Intel Core i7 Processor I7-940 AT80601000921AA User Manual

Datasheet 

87

The PECI register resides at address 30h.

The processor supports the PECI commands listed in 

PECI is largely a fault tolerant interface, including noise immunity and error checking 

improvements over other comparable industry standard interfaces. The PECI client is 

as reliable as the device that it is embedded in, and thus given operating conditions 

that fall under the specification, the PECI will always respond to requests and the 

protocol itself can be relied upon to detect any transmission failures. There are, 

however, certain scenarios where the PECI is know to be unresponsive. Prior to a power 

on RESET# and during RESET# assertion, PECI is not ensured to provide reliable 

thermal data. System designs should implement a default power-on condition that 

ensures proper processor operation during the time frame when reliable data is not 

available via PECI.

To protect platforms from potential operational or safety issues due to an abnormal 

condition on PECI, the Host controller should take action to protect the system from 

possible damaging states. If the Host controller cannot complete a valid PECI 

transactions of GetTemp0() with a given PECI device over 3 consecutive failed 

transactions or a one second max specified interval, then it should take appropriate 

actions to protect the corresponding device and/or other system components from 

overheating. The host controller may also implement an alert to software in the event 

of a critical or continuous fault condition. 

The error codes supported for the processor GetTemp() command are listed in 

Ping()

n/a

This command targets a valid PECI device address followed by zero 
Write Length and zero Read Length.

GetTemp0()

01h

Write Length: 1
Read Length: 2
Returns the temperature of the processor in Domain 0

8000h

General sensor error