement are the absence of bus master control registers (4) on the Add-On side and the
addition of two “pass-through” registers. Table 1 lists
the Add-On interface registers.
This register group represents the primary method for
communication between the Add-On and PCI buses
Table 34. Operation Registers — Add-On Interface
Address
Abbreviation
Register Name
00h
AIMB1
Add-On Incoming Mailbox Register #1
04h
AIMB2
Add-On Incoming Mailbox Register #2
08h
AIMB3
Add-On Incoming Mailbox Register #3
0Ch
AIMB4
Add-On Incoming Mailbox Register #4
10h
AOMB1
Add-On Outgoing Mailbox Register #1
14h
AOMB2
Add-On Outgoing Mailbox Register #2
18h
AOMB3
Add-On Outgoing Mailbox Register #3
1Ch
AOMB4
Add-On Outgoing Mailbox Register #4
20h
AFIFO
Add-On FIFO port
24h
MWAR1
28h
APTA
Add-On Pass-Through Address
2Ch
APTD
Add-On Pass-Through Data
30h
MRAR1
Bus Master Read Address Register
34h
AMBEF
Add-On Mailbox Empty/Full Status
38h
AINT
3Ch
AGCSTS
Add-On General Control and Status Register
58h
MWTC1
Bus Master Write Transfer Count
5Ch
MRTC1
Bus Master Read Transfer Count
Bus Master Write Address Register
Add-On Interrupt control
1. See Add-On Initiated Bus Mastering.
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ADD-ON INCOMING MAILBOX REGISTERS (AIMBX)
Register Names
Add-On Incoming Mailboxes
1-4
Add-On Address Offset
00h, 04h, 08h, 0Ch
Power-up value
XXXXXXXXh
Attribute
Read Only
Size
32 bits
These four DWORD registers provide a method for receiving
data, commands, or command parameters from the PCI
interface. Add-On read operations to these registers may be
in any width (byte, word, or DWORD). These registers are
read-only. Writes to this address space have no effect.
Reading from one of these registers can optionally cause a
PCI bus interrupt (if desired) when the PCI interrupt control/
status register is properly configured.
ADD-ON OUTGOING MAILBOX REGISTERS (AOMBX)
Register Names
Add-On Outgoing Mailboxes
1-4
Add-On Address Offset
10h, 14h, 18h, 1Ch
Power-up value
XXXXXXXXh
Attribute
Read/Write
Size
32 bits
These four DWORD registers provide a method for sending
data, commands, or command parameters or status to the
PCI interface. Add-On write operations to these registers
may be in any width (byte, word, or DWORD). These registers may also be read. Writing to one of these registers can
optionally cause a PCI bus interrupt (if desired) when the
PCI interrupt control/status register is properly configured.
Mailbox 4, byte 3 only exists as device pins on the S5935
device when used with a serial nonvolatile memory. This
byte is not available if a byte-wide nv memory is used.
ADD-ON FIFO REGISTER PORT (AFIFO)
Register Name
Add-On FIFO Port
Add-On Address
Offset
20h
Power-up value
XXXXXXXXh
Attribute
Read/Write
Size
32 bits
AMCC Confidential and Proprietary
This location provides access to the bidirectional FIFO. Separate registers are
involved when reading and writing to this location. Accordingly, it is not possible
to read what was written to this location. The sequence of filling and emptying
this FIFO is established by the PCI interface interrupt control and Status Register.
The FIFO’s fullness may be observed by reading the master control/status register or AGCSTS register Additionally, two signal pins are provided which reveal
whether data is available (RDEMPTY) or space to write into the FIFO is available
(WRFULL). These signals may be used to interface with user supplied DMA
logic. Caution must be exercised when using these flags for FIFO transfers
involving 64 bit endian conversion since the FIFO must operate on DWORD
pairs.
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ADD-ON CONTROLLED BUS MASTER
WRITE ADDRESS REGISTER (MWAR)
Register Name
Master Write Address
Add-On Address Offset
24h
Power-up value
00000000h
Attribute
Read/Write
Size
32 bits
This register is only accessible when Add-On initiated
bus mastering is enabled.
This register is used to establish the PCI address for
data moving from the Add-On bus to the PCI bus during PCI bus memory write operations. It consists of a
30-bit counter with the low-order two bits hardwired as
zeros. Transfers may be any non-zero byte length as
defined by the transfer count register, MWTC and
must begin on a DWORD boundary. This DWORD
boundary starting constraint is placed upon this controller’s PCI bus master transfers so that byte lane
alignment can be maintained between the S5935 controller’s internal FIFO data path, the Add-On interface,
and the PCI bus.
Note: Applications which require a non-DWORD starting boundary will need to move the first few bytes
under software program control (and without using the
FIFO) to establish a DWORD boundary. After the
DWORD boundary is established the S5935 can begin
the task of PCI bus master data transfers.
The Master Write Address Register is continually
updated during the transfer process and will always be
pointing to the next unwritten location. Reading of this
register during a transfer process (done when the
S5935 controller is functioning as a target, i.e. not a
bus master) is permitted and may be used to monitor
the progress of the transfer. During the address phase
for bus master write transfers, the two least significant
bits presented on the PCI bus pins AD[31:0] will
always be zero. This identifies to the target memory
that the burst address sequence will be in a linear
order rather than in an Intel 486 or Pentium™ cache
line fill sequence. Also, the PCI bus address bit A1 will
always be zero when this controller is the bus master.
This signifies to the target that the S5935 controller is
burst capable and that the target should not arbitrarily
disconnect after the first data phase of this operation.
Figure 32. Add-On Controlled Bus Master Write Address Register
31
2
1
0
Bit
0
0
Value
DWORD Address (RO)
Write Transfer Address (R/W)
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ADD-ON PASS-THRU ADDRESS REGISTER (APTA)
Register
Name
Add-On Pass-Thru Address
Add-On
Address
Offset
28h
Power-up
value
XXXXXXXXh
Attribute
Read Only
Size
32 bits
This register is employed when a response is desired when one of the Base
address decode regions is selected during an active PCI bus cycle. When
one of the base address decode registers 1-4 encounters a PCI bus cycle
which selects the region defined by it, this device latches that current cycle’s
active address and asserts the signal PTATN# (Pass-Thru Attention). Wait
states are generated on the PCI bus until either data is transferred or the PCI
bus cycle is aborted by the initiator.
This register provides a method for “live” data (registered) transfers.
Intended uses include the emulating of other hardware as well as enabling
the connection of existing external hardware to interface to the PCI bus
through the S5935.
ADD-ON PASS-THRU DATA REGISTER (APTD)
Register Name
Add-On Pass-Thru Data
Add-On
Address Offset
2Ch
Power-up value
XXXXXXXXh
Attribute
Read/Write
Size
32 bits
AMCC Confidential and Proprietary
This register, along with APTA described above, is employed when a
response is desired should one of the Base address decode regions become
selected during an active PCI bus cycle. When one of the base address
decode registers 1-4 encounters a PCI bus cycle which selects the region
defined by it, the APTA register will contain that current cycle’s active address
and the device asserts the signal PTATN# (Pass-Thru ATentioN). Wait states
are generated on the PCI bus until this register is read (PCI bus writes) or this
register is written (PCI bus reads).
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ADD-ON CONTROLLED BUS MASTER
READ ADDRESS REGISTER (MRAR)
Register Name
Master Read Address
Add-On
Address Offset
30h
Power-up value
00000000h
Attribute
Read/Write
Size
32 bits
This register is only accessible when Add-On initiated
bus mastering is enabled.
This register is used to establish the PCI address for
data moving to the Add-On bus from the PCI bus during PCI bus memory read operations. It consists of a
30-bit counter with the low-order two bits hardwired as
zeros. Transfers may be any non-zero byte length as
defined by the transfer count register, MRTC and must
begin on a DWORD boundary. This DWORD boundary starting constraint is placed upon this controller’s
PCI bus master transfers so that byte lane alignment
can be maintained between the S5395X controller’s
internal FIFO data path, the Add-On interface and the
PCI bus.
Note: Applications which require a non-DWORD starting boundary will need to move the first few bytes
under software program control (and without using the
FIFO) to establish a DWORD boundary. After the
DWORD boundary is established the S5935 can begin
the task of PCI bus master data transfers.
The Master Read Address Register is continually
updated during the transfer process and will always be
pointing to the next unread location. Reading of this
register during a transfer process (done when the
S5935 controller is functioning as a target—i.e., not a
bus master) is permitted and may be used to monitor
the progress of the transfer. During the address phase
for bus master read transfers, the two least significant
bits presented on the PCI bus AD[31:0] will always be
zero. This identifies to the target memory that the burst
address sequence will be in a linear order rather than
in an Intel 486 or Pentium™ cache line fill sequence.
Also, the PCI bus address bit A1 will always be zero
when this controller is the bus master. This signifies to
the target that the controller is burst capable and that
the target should not arbitrarily disconnect after the
first data phase of this operation.
Under certain circumstances, MRAR can be accessed
from the Add-On bus instead of the PCI bus.
Figure 33. Add-On Controlled Bus Master Read Address Register
31
2
1
0
Bit
0
0
Value
DWORD Address (RO)
Read Transfer Address (R/W)
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ADD-ON EMPTY/FULL STATUS REGISTER
(AMBEF)
Register Name
Add-On Mailbox Empty/Full Status
Add-On
Address Offset
34h
Power-up value
00000000h
Attribute
Read Only
Size
32 bits
This register provides empty/full visibility of each byte
within the mailboxes. The empty/full status for the Outgoing mailboxes are displayed on the high order 16
bits and the empty/full status for the incoming mailboxes are presented on the low order 16 bits. A value
of one signifies that a given mailbox had been written
by the sourcing interface but had not yet been read by
the corresponding destination interface. An incoming
mailbox is defined as one in which data travels from
the PCI bus into the Add-On bus and an outgoing mailbox is defined as one where data goes OUT from the
Add-On bus to the PCI interface.
Figure 34. Add-On Mailbox Empty/Full Status Register
31
16 15
0 Bit
Value
Incoming Mailbox
Status (RO)
Outgoing Mailbox
Status (RO)
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Table 35. Add-On Mailbox Empty/Full Status Register
Bit
Description
31:16
Outgoing Mailbox Status. This field indicates which outgoing mailbox registers have been written by the Add-On bus
interface but have not yet been read by the PCI bus. Each bit location corresponds to a specific byte within one of
the four outgoing mailboxes. A value of one for each bit signifies that the specified mailbox byte is full, a value of
zero signifies empty. The mapping of these status bits to bytes within each mailbox is as follows:
Bit 31 = Outgoing mailbox 4 byte 3
Bit 30 = Outgoing mailbox 4 byte 2
Bit 29 = Outgoing mailbox 4 byte 1
Bit 28 = Outgoing mailbox 4 byte 0
Bit 27 = Outgoing mailbox 3 byte 3
Bit 26 = Outgoing mailbox 3 byte 2
Bit 25 = Outgoing mailbox 3 byte 1
Bit 24 = Outgoing mailbox 3 byte 0
Bit 23 = Outgoing mailbox 2 byte 3
Bit 22 = Outgoing mailbox 2 byte 2
Bit 21 = Outgoing mailbox 2 byte 1
Bit 20 = Outgoing mailbox 2 byte 0
Bit 19 = Outgoing mailbox 1 byte 3
Bit 18 = Outgoing mailbox 1 byte 2
Bit 17 = Outgoing mailbox 1 byte 1
Bit 16 = Outgoing mailbox 1 byte 0
15:00
Incoming Mailbox Status. This field indicates which incoming mailbox registers have been written by the PCI bus but
not yet been read by the Add-On interface. Each bit location corresponds to a specific byte within one of the four
incoming mailboxes. A value of one for each bit signifies that the specified mailbox byte is full, a value of zero signifies empty. The mapping of these status bits to bytes within each mailbox is as follows:
Bit 15 = Incoming mailbox 4 byte 3
Bit 14 = Incoming mailbox 4 byte 2
Bit 13 = Incoming mailbox 4 byte 1
Bit 12 = Incoming mailbox 4 byte 0
Bit 11 = Incoming mailbox 3 byte 3
Bit 10 = Incoming mailbox 3 byte 2
Bit 9 = Incoming mailbox 3 byte 1
Bit 8 = Incoming mailbox 3 byte 0
Bit 7 = Incoming mailbox 2 byte 3
Bit 6 = Incoming mailbox 2 byte 2
Bit 5 = Incoming mailbox 2 byte 1
Bit 4 = Incoming mailbox 2 byte 0
Bit 3 = Incoming mailbox 1 byte 3
Bit 2 = Incoming mailbox 1 byte 2
Bit 1 = Incoming mailbox 1 byte 1
Bit 0 = Incoming mailbox 1 byte 0
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ADD-ON INTERRUPT CONTROL/STATUS
REGISTER (AINT)
Register Name
Add-On Interrupt Control and Status
Add-On
Address Offset
38h
Power-up value
00000000h
Attribute
Read/Write, Read/Write_One_Clear
Size
32 bits
This register provides the method for choosing which
conditions are to produce an interrupt on the Add-On
bus interface, a method for viewing the cause for the
interrupt, and a method for acknowledging (removing)
the interrupt’s assertion.
Interrupt sources:
•
•
•
•
•
•
One of the Incoming mailboxes (1,2,3 or 4)
becomes full.
One of the Outgoing mailboxes (1,2,3 or 4)
becomes empty.
Built-in self test issued.
Write Transfer Count = zero
Read Transfer Count = zero
Target/Master Abort
Figure 35. Add-On Interrupt Control/Status Register
Interrupt Status
24 23 21 201918 17 16 1514
31
0 0 0 0 0 0 0 0
0
12
0
Interrupt Selection
8
4
0 Bit
Value
0 0 0
Interrupt Asserted (RO)
Interrupt Source (R/W)
Enable & Selection
Bus Mastering
Error Interrupt (R/WC)
D4-D0 Incoming Mailbox
(Becomes Full)
BIST (R/WC)
D4=Enable Interrrupt
Read Transfer
Complete (R/WC)
D3-D2=Mailbox #
Write Transfer
Complete (R/WC)
0
0
1
1
Outgoing Mailbox
Interrupt (R/WC)
0=Mailbox
1=Mailbox
0=Mailbox
1=Mailbox
1
2
3
4
D0-D1=Byte #
Incoming Mailbox
Interrupt (R/WC)
0
0
1
1
0=Byte 0
1=Byte 1
0=Byte 2
1=Byte 3
D12-D8 Outgoing Mailbox (R/W)
(Goes empty)
D12=Enable Interrupt
D11-D10=Mailbox
0
0
1
1
Interrupt on Write
Transfer Complete
Interrupt on Read
Transfer Complete
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0=Mailbox
1=Mailbox
0=Mailbox
1=Mailbox
1
2
3
4
D9-D8=Byte #
0 0=Byte 0
0 1=Byte 1
1 0=Byte 2
1 1=Byte 3
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Table 36. Interrupt Control/Status Register
Bit
Description
31:24
Reserved. Always zero.
23
Interrupt asserted. This read-only status bit indicates that one or more interrupt conditions is present. This bit is
nothing more than the ORing of the interrupt conditions described by bits, 20, 17 and 16 of this register.
22
Reserved. Always zero.
21
Master/Target Abort. This bit signifies that an interrupt has been generated due to the S5935 encountering a Master
or Target abort during an S5935 initiated PCI bus cycle. This bit operates as read or write one clear. Writing a one to
this bit causes it to be cleared. Writing a zero to this bit does nothing.
20
BIST. Built-In Self-Test interrupt. This interrupt occurs when a self test is initiated by the PCI interface writing of the
BIST configuration register. This bit will stay set until cleared by writing a one to this location. Self test completion
codes may be passed to the PCI BIST register by writing to the AGCSTS register.
19
Read Transfer Complete. This bit signifies that an interrupt has been generated due to the completion of a PCI bus
master operation involving the transfer of data from the PCI bus to the Add-On. This interrupt will occur when the
Master Read Transfer Count register reaches zero. This bit operates as read or write one clear. A write to this bit
with the data of one will cause this bit to be reset; a write to this bit with the data of zero will not change the state of
this bit.
18
Write Transfer Complete. This bit signifies that an interrupt has been generated due to the completion of a PCI bus
master operation involving the transfer of data to the PCI bus from the Add-On. This interrupt will occur when the
Master Write Transfer Count register reaches zero. This bit operates as read or write one clear. A write to this bit
with the data of one will cause this bit to be reset; a write to this bit with the data of zero will not change the state of
this bit.
17
Outgoing Mailbox Interrupt. This bit sets when the mailbox selected by bits 12 through 8 of this register is read by
the PCI interface. This bit operates as read or write one clear. A write to this bit with the data as one will cause this
bit to be reset; a write to this bit with the data as zero will not change the state of this bit.
16
Incoming Mailbox Interrupt. This bit sets when the mailbox selected by bits 4 through 0 of this register are written by
the PCI interface. This bit operates as read or write one clear. A write to this bit with the data of one will cause this
bit to be reset; a write to this bit with the data as zero will not change the state of this bit.
15
Interrupt on Read Transfer Complete. This bit enables the occurrence of an interrupt when the read transfer count
reaches zero. This bit is read/write.
14
Interrupt on Write Transfer Complete. This bit enables the occurrence of an interrupt when the write transfer count
reaches zero. This bit is read/write.
13
Reserved. Always zero.
12
Enable outgoing mailbox interrupt. This bit allows a read by the PCI of the outgoing mailbox register identified by
bits 11 through 8 to produce an Add-On interface interrupt. This bit is read/write.
11:10
Outgoing Mailbox Interrupt Select. This field selects which of the four outgoing mailboxes is to be the source for
causing an outgoing mailbox interrupt. [00]b selects mailbox 1, [01]b selects mailbox 2, [10]b selects mailbox 3 and
[11]b selects mailbox 4. This field is read/write.
9:8
Outgoing Mailbox Byte Interrupt select. This field selects which byte of the mailbox selected by bits 11 and 10 above
is to actually cause the interrupt. [00]b selects byte 0, [01]b selects byte 1, [10]b selects byte 2, and [11]b selects
byte 3. This field is read/write.
7:5
Reserved. Always zero.
4
84
Enable incoming mailbox interrupt. This bit allows a write from the PCI bus to the incoming mailbox register identified by bits 3 through 0 to produce an Add-On interface interrupt. This bit is read/write.
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Table 36. Interrupt Control/Status Register (Continued)
Bit
Description
3:2
Incoming Mailbox Interrupt Select. This field selects which of the four incoming mailboxes is to be the source for
causing an incoming mailbox interrupt. [00]b selects mailbox 1, [01]b selects mailbox 2, [10]b selects mailbox 3 and
[11]b selects mailbox 4. This field is read/write.
1:0
Incoming Mailbox Byte Interrupt select. This field selects which byte of the mailbox selected by bits 3 and 2 above is
to actually cause the interrupt. [00]b selects byte 0, [01]b selects byte 2, and so on.
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ADD-ON GENERAL CONTROL/STATUS
REGISTER (AGCSTS)
Register Name
This register provides for overall control of the Add-On
portion of this device. It is used to provide a method to
perform software resets of the mailbox and FIFO flags.
The following Add-On controls are provided:
Add-On General Control and Status
Add-On
Address Offset
3Ch
Power-up value
000000F4h (PCI initiated bus mastering) 00000034h (Add-On initiated bus
mastering)
Attribute
Read/Write, Read Only, Write Only
Size
32 bits
•
•
•
•
Reset PCI to Add-On FIFO flags
Reset Add-On to PCI FIFO flags
Reset mailbox empty full status flags
Write/read external non-volatile memory.
The following status flags are provided to the Add-On:
•
•
•
•
•
•
Add-On to PCI FIFO FULL
Add-On to PCI FIFO has four or more empty
locations
Add-On to PCI FIFO EMPTY
PCI to Add-On FIFO FULL
PCI to Add-On FIFO has four or more words
loaded
PCI to Add-On FIFO EMPTY
Figure 36. Add-On General Control/Status Register
31
292827 2524 23
0
nvRAM Access Ctrl
Transfer Count
Enable
Reset Controls
D27=Mailbox Flags
D26=PCI to Add-on FIFO
Status Flags
D25=Add-on to PCI FIFO
Status Flags
nv operation
address/data
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12 11
75 6
0
0 Bit
Value
FIFO STATUS (RO)
D5=PCI to Add-on FIFO Empty
D4=PCI to Add-on 4+ Spaces
D3=PCI to Add-on FIFO Full
D2=Add-on to PCI FIFO Empty
D1=Add-on to PCI FIFO 4+ Words
D0=Add-on to PCI FIFO Full
D6=Read Transfer Count
Equals Zero (RO)
D7=Write Transfer Count
Equals Zero (RO)
BIST Condition Code(R/W)
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Table 37. Add-On General Control/Status Register
Bit
Description
31:29
nvRAM/EPROM Access Control. This field provides a method for access to the optional, external non-volatile memory. Write operations are achieved by a sequence of byte operations involving these bits and the 8-bit field of bits 23
through 16. The sequence requires that the low-order address, high-order address, and then a data byte be loaded
in order. Bit 31 of this field acts as an enable/clock and ready for the access to the external memory. D31 must be
written to a 1 before an access can begin, and subsequent accesses must wait for bit D31 to become zero (ready).
D31
D30
D29
W/R
0
X
X
W
Inactive
1
0
0
W
Load low address byte
1
0
1
W
Load high address byte
1
1
0
W
Begin write
1
1
1
W
Begin read
0
X
X
R
Ready
1
X
X
R
Busy
Cautionary note: The non-volatile memory interface is also available for access by the PCI bus interface. Accesses
by both the Add-On and PCI bus to the nv memory are not directly supported by this component. Software must be
designed to prevent the simultaneous access of nv memory to prevent data corruption within the memory and provide for accurate data retrieval.
28
Transfer Count Enable. When set, transfer counts are used for Add-On initiated bus master transfers. When clear,
transfer counts are ignored.
27
Mailbox Flag Reset. Writing a 1 to this bit causes all mailbox status flags to become reset (EMPTY). It is not necessary to write this bit as 0 because it is used internally to produce a reset pulse. Since reading of this bit will always
produce zeros, this bit is write only.
26
Add-On to PCI FIFO Status Reset. Writing a one to this bit causes the Outbound (Bus master writes) FIFO empty
flag to set indicating empty and the FIFO FULL flag to reset and the FIFO Four Plus words available flag to reset. It
is not necessary to write this bit as zero because it is used internally to produce a reset pulse. Since reading of this
bit would always produce zeros, this bit is write only.
25
PCI to Add-On FIFO Status Reset. Writing a 1 to this bit causes the Inbound (Bus master reads) FIFO empty flag to
set indicating empty and the FIFO FULL flag to reset and the FIFO Four Plus spaces flag to set. It is not necessary
to write this bit as 0 because it is used internally to produce a reset pulse. Since reading of this bit would always produce zeros, this bit is write only.
24
Reserved. Always zero.
23:16
Non-volatile memory address/data port. This 8-bit field is used in conjunction with bit 31, 30 and 29 of this register to
access the external non-volatile memory. The contents written are either low address, high address, or data as
defined by bits 30 and 29. This register will contain the external non-volatile memory data when the proper read
sequence for bits 31 through 29 is performed.
15:12
BIST condition code. This field is directly connected to the PCI configuration self test register. Bit 15 through 12
maps with the BIST register bits 3 through 0, respectively.
11:8
7
Reserved. Always zero.
Add-On to PCI Transfer Count Equal Zero (RO). This bit as a one signifies that the write transfer count is all zeros.
Only when Add-On initiated bus mastering is enabled.
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Table 37. Add-On General Control/Status Register (Continued)
88
Bit
Description
6
PCI to Add-On Transfer Count Equals Zero (RO). This bit as a one signifies that the read transfer count is all zeros.
Only when Add-On initiated bus mastering is enabled.
5
PCI to Add-On FIFO Empty. This bit is a 1 when the PCI to Add-On FIFO is empty.
4
PCI to Add-On FIFO 4+ spaces. This bit is a 1 when there are four or more open spaces in the PCI to Add-On FIFO.
3
PCI to Add-On FIFO Full. This bit is a 1 when the PCI to Add-On FIFO is full.
2
Add-On to PCI FIFO Empty. This bit is a 1 when the Add-On to PCI FIFO is empty.
1
Add-On PCI FIFO 4+ words. This bit is a 1 when there are four or more full locations in the Add-On to PCI FIFO.
0
Add-On to PCI FIFO Full. This bit is a 1 when the Add-On to PCI FIFO is full.
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ADD-ON CONTROLLED BUS MASTER
WRITE TRANSFER COUNT REGISTER
(MWTC)
Register Name
Master Write Transfer Count
Add-On
Address Offset
58h
Power-up value
00000000h
Attribute
Read/Write
Size
32 bits
This register is only accessible when Add-On initiated
bus mastering is enabled.
The master write transfer count register is used to convey to the S5935 controller the actual number of bytes
that are to be transferred. The value in this register is
decremented with each bus master PCI write operation until the transfer count reaches zero.
Upon reaching zero, the transfer operation ceases and
an interrupt may be optionally generated to either the
PCI or Add-On bus interface. Transfers which are not
whole multiples of DWORDs in size result in a partial
word ending cycle. This partial word ending cycle is
possible since all bus master transfers for this controller are required to begin on a DWORD boundary.
Figure 37. Add-On Controlled Bus Master Write Transfer Count Register
31
26
00
25
0
Bit
Value
Transfer Count
in Bytes (R/W)
Reserved = O's (RO)
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ADD-ON CONTROLLED BUS MASTER
READ TRANSFER COUNT REGISTER
(MRTC)
Register Name
Master Read Transfer Count
Add-On
Address Offset
5Ch
Power-up value
00000000h
Attribute
Read/Write
Size
32 bits
This register is only accessible when Add-On initiated
bus mastering is enabled.
The master read transfer count register is used to convey to the PCI controller the actual number of bytes
that are to be transferred. The value in this register is
decremented with each bus master PCI read operation until the transfer count reaches zero. Upon
reaching zero, the transfer operation ceases and an
interrupt may be optionally generated to either the PCI
or Add-On bus interface. Transfers which are not
whole multiples of DWORDs in size result in a partial
word ending cycle. This partial word ending cycle is
possible since all bus master transfers for this controller are required to begin on a DWORD boundary.
Figure 38. Add-On Controlled Bus Master Read Transfer Count Register
31
26 25
00
0 Bit
Value
Transfer Count
in Bytes (R/W)
Reserved = 0's (RO)
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INITIALIZATION
All PCI bus agents and bridges are required to implement PCI Configuration Registers. When multiple PCI
devices are present, these registers must be unique to
each device in the system. The specified PCI procedure for uniquely selecting a device’s configuration
space involves a dedicated signal, called IDSEL, connected to each motherboard PCI bus device and PCI
slot.
The host executes configuration cycles after reset to
each device on the PCI bus. The configuration registers provide information on PCI agent operation and
memory or I/O space requirements. These allow the
PCI BIOS to enable the device and locate it within system memory or I/O space.
After a PCI reset, the S5935 can be configured for a
specific application by downloading device setup information from an external non-volatile memory into the
device Configuration Registers. The S5935 can also
be used in a default configuration, with no external
boot device.
When using a non-volatile boot memory to customize
operation, 64 bytes are required for S5935 setup information. The rest of the boot device may be used to
implement an Expansion BIOS, if desired. Some of the
setup information is used to initialize the S5935 PCI
Configuration Registers, other information is not downloaded into registers, but is used to define S5935
operation (FIFO interface, Pass-Thru operation, etc.).
PCI RESET
Immediately following the assertion of the PCI RST#
signal, the Add-On reset output SYSRST# is asserted.
Immediately following the deassertion of RST#,
SYSRST# is deasserted. The Add-On reset output
may be used to initialize state machines, reset Add-On
microprocessors, or reset other Add-On logic devices.
All S5935 Operation Registers and Configuration Registers are initialized to their default states at reset. The
default values for the Configuration Registers may be
overwritten with the contents of an external nv boot
memory during device initialization, allowing a custom
device configuration. Configuration accesses by the
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host CPU to the S5935 produce PCI bus wait states
until one of the following events occurs:
•
•
The S5935 identifies that there is no valid boot
memory (and default Configuration Register
values are used).
The S5935 finishes downloading all configuration information from a valid boot memory.
LOADING FROM BYTE-WIDE NV MEMORIES
The SNV input on the S5935 indicates what type of
external boot-load device is present (if any). If SNV is
tied low, a byte-wide nv memory is assumed. In this
case, immediately after the PCI bus reset is deasserted, the address 0040h is presented on the nv
memory interface address bus EA[15:0]. Eight PCI
clocks later (240 ns at 33 MHz), data is read from the
nv memory data bus EQ[7:0] and address 0041h is
presented. After an additional eight PCI clocks, data is
again read from EQ7:0. If both accesses read are all
ones (FFh), it implies an illegal Vendor ID value, and
the external nv memory is not valid or not present. In
this situation, the AMCC default configuration values
are used.
If either of the accesses to address 0040h and 0041h
contain zeros (not FFh), the next accesses are to locations 0050h, 0051h, 0052h, and 0053h. At these
locations, the data must be C0h (or C1h or C2h), FFh,
E8h, and 10h, respectively, for the external nv memory
to be valid. Once a valid external nv memory has been
recognized, it is read, sequentially, from location
0040h to 007Fh. The appropriate data is loaded into
the PCI Configuration Registers as described in Chapter 4. Some of the boot device data is not downloaded
into Configuration Registers, but is used to enable features and configure S5935 operation. Upon
completion of this procedure, the boot-load sequence
terminates and PCI configuration accesses to the
S5935 are acknowledged with the PCI Target Ready
(TRDY#) output.
Table 1 lists the required nv memory contents for a
valid configuration nv memory device.
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Table 38. Valid External Boot Memory Contents
Address
Data
Notes
0040h-41h
not FFFFh
This is the location that the S5933 PCI Controller will load a customized vendor ID. (FFFFh
is an illegal vendor ID.)
0050h
C2h, C1h or C0h
This is the least significant byte of the region which initializes the base address register #0
of the S5933 configuration register (Section 3.11). A value of C1h assigns the 16 DWORD
locations of the PCI operation registers into I/O space, a value of C0h defines memory
space, a value of C2h defines memory space below 1 Mbyte.
0051
FFh
Required.
0052h
E8h
Required.
0053h
10h
Required.
LOADING FROM SERIAL NV MEMORIES
SNV tied high indicates that a serial nv memory (or no
external device) is present. When serial nv memories
are used, data transfer is performed through a twowire, bidirectional data transfer protocol as defined by
commercial serial EEPROM/Flash offerings. These
devices have the advantages of low pin counts, small
package size, and economical price.
A serial nv memory is considered valid if the first serial
accesses contain the correct per-byte acknowledgments (see Figure 3). If the serial per-byte
acknowledgment is not observed, the S5935 determines that no external serial nv memory is present
and the AMCC default Configuration Register values
are used.
Two pins are used to transfer data between the S5935
PCI controller and the external serial memory: a serial
clock pin, SCL, and a serial data pin, SDA. The serial
clock pin is an output from the S5935, and the serial
data pin is bidirectional. The serial clock is derived by
dividing the PCI bus clock by 512. This means that the
frequency of the serial clock is approximately 65 kHz
for a 33-MHz PCI bus clock.
Note: When a serial boot device is used, EA9 is defined as a SCL divide by control pin.
If EA9 = 1 then SCL = PCLK/512
If EA9 = 0 then SCL = PCLK/8
This pin should be pulled high.
by an address transfer. Each address/data transfer
consists of 8 bits of information followed by a 1-bit
acknowledgment. When the exchange is complete, a
stop event is issued. Figure 1 shows the unique relationship defining both a start and stop event. Figure 2
shows the required timing for address/data with
respect to the serial clock.
For random accesses, the sequence involves one
clock to define the start of the sequence, eight clocks
to send the slave address and read/write command,
followed by a one-clock acknowledge, and so on. Figure 3 shows the sequence for a random write access
requiring 29 serial clock transitions. At the clock speed
for the S5935, this corresponds to one byte of data
transferred approximately every 0.5 milliseconds.
Read accesses may be either random or sequential.
Random read access requires a dummy write to load
the word address and require 39 serial clock transitions. Figure 4 shows the sequence for a random byte
read.
To initialize the S5935 controller’s PCI Configuration
Registers, the smallest serial device necessary is a
128 x 8 organization. Although the S5935 controller
only requires 64 bytes, these bytes must begin at a 64byte address offset (0040h through 007Fh). This offset
constraint permits the configuration image to be
shared with a memory containing expansion BIOS
code and the necessary preamble to identify an
expansion BIOS. The largest serial device which may
be used is 2 Kbytes.
