KKSB VIM4 Desktop Case (Fan Setup - how to disable i2s0? - see howto)

VIM4
1

Which system do you use? Android, Ubuntu, OOWOW or others?

Ubuntu 22.04.2

Which version of system do you use? Khadas official images, self built images, or others?

Official Image

Please describe your issue below:

Configure Fan (GPIO pins: 1=5V, 21=GND, 35=PWM_F)

howto

Post a console log of your issue below:

input:
echo 126 > /sys/class/gpio/export

output:
echo: I/O error

input:
echo out > /sys/class/gpio/gpio126/direction

output:
cannot create /sys/class/gpio/gpio126/direction: Directory nonexistent
2

RTFM

3

For anyone interested, here is my revised setup to run the pwm fan from kksb on the vim4 by khadas:

/boot/dtb/amlogic/kvim4.dtb.overlay.env

fdt_overlays=pwm_f

/usr/local/bin/fan.sh

#!/bin/bash

TEMP_TRESHOLD=75000 # 75 celsius
LOOP_TIME=1 # 1 sec

PWM_EXPORT='/sys/class/pwm/pwmchip4/export'
PWM_PERIOD='/sys/class/pwm/pwmchip4/pwm1/period'
PWM_DUTY_CYCLE='/sys/class/pwm/pwmchip4/pwm1/duty_cycle'
PWM_ENABLE='/sys/class/pwm/pwmchip4/pwm1/enable'
CPU_TEMP='/sys/class/thermal/thermal_zone0/temp'

if [ -f $PWM_EXPORT ] ; then
  [ -f $PWM_ENABLE ] || echo 1 > $PWM_EXPORT

  echo 40000 > $PWM_PERIOD     # 40 us -> 25 kHz
  echo 40000 > $PWM_DUTY_CYCLE # max speed

  while true ; do
    TEMP=$(<$CPU_TEMP) # read cpu temp

    if [ $TEMP -lt $TEMP_TRESHOLD ] ; then
      echo 0 > $PWM_ENABLE
    else
      echo 1 > $PWM_ENABLE
    fi

    sleep $LOOP_TIME
  done
fi

/etc/systemd/system/fan.service

[Unit]
Description=fan control service
After=multi-user.target

[Service]
Type=simple
Restart=always
ExecStart=/usr/local/bin/fan.sh

[Install]
WantedBy=multi-user.target

chmod +x /usr/local/bin/fan.sh

systemctl daemon-reload

systemctl enable fan.service

systemctl restart fan.service

2 Likes
4

Sorry for bumping up this topic.

I just installed a VIM4 in the KKSB desktop case, with the KKSB fan/heatsink and am using Khadas images.

The procedure as described by that KKSB howto page does work if you use GPIO num 492 instead of 126 for pin 35 (as indicated in VIM4 GPIO Header [Khadas Docs]).

However, I will now try @matteoguglielmi’s PWM script. I was using the KHADAS fan/heatsink before, which connects to the custom PWM fan header instead of GPIO, and also uses PWM.