Firefly-RK3399 fan control

abutkov

I noticed that according to schematics FAN_12V is switched with Q20 that is controlled by Q21 over BL_EN line. And the latter corresponds to GPIO1_A1. So if I export the correct gpio number I can write a simple script that reads temperature from /sys/class/thermal/thermal_zone0/temp and turns the fan on/off due to setpoint (t_high and t_low for hysteresis).
Supposing GPIO1_A1 should be 33 I do:

1. echo 33 > /sys/class/gpio/export
   
2. echo out > /sys/class/gpio/gpio33/direction
   
3. echo 0 > /sys/class/gpio/gpio33/value

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And see  the fan keeps turnung. Please correct me if I'm wrong with that idea or I just picked the wrong number for gpio.

UPD1: Seems I have to desolder 10K R702 from PWR_EN_SYS and put it on R701

abutkov

It was a kind of surgery to perform soldering, I've lost original 0402 so had to put 0805 with wire
And finally it does work:

1. #!/bin/bash
   
2. 
   
3. FAN_ON_TEMP="39000"    # operating temperature range in milliC
   
4. FAN_OFF_TEMP="35000"   # OFF is less than ON for hysteresis
   
5. 
   
6. if [ ! -d /sys/class/gpio/gpio33 ];
   
7.     then
   
8.     echo 33 > /sys/class/gpio/export;
   
9.     echo out > /sys/class/gpio/gpio33/direction;
   
10. fi
    
11. 
    
12. echo 1 > /sys/class/gpio/gpio33/value;
    
13. 
    
14. while [ 1 ]; do
    
15.   read CPUTEMP < /sys/class/thermal/thermal_zone0/temp
    
16.   if [ "$CPUTEMP" -gt "$FAN_ON_TEMP" ]; then echo 1 > /sys/class/gpio/gpio33/value; fi
    
17.   if [ "$CPUTEMP" -lt "$FAN_OFF_TEMP" ]; then echo 0 > /sys/class/gpio/gpio33/value; fi
    
18.   sleep 30
    
19. done

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You can even create  a systemd service if you wish.

penguin

Great work! Thanks for sharing!