Communications with the serial memory involve several clock transitions. A start event signals the
beginning of a transaction and is immediately followed
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Figure 39. Serial Interface Definition of Start and Stop
SCL
SDA
START BIT
STOP BIT
Figure 40. Serial Interface Clock/Data Relationship
SCL
SDA
DATA STABLE
DATA CHANGE
DATA STABLE
Figure 41. Serial Interface Byte Access — Write
S
T
A
R
T
SLAVE R/W
ADDRESS
WORD
ADDRESS
S
T
O
P
DATA
*
0A
1010
A
C
K
A
C
K
C
K
Figure 42. Serial Interface Byte Access — Read
S
T
A
R
T
SLAVE R/W
ADDRESS
S
T
A
R
T
WORD
ADDRESS
SLAVE R/W
ADDRESS
S
T
O
P
DATA
*
1010
0A
C
K
94
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A
C
K
1010
1A
C
K
A
C
K
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PCI BUS CONFIGURATION CYCLES
The configuration registers for the S5935 PCI controller can only be ac cessed under the follow ing
conditions:
Cycles beginning with the assertion IDSEL and
FRAME# along with the two configuration command
states for C/BE[3:0] (configuration read or write)
access an individual device’s configuration space.
During the address phase of the configuration cycle
just described, the values of AD0 and AD1 identify if
the access is a Type 0 configuration cycle or a Type 1
configuration cycle. Type 0 cycles have AD0 and AD1
equal to 0 and are used to access PCI bus agents.
Type 1 configuration cycles are intended only for
bridge devices and have AD0 as a 1 with AD1 as a 0
during the address phase.
•
•
•
•
•
The S5935 PCI device is a bus agent (not a bridge)
and responds only to a Type 0 configuration accesses.
Figure 5 depicts the state of the AD bus during the
address phase of a Type 0 configuration access. The
S5935 controller does not support the multiple function
numbers field (AD[10:8]) and only responds to the allzero function number value.
IDSEL high (PCI slot unique signal which identifies access to configuration registers) along
with FRAME# low.
Address bits A0 and A1 are 0 (Identifies a Type
0 configuration access).
Address bits A31-A11 are ignored.
Address bits A8, A9, and A10 are 0 (Function
number field of zero supported).
Command bits, C/BE[3:0]# must identify a configuration cycle command (101X).
Figure 6 describes the signal timing relationships for
configuration read cycles. Figure 7 describes configuration write cycles.
Figure 43. PCI AD Bus Definition During a Type 0 Configuration Access
31
11
10
8
7
2
1
0
00
RESERVED
FUNCTION
NUMBER
REGISTER
NUMBER
TYPE 0
00XXXXXX INTERNAL
- REGISTER
ADDRESS
(DEVICE ID, ETC.)
ONLY 000 VALUE SUPPORTED BY THIS
DEVICE.
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Figure 44. Type 0 Configuration Read Cycles
1
3
2
NOTE
4
PCI CLOCK
FRAME #
IF FRAME # STILL ASSERTED
DURING CLOCK 2, CONTROLLER
ASSERTS STOP# DURING 3
(I)
(T)
AD [31:0]
(I)
C/BE [3:0]#
(I)
IRDY#
(I)
TRDY#
(T)
IDSEL
(I)
DEVSEL#
DRIVEN BY CONTROLLER
DURING CLOCK 3
DATA
ADDRESS
CONFIG. READ CMD
BYTE ENABLES
DRIVEN BY CONTROLLER
DURING CLOCKS 2,3 +4
DRIVEN BY CONTROLLER
DURING CLOCKS 2,3 +4
(T)
SELECT
CONDITION
(I) = DRIVEN BY INITIATOR
(T) = DRIVEN BY TARGET
Figure 45. Type 0 Configuration Write Cycles
1
2
3
4
NOTE
PCI CLOCK
FRAME #
(I)
AD [31:0]
(I)
C/BE [3:0]#
(I)
IRDY#
(I)
TRDY#
(T)
IDSEL
(I)
DEVSEL#
(T)
FRAME # DEASSERTED
IN CLOCK 2, SIGNIFIES
ONLY ONE DATA PHASE
ADDRESS
CONFIG WRITE CMD
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BYTE ENABLES
DRIVEN BY CONTROLLER
DURING CLOCKS 2+3
DRIVEN BY CONTROLLER
DURING CLOCKS 2+3
SELECT
CONDITION
96
DATA
(I) = DRIVEN BY INITIATOR
(T) = DRIVEN BY TARGET
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EXPANSION BIOS ROMS
This section provides an example of a typical PC-compatible expansion BIOS ROM. Address offsets 0040h
through 007Fh represent the portion of the external nv
memory used to boot-load the S5935 controller.
Whether the expansion ROM is intended to be execut-
able code is determined by the contents of the first
three locations (starting at offset 0h) and a byte checksum over the defined length. The defined length is
specified in the byte at address offset 0002h. Table 2
lists each field location by its address offset, its length,
its value, and description.
Table 39. PC Compatible Expansion ROM
Byte Offset
Byte Length
Binary Value
Description
Example
0h
1
55h
BIOS ROM signature byte 1
55h
1h
1
AAh
BIOS ROM signature byte 2
AAh
2h
1
var.
Length in multiples of 512 bytes
01h
3h
4
var.
Entry point for INIT function.
7h-17h
17h
var.
Reserved (application unique data)
18h-19h
2
var.
Pointer to PCI Data Structure (see Table 3)
20h-3Fh
32h
var
user-defined
The following represents the boot-load image for the S5935 controller’s PCI configuration register:
40h
2
[your vendor ID]
10e8h
42h
2
[your device ID]
4750h
44h
1
not used
00h
45h
1
[Bus Master Config.]
80h
46h
2
not used
48h
1
[your revision ID]
49h
3
[your class code]
4Ch
1
not used
4Dh
1
[your latency timer #]
00h
4Eh
1
[your header type]
00h
4Fh
1
[self-test if desired]
80h or 00h
50h
1
C0h, C1h or C2h
C0h, C1h or
C2h
51h
1
FFh
FFh
52h
1
E8h
E8h
53h
1
10h
10h
54h
4
[base addr. #1]
xxxxxxxxh
58h
4
[base addr. #2]
xxxxxxxxh
5Ch
4
[base addr. #3]
xxxxxxxxh
60h
4
[base addr. #4]
xxxxxxxxh
64h
4
[base addr. #5]
xxxxxxxxh
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Table 39. PC Compatible Expansion ROM
Byte Offset
Byte Length
Binary Value
Description
Example
(example shows 32K bytes)
FFFF8001h
68h
8
not used
70h
4
[Expansion ROM base addr.]
74h
8
not used
7Ch
1
[Interrupt line]
0Ch
7Dh
1
[Interrupt pin]
01h
7Eh
1
[Min-Grant]
00h
7Fh
1
[Max_lat]
00h
80h —
application specific
(1FFh), or
(2FFh), or
(3FFh), etc.
Byte checksum, location dependent on value for length field at offset 0002h.
A 16-bit pointer at location 18h of the PC expansion
ROM identifies the start offset of the PCI data structure. The PCI data structure is shown in Table 3 and
contains various vendor, product, and program evolutions. If a valid external nv memory is identified by the
S5935, the PCI data structure is used to configure the
S5935. The PCI data structure is not necessary for this
device to operate. If no external nv memory is implemented, the S5935 boots with the default configuration
values.
Note: If a serial BIOS ROM is used, the access time
for large serial devices should be considered, since it
may cause a lengthy system delay during initialization.
For example, a 2-Kbyte serial device takes about 1
second to be read. Many systems, even when BIOS
ROMs are ultimately shadowed into system RAM, may
read this memory space twice (once to validate its size
and checksum, and once to move it into RAM). Execution directly from a serial BIOS ROM, although
possible, may be unacceptably slow.
Table 40. PCI Data Structure
Byte Offset
Byte
Length
Binary
Value
0h
4
‘PCIR’
Signature, the ASCII string ‘PCIR’ where ‘P’ is at offset 0, ‘C’ at offset 1, and so on.
4h
2
var.
Vendor Identification
6h
2
var.
Device Identification
8h
2
var.
Pointer to Vital Product Data
Ah
2
var.
PCI Data Structure Length (starts with signature field)
Ch
1
var.
PCI Data Structure Revision (=0 for this definition)
Dh
3
var.
Class Code
10h
2
var.
Image Length
12h
2
var.
Revision Level
14h
1
var.
Code Type
15h
1
var.
Indicator (bit D7=1 signifies “last image”)
16h
2
0000h
Reserved
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PCI BUS INTERFACE
This section describes the various events which occur
on the S5935 PCI bus interface. Since the S5935 controller functions as both a target (slave) and an initiator
(master), signal timing detail is given for both situations this Section presents the signal relationships
involved in performing basic read or write transfers on
the PCI bus and also describes the different ways
these cycles may complete.
PCI BUS TRANSACTIONS
Because the PCI bus has multiplexed address/data
pins, AD[31:0], each PCI bus transaction consists of
two phases: Address and Data. An address phase is
defined by the clock period when the signal FRAME#
transitions from inactive (high) to active (low). During
the address phase, a bus command is also driven by
the initiator on signal pins C/BE[3:0]#. If the command
indicates a PCI read, the clock cycle following the
address phase is used to perform a “bus turn-around”
cycle. A turn-around cycle is a clock period in which
the AD bus is not driven by the initiator or the target
device. This is used to avoid PCI bus contention. For a
write command, a turn-around cycle is not needed,
and the bus goes directly from the address phase to
the data phase.
All PCI bus transactions consist of an address phase
(described above), followed by one or more data
phases. The address phase is only one PCI clock long
and the bus cycle information (address and command)
is latched internally by the S5935. The number of data
phases depends on how many data transfers are
desired or are possible with a given initiator-target pair.
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A data phase consists of at least one PCI clock.
FRAME# is deasserted to indicate that the final data
phase of a PCI cycle is occurring. Wait states may be
added to any data phase (each wait state is one PCI
clock).
The PCI bus command presented on the C/BE[3:0]#
pins during the address phase can represent 16 possible states. Table 1 lists the PCI commands and
identifies those which are supported by the S5935
controller as a target and those which may be produced by the S5935 controller as an initiator. A “Yes”
in the “Supported As Target” column in Table 1 indicates t he S5935 cont roller as serts the signal
DEVSEL# when that command is issued along with
the appropriate PCI address. Two commands are supported by the S5935 controller as an initiator: Memory
Read and Memory Write.
The completion or termination of a PCI cycle can be
signaled in several ways. In most cases, the completion of the final data phase is indicated by the
assertion of ready signals from both the target
(TRDY#) and initiator (IRDY#) while FRAME# is inactive. In some cases, the target is not be able to
continue or support a burst transfer and asserts the
STOP# signal. This is referred to as a target disconnect. There are also cases where an addressed
device does not exist, and the signal DEVSEL# never
becomes active. When no DEVSEL# is asserted in
response to a PCI cycle, the initiator is responsible for
ending the cycle. This is referred to as a master abort.
The bus is returned to the idle phase when both
FRAME# and IRDY# are deasserted.
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Table 41. Supported PCI Bus Commands
C/BE[3:0]#
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
Command Type
Interrupt Acknowledge
Special Cycle
I/O Read
I/O Write
Reserved
Reserved
Memory Read
Memory Write
Reserved
Reserved
Configuration Read
Configuration Write
Memory Read Multiple
Reserved
Memory Read Line
Memory Write & Invalidate
Supported As Target
Supported As Initiator
No
No
Yes
Yes
No
No
Yes
Yes
No
No
Yes
Yes
Yes1
No
Yes1
Yes2
No
No
No
No
No
No
Yes
Yes
No
No
No
No
No3
No
No
No
1. Memory Read Multiple and Read Line are treated as Memory Reads.
2. Memory Write & Invalidate commands are treated as Memory Writes.
3. Must be enabled by bit 15 MCSR.
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PCI BURST TRANSFERS
regions defined by the Base Address Registers 1-4
may be bursts, if desired.
The PCI bus, by default, expects burst transfers to be
executed. To successfully perform a burst transfer,
both the initiator and target must order their burst
address sequence in an identical fashion. There are
two different ordering schemes: linear address incrementing and 80486 cache line fill sequencing. The
exact ordering scheme for a bus transaction is defined
by the state of the two least significant AD lines during
the address phase. The decoding for these lines is
shown below:
AD[1:0]
PCI Read Transfers
The S5935 responds to PCI bus memory or I/O read
transfers when it is selected (target). As a PCI bus initiator, the S5935 controller may also produce PCI bus
memory read operations.
Figure 1 depicts the fastest burst read transfer possible for the PCI bus. The timings shown in Figure 1 are
representative of the S5935 as a PCI initiator with a
fast, zero-wait-state memory target. The signals driven
by the S5935 during the transfer are FRAME#, C/
BE[3:0]#, and IRDY#. The signals driven by the target
are DEVSEL# and TRDY#. AD[31:0] are driven by
both the target and initiator during read transactions
(only one during any given clock). Clock period 2 is a
required bus turn-around clock which ensures bus
contention between the initiator and target does not
occur.
Burst Order
00
Linear sequence
01
Reserved
10
Cacheline Wrap Mode
11
Reserved
Targets drive DEVSEL# and TRDY# after the end of
the address phase (boundary of clock periods 1 and 2
of Figure 1). TRDY# is not driven until the target can
provide valid data for the PCI read. When the S5935
becomes the PCI initiator, it attempts to perform sustained zero-wait state burst reads until one of the
following occurs:
The S5935 supports both the linear and the cache line
burst ordering. When the S5935 controller is an initiator, it always employs a linear ordering.
Some accesses to the S5935 controller (as a target)
can not be burst transfers. For example, the S5935
does not allow burst transfers when accesses are
made to the configuration or operation registers
(including the FIFO as a target). Attempts to perform
burst transfers to these regions cause STOP# to be
asserted during the first data phase. The S5935 completes the initial data phase successfully, but asserting
STOP# indicates that the next access needs to be a
completely new cycle. Accesses to memory or I/O
•
•
•
•
•
•
The memory target aborts the transfer
PCI bus grant (GNT#) is removed
The PCI to Add-On FIFO becomes full
A higher priority (Add-On to PCI) S5935 transfer is pending (if programmed for priority)
The read transfer byte count reaches zero
Bus mastering is disabled from the Add-On
interface
Figure 46. Zero Wait State Burst Read PCI Bus Transfer (S5935 as Initiator)
3
12
45
6
PCI CLOCK
FRAME #
(I)
AD [31:0]
C/BE [3:0]#
(I)
(T)
ADDRESS
DATA (1)
BUS COMMAND
BYTE ENABLES (1)
(T)
(T)
DATA (2)
DATA (3)
BYTE EN (2)
BYTE EN (3)
(I)
IRDY#
(I)
TRDY#
(T)
DEVSEL#
(T)
(I) = DRIVEN BY INITIATOR
(T) = DRIVEN BY TARGET
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Read accesses from the S5935 operation registers
(S5935 as a target) are shown in Figure 2. The S5935
conditionally asserts STOP# in clock period 3 if the initiator keeps FRAME# asserted during clock period 2
with IRDY# asserted (indicating a burst is being
attempted). Wait states may be added by the initiator
by not asserting the signal IRDY# during clock 3 and
beyond. If FRAME# remains asserted, but IRDY# is
not asserted, the initiator is just adding wait states, not
necessarily attempting a burst.
target disconnect and occurs when a read attempt is
made to an empty S5935 FIFO. The assertion of
STOP# without the assertion of TRDY# indicates that
the initiator should retry the operation later.
When burst read transfers are attempted to the S5935
operation registers, STOP# is asserted during the first
data transfer to indicate to the initiator that no further
transfers (data phases) are possible. This is a target
initiated termination where the target disconnects after
the first data transfer. Figure 3 shows the signal relationships during a burst read attempt to the S5935
operation registers.
There is only one condition where accesses to S5935
operation registers do not return TRDY# but do assert
STOP#. This is called a target-initiated termination or
Figure 47. Single Data Phase PCI Bus Read of S5935 Registers (S5935 as Target)
FRAME #
3
2
1
45
(I)
AD [31:0]
(I)
(I)
TRDY#
(T)
DEVSEL#
(T)
STOP#
(T)
(T)
DATA
BUS COMMAND
C/BE [3:0]#
IRDY#
(I)
ADDRESS
BYTE ENABLES
(I) = DRIVEN BY INITIATOR
(T) = DRIVEN BY TARGET
Figure 48. Burst PCI Bus Read Attempt to S5935 Registers (S5935 as Target)
2
1
3
45
PCI CLOCK
FRAME #
(I)
AD [31:0]
C/BE [3:0]#
(I)
IRDY#
(I)
TRDY#
(T)
DEVSEL#
(T)
STOP#
(T)
(I)
(T)
ADDRESS
DATA
BUS COMMAND
BYTE ENABLES (1)
BE (2)
(I) = DRIVEN BY INITIATOR
(T) = DRIVEN BY TARGET
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tained zero-wait state burst writes until one of the
following occurs:
PCI Write Transfers
Write transfers on the PCI bus are one clock period
shorter than read transfers. This is because the
AD[31:0] bus does not require a turn-around cycle
between the address and data phases. When the
S5935 is accessed (target), it responds to a PCI bus
memory or I/O transfers. As a PCI initiator, the S5935
controller can also execute PCI memory write
operations.
•
•
•
•
•
•
The timing diagram in Figure 4 represents an S5935
initiator PCI write operation transferring to a fast, zerowait-state memory target. The signals driven by the
S5935 during the transfer are FRAME#, AD[31:0], C/
BE[3:0]#, and IRDY#. The signals driven by the target
are DEVSEL# and TRDY#. As with PCI reads, targets
assert DEVSEL# and TRDY# after the clock defining
the end of the address phase (boundary of clock periods 1 and 2 of Figure 4). TRDY# is not driven until the
target has accepted the data for the PCI write. When
the S5935 becomes the PCI initiator, it attempts sus-
The memory target aborts the transfer
PCI bus grant (GNT# is removed)
The Add-On to PCI FIFO becomes empty
A higher priority (PCI to Add-On) S5935 transfer is pending (if programmed for priority)
The write transfer byte count reaches zero
Bus mastering is disabled from the Add-On
interface
Write accesses to the S5935 operation registers
(S5935 as a target) are shown in Figure 5. Here, the
S5935 asserts the signal STOP# in clock period 3.
STOP# is asserted because the S5935 supports fast,
zero-wait-state write cycles but does not support burst
writes to operation registers. Wait states may be
added by the initiator by not asserting the signal
IRDY# during clock 2 and beyond. There is only one
condition where writes to S5935 operation registers do
not return TRDY# (but do assert STOP#). This is
called a target-initiated termination or target disconnect and occurs when a write attempt is made to a full
S5935 FIFO. As with the read transfers, the assertion
of STOP# without the assertion of TRDY# indicates
the initiator should retry the operation later.
Figure 49. Zero Wait State Burst Write PCI Bus Transfer (S5935 as Initiator)
3
2
1
6
45
PCI CLOCK
FRAME #
AD [31:0]
C/BE [3:0]#
(I)
(I)
(I)
IRDY#
(I)
TRDY#
(T)
DEVSEL#
(T)
ADDRESS
BUS COMMAND*
* BUS COMMAND = MEMORY WRITE
104
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DATA 1
BYTE EN 1
DATA
TRANSFER
#1
DATA 2
DATA 3
BYTE EN 2
BYTE EN 3
DATA
TRANSFER
#2
DATA
TRANSFER
#3
(I) = DRIVEN BY INITIATOR
(T) = DRIVEN BY TARGET
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Master-Initiated Termination
Normal Cycle Completion
Occasionally, a PCI transfer must be terminated by the
initiator. Typically, the initiator terminates a transfer
upon the successful completion of the transfer. Sometimes, the initiator’s bus mastership is relinquished by
the bus arbiter (GNT# is removed), often because
another device requires bus ownership. This is called
initiator preemption and is discussed in later Sections.
When the S5935 is an initiator and does not observe a
DEVSEL# response to its assertion of FRAME#, it terminates the cycle (master abort).
A successful data transfer occurs when both the initiator and target assert their respective ready signals,
IRDY# and TRDY#. The last data phase is indicated
by the initiator when FRAME# is deasserted during a
data transfer. A normal cycle completion occurred if
the target does not assert STOP#. Figure 6 shows the
signal relationships defining a normal transfer
completion.
Figure 50. Single Data Phase PCI Bus Write of S5935 Registers (S5935 as Target)
3
2
1
6
45
PCI CLOCK
FRAME #
AD [31:0]
C/BE [3:0]#
(I)
IF BURST
ATTEMPT
ADDRESS
(I)
(I)
IRDY#
(I)
TRDY#
(T)
DEVSEL#
(T)
STOP#
(T)
BUS COMMAND
DATA 1
BYTE EN 1
DATA 2
BYTE EN 2
NO
DATA
TRANSFERRED
DATA
TRANSFER #1
(I) = DRIVEN BY INITIATOR
(T) = DRIVEN BY TARGET
Figure 51. Master-Initiated, Normal Completion (S5935 as either Target or Initiator)
1
2
3
PCI CLOCK
FRAME #
(I)
IRDY#
(I)
TRDY#
(T)
DEVSEL# (T)
STOP#
(T)
NORMAL
COMPLETION
(I) = DRIVEN BY INITIATOR
(T) = DRIVEN BY TARGET
PCI BUS INTERFACE S5935
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Latency Timer register can cause two preemption
situations:
Initiator Preemption
A PCI initiator (bus master) is said to be preempted
when the system platform deasserts the initiator’s bus
grant signal, GNT#, while it still requests the bus
(REQ# asserted). This situation occurs if the initiator’s
latency timer expires and the system platform (bus
arbitrator) has a bus master request from another
device. The S5935 Master Latency Timer register controls the S5935 responsiveness to the removal of a
bus grant (preemption). The presence of a Master
1. Removal of GNT# when the latency timer is nonzero (S5935 is guaranteed to still “own the bus”).
2. Removal of the GNT# after the latency timer has
expired.
The first situation is depicted in Figure 7, when the
latency timer has not expired. Preemption with a zero
or expired latency timer is shown in Figure 8.
Figure 52. Master Initiated Termination Due to Preemption and Latency Timer Active (S5935 as Master)
3
2
1
4
6
5
PCI CLOCK
GNT #
FRAME
(I)
IRDY#
(I)
TRDY#
(T)
S5933 LATENCY
=3
TIMER
=1
=2
=0
PREEMPTION
DATA
DATA
DATA
TRANSFERRED
(I) = DRIVEN BY INITIATOR
(T) = DRIVEN BY TARGET
TIMEOUT
SENSED
TRANSFERRED
TRANSFERRED
DATA
TRANSFERRED
Figure 53. Master Initiated Termination Due to Preemption and Latency Timer Expired (S5935 as Master)
1
2
3
4
5
PCI CLOCK
GNT #
FRAME (I)
IRDY#
(I)
TRDY# (T)
S5933
=1
LATENCY
TIMER
=0
PREEMPTION
106
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DATA
TRANSFERRED
(I) = DRIVEN BY INITIATOR
(T) = DRIVEN BY TARGET
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Master Abort
PCI accesses to nonexistent or disabled targets never
observe DEVSEL# being asserted. In this situation, it
is necessary for the initiator to abort the transaction
(master abort). As an initiator, S5935 waits for six
clock periods after asserting FRAME# to determine
whether a master abort is required. These six clock
periods allow slow targets, which may require several
bus clocks before being able to assert DEVSEL#, to
respond. It is also possible a PCI bridge device is
present which employs “subtractive” decoding. A
device which does a subtractive decode asserts
DEVSEL#, claiming the cycle, when it sees that no
other device has asserted it three clocks after the
address phase.
If DEVSEL# is not asserted, the S5935 deasserts
FRAME# (if asserted) upon the sixth clock period (Figure 9). IRDY# is deasserted by the S5935 during the
next clock. The occurrence of a master abort causes
the S5935 to set bit 13 (Master Abort) of the PCI Status Register, indicating an error condition.
Target-Initiated Termination
There are situations where the target may end a transfer prematurely. This is called “target-initiated
termination.” Target terminations fall into three categories: disconnect, retry, and target abort. Only the
disconnect termination completes a data transfer.
Figure 54. Master Abort, No Response
1
2
4
3
5
67
8
PCI CLOCK
FRAME #
(I)
IRDY#
(I)
TRDY#
(T)
DEVSEL#
(T)
FAST
DEVICE
MEDIUM
DEVICE
SLOW
DEVICE
BRIDGE
DEVICE
(I) = DRIVEN BY INITIATOR
(T) = DRIVEN BY TARGET
(SUBTRACTIVE
DECODE)
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S5935 – PCI Product
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clock but does not complete the data transfer until
IRDY# is asserted. This situation can only occur when
the S5935 is a target. When the S5935 is an initiator,
IRDY# is always asserted during the data phase (no
initiator wait states). The timing diagram in Figure 10b
applies to the S5935 as either a target disconnecting
or an initiator with its target performing a disconnect.
The S5935 performs a target disconnect if a burst
access is attempted to the PCI Operation Registers.
Target Disconnects
There are many situations where a target may disconnect. Slow responding targets may disconnect to
permit more efficient (faster) devices to be accessed
while they prepare for the next data phase, or a target
may disconnect if it recognizes that the next data
phase in a burst transfer is out of its address range. A
target disconnects by asserting STOP#, TRDY#, and
DEVSEL# as shown in Figures 10a and 10b. The initiator in Figure 10a responds to the disconnect
condition by deasserting FRAME# on the following
Figure 55. Target Disconnect Example 1 (IRDY# deasserted)
1
2
3
PCI CLOCK
FRAME #
(I)
IRDY#
(I)
TRDY#
(T)
STOP#
(T)
DEVSEL#
(T)
(I) = DRIVEN BY INITIATOR
(T) = DRIVEN BY TARGET
DATA
TARGET DISCONNECT
TRANSFERRED
IDENTIFIED
Figure 10b. Target Disconnect Example 2 (IRDY# asserted)
1
2
3
PCI CLOCK
FRAME #
(I)
IRDY#
(I)
TRDY#
(T)
STOP#
(T)
DEVSEL#
(T)
(I) = DRIVEN BY INITIATOR
(T) = DRIVEN BY TARGET
DATA
TARGET DISCONNECT
TRANSFERRED SIGNALED, DATA TRANSFERRED
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Target Requested Retries
Target Aborts
When the S5935 FIFO registers are accessed (S5935
as a target) and data is unavailable (empty FIFO) for
read transfers or cannot be accepted for write transfers (full FIFO), the S5935 immediately terminates the
cycle by requesting a retry. The S5935 also initiates a
retry for Pass-Thru writes where the Add-On has not
completed the preceding Pass-Thru write by asserting
PTRDY#, and for Pass-Thru reads where the Add-On
cannot supply data within 8 PCI clocks (16 clocks for
the first data phase of a burst). A retry is requested by
a target asserting both STOP# and DEVSEL# while
TRDY# is deasserted. Figure 11 shows the behavior of
the S5935 when performing a target-initiated retry.
A target abort termination represents an error condition where no number of retries will produce a
successful target access. A target abort is uniquely
identified by the target deasserting DEVSEL# and
TRDY# while STOP# is asserted. When a target performs an abort, it must also set bit 11 of its PCI Status
register. The S5935 configuration and operation registers never respond with a target abort when accessed.
If the S5935 encounters this condition when operating
as a PCI initiator, the S5935 sets bit 12 (received target abort) in the PCI Status register. Figure 12 depicts
a target abort cycle.
Target termination types are summarized in Table 2.
Figure 56. Target-Initiated Retry
2
1
3
45
PCI CLOCK
FRAME #
(I)
IRDY#
(I)
TRDY#
(T)
STOP#
(T)
DEVSEL#
(T)
TARGET
RETRY
SIGNALED
INITIATOR
SEQUENCES IRDY#
+ FRAME# TO RETURN
TO IDLE STATE
(I) = DRIVEN BY INITIATOR
(T) = DRIVEN BY TARGET
Table 42. Target Termination Types
Termination
DEVSEL#
STOP#
TRDY#
Comment
Disconnect
on
on
on
Data is transferred. Transaction needs to be reinitiated to complete.
Retry
on
on
off
Data was not transferred. Transaction should be tried later.
Abort
off
on
off
Data was not transferred. Fatal error.
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Figure 57. Target Abort Example
3
2
1
PCI CLOCK
FRAME #
(I)
IRDY#
(I)
TRDY#
(T)
STOP#
(T)
DEVSEL#
(T)
(I) = DRIVEN BY INITIATOR
(T) = DRIVEN BY TARGET
TARGET ABORT
IDENTIFIED
Figure 58. PCI Bus Arbitration and S5935 Bus Ownership Example
2
1
34
56
89
7
S5933 REQ#
"OTHER" REQ#
S5933 GNT#
"OTHER" GNT#
FRAME#
ADDRESS
AD[31:0]
DATA
ADDRESS
DATA
ADDRESS
DATA
IRDY#
TRDY#
IDLE
S5933
TRANSACTION
IDLE
(TURNAROUND)
"OTHER",
PREEMPTING
MASTER
TRANSACTION
IDLE
(TURNAROUND)
S5933
TRANSACTION(S)
(I) = DRIVEN BY INITIATOR
(T) = DRIVEN BY TARGET
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S5935 – PCI Product
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PCI BUS MASTERSHIP
When the S5935 requires PCI bus mastership, it presents a request via the REQ# signal. This signal is
connected to the system’s PCI bus arbiter.
Only one initiator (bus master) may control the PCI
bus at a given time. The bus arbiter determines which
initiator is given control of the bus. Control is granted
to a requesting device by the arbiter asserting that
device’s grant signal (GNT#). Each REQ#/ GNT# signal pair is unique to a given PCI agent.
After asserting REQ#, the S5935 assumes bus ownership on the first PCI clock edge where its GNT# input
is asserted along with FRAME# and IRDY# deasserted (indicating no other device is generating PCI
bus cycles). Once ownership is established by the
S5935, it maintains ownership as long as the arbiter
keeps its GNT# asserted. If GNT# is deasserted, the
S5935 completes the current transaction.
The S5935 does this by deasserting FRAME# and
then deasserting IRDY# upon data transfer. Figure 13
shows a sequence where the S5935 is granted ownership of the bus and then is preempted by another
master before the S5935 can finish its current
transaction.
Once a PCI initiator has been granted the bus, the PCI
specification defines the delay from the grant to the
new initiator’s assertion of FRAME# as the “bus acquisition latency.” Afterwards, the delay from FRAME#
asserted to target ready (TRDY#) asserted is defined
as “target latency.” Figure 14 shows a time-line depicting the components of PCI bus access latency.
There are numerous configuration variations possible
with the PCI specification. A system designer can
determine whether a bus master can support a critical,
timely transfer by establishing a specific configuration
and by defining these latency values. The S5935, as
an initiator, produces the fastest response allowable
for its bus acquisition latency (GNT# to FRAME#
asserted). The S5935 also implements the PCI Master
Latency Timer. Once granted the bus, the S5935 is
guaranteed ownership for a minimum amount of time
defined by the Master Latency Timer. The S5935, as
an initiator, cannot control the responsiveness of a
particular target nor the bus arbitration delay.
The PCI specification provides two mechanisms to
control the amount of time a master may own the bus.
One mechanism is through the master (master initiated termination). The other is by the target and is
achieved through a target-initiated disconnect.
Bus Mastership Latency Components
Bus Arbitration
It is often necessary for system designers to predict
and guarantee that a minimum data transfer rate is
sustainable to support a particular application. In the
design of a bus mastering application, knowledge of
the maximum delay a device might encounter from the
time it requests the PCI bus to the time in which it is
actually granted the bus is desirable. This allows the
design to provide adequate data buffering. The PCI
specification refers to this bus request to grant delay
as “arbitration latency.”
Although the PCI specification defines the condition
that constitutes bus ownership, it does not provide
rules to be used by the system’s PCI bus arbiter in
deciding which master is to be granted the PCI bus
next. The arbitration priority scheme implemented by a
system may be fixed, rotational, or custom. The arbitration latency is a function of the system, not the
S5935.
Figure 59. PCI Bus Access Latency Components
Bus Access Latency
REQ#
Asserted
GNT#
Asserted
--Arbitration Latency--
AMCC Confidential and Proprietary
--Bus Acquisition-Latency
FRAME#
Asserted
TRDY#
Asserted
--Target Latency--
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S5935 – PCI Product
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potentially monopolizing the PCI bus and also allows
more accurate estimations for bus access latency.
