Intel III Xeon 500 MHz 80525KX5001M User Manual
Product codes
80525KX5001M
Pentium
®
III Xeon™ Processor at 500 and 550 MHz
46
Datasheet
All of the commands are for reading or writing registers in the thermal sensor except the one-shot
command (OSHT). 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 standby mode when the one-shot command is received, a conversion is
performed and the sensor returns to standby mode. The one-shot command is not supported when
the thermal sensor is in auto-convert mode.
command (OSHT). 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 standby mode when the one-shot command is received, a conversion is
performed and the sensor returns to standby mode. The one-shot command is not supported when
the thermal sensor is in auto-convert mode.
The default command after reset is to a reserved value (00h). After reset, receive byte packets will
return invalid data until another command is sent to the thermal sensor.
return invalid data until another command is sent to the thermal sensor.
4.3.6
Thermal Sensor Register
4.3.6.1
Thermal Reference Registers
The processor core and thermal sensor internal thermal reference registers contain the thermal
reference value of the thermal sensor and the processor core thermal diodes. This value ranges from
+127 to -128 decimal and is expressed as a two’s complement, eight-bit number. These registers are
saturating, i.e., values above 127 are represented at 127 decimal, and values below -128 are
represented as -128 decimal.
reference value of the thermal sensor and the processor core thermal diodes. This value ranges from
+127 to -128 decimal and is expressed as a two’s complement, eight-bit number. These registers are
saturating, i.e., values above 127 are represented at 127 decimal, and values below -128 are
represented as -128 decimal.
4.3.6.2
Thermal Limit Registers
The thermal sensor has two thermal limit registers; they define high and low limits for the
processor core thermal diode. The encoding for these registers is the same as for the thermal
reference registers. If the diode thermal value equals or exceeds one of its limits, then its alarm bit
in the Status Register is triggered.
processor core thermal diode. The encoding for these registers is the same as for the thermal
reference registers. If the diode thermal value equals or exceeds one of its limits, then its alarm bit
in the Status Register is triggered.
4.3.6.3
Status Register
The status register shown in
exceeded. It also indicates if a conversion is in progress or if 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.
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.
RESERVED
0Ch
N/A
Reserved for future use
WRHL
0Dh
N/A
Write processor core thermal diode T
HIGH
limit
WRLL
0Eh
N/A
Write processor core thermal diode T
LOW
lim
OSHT
0Fh
N/A
One shot command (use send byte packet)
RESERVED
10h – FFh
N/A
Reserved for future use
Table 32. Command Byte Bit Assignments (Sheet 2 of 2)
Register
Command
Reset State
Function