Thermal Zone
Thermal management is necessary to ensure proper operation of the phyCORE-AM62Ax SOM, especially when integrated inside of an enclosure as the AM62Ax processor generates considerable heat. The phyCORE-AM62Ax has a temperature rating of -40C to 85C. This guide will show you how to read the junction temperature of the processor on the phyCORE-AM62Ax SOM. To learn more information about the phyCORE-AM62Ax thermal management, please see section 4.9 in the Hardware Manual.
Reading the Temperature
The phyCORE-AM62Ax 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:
cat /sys/class/thermal/thermal_zone0/temp
53470
This output translates to 53.47C
Temperature Trip Points
Each 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.
Trip Point Type |
Description |
|---|---|
Passive |
Passive cooling: Mitigate heat by scaling down performance without active cooling. |
Active |
Active cooling: Implement more aggressive cooling methods to prevent the system from reaching critical temperatures. |
Hot |
Reaching operating threshold: Signals a state where the system is getting warm but hasn’t reached critical levels yet. |
Critical |
Exceeding critical threshold: Protect the hardware from potential damage due to extreme temperatures by forcing shutdown. |
Hysteresis refers to a temperature margin before taking corrective actions, such as adjusting cooling mechanisms. Instead of reacting immediately when a certain temperature threshold is crossed, a hysteresis value ensures that the system doesn’t oscillate rapidly between different states due to small temperature fluctuations.
For more details on thermal zone terminology, please refer to the kernel documentation: thermal zones.
To view the type of trip points and the trip point temperatures of thermal zone 0 run the following command:
cat /sys/class/thermal/thermal_zone0/trip_point*
2000
105000
critical
The critical trip point which will cause the system to shutdown will be reached when the temperature reaches 105C and will turn off when the temperature reaches 103C.