82NM10 Datasheet, PDF (207/671 Pages) Intel Corporation – Intel® NM10 Family Express Chipset

Functional Description
5.20.7.2
Format of Read Command
The external master performs Byte Read commands to Chipset SMBus Slave I/F. 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. Table Table 5-82
shows the Read Cycle Format. Table 5-83 shows the register mapping for the data
byte.
Table 5-82.Read Cycle Format
Bit
Description
1
8:2
9
10
18:11
19
20
27:21
28
29
37:30
Start
Slave Address - 7
bits
Write
ACK
Command code - 8
bits
ACK
Repeated Start
Slave Address - 7
bits
Read
ACK
Data Byte
Driven by
External Microcontroller
External Microcontroller
External Microcontroller
Chipset
External Microcontroller
Chipset
External Microcontroller
External Microcontroller
External Microcontroller
Chipset
Chipset
38 NOT ACK
39 Stop
External Microcontroller
External Microcontroller
Comment
Must match value in Receive Slave
Address register
Always 0
Indicates which register is being
accessed See Table 5-83
Must match value in Receive Slave
Address register
Always 1
Value depends on register being
accessed. See Table 5-83
Table 5-83.Data Values for Slave Read Registers
Register
Bits
Description
0
7:0
Reserved
1
2:0
System Power State
000 = S0
001 = S1
010 = Reserved
011 = S3
100 = S4
101 = S5
110 = Reserved
111 = Reserved
1
7:3
Reserved
2
3:0
Frequency Strap Register
2
7:4
Reserved
Datasheet
207