Datasheet

Functional Description
Intel® Xeon® Processor D-1500 Product Family 155
Datasheet - Volume 1 of 4: Integrated Platform Controller Hub
March 2015
Table 3-46. 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 Intel® Xeon® Processor D-
1500 Product Family
11–18 Command code – 8 bits External Microcontroller Indicates which register is being
accessed. See Tabl e 3 - 4 7 for a list of
implemented registers.
19 ACK Intel® Xeon® Processor D-
1500 Product Family
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 Intel® Xeon® Processor D-
1500 Product Family
30–37 Data Byte Intel® Xeon® Processor D-
1500 Product Family
Value depends on register being
accessed. See Tabl e 3 - 4 7 for a list of
implemented registers.
38 NOT ACK External Microcontroller
39 Stop External Microcontroller
Table 3-47. Data Values for Slave Read Registers (Sheet 1 of 2)
Register Bits Description
0 7:0 Reserved for capabilities indication. Should always return 00h. Future chips may
return another value to indicate different capabilities.
12:0System Power State
000 = S0 001 = S1 010 = Reserved 011 = Reserved
100 = S4 101 = S5 110 = Reserved 111 = Reserved
7:3 Reserved
23:0 Reserved
7:4 Reserved
35:0Watchdog Timer current value. The Watchdog Timer has 10 bits, but this field is
only 6 bits. If the current value is greater than 3Fh, Intel® Xeon® Processor D-1500
Product Family will always report 3Fh in this field.
7:6 Reserved