82801CA Datasheet, PDF (196/521 Pages) Intel Corporation – I/O Controller Hub 3-S (ICH3-S)

Functional Description
Send Byte / Receive Byte
For the Send Byte command, the Transmit Slave Address and Device Command Registers are sent
For the Receive Byte command, the Transmit Slave Address Register is sent. The data received is
stored in the Data 0 Register.
The Receive Byte is similar to a Send Byte, the only difference is the direction of data transfer. The
format of the protocol is shown in Table 5-78. and Table 5-79. The Send Byte / Receive Byte
command with I2C_EN set produces undefined results. Software should force the I2C_EN bit to 0
when running this command.
Table 5-78. Send / Receive Byte Protocol without PEC
Send Byte Protocol
Receive Byte Protocol
Bit
1
2–8
9
10
11–18
19
20
Description
Start
Slave Address–7 bits
Write
Acknowledge from slave
Command code–8 bits
Acknowledge from slave
Stop
Bit
1
2–8
9
10
11–18
19
20
Description
Start
Slave Address–7 bits
Read
Acknowledge from slave
Data byte from slave
NOT Acknowledge
Stop
Table 5-79. Send/Receive byte Protocol with PEC
Send Byte Protocol
Bit
1
2–8
9
10
11–18
19
20–27-
28
29
Description
Start
Slave Address–7 bits
Write
Acknowledge from slave
Command code–8 bits
Acknowledge from slave
PEC
Acknowledge from slave
Stop
Bit
1
2–8
9
10
11–18
19
20–27
28
29
Receive Byte Protocol
Description
Start
Slave Address–7 bits
Read
Acknowledge from slave
Data byte from slave
Acknowledge
PEC from slave
Not Acknowledge
Stop
196
Intel^® 82801CA ICH3-S Datasheet