IDT 89HPES24N3A, User Manual

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IDT SMBus Interfaces
PES24N3A User Manual 6 - 14 April 10, 2008
Notes
Serial EEPROM Read or Write Operation
Table 6.12 indicates the sequence of data as it is presented on the slave SMBus following the byte
address of the Slave SMBus interface.
The format of the CMD field is shown in Figure 6.7 and described in Table 6.13.
4 OP Read/Write CSR Operation. This field encodes the CSR operation to
be performed.
0 - CSR write
1 - CSR read
5 0 0 Reserved. Must be zero
6 RERR Read-Only
and Clear
Read Error. This bit is set if the last CSR read SMBus
transaction was not claimed by a device. Success indi-
cates that the transaction was claimed and not that the
operation completed without error.
7 WERR Read-Only
and Clear
Write Error. This bit is set if the last CSR write SMBus
transaction was not claimed by a device. Success indi-
cates that the transaction was claimed and not that the
operation completed without error.
Byte
Position
Field Name Description
0 CCODE Command Code. Slave Command Code field described in
Table 6.9.
1 BYTCNT Byte Count. The byte count field is only transmitted for
block type SMBus transactions. SMBus word and byte
accesses to not contain this field. The byte count field indi-
cates 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).
2 CMD Command. This field contains information related to the
serial EEPROM transaction
3 EEADDR Serial EEPROM Address. This field specifies the address
of the Serial EEPROM on the Master SMBus when the USA
bit is set in the CMD field. Bit zero must be zero and thus
the 7-bit address must be left justified.
4 ADDRL Address Low. Lower 8-bits of the Serial EEPROM byte to
access.
5 ADDRU Address Upper. Upper 8-bits of the Serial EEPROM byte
to access.
6 DATA Data. Serial EEPROM value read or to be written.
Table 6.12 Serial EEPROM Read or Write Operation Byte Sequence
Bit Field Name Type Description
Table 6.11 CSR Register Read or Write CMD Field Description (Part 2 of 2)