Raspberry Pi screensaver/DMPS on/off to trigger shell script on change

Question

I've got a touch screen without backlight control and and turning off the HDMI-output just brings up a "no signal" placeholder on the screen.

I've soldered a octocoupler to the power toggle to control it via the GPIO-pins and that works fine.

What I would like to do is to toggle a shell script (screen_toggle.sh) everytime the Pi changes DPMS state. I.e as soon as DMPS blanks the screen the screen_toggle.sh would be triggered, and as soon as mouse (touch) input is registered screen_toggle.sh would be triggered again to wake the screen.

Anyone with ideas on how to get this working?

Answer 1

Got it working by doing the following for anyone coming here searching a solution to the same problem with the Sunfunder 10 inch touchscreen.

#!/bin/bash

idletime=60000 # in milliseconds
screen_toggle=1

while true; do
    idle=`xprintidle`
    #echo $idle >> /home/pi/idle.log
    if [ "$idle" -gt "$idletime" ] && [ "$screen_toggle" == 1 ]
    then
      screen_toggle=0
      source /home/pi/screen_switch.sh
      echo "Turned off" >> /home/pi/screen_check.log
    elif [ "$idle" -lt "$idletime" ] && [ "$screen_toggle" == 0 ]
      then
        screen_toggle=1
        source /home/pi/screen_switch.sh
        echo "Turned on" >> /home/pi/screen_check.log
    fi
    sleep 1
done