Bus Acquisition
Once GNT# is asserted, giving bus ownership to the
S5935, the S5935 must wait until the PCI bus
becomes idle. This delay is called bus acquisition
latency and involves the state of the signals FRAME#
and IRDY#. The current bus master must complete its
current transaction before the S5935 may drive the
bus. Table 3 depicts the four possible combinations of
FRAME# and IRDY# with their interpretation.
Target Locking
It is possible for a PCI bus master to obtain exclusive
access to a target (“locking”) through use of the PCI
bus signal LOCK#. LOCK# is different from the other
PCI bus signals because its ownership may belong to
any bus master, even if it does not currently have ownership of the PCI bus. The ownership of LOCK#, if not
already claimed by another master, may be achieved
by the current PCI bus master on the clock period following the initial assertion of FRAME#. Figure 15
describes the signal relationship for establishing a
lock. The ownership of LOCK#, once established, persists even while other bus masters control the bus.
Ownership can only be relinquished by the master
which originally established the lock.
Target Latency
The PCI specification requires that a selected target
relinquish the bus should an access to that target
require more than eight PCI clock periods (16 clocks
for the first data phase in a burst). Slow targets can
exist within the PCI specification by using the target
initiated retry. This prevents slow target devices from
Figure 60. Engaging the LOCK# Signal
3
2
1
6
45
PCI CLOCK
(I)
FRAME #
STILL DRIVEN BY PREVIOUS
OWNER (TARGET IS LOCKED)
LOCK #
(T)
(I)
AD[31:0]
DATA
ADDRESS
IRDY#
(I)
TRDY#
(T)
DEVSEL#
(T)
TARGET
BECOMES
LOCKED
LOCK
MECHANISM
AVAILABLE
UPON FIRST
ACCESS
LOCK MECHANISM
AVAILABLE
(I) = DRIVEN BY INITIATOR
(T) = DRIVEN BY TARGET
BUS
IDLE
LOCK ESTABLISHED
LOCK MAINTAINED
Table 43. Possible Combinations of FRAME# and IRDY#
FRAME#
IRDY#
deasserted
deasserted
Bus Idle
deasserted
asserted
The initiator is ready to complete the last data transfer of a transaction.
asserted
deasserted
An Initiator has a transaction in progress but is not able to complete the data transfer on this
clock.
asserted
asserted
An initiator has a transaction in progress and is able to complete a data transfer.
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Targets selected with LOCK# deasserted during the
assertion of FRAME# (clock period 1 of Figure 15),
which encounter the assertion of LOCK# during the
following clock (clock period 2 of Figure 15) are thereafter considered “locked.” A target, once locked,
requires that subsequent accesses to it deassert
LOCK# while FRAME# is asserted. Figure 16 show a
subsequent access to a locked target by the master
which locked it. Because LOCK# is owned by a single
master, only that master is able to deassert it at the
beginning of a transaction (allowing successful access
to the locked target). A locked target can only be
unlocked during the clock period following the last data
transfer of a transaction when the LOCK# signal is
deasserted.
An unlocked target ignores LOCK# when it observes
that LOCK# is already asserted during the first clock
period of a transaction. This allows other masters to
access other (unlocked) targets. If an access to a
locked target is attempted by a master other than the
one that locked it, the target responds with a retry
request, as shown in Figure 17.
The S5935 responds to and supports bus masters
which lock it as a target. When the S5935 is a bus
master, it never attempts to lock a target, but it honors
a target’s request for retry if that target is locked by
another master.
Figure 61. Access to a Locked Target by its Owner
3
2
1
45
PCI CLOCK
FRAME #
(I)
LOCK #
AD [31:0]
(I)
IRDY#
(I)
TRDY#
(T)
DEVSEL#
(T)
DATA
DATA
ADDRESS
LOCKED
TARGET
IDENTIFIES
OWNER
CONDITION
WHICH
UNLOCKS
TARGET
(I) = DRIVEN BY INITIATOR
(T) = DRIVEN BY TARGET
Figure 62. Access Attempt to a Locked Target
1
3
2
45
PCI CLOCK
FRAME #
(I)
LOCK #
AD [31:0]
(I)
ADDRESS
IRDY#
(I)
TRDY#
(T)
DEVSEL#
(T)
STOP#
(T)
LOCKED
TARGET IDENTIFIES
THAT BUS MASTER
IS NOT ITS OWNER
AMCC Confidential and Proprietary
DATA
CAUSES TARGET
RETRY TERMINATION
(I) = DRIVEN BY INITIATOR
(T) = DRIVEN BY TARGET
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Data Book
PCI BUS INTERRUPTS
The S5935 controller is able to generate PCI bus interrupts by asserting the PCI bus interrupt signal (INTA#).
INTA# is a multisourced, wire-ORed signal on the PCI
bus and is driven by an open drain output on the
S5935. The assertion and deassertion of INTA# have
no fixed timing relationship with respect to the PCI bus
clock. Once the S5935 asserts INTA#, it remains
asserted until the interrupt source is cleared by a write
to the Interrupt Control/Status Register (INTCSR).
PCI BUS PARITY ERRORS
The PCI specification defines two error-reporting signals, PERR# and SERR#. These signals indicate a
parity error condition on the signals AD[31:0], C/
BE[3:0]#, and PAR. The validity of the PAR signal is
delayed one clock period from its corresponding
AD[31:0] and C/BE[3:0]# signals. Even parity exists
when the total number of ones in the group of signals
is equal to an even number. PERR# is the errorreporting mechanism for parity errors that occur during
the data phase for all but PCI Special Cycle commands. SERR# is the error-reporting mechanism for
parity errors that occur during the address phase.
The timing diagram in Figure 18 shows the timing relationships between the signals AD[31:0], C/BE[3:0]#,
PAR, PERR# and SERR#.
The S5935 asserts SERR# if it detects odd parity during an address phase, if enabled. The SERR# enable
bit is bit 8 in the S5935 PCI Command Register. The
odd parity error condition involves the state of signals
AD[31:0] and C/BE[3:0]# when FRAME# is first
asserted and the PAR signal during the following
clock. If an error is detected, the S5935 asserts
SERR# on the following (after PAR valid) clock. Since
many targets may observe an error on an address
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DS1527
phase, the SERR# signal is an open drain multisourced, wire-ORed signal on the PCI bus. The S5935
drives SERR# low for one clock period when an
address phase error is detected. Once an SERR error
is detected by the S5935, the PCI Status register bit
14, System Error, is set and remains until cleared
through software or a hardware reset.
The PERR# signal is similar to the SERR# with two
differences: it reports errors for the data phase and is
only asserted by the device receiving the data. The
S5935 drives this signal (removed from tri-state) when
it is the selected target for write transactions or when it
is the current master for bus read transactions. The
parity error conditions are only reflected by the PERR#
pin if the Parity Error Enable bit (bit 6) of the PCI Command register is set. Upon the detection of a data
parity error, the Detected Parity Error bit (bit 15) of the
PCI Status Register is set. Unlike the PERR# signal
pin, this Status bit sets regardless of the state of the
PCI Command register Parity Error Enable bit. An
additional status bit (bit 8) called “Data Parity
Reported” of the PCI Status register is employed to
report parity errors that occur when the S5935 is the
bus master. The “Data Parity Error Reported” status
requires that the Parity Error Enable bit be set in the
PCI Command register.
The assertion of PERR# occurs two clock periods following the data transfer. This two-clock delay occurs
because the PAR signal does not become valid until
the clock following the transfer, and an additional clock
is provided to generate and assert PERR# once an
error is detected. PERR# is only asserted for one
clock cycle for each error sensed. The S5935 only
qualifies the parity error detection during the actual
data transfer portion of a data phase (when both
IRDY# and TRDY# are asserted).
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S5935 – PCI Product
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Figure 63. Error Reporting Signals
12
6
5
4
3
7
8
9
PCI CLOCK
FRAME
(I)
(T)
(I)
AD[31:0]
(I)
C/BE[3:0]#
ADDR
A
CMD
AA
(I)
DATA A
BYTE ENABLES
SERR#
(T)
PERR#
(T)
DATA
CMD BB
BE's
(I)
(T)
PAR
ADDR BB
GOOD
A
ERROR
A
READ TRANSACTION
GOOD
A
ERROR
GOOD
B
ERROR
GOOD
B
ERROR
WRITE B
TRANSACTION
(I) = DRIVEN BY INITIATOR
(T) = DRIVEN BY TARGET
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ADD-ON BUS INTERFACE
This chapter describes the Add-On bus interface for
the S5935. The S5935 is designed to support connection to a variety of microprocessor buses and/or
peripheral devices. The Add-On interface controls
S5935 operation through the Add-On Operation Registers. These registers act as the Pass-Thru, FIFO,
non-volatile memory and mailbox interfaces as well as
offering control and status information.
Depending on the register being accessed, the interface may be synchronous or asynchronous. To
enhance performance and simplify Add-On logic
design, some registers allow direct access with a single device input pin. The following sections describe
the various interfaces to the PCI bus and how they are
accessed from the Add-On interface.
ADD-ON OPERATION REGISTER
ACCESSES
The S5935 Add-On bus interface is very similar to that
of a memory or peripheral device found in a microprocessor-based system. A 32-bit data bus with individual
read and write strobes, a chip enable and byte
enables are provided. Other Add-On interface signals
are provided to simplify Add-On logic design.
Accesses to the S5935 registers are done primarily
synchronously to BPCLK. For S5935 functions that
are compatible with an Add-On microprocessor interface, it is helpful to allow an asynchronous interface,
as the processor may not operate at the PCI bus clock
frequency.
Add-On Interface Signals
The Add-On interface provides a small number of system signals to allow the Add-On to monitor PCI bus
activity, indicate status conditions (interrupts), and
allow Add-On bus configuration. A standard bus interface is provided for Add-On Operation Register
accesses.
System Signals
BPCLK and SYSRST# allow the Add-On interface to
monitor the PCI bus status. BPCLK is a buffered version of the PCI clock. The PCI clock can operate from
0 MHz to 33 MHz. SYSRST# is a buffered version of
the PCI reset signal, and may also be toggled by host
application software through bit 24 of the Bus Master
Control/Status Register (MCSR).
IRQ# is the Add-On interrupt output. This signal is
active low and can indicate a number of conditions.
Add-On interrupts may be generated from the mailbox
or FIFO interfaces. The exact conditions which generate an interrupt are discussed in the mailbox and FIFO
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chapters. The interrupt output is deasserted when
acknowledged by an access to the Add-On Interrupt
Control/Status Register (AINT). All interrupt sources
are cleared by writing a one to the corresponding interrupt bit.
The MODE input on the Add-On interface configures
the datapath width for the Add-On interface. MODE
low indicates a 32-bit data bus. MODE high indicates a
16-bit data bus. For 16-bit operation, BE3# is redefined as ADR1, providing an extra address input.
ADR1 selects the low or high words of the 32-bit
S5935 Add-On Operation Registers.
Register Access Signals
Simple register accesses to the S5935 Add-On Operation Registers take two forms: synchronous to BPCLK
and asynchronous. The following signals are required
to complete a register access to the S5935.
BE[3:0]# Byte Enable Inputs. These S5935 inputs
identify valid byte lanes during Add-On transactions. When MODE is set for 16-bit operation,
BE2# is not defined and BE3# becomes ADR1.
ADR[6:2] Address Inputs. These address pins identify
the specific Add-On Operation Register being
accessed. When configured for 16-bit operation
(MODE=1), an additional input, ADR1 is available
to allow the 32-bit operation registers to be
accessed with two 16-bit cycles.
RD# Read Strobe Input.
WR# Write Strobe Input.
SELECT# Chip Select Input. This input identifies a
valid S5935 access.
DQ[31:0] Bidirectional Data Bus. These I/O pins are
the S5935 data bus. When configured for 16-bit
operation, only DQ[15:0] are valid.
In addition, there are dedicated signals for FIFO
accesses (RDFIFO# and WRFIFO#) and Pass-Thru
address accesses (PTADR#). These are discussed
separately in the FIFO and Pass-Thru sections of this
chapter.
The internal interfaces of the S5935 allow Add-On
Operation Registers to be accessed asynchronous to
BPCLK (synchronous to the rising edge of the read or
write strobe). The exception to this is the Add-On General Control/Status Register. This is due to the async
nature of FIFO status bits changing as the PCI bus
reads data. For Pass-Thru operations, the Pass-Thru
Data Register accesses are synchronous to BPCLK to
support burst transfers. The FIFO port is also
accessed synchronous to BPCLK.
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Asynchronous Register Accesses
For many Add-On applications, Add-On logic does not
operate at the PCI bus frequency. This is especially
true for Add-Ons implementing a microprocessor,
which may be operating at a lower (or higher) frequency. Figures 1 and 2 show asynchronous Add-On
Operation Register accesses. Exact AC timings are
detailed in the Electrical and AC Characteristics chapter (Chapter 13).
For asynchronous reads (Figure 1), data is driven on
the data bus when RD# is asserted. When RD# is not
asserted, the DQ[31:0] outputs float. A valid address
and valid byte enables must be presented before correct data is driven. RD# has both a minimum inactive
time and a minimum active time for asynchronous
accesses.
For asynchronous writes (Figure 2), data is clocked
into the S5935 on the rising edge of the WR# input.
Address, byte enables, and data must all meet setup
and hold times relative to the rising edge or WR#.
WR# has both a minimum inactive time and a minimum active time for asynchronous accesses.
Synchronous FIFO and Pass-Thru Data Register
Accesses
To obtain the highest data transfer rates possible, AddOn logic should operate synchronously with the PCI
clock. The buffered PCI clock (BPCLK) is provided for
this purpose. A synchronous interface with Pass-Thru
mode or the FIFO allows data to be transferred at the
maximum PCI bus bandwidth (132 MBytes/sec) by
allowing burst accesses with the Add-On interface.
The RD# and WR# inputs become enables, using
BPCLK to clock data into and out of registers. This
section applies only to synchronous accesses to the
FIFO (AFIFO) and Pass-Thru Data (APTD) registers.
Figures 3 and 4 show single-cycle, synchronous FIFO
and Pass-Thru Operation Register accesses. Exact
AC timings are detailed in the Electrical and AC Characteristics chapter.
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For synchronous reads (Figure 3), data is driven onto
the data bus when RD# (or RDFIFO#) is asserted.
When RD# is not asserted, the DQ[31:0] outputs float.
The address, byte enable, and RD# inputs must meet
setup and hold times relative to the rising edge of
BPCLK. Burst reads may be performed by holding
RD# low.
For synchronous writes (Figure 4), data is clocked into
the register on the rising edge of BPCLK. Address,
byte enables, and data must all meet setup and hold
times relative to the rising edge or BPCLK. Burst
writes may be performed by holding WR# (or
WRFIFO#) low. When holding WR# low, data is
clocked in on each BPCLK rising edge.
nv Memory Accesses Through the Add-On General Control/Status Register
To access nv memory contents through the Add-On
General Control/Status Register (AGCSTS), special
considerations must be made. Internally, all nv memory accesses by the S5935 are synchronized to a
divided-down version of the PCI bus clock. Because of
this, if nv memory accesses are performed through the
AGCSTS register, the register access must be synchronized to BPCLK. The rising edge RD# or WR# is
still used to clock data, but these inputs along with the
address and byte enables are synchronized to
BPCLK. Accesses to AGCSTS for monitoring FIFO or
mailbox status, etc., may be done asynchronous to
BPCLK.
MAILBOX BUS INTERFACE
The mailbox register names may need some clarification. For the Add-On interface, an outgoing mailbox
refers to a mailbox sending information to the PCI bus.
An incoming mailbox refers to a mailbox receiving
information from the PCI bus. An outgoing mailbox on
the Add-On interface is, internally, the same as the
corresponding incoming mailbox on the PCI interface
and vice-versa.
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Figure 64. Asynchronous Add-On Operation Register Read
BE[3:0]#
Valid Byte Enables
ADR[6:2]
Valid Address
DQ[31:0]
Valid Data Out
SELECT#
RD#
Figure 65. Asynchronous Add-On Operation Register Write
BE[3:0]#
Valid Byte Enables
ADR[6:2]
Valid Address
DQ[31:0]
Valid Data In
SELECT#
WR#
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Figure 66. Synchronous FIFO or Pass-Thru Data Register Read
BPCLK
ADR[6:2]
BE[3:0]#
Valid 1
DQ[31:0]
Valid 2
Valid Data Out 1
Valid Data Out 2
RD#
RDFIFO#
SELECT#
Figure 67. Synchronous FIFO or Pass-Thru Data Register Write
BPCLK
ADR[6:2]
BE[3:0]#
DQ[31:0]
Valid 1
Valid Data In 1
Valid 2
Valid Data In 2
WR#
WRFIFO#
SELECT#
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Mailbox Interrupts
Mailboxes can be configured to generate Add-On
interrupts (IRQ#) and/or allow the Add-On to generate
PCI interrupts (INTA#). Mailbox empty/full status conditions be can used to interrupt the Add-On or PCI
host to indicate some action is required. An individual
mailbox byte is selected to generate an interrupt when
accessed. An outgoing mailbox becoming empty or an
incoming mailbox becoming full asserts the interrupt
output (if enabled).
When used with a serial nv memory boot device, the
mailboxes also provide a way to generate PCI interrupts (INTA#) through hardware. When a serial nv
memory boot device is used, the device pin functions
EA0 - EA8 are redefined. These pins then provide
direct, external access to the Add-On outgoing mailbox 4, byte 3 (which is also PCI incoming mailbox 4,
byte 3).
FIFO BUS INTERFACE
The FIFO register on the Add-On interface may only
be accessed synchronously or asynchronously. Location 45h, bits 6 and 5 in the nv memory boot device
must be programmed to a “0” for correct operation.
FIFO Direct Access Inputs
RDFIFO# and WRFIFO# are referred to as FIFO
‘direct access’ inputs. Asserting RDFIFO# is functionally identical to accessing the FIFO with RD#,
SELECT#, BE[3:0]#, and ADR[6:2]. Asserting
WRFIFO# is functionally identical to accessing the
FIFO with WR#, SELECT#, BE[3:0]#, and ADR[6:2].
RD# and WR# must be deasserted when RDFIFO# or
WRFIFO# is asserted, but SELECT# may be
asserted. These inputs automatically drive the address
(internally) to 20h and assert all byte enables. The
ADR[6:2] and BE[3:0]# inputs are ignored when using
the FIFO direct access inputs. RDF IF O# and
WRFIFO# are useful for Add-On designs which cascade an external FIFO into the S5935 FIFO or use
dedicated external logic to access the FIFO.
Direct access signals always access the FIFO as 16bits or 32-bits, whatever the MODE pin is configured
for. For 16-bit mode, two consecutive accesses fill or
empty the 32-bit FIFO register.
FIFO Status Signals
The FIFO Status signals indicate to the Add-On logic
the current state of the S5935 FIFO. A FIFO status
change caused by a PCI FIFO access is reflected one
PCI clock period after the PCI access is completed
(TRDY# asserted). A FIFO status change caused by
an Add-On FIFO access is reflected immediately (after
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a short propagation delay) after the access occurs. For
Add-On accesses, FIFO status is updated after the rising edge of BPCLK for synchronous interfaces or after
the rising edge of the read or write strobe for asynchronous interfaces.
FIFO Control Signals
For Add-On initiated PCI bus mastering, the FIFO status reset controls FWC# (Add-On to PCI FIFO clear)
and FRC# (PCI to Add-On FIFO clear) are available.
FWC# and FRC# must be asserted for a minimum of
one BPCLK period to be recognized. These inputs are
sampled at the rising edge of BPCLK. These inputs
should not be asserted unless the FIFO is idle. Asserting a FIFO status reset input during a PCI or Add-On
FIFO access results in indeterminate operation.
For Add-On initiated bus master transfers, AMREN
(Add-On bus master read enable) and AMWEN (AddOn bus master write enable) are used, in conjunction
with the appropriate FIFO status signals, to enable the
S5935 to assert its PCI bus request (REQ#).
PASS-THRU BUS INTERFACE
The S5935 Pass-Thru interface is synchronous. The
Add-On Pass-Thru Address (APTA) and Add-On
Pass-Thru Data (APTD) registers may be accessed
pseudo-synchronously.
Although BPCLK is used to clock data into and out of
the Pass-Thru registers, accesses may be performed
asynchronously. For reads, APTA or APTD data
remains valid as long as RD# (or PTADR#) is
asserted. A new value is not driven until PTRDY# is
asserted by Add-On logic. For writes to APTD, data is
clocked into the S5935 on every BPCLK rising edge,
but is not passed to the PCI bus until PTRDY# is
asserted. PTRDY# must by synchronized to BPCLK.
Pass-Thru Status Indicators
The Pass-Thru status indicators indicate that a PassThru access is in process and what action is required
by the Add-On logic to complete the access. All PassThru status indicators are synchronous with the PCI
clock.
Pass-Thru Control Inputs
Some Pass-Thru implementations may require an
address corresponding to the Pass-Thru data. The
Add-On Pass-Thru Address Register (APTA) contains
the PCI address for the Pass-Thru cycle. To allow
access to the Pass-Thru address without generating
an Add-On read cycle, PTADR# is provided. PTADR#
is a direct access input for the Pass-Thru address.
Asserting PTADR# is functionally identical to accessing the Pass-Thru address register with RD#,
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SELECT#, BE[3:0]#, and ADR[6:2]. RD# and WR#
must be deasserted when PTADR# is asserted, but
SELECT# may be asserted. These inputs automatically drive the address (internally) to 28h and assert all
byte enables. The ADR[6:2] and BE[3:0]# are ignored
when using the PTADR# direct access input. When
PTADR# is asserted, the contents of the APTA register
are immediately driven onto the Add-On data bus.
The PTADR# direct access signal accesses the PassThru address register as 16-bits or 32-bits, whatever
the MODE pin is configured for. For 16-bit mode,
PTADR# only presents the lower 16-bits of the APTA
register.
PTRDY# indicates that the Add-On has completed the
current Pass-Thru access. Multiple Add-On reads or
writes may occur to the Pass-Thru data (APTD) register before asserting PTRDY#. This may be required for
8-bit or 16-bit Add-On interfaces using multiple
accesses to the 32-bit Pass-Thru data register. In
some cases, the Add-On bus may be 32-bits, but logic
may require multiple BPCLK periods to read or write
data. In this situation, accesses may be extended by
holding off PTRDY#. PTRDY# must be synchronized
to BPCLK.
NON-VOLATILE MEMORY INTERFACE
The S5935 allows read and write access to the nv
memory device used for configuration. Reads are necessary during device initialization as configuration
information is downloaded into the S5935. If an expansion BIOS is implemented in the nv memory, the host
transfers (shadows) the code into system DRAM.
Writes are useful for in-field updates to expansion
BIOS code. This allows software to update the nv
memory contents without altering hardware.
Non-Volatile Memory Interface Signals
For serial nv memory devices, there are only two signals used to interface with nv memory. SCL is the
serial clock, and SDA is the serial data line. The functionality of these signals is described in-detail in the
PIN description Section of this book. The designer
does not need to generate the timings for SCL and
SDA. The S5935 automatically performs the correct
serial access when programmed for serial devices.
For byte-wide nv memory devices, there is an 8-bit
data bus (EQ7:0), and a 16-bit address bus (EA15:0)
dedicated for the nv memory interface. When a serial
nv memory is implemented, many of these pins have
alternate functions. The S5935 also has read (ERD#)
and write (EWR#) outputs to drive the OE# and WR#
inputs on a byte-wide nv memory. The designer does
not need to generate the timings for these outputs.
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The S5935 automatically performs the read and write
accesses when programmed for byte wide devices.
Accessing Non-Volatile Memory
The nv memory, if implemented, can be accessed
through the PCI interface or the Add-On interface.
Accesses from both the PCI side and the Add-On side
must be synchronous with the PCI clock (BPCLK for
the Add-On). Accesses to the nv memory from the PCI
interface are through the Bus Master Control/Status
Register (MCSR) PCI Operation Register.
Accesses to the nv memory from the Add-On interface
are through the Add-On General Control/Status Register (AGCSTS) Add-On Operation Register. Accesses
to the MCSR register are from the PCI bus and are,
therefore, automatically synchronous to the PCI clock.
Accesses to the AGCSTS register from the Add-On
side must be synchronous with respect to BPCLK.
Some nv memories may contain Expansion ROM
BIOS code for use by the host software. During initialization, the Expansion BIOS is located within system
memory. The starting location of the nv memory is
stored in the Expansion ROM Base Address Register
in the S5935 PCI Configuration Registers. A PCI read
from this region results in the S5935 performing four
consecutive byte access to the nv memory device.
Writes to the nv memory are not allowed by writing to
this region. Writes to the nv memory must be performed as described below.
The S5935 contains two latches within the MCSR register to control and access the NVRAM. One is an 8 bit
latch called the NVRAM Address/Data Register which
is used to hold NVRAM address and data information.
The other is a 3 bit latch called the NVRAM Access
Control Register which is used to direct the address
and data information and to control the NVRAM itself.
Reading or writing to the NVRAM is performed through
bits D31:29 of this register. These bits are enable and
decode controls rather than a command or instruction
to be executed. D31 of this register is the primary
enable bit which allows all accesses to occur. When
written to a ‘1’, D31 enables the decode bits D30 and
D29 to direct the data contained in the address/data
latch, D23:16, to the low address, high address or data
latches. D31 should be thought of as “opening a door”
where as long as D31 = 1, then the door is open for
address or data information to be altered. The table on
page 5-16 of the S5935 data book shows the D31:29
bit combinations for reading, writing, and loading address/data information. Additionally, D31 doubles as
an S5935 status bit. A ‘1’ indicates that the S5935 is
currently busy reading or writing to the NVRAM. A ‘0’
indicates a complete or inactive state.
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For the examples below, we will assume the S5935 is
I/O mapped with a base address of FC00h. These
examples will read one byte of the Vendor ID and write
one byte to the Vendor ID.
This example will write 1 byte from NVRAM location 0040h and read it back:
In
FC00h + 3Fh (offset of NVRAM Access Control Register) until D31 = 0 (not busy).
Out
FC00h + 3FH an 80h (CMD to load the low address byte). This sets decode bits and opens door for low address
latch.
Out
FC00h + 3Eh (offset of Address/Data Register) 40h (the low byte of the address desired) 40h goes into latch but is
not latched yet.
Out
FC00h + 3Fh an A0h (CMD to load the high address byte). This latches the low address through changing the
decode bits and opens the door for the high address latch.
Out
FC00h + 3Eh a 00h (the high byte of the address desired). 00h goes into the latch but is not latched yet.
Out
FC00h + 3Fh an 00h (inactive CMD). This latches the high address through the disabling D31, ‘closes the door’.
Out
FC00h + 3Eh DATA (the data byte to be written). DATA byte goes into the latch but is not latched yet.
Out
FC00h + 3Fh a C0h (CMD to write the data byte). This latches the data byte through changing the decode bits and
begins to write NVRAM data operation.
In
FC00h + 3Fh until D31 = 0 (not busy).
Out
FC00h + 3Fh an E0h (CMD to read the address latched).
In
FC00h + 3Fh until D31 = 0 (not busy).
In
FC00h + 3Eh the data.
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This example will read 1 byte from NVRAM location 0040h:
In
FC00h + 3Fh (offset of NVRAM Access Control Register) until D31 = 0 (not busy).
Out
FC00h + 3Fh an 80h (CMD to load the low address byte). This sets decode bits and opens door for low address
latch.
Out
FC00h + 3Eh (offset of Address/Data Register) 40h (the low byte of the address desired) 40h goes into latch but is
not latched yet.
Out
FC00h + 3Fh an A0h (CMD to load the high address byte). This latches the low address through changing the
decode bits and opens the door for the high address latch.
Out
FC00h + 3Eh a 00h (the high byte of the address desired) 00h goes into latch but is not latched yet.
Out
FC00h + 3Fh an E0h (CMD to read NVRAM data). This latches the high address through changing the decode bits
and begins to read the NVRAM data operation.
In
FC00h + 3Fh until D31 = 0 (not busy).
In
FC00h + 3Eh the data.
This example will read 1 byte from NVRAM location 0041h and contains an extra step to demonstrate D31 operation:
In
FC00h + 3Fh (offset of NVRAM Access Control Register) until D31 = 0 (not busy).
Out
FC00h + 3Fh an 80h (CMD to load the low address byte). This sets decode bits and opens the door for low
address latch.
Out
FC00h + 3Eh (offset of Address/Data Register) 40h (the low byte of the address desired) 40h goes into latch but is
not latched yet.
Out
FC00h + 3Eh (offset of Address/Data Register) 41h (the low byte of the address desired) 41h goes into latch but is
not latched yet.
Out
FC00h + 3Fh an A0h (CMD to load the high address byte). This latches the low address through changing the
decode bits and opens the door for the high address latch.
Out
FC00h + 3Eh 00h (the high byte of the address desired) 00h goes into latch but is not latched yet.
Out
FC00h + 3Fh an E0h (CMD to read the address latched). This latches the high address through changing the
decode bits and begins the read NVRAM data operation.
In
FC00h + 3Fh until D31 = 0 (not busy).
In
FC00h + 3Eh the data.
Notes:
1. Latched addresses do not automatically increment after a read or write. They must be loaded with new values.
2. Latched addresses remain after reads and writes. It is allowable to only update one address byte for the next access.
3. A processor may perform a one word write to load an address byte and control command simultaneously.
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nv Memory Device Timing Requirements
For serial nv memory devices, the serial clock output
frequency is the PCI clock frequency divided by 512.
This is approximately 65 KHz (with a 33 MHz PCI
clock). Any serial memory device that operates at this
frequency is compatible with the S5935.
For byte-wide accesses, the S5935 generates the
waveforms shown in Figures 5 and 6. Figure 5 shows
an nv memory read operation. Figure 6 shows an nv
memory write operation. Read operations are always
the same length. Write operations, due to the characteristics of reprogrammable nv memory devices, may
be controlled through a programming sequence.
Memory Device Requirements for Read Accesses
Timing
Read cycle time
Address valid to data valid
Address valid to read active
Read active to data valid
Read pulse width
Data hold from read inactive
Spec.
T = 30 ns
8T(max)
240 ns
7T–10(max)
200 ns
T(max)
30 ns
6T–10(max)
170 ns
6T(max)
180 ns
—
2 ns
Figure 68. nv Memory Read Operation
t35
ERD#
t37
(OUTPUT)
t38
EA[15:0]
(OUTPUT)
t36
t39
Address Valid
t40
EQ[7:0]
(INPUT)
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t41
Data Valid
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Memory Device Requirements for Write Accesses
Timing
Spec.
T = 30 ns
8T
Note 1
T(max)
30 ns
6T+10(max)
190 ns
Data hold from write inactive
T(max)
30 ns
Write pulse width
6T(max)
180 ns
Note 2
2 ns
Write cycle time
Address valid to write active
Data valid to write inactive
Write inactive
Figure 69. nv Memory Write Operation
t42
t43
EWR#
t44
(OUTPUT)
t39
t38
EA[15:0]
Address Valid
(OUTPUT)
t45
EQ[7:0]
(OUTPUT)
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t46
Data Valid
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MAILBOX OVERVIEW
On interface. One outgoing and one incoming mailbox
on each interface can be configured to generate
interrupts.
The S5935 has eight 32-bit mailbox registers. The
mailboxes are useful for passing command and status
information between the Add-On and the PCI bus. The
PCI interface has four incoming mailboxes (Add-On to
PCI) and four outgoing mailboxes (PCI to Add-On).
The Add-On interface has four incoming mailboxes
(PCI to Add-On) and four outgoing mailboxes (Add-On
to PCI). The PCI incoming and Add-On outgoing mailboxes are the same, internally. The Add-On incoming
and PCI outgoing mailboxes are also the same,
internally.
FUNCTIONAL DESCRIPTION
Figure 1 shows a block diagram of the PCI to Add-On
mailbox registers. Add-On incoming mailbox read
accesses pass through an output interlock latch. This
prevents a PCI bus write to a PCI outgoing mailbox
from corrupting data being read by the Add-On. Figure
2 shows a block diagram of the Add-On to PCI mailbox
registers. PCI incoming mailbox reads also pass
through an interlocking mechanism. This prevents an
Add-On write to an outgoing mailbox from corrupting
data being read by the PCI bus. The following sections
describe the mailbox flag functionality and the mailbox
interrupt capabilities.
The mailbox status may be monitored in two ways.
