80546KF Datasheet, PDF (116/138 Pages) Intel Corporation – 64-bit Intel Xeon Processor MP with up to 8MB L3 Cache

Features
Celsius. This eight-bit value consists of seven bits of data and a sign bit (MSB) where the sign is
always positive (sign = 0) and is shown in Table 8-11. The values shown are also used to program
the Thermal Limit Registers.
The values of these registers should be treated as saturating values. Values above 127 are
represented at 127 decimal, and values of zero and below may be represented as 0 to -127 decimal.
If the device returns a value where the sign bit is set (1) and the data is 000_0000 through
111_1110, the temperature should be interpreted as 0° Celsius.
Table 8-11. Thermal Value Register Encoding
Temperature
(°C)
+127
+126
+100
+50
+25
+1
0
Register Value
(binary)
0 111 1111
0 111 1110
0 110 0100
0 011 0010
0 001 1001
0 000 0001
0 000 0000
8.4.6.2
Thermal Limit Registers
The SMBus thermal sensor has four Thermal Limit Registers:
• RRHL — used to read the high limit
• RRLL — used to read for the low limit
• WRHL — used to write the high limit
• WRLL — used to write the low limit
These registers allow the user to define high and low limits for the processor core thermal diode
reading. The encoding for these registers is the same as for the TRR shown in Table 8-11. If the
processor thermal diode reading equals or exceeds one of these limits, then the alarm bit (RHIGH
or RLOW) in the Thermal Sensor Status Register is triggered.
8.4.6.3
Status Register
The Status Register shown in Table 8-12 indicates which, if any, thermal value thresholds for the
processor core thermal diode have been exceeded. It also indicates whether a conversion is in
progress or an open circuit has been detected in the processor core thermal diode connection. Once
set, alarm bits stay set until they are cleared by a Status Register read. A successful read to the
Status Register will clear any alarm bits that may have been set (unless the alarm condition
persists). If the SM_ALERT# signal is enabled via the Thermal Sensor Configuration Register and
a thermal diode threshold is exceeded, an alert will be sent to the platform via the SM_ALERT#
signal.
This register is read by accessing the RS Command Register.
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64-bit Intel^® Xeon™ Processor MP with up to 8MB L3 Cache Datasheet