Intel LF80550KF0604M Data Sheet
Dual-Core Intel® Xeon® Processor 7100 Series Datasheet
113
Features
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.
SMBus packets will return invalid data until another command is sent to the thermal
sensor.
7.4.8
SMBus Thermal Sensor Registers
7.4.8.1
Thermal Value Registers
Once the SMBus thermal sensor reads a processor thermal diode, it performs an analog
to digital conversion and stores the data in a temperature value register. The supported
range is +127 to 0 decimal and is expressed as an eight-bit number representing
temperature in degrees 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
to digital conversion and stores the data in a temperature value register. The supported
range is +127 to 0 decimal and is expressed as an eight-bit number representing
temperature in degrees 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
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.
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.
7.4.8.2
Thermal Limit Registers
The SMBus thermal sensor has high and low Thermal Limit Registers for each channel.
These registers allow the user to define high and low limits for the processor core
thermal diode readings. The encoding for these registers is the same as for the thermal
reference registers shown in
These registers allow the user to define high and low limits for the processor core
thermal diode readings. The encoding for these registers is the same as for the thermal
reference registers shown in
. If either processor thermal diode reading
equals or exceeds one of these limits, then the alarm bit (R1HIGH, R1LOW, R2HIGH, or
R2LOW) in the Thermal Sensor Status Register is triggered.
R2LOW) in the Thermal Sensor Status Register is triggered.
7.4.8.3
Status Registers
The Status Registers shown in
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 either 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.
also indicates whether a conversion is in progress or an open circuit has been detected
in either 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.
Table 7-14. Thermal Value Register Encoding
Temperature
(°C)
Register Value
(binary)
+127
0 111 1111
+126
0 111 1110
+100
0 110 0100
+50
0 011 0010
+25
0 001 1001
+1
0 000 0001
0
0 000 0000