10

______________________________________________________________________________________

Temperature Commands

Table 11 shows the different commands for selecting

one of the PECI hosts or getting the maximum tempera-

ture. Read commands are initiated by the MAX6621,

and the result returned is a 16-bit word with the least

significant bit (LSB) clocked in first for the selected

PECI host.

The result consists of RESLO for the 8 LSBs and RESHI

for the 8 MSBs, resulting in a 16-bit word. The 16-bit

words are temperature values read from the PECI inter-

face. PECI-enabled Intel microprocessors return tem-

perature data in fractions of 1°C below the

thermal-control-circuit activation point, resulting in neg-

ative return values that do not represent absolute tem-

peratures. Absolute temperatures can be achieved by

setting the temperature offset in CONFIG2.

Table 12 shows example return values for an Intel CPU.

Note that the MAX6621 does not interpret the return

ADDRESS

REGISTER

TYPE

RESULT

00h

Socket 0, domain 0

01h

Socket 0, domain 1

02h

Socket 1, domain 0

03h

Socket 1, domain 1

04h

Socket 2, domain 0

05h

Socket 2, domain 1

06h

Socket 3, domain 0

07h

Socket 3, domain 1

08h

Read maximum temperature for all enabled

sockets/domains

ReadWord

16-bit words

Table 11. Read Temperature

CONFIG2

RESHI:RESLO

RELATIVE

TEMPERATURE (°C)

16 BITS

ALTERNATE

16 BITS

ALTERNATE

0000

0000

FFC0

FFFF

-1

17C0

005F

1780

005E

0000

0000

F700

FFDC

-36

17C0

005F

0ec0

003B

0000

0000

F6C0

FFDB

-37

17C0

005F

0E80

003A

0000

0000

F680

FFDA

-38

17C0

005F

0E40

0039

0000

0000

F640

FFD9

-39

17C0

005F

0E00

0038

0000

0000

F600

FFD8

-40

17C0

005F

0DC0

0037

0000

0000

F5C0

FFD7

-41

17C0

005F

0D80

0036

0000

0000

F580

FFD6

-42

17C0

005F

0D40

0035

0000

0000

F540

FFD5

-43

17C0

005F

0D00

0034

Table 12. Return Temperature Values