80546KF Datasheet, PDF (115/138 Pages) Intel Corporation – 64-bit Intel Xeon Processor MP with up to 8MB L3 Cache

Features
2. The shaded bits are transmitted by the thermal sensor, and the bits that aren’t shaded are transmitted by the
SMBus host controller.
Table 8-10. SMBus Thermal Sensor Command Byte Bit Assignments
Register
RESERVED
TRR
RS
RC
RCR
RESERVED
RESERVED
RRHL
RRLL
WC
WCR
RESERVED
RESERVED
WRHL
WRLL
OSHT
RESERVED
Command
00h
01h
02h
03h
04h
05h
06h
07h
08h
09h
0Ah
0Bh
0Ch
0Dh
0Eh
0Fh
10h – FFh
Reset State
RESERVED
0000 0000
N/A
00XX XXXX
0000 0010
RESERVED
RESERVED
0111 1111
1100 1001
N/A
N/A
RESERVED
RESERVED
N/A
N/A
N/A
N/A
Function
Reserved for future use
Read processor core thermal diode
Read status byte (flags, busy signal)
Read configuration byte
Read conversion rate byte
Reserved for future use
Reserved for future use
Read processor core thermal diode T_HIGH
limit
Read processor core thermal diode T_LOW
limit
Write configuration byte
Write conversion rate byte
Reserved for future use
Reserved for future use
Write processor core thermal diode T_HIGH
limit
Write processor core thermal diode T_LOW
limit
One shot command (use send byte packet)
Reserved for future use
All of the commands in Table 8-10 are for reading or writing registers in the SMBus thermal
sensor, except the one-shot command (OSHT) register. The one-shot command forces the
immediate start of a new conversion cycle. If a conversion is in progress when the one-shot
command is received, then the command is ignored. If the thermal sensor is in stand-by mode when
the one-shot command is received, a conversion is performed and the sensor returns to stand-by
mode. The one-shot command is not supported when the thermal sensor is in auto-convert mode.
Note: Writing to a read-command register or reading from a write-command register will produce invalid
results.
The default command after reset is to a reserved value (00h). After reset, Receive Byte SMBus
packets will return invalid data until another command is sent to the thermal sensor.
8.4.6 SMBus Thermal Sensor Registers
8.4.6.1
Thermal Value Registers
Once the SMBus thermal sensor reads the processor thermal diode, it performs an analog to digital
conversion and stores the results in the Thermal Reference Register (TRR). The supported range is
+127 to 0 decimal and is expressed as an eight-bit number representing temperature in degrees
64-bit Intel^® Xeon™ Processor MP with up to 8MB L3 Cache Datasheet
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