The PCI and Add-On interfaces each have a mailbox
status register to indicate the empty/full status of bytes
within the mailboxes. The mailboxes may also be configured to generate interrupts to the PCI and/or AddFigure 70. Block Diagram - PCI to Add-On Mailbox Register
PCI BUS INTERFACE
PCI BUS
"OUTGOING MAILBOX"
ADD-ON
BUS
"INCOMING
MAILBOX"
SELECT
OUTPUT
INTERLOCK
LATCH
D
Q
D
LOAD ENABLE
OUTPUT
DRIVER
Q
EN
EN
READ ENABLE
D
ADD-ON
RD#
SELECT#
MAILBOX
FULL
S
"O"
ADD-ON
BUS
"INCOMING MAILBOX"
ADD-ON INTERFACE
MAILBOX
REGISTER
Q
EMPTY/FULL FF
SELECTED READ ENABLE
Figure 71. Block Diagram - Add-On to PCI Mailbox Register
OUTPUT
INTERLOCK
LATCH
PCI
"INCOMING
MAILBOX"
SELECT
MAILBOX
REGISTER
QD
ADD-ON
BUS
"OUTGOING
MAILBOX"
QD
EN
PCI READ PULSE
ADD-ON WRITE PULSE
MAILBOX
FULL
WR#
SELECT#
ADD-ON INTERFACE
PCI BUS INTERFACE
PCI BUS
"INCOMING MAILBOX"
S
Q
D
"O"
REGISTER
DECODE OF
ADR[6:2]
BE[3:0]#
EMPTY/FULL FF
SELECTED
READ PULSE
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Mailbox Empty/Full Conditions
The PCI and Add-On interfaces each have a mailbox
status register. The PCI Mailbox Empty/Full Status
(MBEF) and Add-On Mailbox Empty/Full Status
(AMBEF) Registers indicate the status of all bytes
within the mailbox registers. A write to an outgoing
mailbox sets the status bits for that mailbox. The byte
enables determine which bytes within the mailbox
become full (and which status bits are set).
An outgoing mailbox for one interface is an incoming
mailbox for the other. Therefore, incoming mailbox stat u s b i ts o n o n e i n t e r f a c e a r e i d e n t i c a l t o t h e
corresponding outgoing mailbox status bits on the
other interface. The following list shows the relationship between the mailbox registers on the PCI and
Add-On interfaces.
PCI Interface
Outgoing Mailbox1
Outgoing Mailbox 2
Outgoing Mailbox 3
Outgoing Mailbox 4
Incoming Mailbox 1
Incoming Mailbox 2
Incoming Mailbox 3
Incoming Mailbox 4
PCI Mailbox Empty/Full
Add-On Interface
=
=
=
=
=
=
=
=
=
Incoming Mailbox 1
Incoming Mailbox 2
Incoming Mailbox 3
Incoming Mailbox 4
Outgoing Mailbox 1
Outgoing Mailbox 2
Outgoing Mailbox 3
Outgoing Mailbox 4
Add-On Mailbox Empty/
Full
A write to an outgoing mailbox also writes data into the
incoming mailbox on the other interface. It also sets
the status bits for the outgoing mailbox and the status
bits for the incoming mailbox on the other interface.
Reading the incoming mailbox clears all corresponding status bits in the Add-On and PCI mailbox status
registers (AMBEF and MBEF).
For example, a PCI write is performed to the PCI outgoing mailbox 2, writing bytes 0 and 1 (BE0# and
BE1# asserted). Reading the PCI Mailbox Empty/Full
Status Register (MBEF) indicates that bits 4 and 5 are
set. These bits indicate that outgoing mailbox 2, bytes
0 and 1 are full. Reading the Add-On Mailbox Empty/
Full Status Register (AMBEF) shows that bits 4 and 5
in this register are also set, indicating Add-On incoming mailbox 2, bytes 0 and 1 are full. An Add-On read
of incoming mailbox 2, bytes 0 and 1 clears the status
bits in both the MBEF and AMBEF status registers.
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To reset individual flags in the MBEF and AMBEF registers, the corresponding byte must be read from the
incoming mailbox. The PCI and Add-On mailbox status registers, MBEF and AMBEF, are read-only.
Mailbox flags may be globally reset from either the PCI
interface or the Add-On interface. The PCI Bus Master
Control/Status Register (MCSR) and the Add-On General Control/Status Register (AGCSTS) each have a
bit to reset all of the mailbox status flags.
Mailbox Interrupts
The designer has the option to generate interrupts to
the PCI and Add-On interfaces when specific mailbox
events occur. The PCI and Add-On interfaces can
each define two conditions where interrupts may be
generated. An interrupt can be generated when an
incoming mailbox becomes full and/or when an outgoing mailbox becomes empty. A specific byte within a
specific mailbox is selected to generate the interrupt.
The conditions defined to generate interrupts to the
PCI interface do not have to be the same as the conditions defined for the Add-On interface. Interrupts are
cleared through software.
For incoming mailbox interrupts, when the specified
byte becomes full, an interrupt is generated. The interrupt might be used to indicate command or status
information has been provided, and must be read. For
PCI incoming mailbox interrupts, the S5935 asserts
the PCI interrupt, INTA#. For Add-On incoming mailbox interrupts, the S5935 asserts the Add-On
interrupt, IRQ#.
For outgoing mailbox interrupts, when the specified
byte becomes empty, an interrupt is generated. The
interrupt might be used to indicate that the other interface has received the last information sent and more
may be written. For PCI outgoing mailbox interrupts,
the S5935 asserts the PCI interrupt, INTA#. For AddOn outgoing mailbox interrupts, the S5935 asserts the
Add-On interrupt, IRQ#.
Add-On Outgoing Mailbox 4, Byte 3 Access
PCI incoming mailbox 4, byte 3 (Add-On outgoing
mailbox 4, byte 3) does not function exactly like the
other mailbox bytes. When an a serial nv memory boot
device or no external boot device is used, the S5935
pins EA7:0 are redefined to provide direct external
access to Add-On outgoing mailbox 4, byte 3. EA8 is
redefined to provide a load clock which may be used
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to generate a PCI interrupt. The pins are redefined as
follows:
Signal Pin
EA0/EMB0
EA1/EMB1
EA2/EMB2
EA3/EMB3
EA4/EMB4
EA5/EMB5
EA6/EMB6
EA7/EMB7
EA8/EMBCLK
Add-On Outgoing Mailbox
Mailbox 4, bit 24
Mailbox 4, bit 25
Mailbox 4, bit 26
Mailbox 4, bit 27
Mailbox 4, bit 28
Mailbox 4, bit 29
Mailbox 4, bit 30
Mailbox 4, bit 31
Mailbox 4, byte 3 load clock
If the S5935 is programmed to generate a PCI interrupt (INTA#), on an Add-On write to outgoing mailbox
4, byte 3, a rising edge on EMBCLK generates a PCI
interrupt. The bits EMB7:0 can be read by the PCI bus
interface by reading the PCI incoming mailbox 4, byte
3. These bits are useful to indicate various conditions
which may have caused the interrupt.
When using the S5935 with a byte-wide boot device,
the capability to generate PCI interrupts with Add-On
hardware does not exist. In this configuration, PCI
incoming mailbox 4, byte 3 (Add-On incoming mailbox
4, byte 3) cannot be used to transfer data from the
Add-On - it always returns zeros when read from the
PCI bus. This mailbox byte is sacrificed to allow the
added functionality provided when a byte-wide boot
device is not used.
BUS INTERFACE
The mailboxes appear on the Add-On and PCI bus
interfaces as eight operation registers. Four are outgoing mailboxes, four are incoming mailboxes. The
mailboxes may be used to generate interrupts to each
of the interfaces. The following sections describe the
Add-On and PCI bus interfaces for the mailbox
registers.
PCI Bus Interface
The mailboxes are only accessible with the S5935 as
a PCI target. The mailbox operation registers do not
support burst accesses by an initiator. A PCI initiator
attempting to burst to the mailbox registers causes the
S5935 to respond with a target disconnect with data.
PCI writes to full outgoing mailboxes overwrite data
currently in that the mailbox. PCI reads from empty
incoming mailboxes return the data that was previously contained in the mailbox. Neither of these
situations cause a target retry or abort.
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PCI incoming and outgoing mailbox interrupts are
enabled in the Interrupt Control/Status Register
(INTCSR). The mailboxes can generate a PCI interrupt (INTA#) under two conditions (individually
enabled). For an incoming mailbox full interrupt, INTA#
is asserted on the PCI clock rising edge after the AddOn mailbox write completes. For an outgoing mailbox
empty interrupt, INTA# is asserted on the PCI clock
rising edge after the Add-On mailbox read completes
(the rising edge of RD#). INTA# is deasserted on the
next PCI clock rising edge after the PCI access to
clear the mailbox interrupt completes (TRDY#
deasserted).
Add-On Bus Interface
The Add-On mailbox interface behaves similar to the
PCI bus interface. Add-On writes to full outgoing mailboxes overwrite data currently in that mailbox. PCI
reads from empty incoming mailboxes return the data
that was previously contained in the mailbox.
Add-On incoming and outgoing mailbox interrupts are
enabled in the Add-On Interrupt Control/Status Register (AINT). The mailboxes can generate the Add-On
IRQ# interrupt under two conditions (individually
enabled). For an incoming mailbox full interrupt, IRQ#
is asserted one PCI clock period after the PCI mailbox
write completes (TRDY# deasserted). For an outgoing
mailbox empty interrupt, IRQ# is asserted one PCI
clock period after the PCI mailbox read completes
(TRDY# deasserted). IRQ# is deasserted immediately
when the Add-On clears the mailbox interrupt.
When the S5935 is used with a serial nv memory boot
device or no external boot device, the device pins
EA8:0 are redefined. EA7:0 become EMB7:0 data
inputs and EA8 becomes EMBCLK, a load clock. This
configuration allows the Add-On to generate PCI interrupts with a low-to-high transition on EMBCLK. The
PCI incoming mailbox interrupt must be enabled and
set for mailbox 4, byte3 in the PCI Interrupt Control/
Status Register (INTCSR). EMBCLK should begin
high and be pulsed low, then high to be recognized.
The rising edge of EMBCLK generates the interrupt.
The rising edge of EMBCLK also latches in the values
on EMB7:0. The S5935 interrupt logic must be cleared
(INTA# deasserted) through INTCSR before further
EMBCLK interrupts are recognized.
8-Bit and 16-Bit Add-On Interfaces
Some Add-On designs may implement an 8-bit or 16bit bus interface. The mailboxes do not require a 32-bit
Add-On interface. For 8-bit interfaces, the 8-bit data
bus may be externally connected to all four bytes of
the 32-bit Add-On interface (DQ 31:24, 23:16, 15:8,
7:0 are all connected). The Add-On device reading or
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writing the mailbox registers may access all mailbox
bytes by cycling through the Add-On byte enable
inputs. A similar solution applies to 16-bit Add-On
buses. This solution works for Add-Ons which always
use just 8-bit or just 16-bit accesses. If the MODE pin
is high, indicating a 16-bit Add-On interface, the previous solution may be modified for an 8-bit interface.
The difference is that ADR1 must be toggled after the
first two accesses to steer the S5935 internal data bus
to the upper 16-bits of the mailboxes.
CONFIGURATION
The PCI interface and the Add-On interface each have
four incoming mailboxes (IMBx or AIBMx) and four
outgoing mailboxes (OMBx or AOMBx) along with a
single mailbox status register (MBEF or AMBEF). Outgoing mailboxes are read/write, incoming mailboxes
and the mailbox status registers are read-only.
The following sections discuss the registers associated with the mailboxes and accesses required for
different modes of mailbox operation.
Mailbox Status
Every byte in each mailbox has a status bit in the Mailbox Empty/Full Status Registers (MBEF and AMBEF).
Writing a particular byte into an outgoing mailbox sets
the corresponding status bit in both the MBEF and
AMBEF registers. A read of a ‘full’ byte in a mailbox
clears the status bit. The MBEF and AMBEF are readonly. Status bits cannot cleared by writes to the status
registers.
The S5935 allows the mailbox status bits to be reset
through software. The Bus Master Control/Status
(MCSR) PCI Operation Register and the Add-On General Control/Status (AGCSTS) Add-On Operation
Register each have a bit to reset mailbox status. Writing a ‘1’ to Mailbox Flag Reset bit in the MCSR or the
AGCSTS register immediately clears all bits in the
both the MBEF and AMBEF registers. Writing a ‘0’ has
no effect. The Mailbox Flag Reset bit is write-only.
The flag bits should be monitored when transferring
data through the mailboxes. Checking the mailbox status before performing an operation prevents data from
being lost or corrupted. The following sequences are
suggested for PCI mailbox operations using status
polling (interrupts disabled):
Reading a PCI Incoming Mailbox:
1. Check Mailbox Status. Read the mailbox status register to determine if any information has been passed from the AddOn interface.
MBEF
Bits 31:16
If a bit is set, valid data is contained in the corresponding mailbox
byte.
2. Read Mailbox(es). Read the mailbox bytes which MBEF indicates are full. This automatically resets the status bits in
the MBEF and AMBEF registers.
IMBx
Bits
31:0 Mailbox data.
Writing a PCI Outgoing Mailbox:
1. Check Mailbox Status. Read the mailbox status register to determine if information previously written to the mailbox has
been read by the Add-On interface. Writes to full mailbox bytes overwrite data currently in the mailbox (if not already
read by the Add-On interface). Repeat until the byte(s) to be written are empty.
MBEF
Bits 15:0
If a bit is set, valid data is contained in the corresponding mailbox byte and has not been read by the
Add-On.
2. Write Mailbox(es). Write to the outgoing mailbox byte(s).
OMBx
Bits 31:0
Mailbox data.
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Mailbox operations for the Add-On interface are functionally identical. The following sequences are suggested for
Add-On mailbox operations using status polling (interrupts disabled):
Reading an Add-On Incoming Mailbox:
1. Check Mailbox Status. Read the mailbox status register to determine if any information has been passed from the PCI interface.
AMBEF
Bits 15:0
If a bit is set, valid data is contained in the corresponding mailbox byte.
2. Read Mailbox(es). Read the mailbox bytes which AMBEF indicates are full. This automatically resets the status bits in
the AMBEF and MBEF registers.
AIMBx
Bits 31:0
Mailbox data.
Writing an Add-On Outgoing Mailbox:
1. Check Mailbox Status. Read the mailbox status register to determine if information previously written to the mailbox has
been read by the PCI interface. Writes to full mailbox bytes overwrite data currently in the mailbox (if not already read
by the PCI interface). Repeat until the byte(s) to be written are empty.
AMBEF
Bits 31:16
If a bit is set, valid data is contained in the corresponding mailbox byte and has not been read by
the PCI bus.
2. Write Mailbox(es). Write to the outgoing mailbox byte(s).
AOMBx
Bits 31:0
Mailbox data.
Mailbox Interrupts
Although polling status is useful, in some cases, polling requires continuous actions by the processor reading or
writing the mailbox. Mailbox interrupt capabilities are provided to avoid much of the processor overhead required
by continuously polling status bits.
The Add-On and PCI interface can each generate interrupts on an incoming mailbox condition and/or an outgoing
mailbox condition. These can be individually enabled/disabled. A specific byte in one incoming mailbox and one
outgoing mailbox is identified to generate the interrupt(s). The tasks required to setup mailbox interrupts are shown
below:
Enabling PCI mailbox interrupts:
1. Enable PCI outgoing mailbox interrupts. A specific byte within one of the outgoing mailboxes is identified to assert
INTA# when read by the Add-On interface.
INTCSR
Bit 4
Enable outgoing mailbox interrupts
INTCSR
Bits 3:2
Identify mailbox to generate interrupt
INTCSR
Bits 1:0
Identify mailbox byte to generate interrupt
2. Enable PCI incoming mailbox interrupts. A specific byte within one of the incoming mailboxes is identified to assert
INTA# when written by the Add-On interface.
130
INTCSR
Bit 12
Enable incoming mailbox interrupts
INTCSR
Bits 11:10
Identify mailbox to generate interrupt
INTCSR
Bits 9:8
Identify mailbox byte to generate interrupt
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Enabling Add-On mailbox interrupts:
1. Enable Add-On outgoing mailbox interrupts. A specific byte within one of the outgoing mailboxes is identified to assert
IRQ# when read by the PCI interface.
AINT
Bit 12
Enable outgoing mailbox interrupts
AINT
Bits 11:10
Identify mailbox to generate interrupt
AINT
Bits 9:8
Identify mailbox byte to generate interrupt
2. Enable Add-On incoming mailbox interrupts. A specific byte within one of the incoming mailboxes is identified to assert
IRQ# when written by the PCI interface.
AINT
Bit 4
Enable incoming mailbox interrupts
AINT
Bits 3:2
Identify mailbox to generate interrupt
AINT
Bits 1:0
Identify mailbox byte to generate interrupt
With either the Add-On or PCI interface, these two steps can be performed with a single access to the appropriate register.
They are shown separately here for clarity.
Once interrupts are enabled, the interrupt service routine must access the mailboxes and clear the interrupt
source. A particular application may not require all of the steps shown. For instance, a design may only use incoming mailbox interrupts and not require support for outgoing mailbox interrupts. The interrupt service routine tasks
are shown below:
Servicing a PCI mailbox interrupt (INTA#):
1. Identify the interrupt source(s). Multiple interrupt sources are available on the S5935. The interrupt service routine must
verify that a mailbox generated the interrupt (and not some other interrupt source).
INTCSR
Bit 16
PCI outgoing mailbox interrupt indicator
INTCSR
Bit 17
PCI incoming mailbox interrupt indicator
2. Check mailbox status. The mailbox status bits indicate which mailbox bytes must be read or written.
MBEF
Bits 31:16
Full PCI incoming mailbox bytes
MBEF
Bits 15:0
Empty PCI outgoing mailbox bytes
3. Access the mailbox. Based on the contents of MBEF, mailboxes are read or written. Reading an incoming mailbox byte
clears the corresponding status bit in MBEF.
OMBx
Bits 31:0
PCI outgoing mailboxes
IMBx
Bits 31:0
PCI incoming mailboxes
4. Clear the interrupt source. The PCI INTA# signal is deasserted by clearing the interrupt request. The request is cleared
by writing a ‘1’ to the appropriate bit.
INTCSR
Bit 16
Clear PCI outgoing mailbox interrupt
INTCSR
Bit 17
Clear PCI incoming mailbox interrupt
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Servicing an Add-On mailbox interrupt (IRQ#):
1. Identify the interrupt source(s). Multiple interrupt sources are available on the S5935. The interrupt service routine must
verify that a mailbox generated the interrupt (and not some other interrupt source).
AINT
Bit 16
Add-On incoming mailbox interrupt indicator
AINT
Bit 17
Add-On outgoing mailbox interrupt indicator
2. Check mailbox status. The mailbox status bits indicate which mailbox bytes must be read or written.
AMBEF
Bits 31:16
Empty Add-On outgoing mailbox bytes
AMBEF
Bits 15:0
Full Add-On incoming mailbox bytes
3. Access the mailbox. Based on the contents of AMBEF, mailboxes are read or written. Reading an incoming mailbox
byte clears the corresponding status bit in AMBEF.
AIMBx
Bits 31:0
Add-On incoming mailboxes
AOMBx
Bits 31:0
Add-On outgoing mailboxes
4. Clear the interrupt source. The Add-On IRQ# signal is deasserted by clearing the interrupt request. The request is
cleared by writing a ‘1’ to the appropriate bit.
AINT
Bit 16
Clear Add-On incoming mailbox interrupt
AINT
Bit 17
Clear Add-On outgoing mailbox interrupt
In both cases, step 3 involves accessing the mailbox. To allow the incoming mailbox interrupt logic to be cleared, the mailbox
status bit must also be cleared. Reading an incoming mailbox clears the status bits. Another option for clearing the status bits
is to use the Mailbox Flag Reset bit in the MCSR and AGCSTS registers, but this clears all status bits, not just for a single
mailbox or mailbox byte. For outgoing mailbox interrupts, the read of a mailbox register is what generated the interrupt; this
ensures the status bits are already clear.
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FIFO OVERVIEW
The S5935 has two internal FIFOs. One FIFO is for
PCI bus to Add-On bus, the other FIFO is for Add-On
bus to PCI bus transfers. Each of these has eight 32bit registers. The FIFOs are both addressed through a
single PCI/Add-On Operation Register offset, but
which internal FIFO is accessed is determined by
whether the access is a read or write.
The FIFO may be either a PCI target or a PCI initiator.
As a target, the FIFO allows a PCI bus master to
access Add-On data. The FIFO also allows the S5935
to become a PCI initiator. Read and write address registers and transfer count registers allow the S5935 to
perform DMA transfers across the PCI bus. The FIFO
may act as initiator and a target at different times in the
same application.
The FIFO can be configured to support various AddOn bus configurations. FIFO status and control signals
allow simple cascading into an external FIFO, the AddOn bus can be 8-, 16-, or 32-bits wide, and data
endian conversion is optional to support any type of
Add-On CPU. PCI and Add-On interrupt capabilities
are available to support bus mastering through the
FIFO.
FUNCTIONAL DESCRIPTION
The S5935 FIFO interface allows a high degree of
functionality and flexibility. Different FIFO management schemes, endian conversion schemes, and
advance conditions allow for a wide variety of Add-On
interfaces. Applications may implement the FIFO as
either a PCI target or program it to enable the S5935
to be a PCI initiator (bus master). The following sections describe, on a functional level, the capabilities of
the S5935 FIFO interface.
FIFO Buffer Management and Endian Conversion
The S5935 provides a high degree of flexibility for controlling the data flow through the FIFO. Each FIFO
(PCI to Add-On and Add-On to PCI) has a specific
FIFO advance condition. For FIFO writes, the byte
which signifies a location is full is configurable. For
FIFO reads, the byte which signifies a location is
empty is configurable. This ability is useful for transferring data through the FIFO with Add-Ons which are not
32-bits wide. Endian conversion may also be performed on data passing through the FIFO.
FIFO Advance Conditions
The specific byte lane used to advance the FIFO,
when accessed, is determined individually for each
FIFO interface (PCI and Add-On). The control bits to
set the advance condition are D29:26 of the Interrupt
Control/Status Register (INTCSR) in the PCI Operation Registers (Figure 1). The default FIFO advance
condition is set to byte 0. With the default setting, a
write to the FIFO with BE0# asserted indicates that the
FIFO location is now full, advancing the FIFO pointer
to the next location. BE0# does not have to be the only
byte enable asserted. Note, the FIFO advance condition may be different for the PCI to Add-On FIFO and
the Add-On to PCI FIFO directions.
Figure 72. INTCSR FIFO Advance and Endian Control Bits
INTCSR
31 30 29
PCI TO ADD-ON FIFO
PCI ADD-ON DWORD
TOGGLE
0 = BYTES 0-3 (DEFAULT)
1 = BYTE 4-7 (NOTE1)
ADD-ON TO PCI FIFO
ADD-ON PCI
DWORD
TOGGLE
0 = BYTES 0-3 (DEFAULT)
1 = BYTE 4-7 (NOTE1)
NOTE 1: D24 AND D25 MUST BE ALSO "1"
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28 27 26 25 24
0
0
1
1
0
1
0
1
NO CONVERSION (DEFAULT)
16 BIT ENDIAN CONV.
32 BIT ENDIAN CONV.
64 BIT ENDIAN CONV
FIFO ADVANCE CONTROL
PCI INTERFACE
0 0 BYTE 0 (DEFAULT)
0 1 BYTE 1
1 0 BYTE 2
1 1 BYTE 3
FIFO ADVANCE CONTROL
ADD-ON INTERFACE
0 0 BYTE 0 (DEFAULT)
0 1 BYTE 1
1 0 BYTE 2
1 1 BYTE 3
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The configurable FIFO advance condition may be
used to transfer data to and from Add-On interfaces
which are not 32-bits wide. For a 16-bit Add-On bus,
the Add-On to PCI FIFO advance condition can be set
to byte 2. This allows a 16-bit write to the lower 16-bits
of the FIFO register (bytes 0 and 1) and a second write
to the upper 16-bits of the FIFO register (bytes 2 and
3). The FIFO does not advance until the second
access. This allows the Add-On to operate with 16-bit
data, while the PCI bus maintains a 32-bit data path.
Figure 73. Figure 2a. 16-bit Endian Conversion
DESTINATION
D 31-24
D 23-16
D 15-8
D 7-0
Endian Conversion
Bits D31:30 and D25:24 of the INTCSR PCI Operation
Register control endian conversion operations for the
FIFO (Figure 1). When endian conversion is performed, it affects data passing in either direction
through the FIFO interface. Figures 2a and 2b show
16-bit and 32-bit endian conversion. It is important to
note that endian conversion is performed on data BEFORE it enters the FIFO. This affects the FIFO
advance condition. Example: the FIFO is configured to
perform 32-bit endian conversion on data, and the
FIFO advance condition is set to byte 0. Byte 3 is written into the FIFO (BE3# asserted). After the endian
conversion, byte 3 becomes byte 0, and the FIFO
advances. This behavior must be considered when not
performing full 32-bit accesses to the FIFO.
Figure 2b. 32-bit Endian Conversion
DESTINATION
BYTE 3
BYTE 2
BYTE 1
BYTE 0
BYTE 3
BYTE 2
BYTE 1
BYTE 0
D 31-24
D 23-16
D 15-8
D 7-0
SOURCE
D 31-24
D 23-16
D 15-8
D 7-0
BYTE 3
BYTE 2
BYTE 1
BYTE 0
BYTE 3
BYTE 2
BYTE 1
BYTE 0
D 31-24
D 23-16
D 15-8
D 7-0
Notes:
1. During operation, the INTCSR FIFO advance condition bits
(D29:26) should only be changed when the FIFO is empty and is
idle on both the Add-On and PCI interfaces.
SOURCE
Notes:
1. During operation, the INTCSR FIFO endian conversion bits
(D25:24) and 64-bit access bits (D31:30) should only be changed
when the FIFO is empty and is idle on both the Add-On and PCI
interfaces.
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64-Bit Endian Conversion
Because the S5935 interfaces to a 32-bit PCI bus, special operation is required to handle 64-bit data endian conversion. Figure 2c shows 64-bit endian conversion. The S5935 must know whether the lower 32-bits enter the
FIFO first or the upper 32-bits enter the FIFO first. INTCSR D31:30 identify which method is used by the application. These bits toggle after each 32-bit operation to indicate if half or all of a 64-bit data operation has been
completed. The initial state of these bits establishes the loading and emptying order for 64-bit data during
operation.
Figure 2c. 64-bit Endian Conversion
DESTINATION
READ ORDER:
BYTES 3-0 FIRST
OR
BYTES 7-4 FIRST
SEE TEXT
D 31-24
D 23-16
D 15-8
D 7-0
SLR
SLR
SLR
SLR
BYTE 7
BYTE 6
BYTE 5
BYTE 4
BYTE 3
BYTE 2
BYTE 1
BYTE 0
BYTE 7
BYTE 6
BYTE 5
BYTE 4
BYTE 3
BYTE 2
BYTE 1
BYTE 0
LOAD ORDER:
BYTES 3-0 FIRST
OR,
BYTES 7-4 FIRST
SEE TEXT
D 31-24
D 23-16
D 15-8
D 7-0
SOURCE
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Add-On FIFO Status Indicators
The Add-On interface implements FIFO status pins to
indicate the full and empty conditions of the PCI to
Add-On and Add-On to PCI FIFOs. These may be
used by the Add-On to allow data transfers between
the FIFO and memory, a peripheral, or even a cascaded external FIFO. The RDEMPTY and WRFULL
status outputs are always available to the Add-On.
Additional status signals are multiplexed with the bytewide, non-volatile memory interface pins. If the S5935
is configured for Add-On initiated bus mastering, these
status signals also become available to the Add-On.
FIFO status is also indicated by bits in the Add-On
General Control/Status and Bus Master Control/Status
Registers. The table below lists all FIFO status outputs
and their functions.
Signal
RDEMPTY
Signal
Function
RDFIFO#
Reads data from the PCI to Add-On FIFO
WRFIFO#
Writes data into the Add-On to PCI FIFO
FRC#
Reset PCI to Add-On FIFO pointers and
status indicators1
FWC#
Reset Add-On to PCI FIFO pointers and
status indicators1
AMREN
Enable bus mastering for Add-On initiated
PCI reads1
AMWEN
Enable bus mastering for Add-On initiated
PCI writes1
1. These signals are only available when a serial non-volatile memory is used and the S5935 is configured for Add-On initiated bus
mastering.
Function
Indicates empty condition of the PCI to
Add-On FIFO
WRFULL
Indicates full condition of the Add-On to
PCI FIFO
FRF
Indicates full condition of the PCI to AddOn FIFO1
FWE
Indicates the empty condition of the AddOn to PCI FIFO1
1. These signals are only available when a serial non-volatile memory is used and the device is configured for Add-On initiated bus
mastering.
Add-On FIFO Control Signals
The Add-On interface implements FIFO control pins to
manipulate the S5935 FIFOs. These may be used by
Add-On to control data transfer between the FIFO and
memory, a peripheral, or even a cascaded external
FIFO. The RDFIFO# and WRFIFO# inputs are always
available. These pins allow direct access to the FIFO
without generating a standard Add-On register access
using RD#, WR#, SELECT#, address pins and the
byte enables.
Additional control signals are multiplexed with the
byte-wide, non-volatile memory interface pins. If a
serial non-volatile memory is used and the S5935 is
configured for Add-On initiated bus mastering, these
control signals also become available. For PCI initiated bus mastering, AMREN, AMWEN, FRC#, and
FWC# functionality is always available through bits in
the Bus Master Control/Status and Add-On General
Control/Status Registers. The FIFO control inputs are
listed below.
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PCI Bus Mastering with the FIFO
The S5935 may initiate PCI bus cycles through the
FIFO interface. The S5935 allows blocks of data to be
transferred to and from the Add-On by specifying a
source/destination address on the PCI bus and a
transfer byte count. This DMA capability allows data to
be transferred across the PCI bus without host CPU
intervention.
Initiating a bus master transfer requires programming
the appropriate address registers and transfer byte
counts. This can be done from either the PCI interface
or the Add-On interface. Initiating bus master transfers
from the add-on is advantageous because the host
CPU does not have to intervene for the S5935 to
become a PCI Initiator. At the end of a transfer the
S5935 may generate an interrupt to either the PCI bus
(for PCI initiated transfers) or Add-On interface (for
Add-On initiated transfers).
Add-On Initiated Bus Mastering
If bit 7 in location 45h of an external serial non-volatile
memory is zero, the Master Read Address Register
(MRAR), Master Write Address Register (MWAR),
Master Read Transfer Count (MRTC), and Master
Write Transfer Count (MWTC) are accessible only
from the Add-On interface. Add-On initiated bus mastering is not possible when a byte-wide boot device is
used due to shared device pins. When configured for
Add-On initiated bus mastering, the S5935 transfers
data until the transfer count reaches zero, or it may be
configured to ignore the transfer count.
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For bus master transfers initiated by the Add-On interface, some applications may not know the size of the
data block to be transferred. To avoid constantly
updating the transfer count register, the transfer count
may be disabled. Bit 28 in the Add-On General Control/Status Register (AGCSTS) performs this function.
Disabling the transfer count also disables the interrupt
capabilities. Regardless of whether Add-On transfer
count is enabled or disabled, the Add-On Master Read
Enable (AMREN) and Add-On Master Write Enable
(AMWEN) inputs control when the S5935 asserts or
deasserts its request to the PCI bus. When Add-On
transfer count is enabled, the S5935 will only request
the bus when both the transfer count (read or write) is
not zero and the appropriate enable line (AMREN or
AMWEN) is active. For Add-On initiated bus mastering, AMWEN and AMREN override the read and write
bus mastering enable bits in the Bus Master Control/
Status Register (MCSR).
PCI Initiated Bus Mastering
If bit 7 in location 45h of the external non-volatile memory is one, the Master Read Address Register
(MRAR), Master Write Address Register (MWAR),
Master Read Transfer Count (MRTC), and Master
Write Transfer Count (MWTC) are accessible only
from the PCI bus interface. In this configuration, the
S5935 transfers data until the transfer count reaches
zero. The transfer count cannot be disabled for PCI
initiated bus mastering. If no external nv memory boot
device is used, the S5935 defaults to PCI initiated bus
mastering.
Address and Transfer Count Registers
The S5935 has two sets of registers used for bus master transfers. There are two operation registers for bus
master read operations and two operation registers for
bus master write operations. One operation register is
for the transfer address (MWAR and MRAR). The
other operation register is for the transfer byte count
(MWTC and MRTC).
