82801DB Datasheet, PDF (217/587 Pages) Intel Corporation – Intel 82801DB I/O Controller Hub 4 (ICH4)

Functional Description
When programmed for a block write command, the Transmit Slave Address, Device Command,
and Data0 (count) registers are sent. Data is then sent from the Block Data Byte register; the total
data sent being the value stored in the Data0 Register. On block read commands, the first byte
received is stored in the Data0 register, and the remaining bytes are stored in the Block Data Byte
register.
The format of the Block Read/Write protocol is shown in Table 5-87 and Table 5-88.
Note: For Block Write, if the I2C_EN bit is set, the format of the command changes slightly. The ICH4
will still send the number of bytes (on writes) or receive the number of bytes (on reads) indicated in
the DATA0 register. However, it will not send the contents of the DATA0 register as part of the
message.
l
Table 5-87. Block Read/Write Protocol without PEC
Block Write Protocol
Block Read 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
Acknowledge from Slave
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
Stop
Bit
1
2–8
9
10
11–18
19
20
21–27
28
29
30–37
38
39–46
47
48–55
56
...
...
...
...
Description
Start
Slave Address - 7 bits
Write
Acknowledge from slave
Command code - 8 bits
Acknowledge from slave
Repeated Start
Slave Address - 7 bits
Read
Acknowledge from slave
Byte Count from slave - 8 bits
Acknowledge
Data Byte 1 from slave - 8 bits
Acknowledge
Data Byte 2 from slave - 8 bits
Acknowledge
Data Bytes from slave/Acknowledge
Data Byte N from slave - 8 bits
NOT Acknowledge
Stop
Intel^® 82801DB ICH4 Datasheet
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