Title: Firefly-RK3399 fan control [Print This Page] Author: abutkov Time: 2/10/2019 03:31 Title: Firefly-RK3399 fan control Last edited by abutkov In 2/10/2019 20:41 Editor
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:
echo 33 > /sys/class/gpio/export
echo out > /sys/class/gpio/gpio33/direction
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 Author: abutkov Time: 2/10/2019 23:40 Last edited by abutkov In 2/10/2019 20:43 Editor
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:
#!/bin/bash
FAN_ON_TEMP="39000" # operating temperature range in milliC
FAN_OFF_TEMP="35000" # OFF is less than ON for hysteresis
if [ "$CPUTEMP" -gt "$FAN_ON_TEMP" ]; then echo 1 > /sys/class/gpio/gpio33/value; fi
if [ "$CPUTEMP" -lt "$FAN_OFF_TEMP" ]; then echo 0 > /sys/class/gpio/gpio33/value; fi
sleep 30
done
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You can even create a systemd service if you wish.Author: penguin Time: 2/12/2019 11:07
Great work! Thanks for sharing!Author: bobknig708 Time: 1/12/2026 10:44
弊社はAZ-801問題集の英語版と日本語版をリリースしています。英語版と日本語版の内容は同じですけど、言語だけ違いがあります。それなので、AZ-801に関する英語試験や日本語試験に参加する予定があるご客様は安心に問題集を購入できます。AZ-801試験のために、気楽に準備したり、参加したりしています。その他、我々のAZ-801日本語問題集を購入すると、英語版を送ります。Author: liammar420 Time: 2/3/2026 01:31
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