The address registers are written with the first address
of the transfer before bus mastering is enabled. Once
a transfer begins, this register is automatically updated
to reflect the address of the current transfer. If a PCI
target disconnects from an S5935 initiated cycle, the
transfer is retried starting from the current address in
the register. If bus grant (GNT#) is removed or bus
mastering is disabled (using AMREN or AMWEN), the
value in the address register reflects the next address
to be accessed. Transfers must begin on DWORD
boundaries.
The transfer count registers contain the number of
bytes to be transferred. The transfer count may be
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written before or after bus mastering is enabled. If bus
mastering is enabled, no transfer occurs until the
transfer count is programmed with a non-zero value.
Once a transfer begins, this register is automatically
updated to reflect the number of bytes remaining to be
transferred. If the transfer count registers are disabled
(for Add-On initiated bus mastering), transfers begin
as soon as bus mastering is enabled.
Although transfers must begin on DWORD boundaries, transfer counts do not have to be multiples of
four bytes. For example, if the write transfer count
(MWTC) register is programmed with a value of 10
(decimal), the S5935 performs two DWORD writes
and a third write with only BE0# and BE1# asserted.
Bus Mastering FIFO Management Schemes
The S5935 provides flexibility in how the FIFO is managed for bus mastering. The FIFO management
scheme determines when the S5935 requests the bus
to initiate PCI bus cycles. The management scheme is
configurable for the PCI to Add-On and Add-On to PCI
FIFO (and may be different for each). Bus mastering
must be enabled for the management scheme to apply
(via the enable bits or AMREN/AMWEN).
For the PCI to Add-On FIFO, there are two management options. The PCI to Add-On FIFO management
option is programmed through the Bus Master Control/
Status Register (MCSR). The FIFO can be programmed to request the bus when any DWORD
location is empty or only when four or more locations
are empty. After the S5935 is granted control of the
PCI bus, the management scheme does not apply.
The device continues to read as long as there is an
open FIFO location. When the PCI to Add-On FIFO is
full or bus mastering is disabled, the PCI bus request
is removed by the S5935.
For the Add-On to PCI FIFO, there are two management options. The Add-On to PCI FIFO management
option is programmed through the Bus Master Control/
Status Register (MCSR). The FIFO can be programmed to request the bus when any DWORD
location is full or only when four or more locations are
full. After the S5935 is granted control of the PCI bus,
the management scheme does not apply. The device
continues to write as long as there is data in the FIFO.
When the Add-On to PCI FIFO is empty or bus mastering is disabled, the PCI bus request is removed by
the S5935.
There are two special cases for the Add-On to PCI
FIFO management scheme. The first case is when the
FIFO is programmed to request the PCI bus only when
four or more locations are full, but the transfer count is
less than 16 bytes. In this situation, the FIFO ignores
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the management scheme and finishes transferring the
data. The second case is when the S5935 is configured for Add-On initiated bus mastering with transfer
counts disabled. In this situation, the FIFO management scheme must be set to request the PCI bus
when one or more locations are full. AMREN and
AMWEN may be used to implement a specific FIFO
management scheme.
FIFO Bus Master Cycle Priority
In many applications, the FIFO is used as a PCI initiator performing both PCI reads and writes. This
requires a priority scheme be implemented. What happens if the FIFO condition for initiating a PCI read and
a PCI write are both met?
Bits D12 and D8 in the Bus Master Control/Status
Register (MCSR) control the read and write cycle priority, respectively. If these bits are both set or both
clear, priority alternates, beginning with a read cycle. If
the read priority is set and the write priority is clear,
read cycles take priority. If the write priority is set and
the read priority is clear, write cycles take priority. Priority arbitration is only done when neither FIFO has
control of the PCI bus (the PCI to Add-On FIFO would
never interrupt an Add-On to PCI FIFO transfer).
FIFO Generated Bus Master Interrupts
Interrupts may be generated under certain conditions
from the FIFO. If PCI initiated bus mastering is used,
INTA# is generated to the PCI interface. If Add-On initiated bus mastering is used, IRQ# is generated to the
Add-On interface. Interrupts may be disabled.
FIFO Interrupts may be generated from one or more of
the following during bus mastering: read transfer count
reaches zero, write transfer count reaches zero, or an
error occurs during bus mastering. Error conditions
include a target or master abort on the PCI bus. Interrupts on PCI error conditions are only enabled if one or
both of the transfer count interrupts are enabled.
The Add-On Interrupt Control/Status Register (AINT)
or the Interrupt Control Status Register (INTCSR) indicates the interrupt source. The interrupt service
routine may read these registers to determine what
action is required. As mailboxes are also capable of
generating interrupts, this must also be considered in
the service routine. Interrupts are also cleared through
these registers.
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BUS INTERFACE
The S5935 FIFO may be accessed from the Add-On
interface or the PCI interface. Add-On FIFO control
and status signals allow a simple interface to the FIFO
with either an Add-On CPU or programmable logic.
The following section describes the PCI and Add-On
interface behavior and hardware interface.
FIFO PCI Interface (Target Mode)
The S5935 FIFO may act as a standard PCI target.
FIFO empty/full status may be determined by the PCI
initiator by reading the status bits in the PCI Bus Master Control/Status Register (MCSR).
The FIFO occupies a single 32-bit register location
within the PCI Operation Registers. A PCI initiator
may not perform burst accesses to a FIFO as it is a
single address. Each data phase of a burst causes
the PCI initiator to increment its address counter (even
though only the first address is driven at the beginning
of the burst). The initiator keeps track of the current
address in case a disconnect occurs. This allows the
initiator to continue the burst from where the disconnect occurred. If the S5935 FIFO initiated a disconnect
during a PCI burst to the FIFO register, the burst would
be resumed at an address other than the FIFO location (because the initiator address counter has
incremented). The S5935 always signals a disconnect
if a burst to any PCI Operation Register is attempted.
Because the PCI to Add-On FIFO and the Add-On to
PCI FIFO occupy a single location within the PCI and
Add-On Operation Registers, which FIFO is accessed
is determined by whether the access is a read or write.
This means that once data is written into the FIFO, the
value written cannot be read back.
For PCI reads from the Add-On to PCI FIFO, the
S5935 asserts TRDY# and completes the PCI cycle
(Figure 3). If the PCI bus attempts to read an empty
FIFO, the S5935 immediately issues a disconnect with
retry (Figure 4). The Add-On to PCI FIFO status indicators change one PCI clock after a PCI read.
For PCI writes to the PCI to Add-On, the S5935
asserts TRDY# and completes the PCI cycle (Figure
5). If the PCI bus attempts to write a full FIFO, the
S5935 immediately issues a disconnect with retry (Figure 6). The PCI to Add-On FIFO status indicators
change one PCI clock after a PCI write.
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FIFO PCI Interface (Initiator Mode)
The S5935 can act as an initiator on the PCI bus. This
allows the device to gain control of the PCI bus to
transfer data to or from the FIFO. Internal address and
transfer count registers control the number of PCI
transfers and the locations of the transfers. The following paragraphs assume the proper registers and bits
are programmed to enable bus mastering.
PCI read and write transfers from the S5935 are very
similar. The FIFO management scheme determines
when the S5935 asserts its PCI bus request (REQ#).
When bus grant (GNT#) is returned, the device begins
running PCI cycles. Once the S5935 controls the bus,
the FIFO management scheme is not important. It only
determines when PCI bus control is initially requested.
PCI bus reads and writes are always performed as
bursts by the S5935, if possible.
Figure 74. PCI Read from a Full S5935 FIFO
PCI Signals
PCI_CLK
FRAME#
AD[31:0]
ADDR
DATA
IRDY#
TRDY#
DEVSEL#
STOP#
Add-on Signals
WRFULL
FWE
Figure 75. PCI Read from an Empty S5935 FIFO (Target Disconnect)
PCI Signals
PCI_CLK
FRAME#
AD[31:0]
ADDR
DATA
IRDY#
TRDY#
DEVSEL#
STOP#
Target Disconnect with Retry
Add-on Signals
WRFULL
FWE
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Figure 76. PCI Write to an Empty S5935 FIFO
PCI Signals
PCI_CLK
FRAME#
AD[31:0]
ADDR
DATA
IRDY#
TRDY#
DEVSEL#
STOP#
Add-on Signals
RDEMPTY
FRF
Figure 77. PCI Write to a Full S5935 FIFO (Target Disconnect)
PCI Signals
PCI_CLK
FRAME#
AD[31:0]
ADDR
DATA
IRDY#
TRDY#
DEVSEL#
STOP#
Target Disconnect with Retry
Add-on Signals
RDEMPTY
FRF
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FIFO PCI Bus Master Reads
Add-On FIFO Register Accesses
For PCI read transfers (filling the PCI to Add-On
FIFO), read cycles are performed until one of the following occurs:
The FIFO may be accessed from the Add-On interface
through the Add-On FIFO Port Register (AFIFO) read
or write. This is offset 20h in the Add-On Operation
Registers. This register is accessed synchronous to
BPCLK. To access the FIFO as a normal Add-On
Operation Register, ADR[6:2], BE[3:0]#, SELECT#,
and RD# or WR# are required.
- Bus Master Read Transfer Count Register
(MRTC), if used, reaches zero
- The PCI to Add-On FIFO is full
- GNT# is removed by the PCI bus arbiter
- AMREN is deasserted
If the transfer count is not zero, GNT# remains
asserted, and AMREN is asserted, the FIFO continues
to read data from the PCI bus until there are no empty
locations in the PCI to Add-On FIFO. If the Add-On
can empty the FIFO as quickly as it can be filled from
the PCI bus, very long bursts are possible. The S5935
deasserts REQ# when it completes the access to fill
the last location in the FIFO. Once REQ# is deasserted, it will not be reasserted until the FIFO
management condition is met.
FIFO PCI Bus Master Writes
For PCI write transfers (emptying the Add-On to PCI
FIFO), write cycles are performed until one of the following occurs:
- Bus Master Write Transfer Count Register
(MWTC), if used, reaches zero
- The Add-On to PCI FIFO is empty
- GNT# is removed by the PCI bus arbiter
- AMWEN is deasserted
If the transfer count is not zero, GNT# remains
asserted, and AMWEN is asserted, The FIFO continues to write data to the PCI bus until there are is no
data in the Add-On to PCI FIFO. If the Add-On can fill
the FIFO as quickly as it can be emptied to the PCI
bus, very long bursts are possible. The S5935 deasserts REQ# when it completes the access to transfer
the last data in the FIFO. Once REQ# is deasserted, it
will not be reasserted until the FIFO management condition is met.
Add-On Bus Interface
The FIFO register may be accessed in two ways from
the Add-On interface. It can be accessed through normal register accesses or directly with the RDFIFO#
and WRFIFO# inputs. In addition, the FIFO register
can also be accessed synchronous to BPCLK. The
Add-On interface also supports datapaths which are
not 32-bits. The method used to access the FIFO from
the Add-On interface is independent of whether the
FIFO is a PCI target or a PCI initiator.
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Figure 7 shows a synchronous FIFO register burst
access. SELECT# must meet setup and hold times
relative to the rising edge of BPCLK. RD# and
SELECT# both asserted enables the DQ outputs, and
the first data location (data 0) in the FIFO is driven on
to the bus. The FIFO address and the byte enables
must be valid before valid data is driven onto the DQ
bus. Data 0 remains valid until the next rising edge of
BPCLK. The rising edge of BPCLK causes the FIFO
pointer to advance to the next location (data 1). The
next rising edge of BPCLK also advances the FIFO
pointer to the next location (data 2). The status outputs
reflect the FIFO condition after it advances, and are
updated off of the rising edge of BPCLK. When RD# or
SELECT# is deasserted, the DQ bus floats. The next
time a valid FIFO access occurs and RD# and
SELECT# are asserted, data 2 is presented on the DQ
bus (as there was no BPCLK edge to advance the
FIFO).
Add-On FIFO Direct Access Mode
Instead of generating an address, byte enables,
SELECT# and a RD# or WR# strobe for every FIFO
access, the S5935 allows a simple, direct access
mode. Using RDFIFO# and WRFIFO# is functionally
identical to performing a standard AFIFO Port Register
access, but requires less logic to implement. Accesses
to the FIFO register using the direct access signals are
always 32-bits wide. The only exception to this is when
the MODE pin is configured for 16-bit operation. In this
situation, all accesses are 16-bits wide. The RD# and
WR# inputs must be inactive when RDFIFO# or
WRFIFO# is active. The ADR[6:2] and BE[3:0]# inputs
are ignored. RDFIFO# and WRFIFO# act as enables
with BPCLK acting as the clock. A Synchronous interface allows higher data rates.
Figure 8 shows a synchronous FIFO register direct
burst access using RDFIFO#. RDFIFO# acts as an
enable and the first data location (data 0) in the FIFO
is driven on to the bus when RDFIFO# is asserted.
Data 0 remains valid until the next rising edge of
BPCLK. The rising edge of BPCLK causes the FIFO
pointer to advance to the next location (data 1). The
next rising edge of BPCLK advances the FIFO pointer
to the next location (data 2). The status outputs reflect
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the FIFO condition after it advances, and are updated
off of the rising edge of BPCLK. When RDFIFO# is
deasserted, the DQ bus floats. The next time
RDFIFO# is asserted, data 2 is presented on the DQ
bus (as there was no BPCLK edge to advance the
FIFO).
A synchronous FIFO interface has the advantage of
allowing data to be accessed more quickly (in bursts)
by the Add-On. As a target, if a full S5935 FIFO is writ-
ten (or an empty FIFO is read) by a PCI initiator, the
S5935 requests a retry. The faster the Add-On interface can empty (or fill) the FIFO, the less often retries
occur. With the S5935 as a PCI initiator, a similar situation occurs. Not emptying or filling the FIFO quickly
enough results in the S5935 giving up control of the
PCI bus. Higher PCI bus data transfer rates are possible through the FIFO with a synchronous interface.
Figure 78. Synchronous FIFO Register Burst Read Access Example
FIFO Pointer Advances
BPCLK
BE[3:0]#
Valid Byte Enables
ADR[6:2]
Valid Address
DQ[31:0]
Data 0
Data 1
Data 2
SELECT#
RD#
RDEMPTY
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Additional Status/Control Signals for Add-On Initiated Bus Mastering
Inputs:
If a serial non-volatile memory is used to configure the
S5935, and the device is configured for Add-On initiated bus mastering, two additional FIFO status signals
and four additional control signals are available to the
Add-On interface. The FRF and FWE outputs provide
additional FIFO status information. Inputs FRC#,
FWC#, AMREN, and AMWEN provide additional FIFO
control. Applications may use these signals to monitor/
control FIFO flags and PCI bus requests. These new
signals are some of the lines that were used for bytewide nvram interface, but now are reconfigured. The
reconfigured lines are as follows:
Add-On bus Mastering Write ENable: This input is
driven high to enable bus master writes.
Outputs:
E_ADDR (15) FRF
FIFO Read Full: Indicates that the PCI to Add-On
FIFO is full.
E_ADDR (14) FWE
EQ (7) AMWEN
EQ (6) AMREN
Add-On bus Mastering Read ENable: This input is
driven high to enable bus master reads.
EQ (5) FRC#
FIFO Read Clear: This line is driven low to clear the
PCI to Add-On FIFO.
EQ (4) FWC#
FIFO Write Clear: This line is driven low to clear the
Add-On to PCI FIFO.
FRF (PCI to Add-On FIFO full) and FWE (Add-On to
PCI FIFO empty) supplement the RDEMPTY and
WRFULL status indicators. These additional status
outputs provide additional FIFO status information for
Add-On FIFO control logic.
FIFO Write Empty: Indicates the last Add-On to PCI
FIFO. Data has transferred to a final buffer and is
queued for transfer, FIFO is empty.
Figure 79. Synchronous FIFO Register Burst RDFIFO# Access Example
FIFO Pointer Advances
BPCLK
DQ[31:0]
Data 0
Data 1
Data 2
RDFIFO#
RDEMPTY
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The FRC# and FWC# inputs allow Add-On logic to
reset the PCI to Add-On or Add-On to PCI FIFO flags.
The FIFO flags can always be reset with software
through the Add-On General Control/Status Register
(AGCSTS) or the Bus Master Control/Status Register
(MCSR), but these hardware inputs are useful for
designs which do no implement a CPU on the Add-On
card. Asserting the FRC# input resets the PCI to AddOn FIFO. Asserting the FWC# input re-sets the AddOn to PCI FIFO.
The AMREN and AMWEN inputs allow Add-On logic
to individually enable and disable bus mastering for
the PCI to Add-On and Add-On to PCI FIFO. These
inputs override the Bus Master Control/Status Register
(MCSR) bus master enable bits. The S5935 may request the PCI bus for the PCI to Add-On FIFO when
AMREN is asserted and may request the PCI bus for
the Add-On to PCI FIFO when AMWEN is asserted. If
AMREN or AMWEN is deasserted, the S5935
removes its PCI bus request and gives up control of
the bus.
AMREN and AMWEN are useful for Add-Ons with
external FIFOs cascaded into the S5935. For PCI bus
master write operations, the entire S5935 Add-On to
PCI FIFO and the external FIFO may be filled before
enabling bus mastering, providing a single long burst
write rather than numerous short bursts.
In some applications, the amount of data to be transferred is not known. During read operations, the
S5935, attempting to fill its PCI to Add-On FIFO, may
access up to eight memory locations beyond what is
required by the Add-On before it stops. In this situation, AMREN can be deasserted to disable PCI reads,
and then FRC# can be asserted to flush the unwanted
data from the FIFO.
FIFO Generated Add-On Interrupts
For Add-On initiated bus mastering, the S5935 may be
configured to generate interrupts to the Add-On interface for the following situations:
- Read transfer count reaches zero
- Write transfer count reaches zero
- An error occurred during the bus master
transaction
The interrupt is posted to the Add-On interface with
the IRQ# output. A high-to-low transition on this output
indicates an interrupt condition. Because there is a
single interrupt output and multiple interrupt conditions, the Add-On Interrupt Control/Status Register
(AINT) must be read to determine the interrupt source.
This register is also used to clear the interrupt, returning IRQ# to its high state. If mailbox interrupts are also
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used, this must be considered in the interrupt service
routine.
8-Bit and 16-Bit FIFO Add-On Interfaces
The S5935 FIFO may also be used to transfer data
between the PCI bus and 8-bit or 16-bit Add-On interfaces. This can be done using FIFO advance
conditions or the S5935 MODE input pin.
The FIFO may be used as an 8-bit or 16-bit wide
FIFO. To use the FIFO as an 8-bit interface, the
advance condition should be set for byte 0 (no data is
transferred in the upper 3 bytes). To use the FIFO as a
16-bit interface, the advance condition should be set
for byte 1 (no data is transferred in the upper 2 bytes).
This allows a simple Add-On bus interface, but it has
the disadvantage of not efficiently utilizing the PCI bus
bandwidth because the host is forced to perform 8-bit
or 16-bit accesses to the FIFO on the PCI bus. This is
the only way to communicate with an 8-bit Add-On
through the FIFO without additional logic to steer byte
lanes on the Add-On data bus. Pass-Thru mode is
more suited to 8-bit Add-On interfaces.
Implementing a 16-bit wide FIFO is a reasonable solution, but to avoid wasting PCI bus bandwidth, the best
method is to allow the PCI bus and the FIFO to operate with 32-bit data. The S5935 can assemble or
disassemble 32-bit quantities for the Add-On interface.
This is possible through the MODE pin. When MODE
is low, the Add-On data bus is 32-bits. When MODE is
high, the Add-On data bus is 16-bits. When MODE is
configured for 16-bit operation, BE3# becomes ADR1.
With the FIFO direct access signals (RDFIFO# and
WRFIFO#), the MODE pin must reflect the actual AddOn data bus width. With MODE = 16-bits, the S5935
automatically takes two consecutive, 16-bit Add-On
writes to the FIFO and assembles a 32-bit value. FIFO
reads operate in the same manner. Two consecutive
Add-On reads empty the 32-bit FIFO register. The 16bit data bus is internally steered to the lower and upper
words of the 32-bit FIFO register.
One consideration needs to be taken when using the
FIFO direct access signals and letting the S5935 do
byte lane steering internally. The default condition
used to advance the FIFO is byte 0. This must be
changed to byte 2 or 3. When MODE is configured for
a 16-bit Add-On bus, the first 16-bit cycle to the FIFO
always accesses the low 16-bits. If the FIFO advance
condition is left at byte 0, the FIFO advances after the
first 16-bit cycle and the data in the upper 16-bits is
directed to the next FIFO location, shifting the data.
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Some applications hold the RDFIFO# and WRFIFO#
inputs active for a synchronous interface. In 16-bit
mode, designs must avoid writing to a full FIFO. The
data for the write is lost, but the internal mechanism to
direct the 16-bit external data bus to the upper 16-bits
of the FIFO register is triggered. This creates a situation where the FIFO is out of step. The next 16-bit
FIFO write is directed to the upper 16-bits of the FIFO,
and the FIFO advances incorrectly. The WRFULL output should be used to gate the WRFIFO# input to
avoid this situation. A similar problem can occur if
Add-On logic attempts to read an empty FIFO in 16-bit
mode. RDEMPTY should be used to gate the
RDFIFO# input to avoid problems with the FIFO getting out of step. In 32-bit mode (MODE = low), these
situations do not occur.
If FIFO accesses are done without the direct access
signals with MODE configured for 16-bits (using ADR,
SELECT#, etc.), external hardware must toggle ADR1
between consecutive 16-bit bus cycles. The FIFO
advance condition must be set to correspond to the
order the application accesses the upper and lower
words in the FIFO register.
CONFIGURATION
The FIFO configuration takes place during initialization
and during operation. During initialization, the bus
master register access rights are defined. During operation, FIFO advance conditions, endian conversion,
and bus mastering capabilities are defined. The following section describes the bits and registers which are
involved with controlling and monitoring FIFO
operation.
FIFO Setup During Initialization
Location 45h in an external non-volatile memory may
be used to configure the S5935 FIFO during initialization. If no external non-volatile memory is used, FIFO
operation is disabled.
The value of bit 7 in location 45h determines if the
address and transfer count registers used in bus mastering are accessible from the PCI bus or from the
Add-On bus. Once the configuration information is
downloaded from non-volatile memory after reset, the
bus mastering initialization method can not be
changed. Access to the bus master address and transfer count registers cannot be alternated between the
PCI bus and the Add-On interface during operation.
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Bits 6 and 5 in location 45h enable FIFO register
accesses using the RDFIFO#, WRFIFO#, RD# and
WR# inputs synchronous to BPCLK. For synchronous
operation, RDFIFO#, WRFIFO#, RD# and WR# operate as enables, using BPCLK to clock data.
Location 45h Configuration Bits
Bit 7
Bus Master Register Access
0
Address and transfer count registers only accessible from the Add-On interface
1
Address and transfer count registers only accessible from the PCI interface (default)
Bit 6
RDFIFO#, RD# Operation
0
Enable - RDFIFO# and RD# functions.
1
Not allowed. Must be 0.
Bit 5
WRFIFO#, WR# Operation
0
Enable - WRFIFO# and WR# functions.
1
Not allowed. Must be 0.
Bit 0
Target Latency Timer Enable
0
Disable PCI Latency Timer Time Out - Will not disconnect with retry if cannot issue TRDY in specified time
1
Enable PCI Latency Timer Time Out - Will be PCI
2.1 compliant
FIFO Status and Control Bits
The FIFO status can be monitored and the FIFO operation controlled from the PCI Operation Registers and/
or the Add-On Operation Registers. The FIFO register
resides at offset 20h in the PCI and Add-On Operation
Registers.
The Bus Master Control/Status (MCSR) PCI Operation
register allows a PCI host to monitor FIFO activity and
control FIFO operation. Reset controls allow the PCI to
Add-On FIFO and Add-On to PCI FIFO flags to be
reset (individually). Status bits indicate if the PCI to
Add-On FIFO is empty, has four or more open spaces,
or is full. Status bits also indicate if the Add-On to PCI
FIFO is empty, has four or more full locations or is full.
Finally, FIFO PCI bus mastering is monitored/controlled though this register.
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The Add-On General Control/Status (AGCSTS) AddOn Operation Register allows an Add-On CPU to monitor FIFO activity and control FIFO operation. Reset
controls allow the PCI to Add-On FIFO and Add-On to
PCI FIFO flags to be reset (individually). Status bits
indicate if the PCI to Add-On FIFO is empty, has four
or more open spaces, or is full. Status bits also indicate if the Add-On to PCI is empty, has four or more
full spaces or is full. FIFO bus mastering status may
be monitored through this register, but all bus master
configuration is through the MCSR PCI Operation
Register.
PCI Initiated FIFO Bus Mastering Setup
For PCI initiated bus mastering, the PCI host sets up
the S5935 to perform bus master transfers. The following tasks must be completed to setup FIFO bus
mastering:
1. Define interrupt capabilities. The PCI to Add-On
and/or Add-On to PCI FIFO can generate a PCI
interrupt to the host when the transfer count
reaches zero.
INTCSR
Bit 15
Enable Interrupt on read transfer
count equal zero
INTCSR
Bit 14
Enable Interrupt on write transfer
count equal zero
2. Reset FIFO flags. This may not be necessary, but
if the state of the FIFO flags is not known, they
should be initialized.
MCSR
Bit 26
Reset Add-On to PCI FIFO flags
MCSR
Bit 25
Reset PCI to Add-On FIFO flags
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3. Define FIFO management scheme. These bits
define what FIFO condition must exist for the PCI
bus request (REQ#) to be asserted by the S5935.
MCSR
Bit 13
PCI to Add-On FIFO management
scheme
MCSR
Bit 9
Add-On to PCI FIFO management
scheme
4. Define PCI to Add-On and Add-On to PCI FIFO
priority. These bits determine which FIFO has priority if both meet the defined condition to request
the PCI bus. If these bits are the same, priority
alternates, with read accesses occurring first.
MCSR
Bit 12
Read vs. write priority
MCSR
Bit 8
Write vs. read priority
5. Define transfer source/destination address.
These registers are written with the first address
that is to be accessed by the S5935. These
address registers are updated after each access
to indicate the next address to be accessed.
Transfers must start on DWORD boundaries.
MWAR
All
Bus master write address
MRAR
All
Bus master read address
6. Define transfer byte counts. These registers are
written with the number of bytes to be transferred.
The transfer count does not have to be a multiple
of four bytes. These registers are updated after
each transfer to reflect the number of bytes
remaining to be transferred.
MWTC
All
Write transfer byte count
MRTC
All
Read transfer byte count
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7. Enable Bus Mastering. Once steps 1-6 are completed, the FIFO may operate as a PCI bus
master. Read and write bus master operation
may be independently enabled or disabled.
MCSR
Bit 14
Enable PCI to Add-On FIFO bus mastering
MCSR
Bit 10
Enable Add-On to PCI FIFO bus mastering
Add-On Initiated FIFO Bus Mastering Setup For AddOn initiated bus mastering, the Add-On sets up the
S5935 to perform bus master transfers. The following
tasks must be completed to setup FIFO bus
mastering:
1. Define transfer count abilities. For Add-On initiated bus mastering, transfer counts may be either
enabled or disabled. Transfer counts for read and
write operations cannot be individually enabled.
The order of the tasks listed above is not particularly
important. It is recommended that bus mastering be
enabled as the last step. Some applications may
choose to leave bus mastering enabled and start
transfers by writing a non-zero value to the transfer
count registers. This also works, provided the entire
transfer count is written in a single access. As a number of the configuration bits and the two enable bits
are all in the MCSR register, it may be most efficient
for the FIFO configuration bits to be set with the same
register access that enables bus mastering.
AGCSTS
Bit 28
Enable transfer count for read and
write bus master transfers
AINT
Bit
15 Enable interrupt on read transfer
count equal zero
If interrupts are enabled, a host interrupt service routine is also required. The service routine determines
the source of the interrupt and resets the interrupt. As
mailbox registers may also be configured to generate
interrupts, the exact source of the interrupt is indicated
in the PCI Interrupt Control/Status Register (INTCSR).
Typically, the interrupt service routine is used to setup
the next transfer by writing new addresses and transfer counts, but some applications may also require
other actions. If read transfer or write transfer complete interrupts are enabled, master and target abort
interrupts are automatically enabled. These indicate a
transfer error has occurred. Writing a one to these bits
clears the corresponding interrupt.
AINT
Bit 14
Enable interrupt on write transfer count
equal zero
2. Define interrupt capabilities. The PCI to Add-On
and/or Add-On to PCI FIFO can generate an
interrupt to the Add-On when the transfer count
reaches zero (if transfer counts are enabled).
3. Reset FIFO flags. This may not be necessary, but
if the state of the FIFO flags is not known, they
should be initialized.
AGCSTS
Bit 25
Reset Add-On to PCI FIFO flags
AGCSTS
Bit 26
Reset PCI to Add-On FIFO flags
INTCSR
Bit 21
Target abort caused interrupt
INTCSR
Bit 20
Master abort caused interrupt
4. Define FIFO management scheme. These bits
define what FIFO condition must exist for the PCI
bus request (REQ#) to be asserted by the S5935.
This must be programmed through the PCI
interface.
INTCSR
Bit 19
Read transfer complete caused interrupt
MCSR
Bit 13
Write transfer complete caused interrupt
PCI to Add-On FIFO management
scheme
MCSR
Bit 9
Add-On to PCI FIFO management
scheme
INTCSR
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5. Define PCI to Add-On and Add-On to PCI FIFO
priority. These bits determine which FIFO has priority if both meet the defined condition to request
the PCI bus. If these bits are the same, priority
alternates, with read accesses occurring first.
This must be programmed through the PCI
interface.
MCSR
Bit 12
Read vs. write priority
MCSR
Bit 8
Write vs. read priority
6. Define transfer source/destination address.
These registers are written with the first address
that is to be accessed by the S5935. These
address registers are updated after each access
to indicate the next address to be accessed.
Transfers must start on DWORD boundaries.
interrupt. As mailbox registers may also be configured
to generate interrupts, the exact source of the interrupt
is indicated in the Add-On Interrupt Control Register
(AINT). Typically, the interrupt service routine is used
to setup the next transfer by writing new addresses
and transfer counts (if enabled), but some applications
may also require other actions. If read transfer or write
transfer complete interrupts are enabled, the master/
target abort interrupt is automatically enabled. These
indicate a transfer error has occurred. Writing a one to
these bits clears the corresponding interrupt.
AINT
Bit 21
Master/target abort caused interrupt
AINT
Bit 19
Read transfer complete caused interrupt
AINT
Bit 18
Write transfer complete caused interrupt
MWARAllBus master write address
MRARAllBus master read address
7. Define transfer byte counts. These registers are
written with the number of bytes to be transferred.
The transfer count does not have to be a multiple
of four bytes. These registers are updated after
each transfer to reflect the number of bytes
remaining to be transferred. If transfer counts are
disabled, these registers do not need to be
programmed.
MWTC
All
Write transfer byte count
MRTC
All
Read transfer byte count
8. Enable Bus Mastering. Once steps 1-7 are completed, the FIFO may operate as a PCI bus
master. Read and write bus master operation
may be independently enabled or disabled. The
AMREN and AMWEN inputs control bus master
enabling for Add-On initiated bus mastering. The
MCSR bus master enable bits are ignored for
Add-On initiated bus mastering.
It is recommended that bus mastering be enabled as
the last step. Some applications may choose to leave
bus mastering enabled (AMREN and AMWEN
asserted) and start transfers by writing a non-zero
value to the transfer count registers (if they are
enabled).
If interrupts are enabled, an Add-On CPU interrupt
service routine is also required. The service routine
determines the source of the interrupt and resets the
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PASS-THRU OVERVIEW
The S5935 provides a simple registered access port to
the PCI bus. Using a handshaking protocol with AddOn card logic, the PCI bus directly accesses resources
on the Add-On. The Pass-Thru data transfer method is
very useful for direct Add-On memory access, or
accessing registers within peripherals on an Add-On
board. Pass-Thru operation requires an external nv
memory boot device to define and configure the
S5935 Pass-Thru regions.
The S5935 provides four user-configurable Pass-Thru
regions. Each region corresponds to a PCI Configuration Base Address Register (BADR1-4). A region
represents a block of address space (the block size is
user-defined). Each block can be mapped into memory or I/O space. Memory mapped regions can request
to be located below 1 MByte (Real Mode address
space for a PC). Each region also has a configurable
bus width for the Add-On bus interface. An 8-, 16-, or
32-bit Add-On interface may be selected, for use with
a variety of Add-On memory or peripheral devices.
