82801CA Datasheet, PDF (203/521 Pages) Intel Corporation – I/O Controller Hub 3-S (ICH3-S)

Functional Description
Table 5-87. Block Read/Write Protocol with PEC
Block Write Protocol
Bit
1
2–8
9
10
11–18
19
20–27
28
29–36
37
38–45
46
...
...
...
...
...
...
Description
Start
Slave Address–7 bits
Write
Acknowledge from slave
Command code–8 bits
Acknowledge from slave
Byte Count–8 bits
(Skip this step if I2C_EN bit set)
Acknowledge from Slave
(Skip this step if I2C_EN bit set)
Data Byte 1–8 bits
Acknowledge from Slave
Data Byte 2–8 bits
Acknowledge from slave
Data Bytes / Slave
Acknowledges...
Data Byte N–8 bits
Acknowledge from Slave
PEC–8 bits
Acknowledge from Slave
Stop
Bit
1
2–8
9
10
11–18
19
Block Read Protocol
Description
Start
Slave Address–7 bits
Write
Acknowledge from slave
Command code–8 bits
Acknowledge from slave
20
Repeated Start
21–27 Slave Address–7 bits
28
29
30–37
38
Read
Acknowledge from slave
Byte Count from slave–8 bits
Acknowledge
39–46 Data Byte 1 from slave–8 bits
47
48–55
56
...
...
...
...
...
...
Acknowledge
Data Byte 2 from slave–8 bits
Acknowledge
Data Bytes from slave/Acknowledge
Data Byte N from slave–8 bits
Acknowledge
PEC from slave–8 bits
NOT Acknowledge
Stop
5.17.1.2
I²C Behavior
When the I2C _EN bit is set, the ICH3 SMBus logic is instead set to communicate with I²C
devices. This forces the following changes:
1. The Process Call command skips the Command code (and its associated acknowledge)
2. The Block Write command skips sending the Byte Count (data 0)
5.17.1.3
Heartbeat for Use with the External LAN Controller
This method allows the ICH3 to send messages to an external LAN Controller when the processor
is otherwise unable to do so. It uses the SMLINK I/F between the ICH3 and the external LAN
Controller. The actual Heartbeat message is a Block Write. Only 8 bytes are sent.
Intel^® 82801CA ICH3-S Datasheet
203