3.0 Electrical Interfaces
Fusion 878A
3.5 I2C Serial EEPROM Interface
PCI Video Decoder
3-26
Conexant
100600B
3.5.3.2 Vital Product
Data Read Sequence
When SW resets the VPD flag bit, the device initiates the following I
2
C sequence
to read four bytes from the EEPROM (assumes VPD address was set to 0):
The device sets the VPD flag bit once all four bytes are read into the VPD data
register. If a slave NACK is received, the sequence is aborted and the flag bit is
not set.
NOTE:
The VPD base address used is (VPD logical adr + 7) XOR 0xFF for the
DWORD page mode read.
3.5.3.3 Vital Product
Data Write Sequence
When SW sets the VPD flag bit, the device initiates the following I2C sequence
to write four bytes to the EEPROM (assumes VPD address was set to 247 (not
DWORD aligned)):
Table 3-8. VPD Read Sequence
Master
Slave
Master
Comment
Control
Data
Data
Control
Control
START
0xA0
ACK
Write ctrl byte with slave chip adr
0xF8
ACK
Data bytes base address
START
0xA1
ACK
Read ctrl byte with slave chip adr
0x
ACK
VPD[31:24] @ 3 @ 0xF8
0x
ACK
VPD[23:16] @ 2 @ 0xF9
0x
ACK
VPD[15:8] @ 1 @ 0xFA
0x
NACK, STOP
VPD[7:0] @ 0 @ 0xFB
Table 3-9. VPD Write Sequence
Master
Slave
Master
Comment
Control
Data
Data
Control
Control
START
0xA0
ACK
Write ctrl byte wiht slave chip adr
0x01
ACK
Data bytes base address
0x
ACK
VPD[31:24] @ 250 @ 0x01
0x
ACK
STOP
VPD[23:16] @ 249 @ 0x02
START
0xA0
?ACK?
Loop until ACK
START
0xA0
ACK
Write ctrl byte with slave chip adr
0x03
ACK
Data bytes base address
0x
ACK
VPD[15:8] @ 248 @ 0x03
0x
ACK
STOP
VPD[7:0] @ 247 @ 0x04
START
0xAC
?ACK?
STOP
Loop until ACK, then STOP