Pass-Thru features can be used only when the S5935
is a PCI target. As a target, the S5935 Pass-Thru
mode supports single data transfers as well as burst
transfers. When accessed with burst transfers, the
S5935 supports data transfers at the full PCI bandwidth. The data transfer rate is only limited by the PCI
initiator performing the access and the speed of the
Add-On logic.
FUNCTIONAL DESCRIPTION
To provide the PCI bus Add-On with direct access to
Add-On resources, the S5935 has an internal PassDS1527
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Thru Address Register (APTA), and a Pass-Thru Data
Register (APTD). These registers are connected to
both the PCI bus interface and the Add-On bus interface. This allows a PCI initiator to perform Pass-Thru
writes (data transferred from the PCI bus to the AddOn bus) or Pass-Thru reads (PCI bus requests data
from the Add-On bus). The S5935 Pass-Thru interface
supports both single cycle (one data phase) and burst
accesses (multiple data phases).
Pass-Thru Transfers
Data transfers between the PCI bus and the Add-On
using the Pass-Thru interface are implemented with a
handshaking scheme. If the PCI bus writes to an
S5935 Pass-Thru region, Add-On logic must read the
data from the S5935 and store it on the Add-On. If the
PCI bus reads from a Pass-Thru region, Add-On logic
must write data to the S5935.
Some applications may require that an address be
passed to the Add-On for Pass-Thru accesses. For
example, a 4 Kbyte Pass-Thru region on the PCI bus
may correspond to a 4 Kbyte block of SRAM on the
Add-On card. If a PCI initiator accessed this region,
the Add-On would need to know the offset within the
memory device to access. The Pass-Thru Address
Register (APTA) allows the Add-On to access address
information for the current PCI cycle. When the PCI
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bus performs burst accesses, the APTA register is
updated by the S5935 to reflect the address of the current data phase.
For PCI writes to the Add-On, the S5935 transfers the
data from the PCI bus into the Pass-Thru Data Register (APTD). The S5935 captures the data from the PCI
bus when TRDY# is asserted. The PCI bus then
becomes available for other transfers. When the PassThru data register becomes full, the S5935 asserts the
Pass-Thru status signals to indicate to the Add-On that
data is present. The Add-On logic may read the data
register and assert PTRDY# to indicate the current
access is complete. Until the current access completes, the S5935 responds to further Pass-Thru
accesses with retries.
For PCI reads from the Add-On, the S5935 asserts the
Pass-Thru status signals to indicate to the Add-On that
data is required. The Add-On logic should write to the
Pass-Thru Data Register and assert PTRDY# to complete the access. The S5935 does not assert TRDY#
to the PCI bus until PTRDY# is asserted by Add-On
logic. If the Add-On cannot provide data quickly
enough, the S5935 signals a retry to the PCI bus. This
allows the PCI bus to perform other tasks, rather than
waiting for a slow target.
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Pass-Thru Status/Control Signals
BUS INTERFACE
The S5935 Pass-Thru registers are accessed using
the standard Add-On register access pins. The PassThru Address Register (APTA) can, optionally, be
accessed using a single, direct access input, PTADR#.
Pass-Thru cycle status indicators are provided to control Add-On logic based on the type of Pass-Thru
access occurring (single cycle, burst, etc.). The following signals are provided for Pass-Thru operation:
The Pass-Thru interface on the S5935 is a PCI targetonly function. Pass-Thru operation allows PCI initiators to read or write resources on the Add-On card. A
PCI initiator may access the Add-On with single data
phase cycles or multiple data phase bursts.
Signal
Function
PTATN#
This output indicates a Pass-Thru access
is occurring
PTBURST#
This output indicates the Pass-Thru
access is a PCI burst access
PTNUM[1:0]
These outputs indicate which Pass-Thru
region decoded the PCI address
PTBE[3:0]#
These outputs indicate which data bytes
are valid (PCI writes), or requested (PCI
reads)
PTWR
This output indicates if the Pass-Thru
access is a PCI read or a write
PTADR#
When asserted, this input drives the
Pass-Thru Address Register contents
onto the Add-On data bus
PTRDY#
When asserted, this input indicates the
current Pass-Thru transfer has been completed by the Add-On
BPCLK
Buffered PCI bus clock output (to synchronize Pass-Thru data register
accesses)
Pass-Thru Add-On Data Bus Sizing
Many applications require an 8-bit or 16-bit Add-On
bus interface. Pass-Thru regions can be configured to
support bus widths other than 32-bits. Each Pass-Thru
region can be defined, during initialization, as 8, 16-,
or 32-bits. All of the regions do not need to be the
same. This feature allows a simple interface to 8-and
16-bit Add-On devices.
To support alternate Add-On bus widths, the S5935
performs internal data bus steering. This allows the
Add-On interface to assemble and disassemble 32-bit
PCI data using multiple Add-On accesses to the PassThru Data Register (APTD). The Add-On byte enable
inputs (BE[3:0]#) are used to access the individual
bytes or words within APTD.
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The Add-On interface implements Pass-Thru status
and control signals used by logic to complete data
transfers initiated by the PCI bus. The Pass-Thru interface is designed to allow Add-On logic to function without knowledge of PCI bus activity. Add-On logic only
needs to react to the Pass-Thru status outputs. The
S5935 PCI interface independently interacts with the
PCI initiator to control data flow between the devices.
The following sections describe the PCI and Add-On
bus interfaces. The PCI interface description provides
a basic overview of how the S5935 interacts with the
PCI bus, and may be useful in system debugging. The
Add-On interface description indicates functions
required by Add-On logic and details the Pass-Thru
handshaking protocol.
PCI Bus Interface
The S5935 decodes all PCI bus cycle addresses. If
the address associated with the current cycle is to one
of S5935 Pass-Thru regions, DEVSEL# is asserted. If
the Pass-Thru logic is currently idle (not busy finishing
a previous Pass-Thru operation), the bus cycle type is
decoded and the Add-On Pass-Thru status outputs
are set to initiate a transfer on the Add-On side. If the
Pass-Thru logic is currently busy completing a previous access, the S5935 signals a retry to PCI initiator.
The following sections describe the behavior of the
PCI interface for Pass-Thru accesses to the S5935.
Single cycle accesses, burst accesses, and target-initiated retries are detailed.
PCI Pass-Thru Single Cycle Accesses
Single cycle transfers are the simplest PCI bus transaction. Single cycle transfers have an address phase
and a single data phase. The PCI bus transaction
starts when an initiator drives address and command
information onto the PCI bus and asserts FRAME#.
The initiator always deasserts frame before the last
data phase. For single cycle transfers, FRAME# is
only asserted during the address phase (indicating the
first data phase is also the last).
When the S5935 sees FRAME# asserted, it samples
the address and command information to determine if
the bus transaction is intended for it. If the address is
within one of the defined Pass-Thru regions, the
S5935 accepts the transfer (assert DEVSEL#), and
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stores the PCI address in the Pass-Thru Address Register (APTA).
For Pass-Thru writes, the S5935 responds immediately (asserting TRDY#) and transfers the data from
the PCI bus into the Pass-Thru Data Register (APTD).
The S5935 then indicates to the Add-On interface that
a Pass-Thru write is taking place and waits for Add-On
logic to read the APTD register and complete the
transfer (assert PTRDY#). Once the S5935 has captured the data from the PCI bus, the transfer is finished
from the PCI bus perspective, and the PCI bus
becomes available for other transfers.
For Pass-Thru reads, the S5935 indicates to the AddOn interface that a Pass-Thru read is taking place and
waits for Add-On logic to write the Pass-Thru Data
Register and complete the transfer (assert PTRDY#).
The S5935 completes the cycle when data is written
into the data register. If the Add-On cannot complete
the write quickly enough, the S5935 requests a retry
from the initiator. See target-requested disconnect
information.
PCI Pass-Thru Burst Accesses
For PCI Pass-Thru burst accesses, the S5935 captures the PCI address and determines if it falls into one
of the defined Pass-Thru regions. Accesses that fall
into a Pass-Thru region are accepted by asserting
DEVSEL#. The S5935 monitors FRAME# and IRDY#
on the PCI bus to identify burst accesses. If the PCI
initiator is performing a burst access, the Pass-Thru
status indicators notify Add-On logic.
For Pass-Thru burst writes, the S5935 responds
immediately (asserting TRDY#). The S5935 transfers
the first data phase of the burst into the Pass-Thru
Data Register (APTD), and stores the PCI address in
the Pass-Thru Address Register (APTA). The Add-On
interface completes the transfer and asserts PTRDY#.
Every time PTRDY# is asserted by the Add-On, the
S5935 begins the next data phase. The next data
phase is latched into the data register. For burst
accesses, APTA is automatically incremented by the
S5935 for each data phase.
For Pass-Thru burst reads, the S5935 claims the PCI
cycle (asserting DEVSEL#). The request for data is
passed on to Add-On logic and the PCI address is
stored in the APTA register. The Add-On interface
completes the transfer and asserts PTRDY#. The
S5935 then drives the requested data on the PCI bus
and asserts TRDY# to begin the next data phase. The
APTA register is automatically incremented by the
S5935 for each data phase.
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PCI Retry Conditions
In some applications, Add-On logic may not be able to
respond to Pass-Thru accesses quickly. In this situation, the S5935 disconnects from the PCI bus,
signaling a retry. This indicates that the initiator should
try the access again at a later time. This allows other
PCI cycles to be run while the logic on the slow target
completes the Pass-Thru access. Ideally, when the initiator retries the access, the target has completed the
access and can respond to the initiator.
With many devices, particularly memories, the first
access takes longer than subsequent accesses
(assuming they are sequential and not random). For
this reason, the PCI specification allows 16 clocks to
respond to the first data phase of a PCI cycle and 8
clocks for subsequent data phases (in the case of a
burst) before a retry must be requested by the S5935.
The S5935 also requests a retry if an initiator attempts
to burst past the end of a Pass-Thru region. The
S5935 updates the Pass-Thru Address Register
(APTA) for each data phase during bursts, and if the
updated address is not within the current Pass-Thru
region, a retry is requested.
For example, a PCI system may map a 512 byte PassThru memory region to 0DC000h to 0DC1FFh. A PCI
initiator attempts a four DWORD burst with a starting
address of 0DC1F8h. The first and second data
phases complete (filling the DWORDs at 0DC1F8h
and 0DC1FCh), but the third data phase causes the
S5935 to request a retry. This forces the initiator to
present the address 0DC200h on the PCI bus. If this
address is part of another S5935 Pass-Thru region,
the device accepts the access.
PCI Write Retries
When the S5935 requests a retry for a PCI Pass-Thru
write, it indicates that the Add-On is still completing a
previous Pass-Thru write access. The Pass-Thru
Address and Data Register contents (APTA and
APTD) are still required for the previous Pass-Thru
operation and cannot be updated by the PCI interface
until the access completes (the Add-On asserts
PTRDY#).
When the Add-On is busy completing a Pass-Thru
write, the S5935 requests an immediate retry for all
Pass-Thru region accesses, allowing the PCI bus to
perform other operations. PCI Operation Registers
may be accessed while the Add-On is still completing
a Pass-Thru access. Only Pass-Thru region accesses
receive retry requests.
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PCI Read Retries
Add-On Bus Interface
When the S5935 requests a retry for a PCI Pass-Thru
read, it indicates that the Add-On could not complete
the read in the required time. The Pass-Thru data cannot be read by the PCI interface until the Add-On
asserts PTRDY#, indicating the access is complete.
The Pass-Thru address and data registers can be
accessed as Add-On operation registers. The interface to the Pass-Thru registers is described in. The
Pass-Thru data register is updated on the rising edge
of BPCLK. For this reason, all Pass-Thru inputs must
be synchronous to BPCLK. In the following sections
the Add-On Pass-Thru interface is described for PassThru single cycle accesses, burst accesses, targetrequested retries, and when using 8-bit and 16-bit
Add-On data buses.
If the retry occurs after the Add-On has completed the
Pass-Thru operation by writing the appropriate data
into the Pass-Thru data register and asserting
PTRDY#, the S5935 asserts DEVSEL# and TRDY# to
complete the PCI read. If the Add-On still has not completed the Pass-Thru read, the S5935 waits for the
required 16 clocks. If the Add-On completes the
access during this time, TRDY# is asserted and the
access is finished. If the Add-On cannot complete the
access within 16 clocks, another retry is requested.
When the Add-On is busy completing a Pass-Thru
read, the S5935 requests an immediate retry for all
Pass-Thru region accesses, except the region currently completing the previous access. This allows the
PCI bus to perform other operations. The next access
to the Pass-Thru region which initiated the retry must
be to the same address which caused the retry.
Another initiator accessing the same Pass-Thru region
causes the S5935 to respond with the original initiator’s data (for reads). S5935 PCI Operation Registers
may be accessed while the Add-On is still completing
a Pass-Thru access. Only other Pass-Thru region
accesses receive retry requests.
Single Cycle Pass-Thru Writes
A single cycle Pass-Thru write operation occurs when
a PCI initiator writes a single value to a Pass-Thru
region. PCI single cycle transfers consists of an
address phase and one data phase. During the
address phase of the PCI transfer, the S5935 stores
the PCI address into the Pass-Thru Address Register
(APTA). If the S5935 determines that the address is
within one of its defined Pass-Thru regions, it captures
the PCI data into the Pass-Thru Data Register (APTD).
Figure 1 shows a single cycle Pass-Thru write access
(Add-On read). The Add-On must read the data stored
in the APTD register and transfer it to its destination.
Note: RD# may be asserted for multiple clocks to allow
interfacing with slow Add-On devices. Data remains
valid until PTRDY# is asserted.
Figure 80. Single Cycle Pass-Thru Write
012345
BPCLK
PTATN#
PTBURST#
PTNUM[1:0]
1
PTWR
PTBE[3:0]#
0h
SELECT#
ADR[6:2]
BE[3:0]#
2Ch
0h
RD#
DQ[31:0]
PT DATA
PTRDY#
PCI Write cycle completed
Note:
For all Add-On accesses using PTADR for address data when in 16 bit mode, ADR[1] must be held low to get the low address word.
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Clock 0:
The PCI bus cycle address information is stored in the S5935 Pass-Thru Address Register.
Clock 1:
The PCI address is recognized as a write to Pass-Thru region 1. The PCI data is stored in the S5935 Pass-Thru
Data Register. PTATN# is asserted to indicate a Pass-Thru access is occurring.
Clock 2:
Pass-Thru status signals indicate what action is required by Add-On logic. Pass-Thru status outputs are valid
when PTATN# is active and are sampled by the Add-On at the rising edge of clock 2.
PTBURST#
Deasserted. The access has a single data phase.
PTNUM[1:0]
01. Indicates the PCI access is to Pass-Thru region 1.
PTWR
Asserted. The Pass-Thru access is a write.
PTBE[3:0]#
0h. Indicates the Pass-Thru access is 32-bits.
SELECT#, address and byte enable inputs are driven to read the Pass-Thru Data Register at offset 2Ch.
DQ[31:0] are driven after RD# and SELECT# are asserted.
Clock 3:
If PTRDY# is asserted at the rising edge of clock 3, PTATN# is immediately deasserted and the Pass-Thru
access is completed at clock 4.
Clock 4:
If Add-On logic requires more time to read the Pass-Thru Data Register (slower memory or peripherals),
PTRDY# can be delayed, extending the cycle. With PTRDY# asserted at the rising edge of clock 4, PTATN# is
deasserted and the Pass-Thru access is completed at clock 5.
Clock 5:
PTATN# and PTBURST# deasserted at the rising edge of clock 5 indicates the Pass-Thru access is complete.
The S5935 can accept new Pass-Thru accesses from the PCI bus at clock 6.
Figure 2 shows a single cycle Pass-Thru write using
the Pass-Thru address information. This provides PCI
cycle address information to select a specific address
location within an Add-On memory or peripheral. AddOn logic must latch the address for use during the data
transfer. Typically, the entire 32-bit address is not
required. The Add-On may implement a scheme
where only the required number of address bits are
latched. It may also be useful to use the Pass-Thru
region identifiers, PTNUM[1:0] as address lines. For
example, Pass-Thru region 1 might be a 64K block of
SRAM for data, while Pass-Thru region 2 might be
64K of SRAM for code storage (down-loaded from the
host during initialization). Using PTNUM0 as address
line A16 allows two unique Add-On memory regions to
be defined.
Figure 81. Single Cycle Pass-Thru Write with PTADR#
012345
6
BPCLK
PTATN#
PTBURST#
PTNUM[1:0]
1
PTWR
PTBE[3:0]#
0h
SELECT#
ADR[6:2]
2Ch
BE[3:0]#
0h
RD#
DQ[31:0]
PT ADDR
PT DATA
PTRDY#
PTADR#
PCI Write cycle completed
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The Add-On PTADR# input directly accesses the
Pass-Thru Address Register and drives the contents
onto the data bus (no BPCLK rising edge is required).
The byte enables, address, and SELECT# inputs are
ignored when PTADR# is asserted. RD# and WR#
must not be asserted when PTADR# is asserted.
Clock 0:
The PCI bus cycle address is stored in the S5935 Pass-Thru Address Register.
Clock 1:
The PCI address is recognized as an access to Pass-Thru region 1. PCI data is stored in the S5935 Pass-Thru
Data Register. PTATN# is asserted to indicate a Pass-Thru access is occurring.
Clock 2:
Pass-Thru status signals indicate what action is required by Add-On logic. Pass-Thru status outputs are valid
when PTATN# is active and are sampled by the Add-On at the rising edge of clock 2.
PTBURST#
Deasserted. The access has a single data phase.
PTNUM[1:0]
01. Indicates the PCI access is to Pass-Thru region 1.
PTWR
Asserted. The Pass-Thru access is a write.
PTBE[3:0]#
0h. Indicate the Pass-Thru access is 32-bits.
The PTADR# input is asserted to read the Pass-Thru Address Register. The byte enable, address, and
SELECT# inputs are changed during this clock to select the Pass-Thru Data Register during clock cycle 3.
Clock 3:
SELECT#, byte enable, and the address inputs remain valid to read the Pass-Thru Data Register at offset 2Ch.
RD# is asserted to drive data register contents onto the DQ bus.
Clock 4:
If PTRDY# is asserted at the rising edge of clock 4, PTATN# is immediately deasserted and the Pass-Thru
access is completed at clock 5.
Clock 5:
If Add-On logic requires more time to read the Pass-Thru Data Register (slower memory or peripherals),
PTRDY# can be delayed, extending the cycle. PTRDY# asserted at the rising edge of clock 5 causes PTATN# to
be immediately deasserted.
Clock 6:
PTATN# and PTBURST# deasserted at the rising edge of clock 6 indicates the Pass-Thru access is complete.
The S5935 can accept new Pass-Thru accesses from the PCI bus at clock 7.
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Single Cycle Pass-Thru Reads
A single cycle Pass-Thru read operation occurs when
a PCI initiator reads a single value from a Pass-Thru
region. PCI single cycle transfers consists of an
address phase and a one data phase. During the address phase of the PCI transfer, the S5935 stores the
PCI address into the Pass-Thru Address Register
(APTA). If the S5935 determines that the address is
within one of its defined Pass-Thru regions, it indicates
to the Add-On that a write to the Pass-Thru Data Register (APTD) is required.
Figure 3 shows a single cycle Pass-Thru read access
(Add-On write) using PTADR#. The Add-On reads
data from a source on the Add-On and writes it to the
APTD register.
Clock 0:
PCI address information is stored in the S5935 Pass-Thru Address Register. The PCI cycle is recognized as an
access to Pass-Thru region 1. PTATN# is asserted by the S5935 to indicate a Pass-Thru access is occurring.
Clock 1:
Pass-Thru status signals indicate what action is required by Add-On logic. Pass-Thru status outputs are valid
when PTATN# is active and are sampled by the Add-On at the rising edge of clock 1.
PTBURST#
Deasserted. The access has a single data phase. PTNUM[1:0] 01. Indicates the PCI access was
to Pass-Thru region 1.
PTWR
Deasserted. The Pass-Thru access is a read.
PTBE[3:0]#
0h. Indicate the Pass-Thru access is 32-bits.
The PTADR# input is asserted to read the Pass-Thru Address Register. The byte enable, address, and SELECT#
inputs are changed during this clock to select the Pass-Thru Data Register during clock cycle 3.
Clock 2:
This clock is required to avoid contention on the DQ bus. Time must be allowed after PTADR# is deasserted for
the DQ outputs to float before Add-On logic attempts to write to the Pass-Thru Data Register.
Clock 3:
SELECT#, byte enables, and the address inputs remain valid to write the Pass-Thru Data Register at offset 2Ch.
If WR# is asserted at the rising edge of clock 3, data on the DQ bus is latched into APTD.
If PTRDY# is asserted at the rising edge of clock 3, PTATN# is immediately deasserted and the Pass-Thru
access is completed at clock 4.
Clock 4:
If Add-On logic requires more time to write the Pass-Thru data register (slower memory or peripherals), PTRDY#
can be delayed, extending the cycle. PTRDY# asserted at the rising edge of clock 4 causes PTATN# to be immediately deasserted and the Pass-Thru access is completed at clock 5.
Clock 5:
PTATN# and PTBURST# deasserted at the rising edge of clock 5 indicates the Pass-Thru access is complete.
The S5935 can accept new Pass-Thru accesses from the PCI bus at clock 6.
Pass-Thru Burst Writes
A Pass-Thru burst write operation occurs when a PCI
initiator writes multiple values to a Pass-Thru region. A
PCI burst cycle consists of an address phase and multiple data phases. During the address phase of the
PCI transfer, the S5935 stores the PCI address into
the Pass-Thru Address Register (APTA). If the S5935
determines that the address is within one of its defined
Pass-Thru regions, it captures the PCI data into the
Pass-Thru Data Register (APTD). After the Add-On
completes each read from the Pass-Thru data register
(asserts PTRDY#), the next data phase is initiated.
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Figure 4 shows a 6 data phase Pass-Thru burst write
(Add-On read). In this case, the Add-On asserts
PTADR# and then reads multiple data phases from the
S5935. This works well for Add-On logic which supports burst cycles. If the Add-On logic does not
support burst accesses, PTADR# may be pulsed
before each data phase. The S5935 automatically
increments the address in the APTA register during
PCI burst cycles. In this example PTRDY# is always
asserted, indicating Add-On logic is capable of accepting data at a rate of one DWORD per clock cycle.
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Clock 0:
PCI address information is stored in the S5935 Pass-Thru Address Register.
Clock 1:
The PCI address is recognized as an access to Pass-Thru region 1. PCI data for the first data phase is stored in
the S5935 Pass-Thru Data Register. PTATN# is asserted by the S5935 to indicate a Pass-Thru access is occurring.
Clock 2:
Pass-Thru status signals indicate what action is required by Add-On logic. Pass-Thru status outputs are valid
when PTATN# is active and are sampled by the Add-On at the rising edge of clock 2.
PTBURST#
Asserted. The access has a multiple data phases.
PTNUM[1:0]
01. Indicates the PCI access was to Pass-Thru region 1.
PTWR
Asserted. The Pass-Thru access is a write.
PTBE[3:0]#
0h. Indicate the Pass-Thru access is 32-bits.
The PTADR# input is asserted to read the Pass-Thru Address Register. The byte enable, address, and
SELECT# inputs are changed during this clock to select the Pass-Thru Data Register during clock cycle 3.
Clock 3:
SELECT#, byte enables, and the address inputs remain driven to read the Pass-Thru Data Register at offset
2Ch. RD# is asserted to drive data register contents onto the DQ bus.
Clock 4:
Add-On logic uses the rising edge of clock 4 to store DATA 1 from the S5935. PTRDY# asserted at the rising
edge of clock 4 completes the current data phase. DATA 2 is driven on the Add-On bus.
Clock 5:
Add-On logic uses the rising edge of clock 5 to store DATA 2 from the S5935. PTRDY# asserted at the rising
edge of clock 5 completes the current data phase. DATA 3 is driven on the Add-On bus.
Clock 6:
Add-On logic uses the rising edge of clock 6 to store DATA 3 from the S5935. PTRDY# asserted at the rising
edge of clock 6 completes the current data phase. On the PCI bus, IRDY# has been deasserted, causing
PTATN# to be deasserted. This is how a PCI initiator adds wait states, if it cannot provide data quickly enough.
Data on the Add-On bus is not valid.
Clock 7:
Because PTATN# remains deasserted, Add-On logic cannot store data at the rising edge of clock 7. PTATN# is
reasserted, indicating the PCI initiator is no longer adding wait states. DATA 4 is driven on the Add-On bus.
Clock 8:
Add-On logic uses the rising edge of clock 8 to store DATA 4 from the S5935. PTRDY# asserted at the rising
edge of clock 8 completes the current data phase. On the PCI bus, IRDY# has been deasserted again, causing
PTATN# to be deasserted. Data on the Add-On bus is not valid.
Clock 9:
The PCI initiator is still adding wait states. Add-On logic cannot store data while PTATN# is deasserted.
Clock
10:
Because PTATN# remains deasserted, Add-On logic cannot read data at the rising edge of clock 10. PTATN# is
reasserted, indicating the PCI initiator is no longer adding wait states. DATA 5 is driven on the Add-On bus.
Clock
11:
Add-On logic uses the rising edge of clock 11 to store DATA 5 from the S5935. PTRDY# asserted at the rising
edge of clock 11 completes the current data phase. DATA 6 is driven on the Add-On bus.
Clock
12:
Add-On logic uses the rising edge of clock 12 to store DATA 6 from the S5935. PTRDY# asserted at the rising
edge of clock 12 completes the final data phase.
Clock
13:
PTATN# and PTBURST# deasserted at the rising edge of clock 13 indicates the Pass-Thru access is complete.
The S5935 can accept new Pass-Thru accesses from the PCI bus at clock 15.
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Figure 82. Single Cycle Pass-Thru Read with PTADR#
6
012345
BPCLK
PTATN#
PTBURST#
1
PTNUM[1:0]
PTWR
0h
PTBE[3:0]#
SELECT#
ADR[6:2]
2Ch
BE[3:0]#
0h
WR#
DQ[31:0]
PT ADDR
PT DATA
PTRDY#
PTADR#
Data stored in Pass-Thru
data register
PCI Read cycle completed
Figure 83. Pass-Thru Burst Write
0
1
2
3
4
5
6
PT ADDRDATA1
DATA2
DATA3
7
8
9
10
11
12
13
BPCLK
PTATN#
PTBURST#
PTNUM[1:0]
1
PTWR
PTBE[3:0]#
0h
SELECT#
ADR[6:2]
2Ch
BE[3:0]#
0h
RD#
DQ[31:0]
XXXX
DATA4
XXXX
DATA5
DATA6
XXXX
PTRDY#
PTADR#
Valid PCI data on DQ bus
Figure 5 also shows a 5 data phase Pass-Thru burst
write, but the Add-On logic uses PTRDY# to control
the rate at which data is transferred. In many applications, Add-On logic is not fast enough to accept data at
every BPCLK rising edge (every 30 ns in a 33 MHz
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PCI Burst Write completed
PCI system). In this example, the Add-On interface
accepts data every other clock. In the example, RD# is
asserted during the entire Add-On burst, but it can be
deasserted when PTRDY# is deasserted, the S5935
functions the same under both conditions.
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Figure 84. Pass-Thru Burst Writes Controlled by PTRDY#
0
1
2
3
4
5
6
7
8
9
10
11
12
13
BPCLK
PTATN#
PTBURST#
PTNUM[1:0] 0
1
PTWR
PTBE[3:0]# Fh
0h
SELECT#
ADR[6:2]
2Ch
BE[3:0]#
0h
RD#
DQ[31:0]
PT ADDR DATA1
DATA2
DATA3
XXXX
DATA4
DATA5
PTRDY#
PTADR#
Valid PCI data on DQ bus
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Clock 0:
PCI address information is stored in the S5935 Pass-Thru Address Register.
Clock 1:
The PCI address is recognized as an access to Pass-Thru region 1. PCI data for the first data phase is stored
in the S5935 Pass-Thru Data Register. PTATN# is asserted by the S5935 to indicate a Pass-Thru access is
occurring.
Clock 2:
Pass-Thru status signals indicate what action is required by Add-On logic. Pass-Thru status outputs are valid
when PTATN# is active and are sampled by the Add-On at the rising edge of clock 2.
PTBURST#
Asserted. The access has multiple data phases.
PTNUM[1:0]
01. Indicates the PCI access is to Pass-Thru region 1.
PTWR
Asserted. The Pass-Thru access is a write.
PTBE[3:0]#
0h. Indicate the Pass-Thru access is 32-bits. The PTADR# input is asserted to read the
Pass-Thru Address Register. The byte en-able, address, and SELECT# inputs are changed
during this clock to select the Pass-Thru Data Register during clock cycle 3.
Clock 3:
SELECT#, byte enable, and the address inputs remain driven to read the Pass-Thru Data Register at offset
2Ch. RD# is asserted to drive data register contents onto the Add-On data bus.
Clock 4:
Add-On logic uses the rising edge of clock 4 to store DATA 1 from the S5935. PTRDY# asserted at the rising
edge of clock 4 completes the current data phase. DATA 2 is driven on the Add-On bus.
Clock 5:
Add-On logic is not fast enough to store DATA 2 by the rising edge of clock 5. PTRDY# deasserted at the rising edge of clock 5 extends the current data phase and DATA 2 remains driven on the Add-On bus.
Clock 6:
Add-On logic uses the rising edge of clock 6 to store DATA 2 from the S5935. PTRDY# asserted at the rising
edge of clock 6 completes the current data phase. DATA 3 is driven on the Add-On bus.
Clock 7:
Add-On logic is not fast enough to store DATA 3 by the rising edge of clock 7. PTRDY# deasserted at the rising edge of clock 7 extends the current data phase is and DATA 3 remains driven on the Add-On bus.
Clock 8:
Add-On logic uses the rising edge of clock 8 to store DATA 3 from the S5935. PTRDY# asserted at the rising
edge of clock 8 completes the current data phase. On the PCI bus, IRDY# has been deasserted, causing
PTATN# to be deasserted. Data on the Add-On bus is not valid.
Clock 9:
Because PTATN# remains deasserted, Add-On logic cannot store data at the rising edge of clock 9. PTATN#
is reasserted, indicating the PCI initiator is no longer adding wait states. DATA 4 is driven on the Add-On bus.
Clock 10:
Add-On logic uses the rising edge of clock 10 to store DATA 4 from the S5935. PTRDY# asserted at the rising
edge of clock 10 completes the current data phase. DATA 5 is driven on the Add-On bus. PTBURST# is deasserted, indicating that on the PCI bus, the burst is complete except for the last data phase. Since the data is
double buffered, there may be one or two pieces of data available to the Add-On when PTBURST# becomes
inactive.
This example shows the single data available case. If another piece of data was available, then PTATN#
would remain active instead of going inactive at clock 12.
Clock 11:
Add-On logic is not fast enough to store DATA 5 by the rising edge of clock 11. PTRDY# deasserted at the rising edge of clock 11 extends the data phase and DATA 5 remains driven on the Add-On bus.
Clock 12:
Add-On logic uses the rising edge of clock 12 to store DATA 5 from the S5935. PTRDY# asserted at the rising
edge of clock 12 completes the final data phase.
Clock 13:
PTATN# deasserted at the rising edge of clock 13 indicates the Pass-Thru access is complete. The S5935
can accept new Pass-Thru accesses from the PCI bus at clock 14.
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into the Pass-Thru Address Register (APTA). If the
S5935 determines that the address is within one of its
defined Pass-Thru regions, it indicates to the Add-On
that a write to the Pass-Thru Data Register (APTD) is
required. Figure 6 shows a 6 data phase Pass-Thru
burst read access (Add-On write) using PTADR#.
Pass-Thru Burst Reads
A Pass-Thru burst read operation occurs when a PCI
initiator reads multiple DWORDs from a Pass-Thru
region. A burst transfer consists of a single address
and a multiple data phases. During the address phase
of the PCI transfer, the S5935 stores the PCI address
Figure 85. Pass-Thru Burst Read
0
1
2
3
4
5
7
6
9
8
10
11
12
13
BPCLK
PTATN#
PTBURST#
PTNUM[1:0]
1
PTWR
PTBE[3:0]#
0h
Fh
SELECT#
ADR[6:2]
2Ch
BE[3:0]#
0h
WR#
DQ[31:0]
PT ADDR DATA1 DATA2
DATA3
DATA4
DATA5
DATA6
DATA7
PTRDY#
PTADR#
Valid Data written into data register
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Clock 0:
PCI address information is stored in the S5935 Pass-Thru Address Register. The PCI address is recognized as
an access to Pass-Thru region 1. PTATN# is asserted by the S5935 to indicate a Pass-Thru access is occurring.
