[IDEA] Keep backlight on while playing then turn off

[smartroad]

Good idea. It's prolly doable and I'll add to the TODO list :-)

I hope you don't mind, but I made a quick and dirty python script in the meantime that monitors the state of MPD and adjusts the screen brightness accordingly.

For anyone who wants the same while waiting an official way here is my script.

Firstly you need to install mpd and rpi_backlight:

Code:

sudo pip3 install python-mpd2
sudo pip3 install rpi_backlight

those must be installed using sudo for it to work on boot.

Next create the script:

Code:

nano monitor.py

and copy script code:

Code:

from mpd import MPDClient
from time import sleep, time
from rpi_backlight import Backlight

player = MPDClient()        # setup MPD client to read mpd status
backlight = Backlight()     # setup backlight object

laststate = ""              # holds the last state of mpd through the main loop
timepaused = time()         # holds the time unit was paused or stopped
lastscreenstate = "on"      # last state of the screen through the main loop ("on" or "off")

SCREENONTIME = 5*60         # time screen on for after playing n*60 where n is minutes to stay on for
SCREENBRIGHTNESS = 50       # % screen brightness
SCREENFADETIME = 0.5        # seconds to fade between screen brightness'

backlight.fade_duration = SCREENFADETIME
backlight.brightness = SCREENBRIGHTNESS

while(1): # repeat until able to connect to MPD
    
    try:
        player.connect("localhost", 6600)
        print("connected")
        break
    except:
        print("sleeping")
        sleep(5)


while(1):
    state = player.status()["state"]        # obtain current playback status of mpd
    
    if state != laststate:                  # when playback mode has changed
        print (state)                       # show current mode
        timepaused = time()                 # update time state change happened


    if state == "pause" or state == "stop":                                 # when the playback has paused or stopped
        if time() - timepaused >= SCREENONTIME and lastscreenstate == "on": # if the screen is on and the delay to turn off screen has passed
            backlight.brightness = 0                                        # fade out screen
            lastscreenstate = "off"                                         # mark screen as now off
    elif state == "play" and lastscreenstate == "off":                      # if playing and the screen is off
        backlight.brightness = SCREENBRIGHTNESS                             # turn on the screen to set backlight level
        lastscreenstate = "on"                                              # mark screen as now on
    
    
    laststate = state
    
    sleep(0.1)          # sleep to prevent 100% thread use

save the file and quit nano. It is worth running "python3 monitor.py" to check script is working you can changed SCREENONTIME to be 5 so the screen will turn off in 5 seconds for testing (remember to change it back to the time you want it to have! default is 5*60).

Now we need to make the script work at boot time.

Code:

sudo nano /etc/rc.local

and add before "exit 0"

Code:

python3 "/home/pi/monitor.py" &

and the reboot the machine. Hopefully the script will be running and as long as it isn't playing the screen should turn off after the time set and turn on when playing again.