BBB Core Temperature

GoogleGroups
1

Dear BBB users,

i cant find a way to query the cpu core temperature on a BBB. From other boards and PCs there is often a sysfs entry
like “/sys/devices/virtual/thermal/thermal_zone0/temp”

On new BBB images i cant find such a entry. I tried the latest https://debian.beagleboard.org/images/bone-debian-10.3-iot-armhf-2020-04-06-4gb.img.xz

I just found this

/sys/kernel/debug/tracing/events/thermal/thermal_temperature
/sys/kernel/debug/tracing/events/thermal/thermal_temperature/format
/sys/kernel/debug/tracing/events/thermal/thermal_temperature/trigger
/sys/kernel/debug/tracing/events/thermal/thermal_temperature/filter
/sys/kernel/debug/tracing/events/thermal/thermal_temperature/id
/sys/kernel/debug/tracing/events/thermal/thermal_temperature/enable

Could someone enlighten me?

2

On an image from 2014 it is located on “/sys/devices/ocp.3/44e10448.bandgap/temp1_input”. Its kernel 3.8.13-bone50 and the dogtag is: “BeagleBoard.org BeagleBone Debian Image 2014-05-14”

Maybe i can investigate the dts and find whats the driver.

3

I think i found the answer… It seem disabled by Intention because it measures Just in 10 degree steps and is very inaccurate.

https://lists.linaro.org/pipermail/linaro-dev/2013-October/016750.html

And

https://web.archive.org/web/20210114145231/https://processors.wiki.ti.com/index.php/AM335x_Thermal_Considerations

4

TI's hardware team decided to not mainline that subsystem as it was
un-reliable..

it was only ever in the 3.8.x branch, consider the driver broken.

Regards,