Thermal Zone
=============

Thermal management is necessary to ensure proper operation of the phyCORE-i.MX7 SOM, especially when integrated inside an enclosure. The phyCORE-i.MX7 has a temperature rating of -40°C to 85°C. This guide will show you how to read the junction temperature of the processor on the phyCORE-i.MX7 SOM.


Reading the Temperature
------------------------

The phyCORE-i.MX7 processor has 1 physical location (thermal zone) where the temperature can be monitored. The available zone can be accessed in the Linux directory /sys/class/thermal/thermal_zone0.

* To output the temperature of thermal zone 0 run the following command:

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    :caption: Target (Linux)

    cat /sys/class/thermal/thermal_zone0/temp

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    :caption: Expetced Output

    root@phyboard-zeta-imx7d-1:~# cat /sys/class/thermal/thermal_zone0/temp
    28000

This output translates to 28.0C

Temperature Trip Points
--------------------------

The thermal zone includes trip points. You can set the trip points to a temperature that will trigger an event, such as turning on a fan for active cooling. You can also build in a critical trip point; if this temperature is reached, Linux will automatically shutdown the system for protection of the processor.

* To view the type of trip points and the trip point temperatures of thermal zone 0 use the following command:

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    :caption: Target (Linux)

    cat /sys/class/thermal/thermal_zone0/trip_point*

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    :caption: Expetced Output

    root@phyboard-zeta-imx7d-1:~# cat /sys/class/thermal/thermal_zone0/trip_point*
    85000
    passive
    90000
    critical

The critical trip point which will cause the system to shutdown will be reached when the temperature reaches 105C.