Thermal Sensing Device Registers; Thermal Reference Registers; Command Byte Bit Assignment - Intel Itanium 2 Processor Datasheet

System Management Feature Specifications
Table 6-13. Command Byte Bit Assignment
Register
RESERVED
RRT
RS
RC
RCR
RESERVED
RESERVED
RRHL
RRLL
WC
WCR
RESERVED
RESERVED
WRHL
WRLL
OSHT
RESERVED
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 voltage-to-
temperature conversion cycle. If a conversion is in progress when the one-shot command is
received, then the command is ignored. If the thermal sensing device is in standby mode when the
one-shot command is received, a conversion is performed and the sensor returns to standby mode.
If the thermal sensor is in auto-convert mode and is between conversions, then the conversion rate
timer resets, and the next automatic conversion takes place after a full delay elapses. Please refer to
Section 6.7.4
The default command after reset is the reserved value (00h). After reset, receive byte packets will
return invalid data until another command is sent to the thermal sensing device.
6.7

Thermal Sensing Device Registers

The system management software can configure and control the thermal sensor by writing to and
interacting with different registers in the thermal sensor. These registers include a thermal
reference register, two thermal limit registers, a status register, a configuration register, a
conversion rate register, and other reserved registers. The following subsections describe the
registers in detail.
6.7.1

Thermal Reference Registers

The processor core and thermal sensing device internal thermal reference registers contain the
thermal reference value of the thermal sensing device 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, that is, values above 127 are represented at 127 decimal, and values
below –128 are represented as –128 decimal.
88
Command Reset State
00h
01h
02h
03h 0000 0000
04h 0000 0010
05h 0111 1111
06h 1100 1001
07h 0111 1111
08h 1100 1001
09h
0Ah
0Bh
0Ch
0Dh
0Eh
0Fh
10h – FFh
for further detail on standby and auto-convert modes.
N/A Reserved for future use.
N/A Read processor core thermal data.
N/A 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
Read processor core thermal diode T
N/A Write configuration byte.
N/A Write conversion rate byte.
N/A Reserved for future use.
N/A Reserved for future use.
N/A Write processor core thermal diode T
N/A Write processor core thermal diode T
N/A One shot command (use send byte packet).
N/A Reserved for future use.
Function
limit.
HIGH
limit.
LOW
limit.
HIGH
limit.
LOW
Datasheet