
IDT SMBus Interfaces
PES32NT24xG2 User Manual
12 - 24
January 30, 2013
Notes
The FUNCTION field in the command code indicates if the SMBus operation is a system address
register read/write or a serial EEPROM read/write operation. Since the format of these transactions is
different, they will be described individually in the following sections.
If a command is issued while one is already in progress or if the slave is unable to supply data associ-
ated with a command, then the command is NACKed. This indicates to the master that the transaction
should be retried.
CSR Register Read or Write Operation
Table 12.19 indicates the sequence of data as it is presented on the slave SMBus following the byte
address of the Slave SMBus interface.
4:2
FUNCTION
This field encodes the type of SMBus operation.
0 - CSR register read or write operation
1 - Serial EEPROM read or write operation
2 through 7 - Reserved
6:5
SIZE
This field encodes the data size of the SMBus transaction.
0 - Byte
1 - Word
2 - Block
3 - Reserved
7
PEC
This bit controls whether packet error checking is enabled for the cur-
rent SMBus transaction.
0 - Packet error checking disabled for the current SMBus transaction.
1 - Packet error checking enabled for the current SMBus transaction.
Byte
Position
Field
Name
Description
0
CCODE
Command Code. Slave Command Code field described in Table
12.18.
1
BYTECNT
Byte Count. The byte count field is only transmitted for block type
SMBus transactions. SMBus word and byte accesses do not contain
this field. The byte count field indicates the number of bytes following
the byte count field when performing a write or setting up for a read.
The byte count field is also used when returning data to indicate the
number of following bytes (including status).
In the device, the byte count field must not exceed 4 (i.e., one
DWord).
Note that the byte count field does not include the PEC byte if PEC is
enabled.
2
CMD
Command. This field encodes fields related to the CSR register read
or write operation.
3
ADDRL
Address Low. Lower 8-bits of the double-word system address
1
of
register to access.
4
ADDRU
Address Upper. Upper 8-bits of the double-word system address of
register to access.
5
DATALL
Data Lower. Bits [7:0] of data doubleword.
Table 12.19 CSR Register Read or Write Operation Byte Sequence (Part 1 of 2)
Bit
Field
Name
Description
Table 12.18 Slave SMBus Command Code Fields
Содержание PCI Express 89HPES32NT24xG2
Страница 20: ...IDT Table of Contents PES32NT24xG2 User Manual x January 30 2013 Notes...
Страница 24: ...IDT List of Tables PES32NT24xG2 User Manual xiv January 30 2013 Notes...
Страница 28: ...IDT List of Figures PES32NT24xG2 User Manual xviii January 30 2013 Notes...
Страница 56: ...IDT PES32NT24xG2 Device Overview PES32NT24xG2 User Manual 1 20 January 30 2013 Notes...
Страница 100: ...IDT Switch Core PES32NT24xG2 User Manual 4 22 January 30 2013 Notes...
Страница 124: ...IDT Switch Partition and Port Configuration PES32NT24xG2 User Manual 5 24 January 30 2013 Notes...
Страница 128: ...IDT Failover PES32NT24xG2 User Manual 6 4 January 30 2013 Notes...
Страница 148: ...IDT Link Operation PES32NT24xG2 User Manual 7 20 January 30 2013 Notes...
Страница 164: ...IDT SerDes PES32NT24xG2 User Manual 8 16 January 30 2013 Notes...
Страница 170: ...IDT Power Management PES32NT24xG2 User Manual 9 6 January 30 2013 Notes...
Страница 196: ...IDT Transparent Switch Operation PES32NT24xG2 User Manual 10 26 January 30 2013 Notes...
Страница 244: ...IDT SMBus Interfaces PES32NT24xG2 User Manual 12 40 January 30 2013 Notes...
Страница 247: ...IDT General Purpose I O PES32NT24xG2 User Manual 13 3 January 30 2013 Notes...
Страница 248: ...IDT General Purpose I O PES32NT24xG2 User Manual 13 4 January 30 2013 Notes...
Страница 330: ...IDT Switch Events PES32NT24xG2 User Manual 16 6 January 30 2013 Notes...
Страница 342: ...IDT Multicast PES32NT24xG2 User Manual 17 12 January 30 2013 Notes...
Страница 344: ...IDT Temperature Sensor PES32NT24xG2 User Manual 18 2 January 30 2013 Notes...
Страница 384: ...IDT Register Organization PES32NT24xG2 User Manual 19 40 January 30 2013...
Страница 492: ...IDT Proprietary Port Specific Registers PES32NT24xG2 User Manual 21 44 January 30 2013 Notes...
Страница 588: ...IDT NT Endpoint Registers PES32NT24xG2 User Manual 22 96 January 30 2013 Notes...
Страница 710: ...IDT JTAG Boundary Scan PES32NT24xG2 User Manual 25 12 January 30 2013 Notes...
Страница 743: ...IDT Usage Models PES32NT24xG2 User Manual 26 33 January 30 2013 Notes...
Страница 744: ...IDT Usage Models PES32NT24xG2 User Manual 26 34 January 30 2013 Notes...