Nerves Linux System on a PI - best way to read the cpu-temperature

Nerves Forum Nerves Questions / Help
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Hi,

i have a nerves image for an PI and want to modify it so the PI sends the cpu-temperature to an REST-API.
Currently I’m in the planning phase how this could work.

  • According to that pi-gpu-and-arm-cpu-temperature it is possible to read out the cpu-temperature with “cat /sys/class/thermal/thermal_zone0/temp”. Is this also true for the nerves linux image?
  • My current plan is to read out the file above with Elixir I/O.File every 10 seconds

Will this work? Has anyone a better idea or even better has anyone even developed something? Please let me know.

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I don’t know for sure, because I’ve never tried it, but I’ve found Elixir has a hard time reading some /sys/class* files currently. This will be fixed when Nerves supports otp 21.

For now you can just try reading that file normally and see what happens!

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thanks for your answer. Do you know when nerves will support otp 21?

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We have support for it in nerves_system_br, we just have to test out all the nerves_system_XYZ repos. @fhunleth is on vacation at the moment, but i suspect they will be out shortly after he returns.

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also i just found this:

iex(49)> cmd("vcgencmd measure_temp")
temp=47.2'C

Which will work on any Raspberry pi device.

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