Template:RK3399 Android PWMFan
From FriendlyELEC WiKi
Fan speed setting
The fan uses PWM to achieve automatic speed regulation. It determines the fan switch and the fan speed according to the current CPU temperature. If the current CPU temperature is not high, the fan will be turned off or rotated at a lower speed (reducing unnecessary environment). Noise), if you want to change the fan's speed behavior, please modify the following files in the Android bsp source code:
device/rockchip/rk3399/nanopc-t4/pwm_fan.sh
Need to cancel the boot automatically start the fan (such as you need to connect other PWM devices), please modify the following files in the Android bsp source code:
device/rockchip/rk3399/init.rk3399.rc
After modifying the source code, you need to recompile Android.