PTBURST# is asserted by the S5935, indicating the current Pass-Thru read is a burst.
Clock 1:
Pass-Thru status signals indicate what action is required by Add-On logic. Pass-Thru status outputs are valid
when PTATN# is active and are sampled by the Add-On at the rising edge of clock 2.
PTBURST#
Deasserted, the S5935 does not yet recognize a PCI burst.
PTNUM[1:0]
01. Indicates the PCI access is to Pass-Thru region 1.
PTWR
Deasserted. The Pass-Thru access is a read.
PTBE[3:0]#
0h. Indicate the Pass-Thru access is 32-bits. The PTADR# input is asserted to read the
Pass-Thru Address Register. The byte enable, address, and SELECT# inputs are changed
during this clock to select the Pass-Thru Data Register during clock cycle 3.
Clock 2:
SELECT#, byte enables, and the address inputs remain driven to read the Pass-Thru Data Register at offset
2Ch.
Clock 3:
WR# asserted at the rising edge of clock 3 writes DATA 1 into the S5935. PTRDY# asserted at the rising edge
of clock 3 completes the current data phase.
Clock 4:
WR# asserted at the rising edge of clock 4 writes DATA 2 into the S5935. PTRDY# asserted at the rising edge
of clock 4 completes the current data phase.
Clock 5:
WR# asserted at the rising edge of clock 5 writes DATA 3 into the S5935. PTRDY# asserted at the rising edge
of clock 5 completes the current data phase. On the PCI bus, IRDY# has been deasserted, causing PTATN# to
be deasserted. This is how a PCI initiator adds wait states, if it cannot read data quickly enough.
Clock 6:
PTATN# remains deasserted at the rising edge of clock 6. The Add-On cannot write DATA 4 until PTATN# is
asserted. PTATN# is reasserted during the cycle, indicating the PCI initiator is no longer adding wait states.
Add-On logic continues to drive DATA 4 on the Add-On bus.
Clock 7:
WR# asserted at the rising edge of clock 7 writes DATA 4 into the S5935. PTRDY# asserted at the rising edge
of clock 7 completes the current data phase. On the PCI bus, IRDY# has been deasserted, causing PTATN# to
be deasserted. The PCI initiator is adding wait states.
Clock 8:
PTATN# remains deasserted at the rising edge of clock 8. The Add-On cannot write DATA 5 until PTATN# is
asserted. Add-On logic continues to drive DATA 5 on the Add-On bus.
Clock 9:
PTATN# remains deasserted at the rising edge of clock 9. The Add-On cannot write DATA 5 until PTATN# is
asserted. Add-On logic continues to drive DATA 5 on the Add-On bus. PTATN# is reasserted during the cycle,
indicating the PCI initiator is done adding wait states.
Clock 10:
WR# asserted at the rising edge of clock 10 writes DATA 5 into the S5935. PTRDY# asserted at the rising edge
of clock 10 completes the current data phase.
Clock 11:
WR# asserted at the rising edge of clock 11 writes DATA 6 into the S5935. PTRDY# asserted at the rising edge
of clock 11 completes the final data phase.
Clock 12:
PTBURST# is deasserted at the rising edge of clock 12 indicating the Pass-Thru burst is complete. The S5935
can accept new Pass-Thru accesses from the PCI bus at clock 14. Any data written into the Pass-Thru data register is not required and is never passed to the PCI interface (as PTRDY# is not asserted at the rising edge of
clock 13).
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Figure 7 also shows a 5 data phase Pass-Thru burst
read, but the Add-On logic uses PTRDY# to control
the rate at which data is transferred. In many applications, Add-On logic is not fast enough to provide data
every BPCLK (every 30 ns in a 33 MHz PCI system).
In this example, the Add-On interface writes data
every other clock cycle. WR# is shown asserted during
the entire Add-On burst, but WR# can be deasserted
when PTRDY# is deasserted, the S5935 functions the
same under both conditions.
Figure 86. PCI Burst Read Controlled by PTRDY#
0
2
1
3
4
5
6
7
8
9
10
11
12
13
BPCLK
PTATN#
PTBURST#
PTNUM[1:0] 0
1
PTWR
0h
PTBE[3:0]# Fh
SELECT#
ADR[6:2]
2Ch
BE[3:0]#
0h
WR#
DQ[31:0]
PT ADDR
DATA1
DATA2
DATA3
DATA4
DATA5
PTRDY#
PTADR#
Valid data written into data register
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Clock 0:
PCI address information is stored in the S5935 Pass-Thru Address Register. The PCI address is recognized as
an access to Pass-Thru region 1. PTATN# is asserted by the S5935 to indicate a Pass-Thru access is occurring.
PTBURST# is asserted by the S5935, indicating the current Pass-Thru read is a burst.
Clock 1:
Pass-Thru status signals indicate what action is required by Add-On logic. Pass-Thru status outputs are valid
when PTATN# is active and are sampled by the Add-On at the rising edge of clock 2.
PTBURST#
Deasserted, the S5935 does not yet recognize a PCI burst.
PTNUM[1:0] 01.
Indicates the PCI access is to Pass-Thru region 1.
PTWR
Deasserted. The Pass-Thru access is a read.
PTBE[3:0]#
0h. Indicate the Pass-Thru access is 32-bits.
The PTADR# input is asserted to read the Pass-Thru Address Register. The byte enable, address, and
SELECT# inputs are changed during this clock to select the Pass-Thru Data Register during clock cycle 3.
Clock 2:
SELECT#, byte enable, and the address inputs remain driven to read the Pass-Thru Data Register at offset
2Ch.
Clock 3:
WR# asserted at the rising edge of clock 3 writes DATA 1 into the S5935. PTRDY# asserted at the rising edge
of clock 3 completes the current data phase.
Clock 4:
Add-On logic drives DATA 2 on the Add-On bus, but PTRDY# deasserted at the rising edge of clock 4 extends
the current data phase.
Clock 5:
WR# asserted at the rising edge of clock 5 writes DATA 2 into the S5935. PTRDY# asserted at the rising edge
of clock 5 completes the current data phase.
Clock 6:
Add-On logic drives DATA 3 on the Add-On bus, but PTRDY# deasserted at the rising edge of clock 6 extends
the current data phase.
Clock 7:
WR# asserted at the rising edge of clock 7 writes DATA 3 into the S5935. PTRDY# asserted at the rising edge
of clock 7 completes the current data phase. On the PCI bus, IRDY# has been deasserted, causing PTATN# to
be deasserted. This is how a PCI initiator adds wait states, if it cannot read data quickly enough.
Clock 8:
PTATN# remains deasserted at the rising edge of clock 8. The Add-On cannot write DATA 4 until PTATN# is
asserted. Add-On logic continues to drive DATA 4 on the Add-On bus. PTATN# is reasserted during the cycle,
indicating the PCI initiator is done adding wait states.
Clock 9:
WR# asserted at the rising edge of clock 9 writes DATA 4 into the S5935. PTRDY# asserted at the rising edge
of clock 9 completes the current data phase.
Clock 10:
Add-On logic drives DATA 5 on the Add-On bus, but PTRDY# deasserted at the rising edge of clock 10 extends
the current data phase.
Clock 11:
PTATN# remains deasserted at the rising edge of clock 11. The Add-On does not have to write DATA 5 until
PTATN# is asserted. Add-On logic continues to drive DATA 5 on the Add-On bus. PTATN# is reasserted during
the cycle, indicating the PCI initiator is done adding wait states.
Clock 12:
PTRDY# asserted at the rising edge of clock 12 completes the final data phase. Any data written into the PassThru data register is not required and is never passed to the PCI interface (as PTRDY# is not asserted at the rising edge of clock 13).
Clock 13:
PTATN# and PTBURST# deasserted at the rising edge of clock 13 indicates the Pass-Thru access is complete.
The S5935 can accept new Pass-Thru accesses from the PCI bus at clock 14.
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Add-On Pass-Thru Disconnect Operation
Slow PCI targets are prevented from degrading PCI
bus performance. The PCI specification allows only 16
clocks for a target to respond before it must request a
retry on single data phase accesses. For burst
accesses, the first data phase is allowed 16 clocks to
complete, all subsequent data phases are allowed 8
clocks each. This requirement allows other PCI initiators to use the bus while the target requesting the retry
completes the original access.
Figure 8 shows the conditions that cause the S5935 to
request a retry from a PCI initiator on the first data
phase of a PCI read operation. FRAME# is asserted
during the rising edge of PCI clock 1. From this point,
the S5935 has 16 clock cycles to respond to the initiator with TRDY# (completing the cycle). FRAME# could
remain asserted, indicating a burst read, but the retry
request conditions are identical for a single data phase
read and the first data phase of a burst read. BPCLK is
identical to PCICLK, lagging by a propagation delay of
a few nanoseconds (see Chapter 13). PTATN# is
asserted on the Add-On interface as soon as FRAME#
is sampled active at a PCICLK rising edge.
Figure 87. Target Requested Retry on the First PCI Data Phase
1
2
3
4
15
16
17
18
1
2
3
14
15
16
17
PCICLK
FRAME#
STOP#
BPCLK
PTATN#
PTRDY#
PTRDY# must be asserted by
this time to present disconnecting
After PTATN# is asserted, PTRDY# must be asserted
by the 15th BPCLK rising edge to prevent the S5935
from requesting a retry. TRDY# is asserted on the PCI
interface one clock cycle after PTRDY# is asserted on
the Add-On interface. If Add-On logic does not return
PTRDY# by the 15th BPCLK rising edge, the S5935
asserts STOP#, requesting a retry from the PCI
initiator.
For Pass-Thru write operations, the S5935 never disconnects on the first or second PCI data phases of a
AMCC Confidential and Proprietary
PTRDY# asserted too late so
S593X disconnects (asserts STOP#)
burst. The first data and second phases are always
accepted immediately by the S5935. No further action
is required by the PCI initiator. The only situation
where the S5935 may respond to a Pass-Thru write
with a retry request is after the second data phase of a
Pass-Thru burst write.
Figure 9 shows the conditions required for the S5935
to request a retry after the second data phase of a
burst transfer. This figure applies to both Pass-Thru
burst read and write operations.
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Figure 88. Target Requested Retry after the First Data Phase of a Burst Operation
1
6
7
8
2
7
8
9
PCICLK
FRAME#
STOP#
0
1
BPCLK
PTATN#
PTRDY#
PCI Data Transfer
Latest assertion of PTRDY#
to prevent disconnect
The previous data phase is completed with the assertion of PTRDY# at the rising edge of BPCLK 0. AddOn logic must assert PTRDY# by the rising edge of
BPCLK 8 to prevent the S5935 from asserting STOP#,
requesting a retry. Meeting this condition allows the
S5935 to assert TRDY# by the rising edge of PCICLK
8, completing the data phase with requiring a retry.
When the S5935 requests a retry, the Pass-Thru status indicators remain valid (allowing the Add-On logic
to complete the access). PTBURST# is the exception
to this. PTBURST# is deasserted to indicate that there
is currently no burst in progress on the PCI bus. The
other Pass-Thru status indicators remain valid until
PTATN# is deasserted. Figure 10 shows the Add-On
bus interface signals after the S5935 requests a retry.
As long as PTATN# remains asserted, Add-On logic
should continue to transfer data. For PCI read operations, one Add-On write operation is required after a
retry request. After the Add-On write, asserting
PTRDY# deasserts PTATN#.
PTRDY# asserted too late,
results in disconnect
data transfers are possible because the S5935 has a
double buffered Pass-Thru data register used for
writes. A PCI burst may have filled both registers
before the S5935 requested a retry. PTATN# remains
asserted until both are emptied. PTRDY# must be
asserted after each read from the Pass-Thru data register. If both registers are full, PTATN# is deasserted
only after PTRDY# is asserted the second time. The
S5935 only accepts further PCI accesses after both
registers are emptied.
8-Bit and 16-Bit Pass-Thru Add-On Bus Interface
The S5935 allows a simple interface to devices with 8bit or 16-bit data buses. Each Pass-Thru region may
be defined as 8-, 16-, or 32-bits, depending on the
contents of the nv memory boot device loaded into the
PCI Base Address Configuration Registers during initialization. The Pass-Thru Add-On interface internally
controls byte lane steering to allow access to the 32bit Pass-Thru Data Register (APTD) from 8-bit or 16bit Add-On buses.
For Pass-Thru write operations, one or two data transfers may remain after the S5935 signals a retry. Two
166
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Figure 89. Pass-Thru Signals after a Target Requested Retry
STOP#
BPCLK
PTATN#
PTBURST#
PTNUM[1:0]
1
PTWR
PTBE[3:0]#
0h
Fh
SELECT#
ADR[6:2]
2Ch
BE[3:0]#
0h
RD#
DQ[31:0]
Data
PTRDY#
Internal byte lane steering may be used whether the
MODE input defines a 16-bit or 32-bit Add-On interface. When a 16-bit Add-On interface is used, the
ADR1 input is used in conjunction with the byte
enables to steer data into the proper APTD register
byte locations.
If MODE defines a 16-bit interface, only 16-bits of
address are driven when PTADR# is asserted. If more
than 16-bits of address are required, the Pass-Thru
A d d r e s s R e g i s t e r ( A PTA ) m u s t b e r e a d w i t h
SELECT#, RD#, byte enable and address inputs. Two
consecutive reads are required to latch all of the
address information (one with ADR1=0, one with
ADR1=1).
Regardless of MODE, various data widths may be
used. For Pass-Thru writes (Add-On APTD reads),
Add-On logic must read the APTD register one byte or
one word at a time (depending on the Add-On bus
width). The internal data bus is steered to the correct
portion of APTD using the BE[3:0]# inputs. Table 1
shows the byte lane steering mechanism used by the
S5935. The BYTEn symbols indicate data bytes in the
Pass-Thru Data Register.
When a read is performed with a BEn# input asserted,
the corresponding PTBEn# output is deasserted. Add-
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On logic cycles through the byte enables to read the
e n t i r e A P T D r e g i s t e r. O n c e a l l d a t a i s r e a d
(PTBE[3:0]# are deasserted), PTRDY# is asserted by
the Add-On, completing the access.
For Pass-Thru reads (Add-On APTD writes), the bytes
requested by the PCI initiator are indicated by the
PTBE[3:0]# outputs. Add-On logic uses the
PTBE[3:0]# signals to determine which bytes must be
written (and which bytes have already been written).
For example, a PCI initiator performs a byte Pass-Thru
read from an 8-bit Pass-Thru region with PCI BE2#
asserted. On the Add-On interface, PTBE2# is
asserted, indicating that the PCI initiator requires data
in this byte. Once the Add-On writes APTD, byte 2,
PTBE2# is deasserted, and the Add-On may assert
PTRDY#, completing the cycle.
Table 2 shows how the external Add-On data bus is
steered to the Pass-Thru Data Register bytes. This
mechanism is determined by the Pass-Thru region
bus width defined during initialization (see Section
12.3). The BYTEn symbols indicate data bytes in the
Pass-Thru Data Register. For example, an 8-bit AddOn write with BE1# asserted results in the data on
DQ[7:0] being steered into BYTE1 of the APTD
register.
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Table 44. Byte Lane Steering for Pass-Thru Data Register Read (PCI Write)
Byte Enables
APTD Register Read Byte Lane Steering
3
2
1
0
DQ[31:24]
DQ[23:16]
DQ[15:8]
DQ[7:0]
x
x
x
0
BYTE3
BYTE2
BYTE1
BYTE0
x
x
0
1
BYTE3
BYTE2
BYTE1
BYTE1
x
0
1
1
BYTE3
BYTE2
BYTE3
BYTE2
0
1
1
1
BYTE3
BYTE3
BYTE3
BYTE3
Table 45. Byte Lane Steering for Pass-Thru Data Register Write (PCI Read)
Defined
PT-Bus Width
168
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APTD Register Write Byte Lane Steering
BYTE3
BYTE2
BYTE1
BYTE0
32-Bit Data Bus
DQ[31:24]
DQ[23:16]
DQ[15:8]
DQ[7:0]
16-Bit Data Bus
DQ[15:8]
DQ[7:0]
DQ[15:8]
DQ[7:0]
8-Bit Data Bus
DQ[7:0]
DQ[7:0]
DQ[7:0]
DQ[7:0]
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To write data into the APTD Register, the PTBEn# output and the BEn# input must both be asserted. The
following describes how APTD Register writes are
controlled:
This process continues until all bytes have been read
from the APTD Register. During clock 5, RD# is deasserted and PTRDY# is asserted. PTRDY# is sampled
by the S5935 at the rising edge of clock 6, and the current data phase is completed. PTATN# is deasserted
and new data can be written from the PCI bus. In this
example, the byte enables are asserted, sequentially,
from BE0# to BE3#. This is not required, bytes may be
accessed in any order.
Write BYTE3 if PTBE3# AND BE3# are asserted
Write BYTE2 if PTBE2# AND BE2# are asserted
Write BYTE1 if PTBE1# AND BE1# are asserted
Write BYTE0 if PTBE0# AND BE0# are asserted
New data is written by the PCI initiator and is available
in the APTD Register during clock 7. RD# is asserted
and the byte enables are cycled again. With each new
data from the PCI bus, the Add-On sequences through
the byte enables to access APTD via DQ[7:0].
After each byte is written into the Pass-Thru data regi s t e r, i ts c or re s po nd i ng PTB E [ 3: 0 ] # o ut pu t i s
deasserted. This allows Add-On logic to monitor which
bytes have been written, and which bytes remain to be
written. When all bytes requested by the PCI initiator
have been written, the PTBE[3:0]# are all be deasserted, and the Add-On asserts PTRDY#.
For 16-bit peripheral devices, the byte steering works
in the same way. Because the Add-On data bus is 16bits wide, only two 16-bit cycles are required to access
the entire APTD Register. Two byte enables can be
asserted during each access.
Figure 11 shows Pass-Thru operation for a region
defined for an 8-bit Add-On bus interface. As the 8-bit
device is connected only to DQ[7:0], the device must
access APTD one byte at a time.
In Figure 11, RD# is held low and the byte enables are
changed each clock. This assumes the Add-On can
accept data at one byte per clock. This is the fastest
transfer possible. For slower devices, wait states may
be added.
The PCI initiator has performed a 32-bit write of
08D49A30h to Pass-Thru region zero. PTBE[3:0]# are
all asserted. At clock 1, the Add-On begins reading the
APTD Register (asserting SELECT#, ADR[6:2], and
RD#). Add-On logic asserts BE0#, and BYTE0 of
APTD is driven on DQ[7:0]. At the rising edge of clock
2, BE0# is sampled by the S5935 and PTBE0# is
deasserted. PTBE[3:1]# are still asserted.
As long as the byte enables remain in a given state,
the corresponding byte of the APTD Register is connected to the DQ bus (the RD# or WR# pulse may
also be lengthened). Each access may be extended
for slower Add-On devices, but extending individual
data phases for Pass-Thru cycles may result in the
S5935 requesting retries by the initiator.
During clock 2, only BE1# is activated, and BYTE1 of
APTD is driven on DQ[7:0]. At the rising edge of clock
3, BE1# is sampled by the S5935 and PTBE1# is
deasserted. PTBE[3:2]# are still asserted.
Figure 90. Pass-Thru Write to an 8-bit Add-On Device
1
2
3
4
5
6
7
8
9
10
11
12
13
BPCLK
PTATN#
PTWR
PTBE[3:0]#
Fh
0h
PTNUM[1:0]
1h
3h
7h
Fh
0h
1h
3h
7h
Dh
Bh
7h
Fh
Eh
Dh
Bh
7h
Fh
0
PTBURST#
SELECT#
BE[3:0]#
Fh
ADR[6:2]
3Ch
Eh
2Ch
Fh
3Ch
RD#
DQ[7:0]
ADDR
30h
9Ah
D4h
08h
DDh
CCh
BBh
AAh
PTADR#
PTRDY#
Note: 8 Bit Mode BE’s are E, D, B, 7; 16 Bit Mode BE’s are C, 3.
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CONFIGURATION
The S5935 Pass-Thru interface utilizes four Base
Address Registers (BADR1:4). Each Base Address
Register corresponds to a Pass-Thru region. The contents of these registers during initialization determine
the characteristics of that particular Pass-Thru region.
Each region can be mapped to memory or I/O space.
Memory mapped devices can, optionally, be mapped
below 1 Mbyte and can be identified as prefetchable.
Both memory and I/O regions can be configured as 8-,
16-, or 32-bits wide.
The designer has the option to use 1, 2, 3, 4 or none of
the Pass-Thru regions. Base Address Registers are
loaded during initialization from the external non-volatile boot device. Without an external boot device, the
default value for the BADR registers is zero (region
disabled). The Base Address Registers are the only
registers that define Pass-Thru operation.
S5935 Base Address Register Definition
Some bits in the Base Address Registers have specific
functions. The following bits have special functions:
D31
D30
Add-On Bus Width
0
0
Region disabled
0
1
8-bits
1
0
16-bits
1
1
32-bits
BADR1:4 bits D31:30 are used only by the S5935.
When the host reads the Base Address Registers during configuration cycles, they always return the same
value as D29. If D29 is zero, D31:30 return zero, indicating the region is disabled. If D29 is one, D31:30
return one. This operation limits each Pass-Thru
region to a maximum size of 512 Mbytes of memory.
For I/O mapped regions, the PCI specification allows
no more than 256 bytes per region. The S5935 allows
larger regions to be requested by the Add-On, but a
PCI BIOS will not allocate the I/O space and will probably disable the region.
Creating a Pass-Thru Region
D0
Memory or I/O mapping. If this bit is clear, the
region should be memory mapped. If this bit is
set, the region should be I/O mapped.
D2:1
Location of a memory region. These bits
request that the region be mapped in a particular part of memory. These bit definitions are
only used for memory mapped regions.
D3
Prefetchable. For memory mapped regions,
the region can be defined as cacheable. If set,
the region is cacheable. If this bit is clear, the
region is not.
D31:30
Pass-Thru region bus width. These two bits are
used by the S5935 to define the data bus width
for a Pass-Thru region. Regardless of the programming of other bits in the BADR register, if
D31:30 are zeros, the Pass-Thru region is disabled.
D2
D1
0
0
Anywhere in 32-bit memory space
0
1
Below 1 Mbyte in memory space (Real Mode
address space)
1
0
Anywhere in 64-bit memory space (not valid
for the S5935)
1
1
Reserved
170
Location
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Page 3-40 describes the values that must be programmed into the non-volatile boot device to request
various block sizes and characteristics for Pass-Thru
regions. After reset, the S5935 downloads the contents of the boot device locations 54h, 58h, 5Ch, and
60h into “masks” for the corresponding Base Address
Registers. The following are some examples for various Pass-Thru region definitions:
NV Memory
Contents
54h = BFFFF002h
58h = 3xxxxxxxh
Pass-Thru Region Definition
Pass-Thru region 1 is a 4Kbyte
region, mapped below 1 Mbyte in
memory space with a 16-bit Add-On
data bus. This memory region is not
cacheable.
Pass-Thru region 2 is disabled.
(D31:30 = 00.)
60h = FFFFFF81h
Pass-Thru region 3 is a 32-bit, 128
byte I/O-mapped region.
64h = 00000000h
Pass-Thru region 4 is disabled.
During the PCI bus configuration, the host CPU writes
all ones to each Base Address Register, and then
reads the contents of the registers back. The mask
downloaded from the boot device determines which
bits are read back as zeros and which are read back
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as ones. The number of zeros read back indicates the
amount of memory or I/O space a particular S5935
Pass-Thru region is requesting.
particular devices on the PCI bus based on Vendor ID
and Device ID values. This allows application software
to access the device’s Configuration Registers.
After the host reads all Base Address Registers in the
system (as every PCI device implements from one to
six), the PCI BIOS allocates memory and I/O space to
each Base Address region. The host then writes the
start address of each region back into the Base
Address Registers. The start address of a region is
always an integer multiple of the region size. For
example, a 64 Kbyte memory region is always
mapped to begin on a 64K boundary in memory. It is
important to note that no PCI device can xbe absolutely located in system memory or I/O space. All
mapping is determined by the system, not the
application.
The Base Address Register values in the S5935’s
Configuration Space may then be read and stored for
use by the program to access application hardware.
The value in the Base Address Registers is the physical address of the first location of that Pass-Thru
region. Some processor architectures allow this
address to be used directly to access the PCI device.
For Intel Architecture systems, the physical address
must be changed into a Segment/Offset combination.
Accessing a Pass-Thru Region
After the system is finished defining all Base Address
Regions within a system, each Base Address Register
contains a physical address. The application software
must now find the location in memory or I/O space of
its hardware. PCI systems provide BIOS or operating
system function calls for application software to find
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For Real Mode operation in an Intel Architecture system (device mapped below 1 Mbyte in memory),
creating a Segment/Offset pair is relatively simple. To
calculate a physical address, the CPU shifts the segment register 4 bits to the left and adds the offset
(resulting in a 20 bit physical address). The value in
the Base Address Register must be read and shifted 4
bits to the right. This is the segment value and should
be stored in one of the Segment registers. An offset of
zero (stored in SI, DI or another offset register)
accesses the first location in the Pass-Thru region.
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ABSOLUTE MAXIMUM RATINGS
Parameter
Min
Max
Units
Storage Temperature
-55
125
°C
Supply Voltage (VCC)
-0.3
7.0
Volts
Input Pin Voltage
-0.5
VCC+ 5.0
Volts
1.05
Watts @ 33 MHz
Power Dissipation
DC CHARACTERISTICS
The Following table summarizes the required parameters defined by the PCI specification as they apply to the
S5935 controller.
PCI Input/Output Electrical Characteristics
Symbol
Parameter
Min
Max
Units
5.25
V
VCC
Supply Voltage
4.75
VIH
Input High Voltage
2.0
VIL
Input Low Voltage
–0.5
IIH
Test Conditions
Notes
V
0.8
V
Input High Leakage Current
70
uA
VIN = 2.7
1
IIL
Input Low Leakage Current
–70
uA
VIN = 0.5
1
VOH
Output High Voltage
V
IOUT = –2mA
VOL
Output Low Voltage
0.55
V
IOUT = 3mA, 6mA
2
CIN
Input Pin Capacitance
10
pF
V in = 0.5
3
CCLK
CLK Pin Capacitance
12
pF
CIDSEL
IDSEL Pin Capaticance
8
pF
2.4
5
Notes:
1. Input leakage applies to all inputs and bi-directional buffers.
2. PCI Bus signals without pull-up resistors will provide the 3 mA output current. Signals which require a pull-up resistor will provide 6 mA output current.
3. The PCI specification limits all PCI inputs not located on the motherboard to 10 pf (the clock is allowed to be 12 pf).
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PCI BUS SIGNALS
The following table summarizes the PCI Bus DC parameters defined by the PCI specification as they apply to the
S5935 controller.
Signal
Type
Direction
CLK
Input
RST#
Input
INTA#
Open Drain
Output
AD[31:0]
t/s
Bi-directional
REQ#
t/s
Output
GNT#
Max
Units
4
mA
mA
4
mA
4
mA
Input
C/BE[3:0]#
t/s
Bi-directional
DEVSEL#
s/t/s
Bi-directional
FRAME#
s/t/s
Bi-directional
4
mA
IRDY#
s/t/s
Bi-directional
4
mA
TRDY#
s/t/s
Bi-directional
4
mA
PERR#
s/t/s
Bi-directional
4
mA
t/s
Bi-directional
4
mA
Output
4
mA
Bi-directional
4
mA
PAR
SERR#
Open Drain
STOP#
s/t/s
LOCK#
Input
IDSEL
Input
174
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Notes
mA
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ADD-ON BUS SIGNALS
Signal
Type
Direction
Max
Units
PCLK
Output
8
mA
IRQ#
Output
4
mA
SYSRST#
Output
4
mA
ADR[6:2]
Input
SELECT
Input
ADR[6:2]
Input
BE[3:0]#
Input
RD#
Input
WR#
Input
Bi-directional
4
mA
WRFULL
Output
4
mA
RDEMPTY
Output
4
mA
RDFIFO#
Input
WRFIFO#
Input
PTATN#
Output
4
mA
PTBURST#
Output
4
mA
PTADR#
Input
PTRDY#
Input
PTWR
Output
4
mA
PTBE[3:0]#
Output
4
mA
PTNUM[1:0]
Output
4
mA
DQ[31:0]
t/s
EQ[7:0]
t/s
Bi-directional
1
mA
EA[8:0]
t/s
Output
1
mA
EA[15:9]
Output
1
mA
MODE
Input
TEST
Output
4
mA
FLT#
Input
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Notes
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Signal
Type
Direction
ERD#/SCL
EWR#/SDA
t/s
Max
Units
Output
1
mA
Bi-directional
1
mA
Notes
AC CHARACTERISTICS
PCI Bus Timings
Functional Operation Range (V CC =5.0V ±5%, 0°C to 70°C, 50 pF load on outputs)
Symbol
Parameter
Min
Max
Units
TCL
Cycle Time
30
ns
t1
High Time
12
ns
t2
Low Time
12
ns
t3
Rise Time (0.8V to 2.0V)
3
ns
t4
Fall Time (2.0V to 0.8V)
3
ns
t5
Output Valid Delay (Bussed Signals)
Output Valid Delay (Point-to-Point Signals)
2
2
11
12
ns
t6
Float to Active Delay
2
t7
Active to Float Delay
28
t8
Rising Edge Setup (Bussed Signals)
Rising Edge Setup (GNT#)
Rising Edge Setup (REQ#)
7
10
12
ns
t9
Hold from PCI Clock Rising Edge
0
ns
t10
PCICLK to BPCLK Delay
2
Notes
Note 1
ns
ns
6.5
ns
Note:
1. Minimum times are for unloaded outputs, maximum times are for 50 pF equivalent loads.
Figure 91. PCI Clock Timing
t1
2.0
t3
VIH2
2.0
0.8
2.0
0.8
t4
2.0
0.8
t2
TCL
176
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Figure 92. PCI Output Timing
1.5
PCI CLK
t5
OUTPUT
DELAY
1.5
TRI-STATE
OUTPUT
1.5
1.5
t6
t7
Figure 93. PCI Input Timing
PCI CLK
t8
INPUT
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t9
Inputs Valid
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ADD-ON BUS TIMINGS
Figure 94. Add-On Clock Timing
t1
2.0
t3
2.0
0.8
2.0
V IH2
0.8
t4
2.0
0.8
t2
TCL
Figure 95. Pass-Thru Clock Relationship to PCI Clock
PCI CLK
t10
BPCLK
178
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Synchronous RDFIFO# Timing
Functional Operation Range (VCC=5.0V 5%, 0 C to 70 C Ta’ 50 pf loaf on outputs).
Symbol
Parameter
Min
Max
Units
Notes
26
ns
1
t144
RDFIFO# Setup tp BPCLK Rising Edge
8
t145
RDFIFO# Low Time
8
t146
RDFIFO# Low to DQ[31:0] Driven
12
ns
t148
RDFIFO# High to DQ[31:0] Float
3
ns
t149
DQ[31:0] Valid from BPCLK Rising Edge
16
ns
3
t165
PCI to ADD-ON FIFO RDEMPTY Valid from BPCLK Rising Edge
12
ns
2
t166
PCI to ADD-ON FIFO FRF Valid from BPCLK Rising Edge
80
ns
ns
Notes:
1. Min and Max times are indicated to allow increased valid data time as shown by dashed lines.
2. 2.State change of RDEMPTY shown below is reference only. Actual change would indicate no Data 3 available.
3. 3.Valid applies after first access. First access is async with following as sync accesses.
Figure 96. Synchronous RDFIFO# Timing
BPCLK
t 144 Max
t 144
t 149
RDFIFO#
t146
DQ[31:0]
10ns
1
14ns
t148
6ns
23
4
t 165
8ns
RDEMPTY
New Valid
Old Valid
t 166
FRF
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Data Book
Synchronous WRFIFO# Timing
Functional Operation Range (VCC= 5.0V 5%, 0 C to 70 C Ta’ 50 pf load on outputs).
