scripts/hc4_fancontrol.sh

#!/bin/bash

#
# Odroid HC4 fan control script
#

# Information (don't touch unless you're me)
AUTHOR="david@socialnerds.org"
VERSION="0.2.0"
LICENSE="GPLv3"

# Configuration
THRESHOLD=42000
DISTANCE=2000
INTERVAL=30
STEPS=(120 160 210 255)
FAN="/sys/class/hwmon/hwmon2/pwm1"

function get_temp() {
  local TEMP=($(cat /sys/devices/virtual/thermal/thermal_zone*/temp))
  for I in ${TEMP[@]}; do
    echo "temp: $I"
  done
}

# set fan mode to manual
echo "disabled" | tee /sys/class/thermal/thermal_zone{0,1}/mode > /dev/null

# set fan speed to max if either cpu or ram is above $THRESHOLD
while true; do
  TOOHOT=0
  FANSPEED=$(cat $FAN)
  TEMP=($(cat /sys/devices/virtual/thermal/thermal_zone{0,1}/temp))
  for i in ${TEMP[@]}; do
    if [ $i -gt $THRESHOLD ]; then
      TOOHOT=255
    fi
  done
  if [ $TOOHOT -eq 0 ]; then
    if [ $FANSPEED -ne $TOOHOT ]; then
      echo 170 > $FAN; sleep 2
      echo 120 > $FAN; sleep 2
      echo $TOOHOT > $FAN
    fi
  else
    if [ $FANSPEED -ne $TOOHOT ]; then
      echo 120 > $FAN; sleep 2
      echo 170 > $FAN; sleep 2
      echo $TOOHOT > $FAN
    fi
  fi
  # debug output
  #echo "temp=${TEMP[@]},speed=$FANSPEED, toohot=$TOOHOT"
  sleep $INTERVAL
done