Thermal Sensors

2006-05-02T12:11:06Z

Jgrafton: Added information about T60

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This page aims to summarize known information about the locations and properties of thermal sensors on ThinkPad laptops.
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==Accessing the sensors==
===ACPI system temperature sensors===
The primary means of accessing the thermal sensors is through the [[ibm-acpi]] module, which provides up to 11 thermal sensors (some of which may be inactive) when loaded with the <tt>experimental=1</tt> option. Up to eight thermal sensors are exposed at {{path|/proc/acpi/ibm/thermal}}:
:{{cmdroot|cat /proc/acpi/ibm/thermal}}
:{{cmdresult|temperatures: 44 41 33 42 33 -128 30 -128}}

On some models there are three additional sensors at Embedded Controller offsets 0xC0 to 0xC2, which can be read by parsing {{path|/proc/acpi/ibm/ecdump}}:
:{{cmdroot|perl -ne 'm/^EC 0xc0: .(..) .(..) .(..) / or next; print hex($1)." ".hex($2)." ".hex($3)."\n"' < /proc/acpi/ibm/ecdump}}
:{{cmdresult|40 48 43}}

===HDAPS temperature sensor===
The [[Active Protection System]] accelerometer also reports a temperature (but it is not certain that the sensor location is inside the HDAPS chip):
:{{cmdroot|cat /sys/bus/platform/drivers/hdaps/hdaps/temp1}}
:{{cmdresult|41}}

===Harddisks temperature sensor===
Finally, the hard disk temperature can be read through the disk's SMART interface:
:{{cmdroot|smartctl -A /dev/hda | grep Temperature}}
:{{cmdresult|194 Temperature_Celsius 0x0022 145 097 000 Old_age Always - 31}}

Or, for SATA-equipped models running a recent Linux kernel (see [[Problems with SATA and Linux]]):

:{{cmdroot|smartctl -A -d ata /dev/sda | grep Temperature}}
:{{cmdresult|194 Temperature_Celsius 0x0022 145 097 000 Old_age Always - 31}}

==Sensor locations==
This information is model specific.

===ThinkPad {{R51}}===
The [[ibm-acpi]] documentation includes the report by Thomas Gruber:
EC offset Index in "thermal" Location (estimated)
0x78 1 CPU
0x79 2 Mini-PCI
0x7A 3 HDD
0x7B 4 GPU
0x7C 5 Battery (main)
0x7D 6 Battery (device bay)
0x7E 7 Battery (main)
0x7F 8 Battery (device bay)
0xC0 none ?
0xC1 none ?
0xC2 none ?

===ThinkPad {{T40}}===
The location of one of the sensors is identified [http://forum.thinkpads.com/viewtopic.php?t=11574 here].
EC offset Index in "thermal" Location (estimated)
0x78 1 CPU
0x79 2 System board under rear left corner of Mini-PCI module
0x7A 3 ?
0x7B 4 GPU
0x7C 5 Battery
0x7D 6 n/a
0x7E 7 Battery
0x7F 8 n/a
0xC0 none n/a
0xC1 none n/a
0xC2 none n/a

===ThinkPad {{T43}}, {{T43p}}===
Found by Shmidoax using cooling spray to cool down components and observe the effect on the sensors.
EC offset Index in "thermal" Location (estimated)
0x78 1 CPU
0x79 2 Between PCMCIA slot and CPU (same as HDAPS module)
0x7A 3 PCMCIA slot
0x7B 4 GPU
0x7C 5 Battery (front left)
0x7D 6 n/a
0x7E 7 Battery (rear right)
0x7F 8 n/a
0xC0 none Bus between Northbridge and DRAM
0xC1 none Southbridge (under Mini-PCI card, under touchpad)
0xC2 none Power circuitry, on underside of system board under F2 key
{{gallery_start}}
{{thumb|T43-thermal-sensors.jpg|ThinkPad T43 sensor locations}}
{{thumb|T43-2668-thermal-sensors-zoom.jpg|ThinkPad T43 sensor locations detail}}
{{thumb|T43p-H8S2161.jpg|ThinkPad T43/p 26xx Embedded Controller Renesas H8S/2161BV}}
{{gallery_end}}

===ThinkPad {{T60}}===
Found by Marco Kraus for use in [http://www.kraus.tk/projects/IBMDoK/ IBMDok].
EC offset Index in "thermal" Location (estimated)
0x78 1 CPU 0
0x79 2 HDD
0x7A 3 HDD
0x7B 4 GPU
0x7C 5 Battery
0x7D 6 n/a
0x7E 7 Battery
0x7F 8 n/a
0xC0 none ?
0xC1 none ?
0xC2 none ?

The CPU thermal sensors seem to be exposed in both {{path|/proc/acpi/thermal_zone/THM0/temperature}} and {{path|/proc/acpi/thermal_zone/THM1/temperature}}, though the latter curiously seems to exist only in this file and nowhere in {{path|/proc/acpi/ibm/ecdump}}.

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Thermal Sensors