Symbol
Parameter
Min
Max
Units
t150
WRFIFO# Setup to BPCLK Rising Edge
12
ns
t150a
WRFIFO# Hold Time to BPCLK Rising Edge
0
ns
t151
DQ[31:0] Setup to BPCLK Rising Edge
7
t151a
DQ[31:0] Hold from BPCLK Rising Edge
0
t167
ADD-ON to PCI WRFULL Valid from BPCLK Rising Edge
11
ns
t168
ADD-ON to PCI FIFO FWE Valid from BPCLK Rising Edge
26
ns
Notes
1
Note:
1. State change of WRFULL shown below is reference only. Actual change would indicate no Data 3 written.
Figure 97. Synchronous WRFIFO# Timing
BPCLK
t150
t 150a
WRFIFO#
t 151
DQ[31:0]
1
2
3
t 167
6ns
WRFULL
New Valid
Old Valid
t 168
FWE
180
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S5935 – PCI Product
Data Book
Asynchronous RD# Register Access Timing
Functional Operation Range (VCC=5.0V 5%, 0 C to 70 C Ta’ 50 pf load on outputs).
Symbol
Parameter
Min
Max
Units
t110
SELECT# Setup to RD# Rising Edge
10
ns
t114a
SELECT# Hold from RD# Rising Edge
-1
ns
t114
ADR[6:2] Setup to RD# Rising Edge
18
ns
t114a
ADR[6:2] Hold from RD# Rising Edge
0
t118
BE[3:0]# Setup to RD# Rising Edge
12
ns
t118a
BE[3:0]# Hold from RD# Rising Edge
0
ns
t129
RD# High Time
16
ns
t130
RD# Low Time
15
ns
t133
DQ[31:0] Valid from RD# Falling Edge
15
ns
t133a
DQ[31:0] Hold from RD# Rising Edge
3
ns
t152
RDEMPTY Status Valid from RD# Rising Edge
10
ns
t153
FRF Status Valid from RD# Rising Edge
75
ns
Notes
Figure 98. Asynchronous RD# FIFO Timing
t 110
SELECT#
t114
ADR[6:2]
t 118
BE[3:0]#
t133a
t 133
DQ[31:0]
t 129
t 130
RD#
t152
5ns
RDEMPTY
T153
FRF
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S5935 – PCI Product
Data Book
Asynchronous WR# Register Access Timing
Functional Operation Range (VCC=5.0V 5%, 0 C to 70 C T 50 pf load on outputs).
Symbol
Parameter
Min
Max
Units
t111
SELECT# Setup to WR# Rising Edge
7
ns
t111a
SELECT# Hold from WR# Rising Edge
0
ns
t115
ADR[6:2] Setup to WR# Rising Edge
8
ns
t115a
ADR[6:2] Hold from WR# Rising Edge
0
ns
t119
BE[3:0]# Setup to WR# Rising Edge
5
ns
t119a
BE[3:0]# Hold from WR# Rising Edge
0
ns
t131
WR# High Time
TBD
ns
t132
WR# Low Time
4
ns
t134
DQ[31:0] Setup to WR# Rising Edge
2
ns
t134a
DQ[31:0] Hold from WR# Rising Edge
3
ns
t154
WRFULL Status Valid from WR# Rising Edge
27
ns
t155
FWE Status Valid from WR# Rising Edge
40
ns
Notes
Figure 99. Asynchronous WR# FIFO Timing
t 111
SELECT#
t 115
ADR[6:2]
t119
BE[3:0]#
t132a
t134
DQ[31:0]
t 132
WR#
t154
13ns
WRFULL
t 155
FWE
182
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Data Book
Synchronous RD# FIFO Timing
Functional Operation Range (VCC=5.0V 5%, 0 C to 70 C T 50 pf load on outputs).
Symbol
Parameter
Min
Max
Units
Notes
30
ns
4
t112
SELECT# Setup to BPCLK Rising Edge
10
t112a
SELECT# Hold from BPCLK Rising Edge
2
t116
ADR[6:2] Setup to BPCLK Rising Edge
14
t116a
ADR[6:2] Hold from BPCLK Rising Edge
1
t120
BE[3:0]# Setup to BPCLK Rising Edge
9
t120a
BE[3:0]# Hold from BPCLK Rising Edge
3
t125
RD# Low to DQ[31:0] Driven
17
ns
t128
RD# High to DQ[31:0] Float
8
ns
t156
RDEMPTY Status Valid to BPCLK Rising Edge
13
ns
t157
FRF Status Valid to BPCLK Rising Edge
74
ns
t124
RD# Setup to BPCLK Rising Edge
11
31
ns
t124a
RD# Hold from BPCLK Rising Edge
1
t127
DQ[31:0] Valid from BPCLK Rising Edge
ns
34
ns
4
ns
29
ns
4
ns
1
4
ns
6
ns
Notes:
1. Data is valid for 22ns for a 31ns t124 RD# Setup.
2. RD# and SELECT# must both be asserted to dric=ve DQ[31:0] - delay is from the last one asserted.
3. When increasing Setup times, ADR[6:2], BE[3:0]#, SELECT#, and RD# timing relations remain relative to each other as shown.
4. Min and Max are indicated to allow increased valid data time as shown by dashed lines. First accesses are async.
Figure 100. Synchronous RD# FIFO Timing
BPCLK
t 112 Max
t 112
t 112a
SELECT#
t116
t 116a
ADR[6:2]
t120
t120a
BE[3:0]#
t 125
DQ[31:0]
t 124
RD#
t128
t 124a
t 156
5ns
RDEMPTY
t157
FRF
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Data Book
Synchronous Multiple RD# FIFO Timing
184
DS1527
2
FRF
RDEMPTY
RD#
DQ[31:0]
t124
t125
BE[3:0]
t120
t116
ADR[6:2]
SELECT#
BPCLK
t112
2ns
11ns
t157
5ns
3
4
5
6
7
8
5ns
t156
t124a
t120a
t116a
t112a
Figure 101. Synchronous RD# FIFO Timing
AMCC Confidential and Proprietary
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S5935 – PCI Product
Data Book
Synchronous WR# FIFO Timing
Functional Operation Range (VCC=5.0V 5%, 0 C to 70 C Ta’ 50 pf load on outputs).
Symbol
Parameter
Min
Max
Units
t113
SELECT# Setup to BPCLK Rising Edge
19
ns
t113a
SELECT# Hold from BPCLK Rising Edge
0
ns
t117
ADR[6:2] Setup to BPCLK Rising Edge
20
ns
t117a
ADR[6:2] Hold from BPCLK Rising Edge
0
ns
t121
BE[3:0]# Setup to BPCLK Rising Edge
15
ns
t121a
BE[3:0]# Hold from BPCLK Rising Edge
0
ns
t123
DQ[31:0] Setup to BPCLK Rising Edge
12
ns
t123a
DQ[31:0] Hold from BPCLK Rising Edge
1
ns
t122
WR# Setup to BPCLK Rising Edge
20
ns
t122a
WR# Hold from BPCLK Rising Edge
0
ns
t159
WRFULL Status Valid to BPCLK Rising Edge
18
ns
t160
FWE Status Valid to BPCLK Rising Edge
26
ns
Notes
Figure 102. Synchronous WR# FIFO Timing
BPCLK
t 113
SELECT#
t117
ADR[6:2]
t 121
BE[3:0]#
t123
t 123a
DQ[31:0]
t122
WR#
t 159
3ns
WRFULL
t160
4ns
FWE
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Data Book
Synchronous Multiple WR# FIFO Timing
186
DS1527
4ns
WRFULL
WR#
t 122
1
DQ[31:0]
t 123
BE[3:0]#
t 121
ADR[6:2]
t 117
SELECT#
BPCLK
t 113
t123a
t160
2
t 123
3
4
5
6
7
8
3ns
t 159
t123a
Figure 103. Synchronous Multiple WR# FIFO Timing
AMCC Confidential and Proprietary
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S5935 – PCI Product
Data Book
Target S5935 Pass-Thru Interface Timings
Functional Operation Range (VCC=5.0V 5%, 0 C to 70 C, 50 pF load on outputs)
Symbol
Parameter
Min
Max
Units
t10a
SELECT# Setup to BPCLK Rising Edge
3
ns
t11a
SELECT# Hold from BPCLK Rising Edge
2
ns
t12
ADR[6:2], BE[3:0]# to Valid DQ [31:0]
t13
ADR[6:2], BE[3:0]# Setup to BPCLK Rising Edge
5
ns
t14
ADR[6:2], BE[3:0]# Hold from BPCLK Rising Edge
2
ns
t17
RD# Low to DQ{31:0] Driven
13
ns
t24
Pass-Thru Status Valid from BPCLK Rising Edge
5
ns
t25
Pass-Thru Status Hold from BPCLK Rising Edge
0
ns
t26
PTRDY# Setup to BPCLK Rising Edge
5
ns
t27
PTRDY# Hold from BPCLK Rising Edge
3
ns
t28
PCICLK to BPCLK delay
2
t29
RD#, WR# Setup to BPCLK Rising Edge
5
ns
t30
RD#, WR# Hold from BPCLK Rising Edge
2
ns
t31
DQ[31:0] Setup to BPCLK Rising Edge
5
ns
t32
DQ[31:0] Hold from BPCLK Rising Edge
2
ns
t33
DQ[31:0] Valid from BPCLK Rising Edge
15
ns
t34
DQ[31:0] Float from RD# Rising Edge
12
ns
16
6.5
Notes
ns
1
ns
Note:
1. This timing also applies to the use of BE[3:0]# to control DQ[31:0] drive.
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S5935 – PCI Product
Data Book
Figure 104. Pass-Thru Data Register Read Timing
BPCLK
t13
ADR[6:2]
BE[3:0]#
t14
Valid 1
Valid 2
t17
DQ[31:0]
t33
Valid Data Out 1
t12
t29
Valid Data Out 2
t30
RD#
t34
SELECT#
t11a
PTRDY#
t26
t27
Figure 105. Pass-Thru Data Register Write Timing
BPCLK
t13
ADR[6:2]
BE[3:0]#
t14
Valid 1
t31
DQ[31:0]
Valid 2
t32
Valid Data In 1
Valid Data In 2
t29
t30
t10a
t11a
WR#
SELECT#
PTRDY#
t26
188
DS1527
t27
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S5935 – PCI Product
Data Book
Figure 106. Pass-Thru Status Indicator Timing
BPCLK
PTATN#
PTWR
PTBURST#
PTNUM[1:0]
PTBE[3:0]#
Valid
t24
Valid
t25
Target Byte-Wide nv Memory Interface Timings
Functional Operation Range (V CC =5.0V ±5%, 0°C to 70°C, 50 pF load on outputs)
Symbol
Parameter
Min
Max
Units
Notes
t35
ERD# Cycle Time
8T
ns
Note 1
t36
ERD# Low Time
6T
ns
Note 1
t37
ERD# High Time
2T
ns
Note 1
t38
EA[15:0] Setup to ERD# or EWR# Low
T
ns
Note 1
t39
EA[15:0] Hold from ERD# or EWR# High
T
ns
Note 1
t40
EQ[7:0] Setup to ERD# Rising Edge
10
ns
Note 1
t41
EQ[7:0] Hold from ERD# Rising Edge
2
ns
Note 1
t42
EWR# Cycle Time
ns
Note 1,2
t43
EWR# Low Time
6T
ns
Note 1
t44
EWR# High Time
2T
ns
Note 1
t45
EQ[7:0] Setup to EWR# Low -10
0
ns
Note 1
t46
EQ[7:0] Hold from EWR# High
T
ns
Note 1
Notes:
1. T represents the clock period for the PCI bus clock (30ns @ 33 MHz).
2. The write cycle time is controlled by both the PCI bus clock and software operations to initiate the write operation of nv memory. This parameter is the result of several software operations to the Bus Master Control/Status Register (MCSR).
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S5935 – PCI Product
Data Book
Figure 107. nv Memory Read Timing
t35
ERD#
t37
(OUTPUT)
t36
t38
EA[15:0]
t39
Address Valid
(OUTPUT)
t40
EQ[7:0]
t41
Data Valid
(INPUT)
Figure 108. nv Memory Write Timing
t42
t43
EWR#
t44
(OUTPUT)
t39
t38
EA[15:0]
Address Valid
(OUTPUT)
t45
EQ[7:0]
(OUTPUT)
190
DS1527
t46
Data Valid
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Data Book
Target Interrupt Timings
Functional Operation Range (V CC =5.0V ±5%, 0°C to 70°C, 50 pF load on outputs)
Symbol
Parameter
Min
Max
Units
Notes
t49
IRQ# Low from BPCLK Rising Edge
15
ns
Note 1
t50
IRQ# High from BPCLK Rising Edge
15
ns
Note 1
Notes:
1. This timing applies to interrupts generated and cleared from the PCI interface.
Figure 109. IRQ# Interrupt Output Timing
BPCLK
IRQ#
t49
t50
Functional Operation Range (V CC =5.0V ±5%, 0°C to 70°C, 50 pF load on outputs)
Symbol
Parameter
Min
Max
Units
t51
EMBCLK Low Time
12
ns
t52
EMBLK High Time
12
ns
t53
EMB[7:0] Setup to EMBCLK Rising Edge
5
ns
t54
EMB[7:0] Hold from EMBCLK Rising Edge
2
ns
Notes
Figure 110. Mailbox 4, Byte 3 Direct Input Timing
t51
t52
EMBCLK
t53
EMB[7:0]
AMCC Confidential and Proprietary
t54
Valid
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Data Book
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192
DS1527
AMCC Confidential and Proprietary
Revision 1.02 – June 27, 2006
S5935 – PCI Product
Data Book
S5935
(160 PQFP)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
80
79
78
77
76
75
74
73
72
71
70
69
68
67
66
65
64
63
62
61
60
59
58
57
56
55
54
53
52
51
50
49
48
47
46
45
44
43
42
41
DQ12
DQ13
DQ14
DQ24
DQ15
SELECT#
WR#
EA3
RD#
VCC
VSS
EA2
ADR2
ADR3
ADR4
DQ25
ADR5
BE1#
BE2#
EA1
BE3#
MODE
INTA#
EA0
AD0
AD1
AD2
DQ26
AD3
VCC
VSS
EQ7/AMWEN
AD4
AD5
AD6
DQ27
AD7
C/BE0#
AD8
EQ6/AMREN
EQ0
AD23
AD22
AD21
DQ31
AD20
AD19
AD18
EQ1
VSS
VCC
AD17
DQ30
AD16
C/BE2#
FRAME#
EQ2
IRDY#
TRDY#
DEVSEL#
EQ3
STOP#
LOCK#
PERR#
DQ29
SERR#
PAR
C/BE1#
EQ4/FWC#
VSS
VCC
AD15
EQ5/FRC#
AD14
AD13
AD12
DQ28
AD11
AD10
AD9
EA10
PTNUM1
PTNUM0
IRQ#
DQ19
SYSRST#
EWR#/SDA
ERD#/SCL
EA11
VSS
VCC
ADR6
DQ18
NC
SNV
NC
EA12
RSVD
RST#
BPCLK
EA13
CLK
GNT#
REQ#
DQ17
AD31
AD30
AD29
EA14/FWE
VSS
VCC
AD28
EA15/FRF
AD27
AD26
AD25
DQ16
AD24
C/BE3#
IDSEL
120
119
118
117
116
115
114
113
112
111
110
109
108
107
106
105
104
103
102
101
100
99
98
97
96
95
94
93
92
91
90
89
88
87
86
85
84
83
82
81
PTBE3#
PTBE2#
PTBE1#
DQ20
PTBE0#
PTRDY#
PTATN#
EA9
PTBURST#
VCC
VSS
EA8
PTWR
PTADR#
RDEMPTY
DQ21
RDFIFO#
WRFULL
WRFIFO#
EA7
DQ0
DQ1
DQ2
EA6
DQ3
DQ4
DQ5
DQ22
DQ6
VCC
VSS
EA5
DQ7
BEO#
DQ8
DQ23
DQ9
DQ10
DQ11
EA4
S5935 Pinout and Pin Assignment - 160 PQFP
AMCC Confidential and Proprietary
DS1527
193
Revision 1.02 – June 27, 2006
S5935 – PCI Product
Data Book
S5935
(208 TQFP)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
104
103
102
101
100
99
98
97
96
95
94
93
92
91
90
89
88
87
86
85
84
83
82
81
80
79
78
77
76
75
74
73
72
71
70
69
68
67
66
65
64
63
62
61
60
59
58
57
56
55
54
53
VDD
VDD
DQ12
DQ13
DQ14
VSS
DQ24
DQ15
SELECT#
WR#
EA3
RD#
VDD
VSS
VSS
VSS
EA2
ADR2
ADR3
N/C
ADR4
DQ25
ADR5
BE1
BE2
EA1
BE3
MODE
INTA#
EA0
AD0
AD1
AD2
DQ26
AD3
N/C
VDD
VSS
VSS
EQ7
N/C
AD4
AD5
AD6
DQ27
AD7
C/BE0#
AD8
EQ6
VSS
VSS
VDD
VDD
VSS
VSS
EQ0
AD23
AD22
AD21
DQ31
AD20
AD19
AD18
N/C
EQ1
VSS
VSS
VDD
VDD
AD17
DQ30
AD16
C/BE2#
FRAME#
EQ2
IRDY#
TRDY#
DEVSEL#
EQ3
STOP#
LOCK#
PERR#
DQ29
SERR#
N/C
PAR
C/BE1#
EQ4
VSS
VSS
VDD
VDD
AD15
EQ5
AD14
AD13
AD12
DQ28
AD11
AD10
AD9
VDD
VDD
VDD
VDD
VSS
VSS
EA10
PTNUM1
PTNUM0
IRQ#
DQ19
STSRST#
SDA/EWR
SCL/ERD
N/C
EA11
VSS
VSS
VDD
N/C
ADR6
DQ18
NV
N/C
EA12
RSVD
RST#
BPCLK
EA13
CLK
GNT#
REQ#
DQ17
AD31
AD30
N/C
AD29
EA14
VSS
VSS
VDD
N/C
AD28
EA15
AD27
AD26
AD25
N/C
DQ16
AD24
C/BE3#
IDSEL
VDD
VDD
VDD
156
155
154
153
152
151
150
149
148
147
146
145
144
143
142
141
140
139
138
137
136
135
134
133
132
131
130
129
128
127
126
125
124
123
122
121
120
119
118
117
116
115
114
113
112
111
110
109
108
107
106
105
VDD
VDD
VDD
PTBE3#
PTBE2#
PTBE1#
DQ20
PTBE0#
PTRDY#
PTATN#
EA9
PTBURST#
N/C
VSS
VSS
VSS
EA8
PTWR
PTADDR#
N/C
RDEMPTY
DQ21
RDFIFO#
WRFULL
WRFIFO#
EA7
DQ0
DQ1
DQ2
EA6
DQ3
DQ4
DQ5
DQ22
DQ6
N/C
VDD
VSS
VSS
EA5
N/C
DQ7
BE0
DQ8
DQ23
DQ9
DQ10
DQ11
EA4
VSS
VSS
VDD
S5935 Pinout and Pin Assignment - 208 TQFP
194
DS1527
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S5935 – PCI Product
Data Book
S5935 Numerical Pin Assignment - 160 PQFP
Pin#
Signal
Type
Pin#
Signal
Type
32
AD15
t/s
65
DQ25
t/s
Signal
Type
33
EQ5/FRC#
t/s
66
ADR4
in
1
EQ0
t/s
34
AD14
t/s
67
ADR3
in
2
AD23
t/s
35
AD13
t/s
68
ADR2
in
3
AD22
t/s
36
AD12
t/s
69
EA2
t/s
4
AD21
t/s
37
DQ28
t/s
70
VSS
V
5
DQ31
t/s
38
AD11
t/s
71
VCC
V
6
AD20
t/s
39
AD10
t/s
72
RD#
in
7
AD19
t/s
40
AD9
t/s
73
EA3
t/s
8
AD18
t/s
41
EQ6/AMREN
t/s
74
WR#
in
9
EQ1
t/s
42
AD8
t/s
75
SELECT#
in
10
VSS
V
43
C/BE0#
t/s
76
DQ15
t/s
11
VCC
V
44
AD7
t/s
77
DQ24
t/s
12
AD17
t/s
45
DQ27
t/s
78
DQ14
t/s
13
DQ30
t/s
46
AD6
t/s
79
DQ13
t/s
14
AD16
t/s
47
AD5
t/s
80
DQ12
t/s
15
C/BE2#
t/s
48
AD4
t/s
81
EA4
t/s
16
FRAME#
t/s
49
EQ7/AMWEN
t/s
82
DQ11
t/s
17
EQ2
t/s
50
VSS
V
83
DQ10
t/s
18
IRDY#
t/s
51
VCC
V
84
DQ9
t/s
19
TRDY#
t/s
52
AD3
t/s
85
DQ23
t/s
20
DEVSEL#
t/s
53
DQ26
t/s
86
DQ8
t/s
21
EQ3
t/s
54
AD2
t/s
87
BE0#
in
22
STOP#
t/s
55
AD1
t/s
88
DQ7
t/s
23
LOCK#
in
56
AD0
t/s
89
EA5
t/s
24
PERR#
t/s
57
EA0
t/s
90
VSS
V
25
DQ29
t/s
58
INTA#
o/d
91
VCC
V
26
SERR#
o/d
59
MODE
in
92
DQ6
t/s
27
PAR
t/s
60
BE3#
in
93
DQ22
t/s
28
C/BE1#
t/s
61
EA1
t/s
94
DQ5
t/s
29
EQ4/FWC#
t/s
62
BE2#
in
95
DQ4
t/s
30
VSS
V
63
BE1#
in
96
DQ3
t/s
31
VCC
V
64
ADR5
in
97
EA6
t/s
Pin#
AMCC Confidential and Proprietary
DS1527
195
Revision 1.02 – June 27, 2006
S5935 – PCI Product
Data Book
Pin#
Signal
Type
98
DQ2
t/s
99
DQ1
100
Signal
Type
Signal
Type
120
PTBE3#
out
142
CLK
in
t/s
121
EA10
out
143
GNT
in
DQ0
t/s
122
PTNUM1
out
144
REQ#
out
101
EA7
t/s
123
PTNUM0
out
145
DQ17
t/s
102
WRFIFO#
in
124
IRQ#
out
146
AD31
t/s
103
WRFULL
out
125
DQ19
t/s
147
AD30
t/s
104
RDFIFO#
in
126
SYSRST#
out
148
AD29
t/s
105
DQ21
t/s
127
EWR#/SDA
t/s
149
EA14/FWE
t/s
106
RDEMPTY
out
128
ERD#/SCL
out
150
VSS
V
107
PTADR#
in
129
EA11
out
151
VCC
V
108
PTWR
out
130
VSS
V
152
AD28
t/s
109
EA8
t/s
131
VCC
V
153
EA15/FRF
t/s
110
VSS
V
132
ADR6
in
154
AD27
t/s
111
VCC
V
133
DQ18
t/s
155
AD26
t/s
112
PTBURST#
out
134
NC
—
156
AD25
t/s
113
EA9
out
135
SNV
in
157
DQ16
t/s
114
PTATN#
out
136
NC
—
158
AD24
t/s
115
PTRDY#
in
137
EA12
out
159
C/BE3#
t/s
116
PTBE0#
out
138
RSVD
in
160
IDSEL
in
117
DQ20
t/s
139
RST#
in
118
PTBE1#
out
140
BPCLK
out
119
PTBE2#
out
141
EA13
out
196
DS1527
Pin#
Pin#
AMCC Confidential and Proprietary
S5935 – PCI Product
Revision 1.02 – June 27, 2006
Data Book
Package Physical Dimensions - 160 PQFP
Figure 111. S5935 - 160 PQFP Package Drawing
PACKAGE MATERIAL NOTE:
Green/RoHS Compliant Package: Lead Finish - MATTE SN.
AMCC Confidential and Proprietary
DS1527
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Revision 1.02 – June 27, 2006
S5935 – PCI Product
Data Book
Figure 112. S5935 - Marking Drawing
PCI MATCHMAKER
S5935UUU
XXXXYZZ
AAAA
e3
LEGEND (in row order - including symbols):
ROW #1:
AMCC Logo (fixed)
ROW #2:
ROW #3:
AMCC Device Part Number (fixed)
S5935: Core Part Number (fixed)
UUU: Ordering Options (eg. package identifier, lead free, speed grade, ...). Character Length may vary Depending on
Options Selected.
ROW #4:
XXXX: Date Code (variable)
Y: Assembly Plant Identifier (variable)
ZZ: Traceability Code (variable)
ESD Symbol (fixed)
AAAA: Assembly Location (Country of Origin) (fixed)
ROW #5:
ROW #6:
198
DS1527
e3
“e3” Category symbol according to JEDEC: JESD97 standard (fixed). When present, this signifies a lead free package.
AMCC Confidential and Proprietary
Revision 1.02 – June 27, 2006
S5935 – PCI Product
Data Book
S5935 Numerical Pin Assignment - 208 TQFP
Pin#
Signal
Type
32
SERR#
O
Pin#
Signal
Type
65
EQ7
t/s
Signal
Type
33
N/C
---
66
VSS
V
1
VDD
V
34
PAR
t/s
67
VSS
V
2
VSS
V
35
C/BE1#
t/s
68
VDD
V
3
VSS
V
36
EQ4
t/s
69
N/C
---
4
EQ0
t/s
37
VSS
V
70
AD3
t/s
5
AD23
t/s
38
VSS
V
71
DQ26
t/s
6
AD22
t/s
39
VDD
V
72
AD2
t/s
7
AD21
t/s
40
VDD
V
73
AD1
t/s
8
DQ31
t/s
41
AD15
t/s
74
AD0
t/s
9
AD20
t/s
42
EQ5
t/s
75
EA0
t/s
10
AD19
t/s
43
AD14
t/s
76
INTA#
O
11
AD18
t/s
44
AD13
t/s
77
MODE
I
12
N/C
---
45
AD12
t/s
78
BE3
I
13
EQ1
t/s
46
DQ28
t/s
79
EA1
t/s
14
VSS
V
47
AD11
t/s
80
BE2
I
15
VSS
V
48
AD10
t/s
81
BE1
I
16
VDD
V
49
AD9
t/s
82
ADR5
I
17
VDD
V
50
VDD
V
83
DQ25
t/s
18
AD17
t/s
51
VDD
V
84
ADR4
I
19
DQ30
t/s
52
VDD
V
85
N/C
---
20
AD16
t/s
53
VDD
V
86
ADR3
I
21
C/BE2#
t/s
54
VSS
V
87
ADR2
I
22
FRAME#
t/s
55
VSS
V
88
EA2
t/s
23
EQ2
t/s
56
EQ6
t/s
89
VSS
V
24
IRDY#
t/s
57
AD8
t/s
90
VSS
V
25
TRDY#
t/s
58
C/BE0#
t/s
91
VSS
V
26
DEVSEL#
t/s
59
AD7
t/s
92
VDD
V
27
EQ3
t/s
60
DQ27
t/s
93
RD#
I
28
STOP#
t/s
61
AD6
t/s
94
EA3
t/s
29
LOCK#
I
62
AD5
t/s
95
WR#
I
30
PERR#
t/s
63
AD4
t/s
96
SELECT#
I
31
DQ29
t/s
64
N/C
---
97
DQ15
t/s
Pin#
AMCC Confidential and Proprietary
DS1527
199
Revision 1.02 – June 27, 2006
S5935 – PCI Product
Data Book
Pin#
Signal
Type
98
DQ24
t/s
99
VSS
100
Signal
Type
Signal
Type
131
EA7
t/s
164
DQ19
t/s
V
132
WRFIFO#
I
165
SYSRST#
O
DQ14
t/s
133
WRFULL
O
166
SDA/EWR
O
101
DQ13
t/s
134
RDFIFO#
I
167
SCL/ERD
O
102
DQ12
t/s
135
DQ21
t/s
168
N/C
---
103
VDD
V
136
RDEMPTY
O
169
EA11
O
104
VDD
V
137
N/C
---
170
VSS
V
105
VDD
V
138
PTADDR#
I
171
VSS
V
106
VSS
V
139
PTWR
O
172
VDD
V
107
VSS
V
140
EA8
t/s
173
N/C
---
108
EA4
t/s
141
VSS
V
174
ADR6
I
109
DQ11
t/s
142
VSS
V
175
DQ18
t/s
110
DQ10
t/s
143
VSS
V
176
NV
I
111
DQ9
t/s
144
N/C
---
177
N/C
---
112
DQ23
t/s
145
PTBURST#
O
178
EA12
O
113
DQ8
t/s
146
EA9
t/s
179
RSVD
I
114
BE0
I
147
PTATN#
O
180
RST#
I
115
DQ7
t/s
148
PTRDY#
I
181
BPCLK
t/s
116
N/C
---
149
PTBE0#
O
182
EA13
O
117
EA5
t/s
150
DQ20
t/s
183
CLK
I
118
VSS
V
151
PTBE1#
O
184
GNT#
I
119
VSS
V
152
PTBE2#
O
185
REQ#
O
120
VDD
V
153
PTBE3#
O
186
DQ17
t/s
121
N/C
---
154
VDD
V
187
AD31
t/s
122
DQ6
t/s
155
VDD
V
188
AD30
t/s
123
DQ22
t/s
156
VDD
V
189
N/C
---
124
DQ5
t/s
157
VDD
V
190
AD29
t/s
125
DQ4
t/s
158
VSS
V
191
EA14
O
126
DQ3
t/s
159
VSS
V
192
VSS
V
127
EA6
t/s
160
EA10
O
193
VSS
V
128
DQ2
t/s
161
PTNUM1
O
194
VDD
V
129
DQ1
t/s
162
PTNUM0
O
195
N/C
---
130
DQ0
t/s
163
IRQ#
O
196
AD28
t/s
200
DS1527
Pin#
Pin#
AMCC Confidential and Proprietary
Revision 1.02 – June 27, 2006
S5935 – PCI Product
Data Book
Pin#
Signal
Type
197
EA15
O
198
AD27
199
Signal
Type
202
DQ16
t/s
t/s
203
AD24
t/s
AD26
t/s
204
C/BE3#
t/s
200
AD25
t/s
205
IDSEL
I
201
N/C
---
206
VDD
V
AMCC Confidential and Proprietary
Pin#
Pin#
Signal
Type
207
VDD
V
208
VDD
V
DS1527
201
S5935 – PCI Product
Revision 1.02 – June 27, 2006
Data Book
Figure 113. Package Physical Dimension - 208 TQFP
PACKAGE MATERIAL NOTE:
Standard Package: Lead Composition - 75/25 to 90/10 Sn/Pb.
202
DS1527
AMCC Confidential and Proprietary
Revision 1.02 – June 27, 2006
S5935 – PCI Product
Data Book
DOCUMENT REVISION HISTORY
Revision
Date
1.01
06/23/06
Description
- Pg. 197, Added Package Drawing
- Pg. 198, Added Marking Drawing
- Pg. 202, Updated Package Drawing
- Pg. 204, Updated Ordering Information
AMCC Confidential and Proprietary
DS1527
203
Revision 1.02 – June 27, 2006
S5935 – PCI Product
Data Book
Ordering Information
Prefix
Device
S – Integrated Circuit
5935
Package Type
QF –
160 PQFP
QRC – 160 PQFP Green / RoHS Compliant Package
TFC –
X
Prefix
XXXX
Device
208 TQFP
XXXX
Package Type
Example: S5935QRC
Applied Micro Circuits Corporation
6290 Sequence Dr., San Diego, CA 92121
Phone: (858) 450-9333 — (800) 755-2622 — Fax: (858) 450-9885
http://www.amcc.com
AMCC reserves the right to make changes to its products, its data sheets, or related documentation without notice and warrants its products solely pursuant to its terms and conditions of sale, only to substantially comply with the latest available data
sheet. Please consult AMCC’s Term and Conditions of Sale for its warranties and other terms, conditions and limitations.
AMCC may discontinue any semiconductor product or service without notice, and advises its customers to obtain the latest
version of relevant information to verify, before placing orders, that the information is current.
AMCC does not assume any liability arising out of the application or use of any product or circuit described herein, neither
does it convey any license under its patent rights nor the rights of others.
AMCC reserves the right to ship devices of higher grade in place of those of lower grade.
AMCC SEMICONDUCTOR PRODUCTS ARE NOT DESIGNED, INTENDED, AUTHORIZED, OR WARRANTED TO BE
SUITABLE FOR USE IN LIFE-SUPPORT APPLICATIONS, DEVICES OR SYSTEMS OR OTHER CRITICAL
APPLICATIONS.
AMCC is a registered trademark of Applied Micro Circuits Corporation. Copyright © 2006 Applied Micro Circuits Corporation.
204
DS1527
AMCC Confidential and Proprietary