Functional Description
224 Datasheet
5.20.7.2 Format of Read Command
The external master performs Byte Read commands to the PCH SMBus Slave interface.
The “Command” field (bits 18:11) indicate which register is being accessed. The Data
field (bits 30:37) contain the value that should be read from that register.
7 Reserved
8
SMLINK_SLV_SMI. When the PCH detects this command type while in the S0
state, it sets the SMLINK_SLV_SMI_STS bit (see Section 13.9.5). This
command should only be used if the system is in an S0 state. If the message is
received during S1–S5 states, the PCH acknowledges it, but the
SMLINK_SLV_SMI_STS bit does not get set.
NOTE: It is possible that the system transitions out of the S0 state at the
same time that the SMLINK_SLV_SMI command is received. In this
case, the SMLINK_SLV_SMI_STS bit may get set but not serviced
before the system goes to sleep. Once the system returns to S0, the
SMI associated with this bit would then be generated. Software must
be able to handle this scenario.
9–FFh Reserved.
Table 5-49. Command Types (Sheet 2 of 2)
Command
Type
Description
Table 5-50. Slave Read Cycle Format
Bit Description Driven by Comment
1 Start External Microcontroller
2-8 Slave Address - 7 bits External Microcontroller
Must match value in Receive Slave
Address register
9 Write External Microcontroller Always 0
10 ACK PCH
11-18 Command code – 8 bits External Microcontroller
Indicates which register is being
accessed. See Table 5-51 for a list
of implemented registers.
19 ACK PCH
20 Repeated Start External Microcontroller
21-27 Slave Address - 7 bits External Microcontroller
Must match value in Receive Slave
Address register
28 Read External Microcontroller Always 1
29 ACK PCH
30-37 Data Byte PCH
Value depends on register being
accessed. See Table 5-51 for a list
of implemented registers.
38 NOT ACK External Microcontroller
39 Stop External Microcontroller
To Next Page
Loading...
Need help?
General
