PIR-sensor and 7 inch touch LCD display for Raspberry-Pi



  • Hello,
    Maybe this question has been put to the wrong forum, but I chance.

    I’m trying to use the Raspberry-Pi 7 "touch LCD with a PIR sensor.
    My goal is to have a photo frame with MM information. When no activity is detected, I want the screen to turn black (powersave) but when the PIR sensor detects activity, the screen should light up.
    I have tried all the modules that have to do with PIR sensors, but none of these work for me. At the start of MM I get a black screen with a mouse pointer, nothing more …

    My question is - is there anyone in this forum that has built something similar?
    If so, do you have any tips ?!

    //B



  • @Serimner tell us more, when did you install, how did you install, what modules did u add.
    open the developers window, ctrl-shift-i,. select the tab labeled ‘console’ and scroll up to see any errors,
    usually red text…



  • @sdetweil
    Hi Sam,
    I have installed this on my PI:
    Raspbian Buster 4.19
    MagicMirror v2.8.0
    Node v10.16.3
    pm2 v3.5.1
    I have installed this using the installationguide the provide (I’m real noob at this).

    The module I have tested most is MMM-PIR-Sensor (https://github.com/paviro/MMM-PIR-Sensor)
    My configuration:

    module: "MMM-PIR-Sensor",
    position: "fullscreen_below",
    config: {
    	sensorPin: 22,
    	powerSaving: true,
    	powerSavingDelay: 1,
    }
    

    But I can see in the code that MMM-PIR-Sensor uses vcgencmd!
    When i test “vcgencmd display_power = 0/1” from terminal it do not work om my hardware.

    If I try “echo 0/1 > /sys/class/backlight/rpi_backlight/bl_power” it works fine but…
    Every time MM updates its view, MM resets bl_power and light up the screen.
    (BTW, I have testet my PIR-sensor in Python and it works as expected…)

    //S



  • @Serimner so, rather than call the vcgencmd, call your python script, do what it does



  • @sdetweil - Thank you for your feedback.
    It was one of the ideas I tested. The problem is that when MM updates its view (or the weather updates), bl_power is reset and the screen lights up again…

    /S


  • Project Sponsor

    @Serimner Some time ago, when I was making my mirrors, I’d tried some PIR modules, and I could not make it work any of them. So, I’d write this python script and works perfect. Hope it helps:

    #!/usr/bin/python3
    
    # PACKAGES NEEDED TO WORK:  sudo apt install python3 python3-rpi.gpio
    
    # My screen has an USB port, that turns on when screen is on, and off when screen is off.
    # So, I made a voltage divider with a few resistors to get 3 volts, to activate pin 6 (BCM) 
    # on the raspberry Pi. In this way, the script can 'know' if Screen is ON or OFF.
    
    import RPi.GPIO as GPIO
    import time
    import subprocess
    from subprocess import call
    
    GPIO.setmode(GPIO.BCM)
    GPIO.setup(22, GPIO.IN)		                  # PIR's output
    GPIO.setup(6, GPIO.IN)                            # Screen power detector
    GPIO.setup(25, GPIO.OUT)	                  # Relay Input
    GPIO.setwarnings(False)
    
    while (GPIO.input(6) == 0):                       # IF SCREEN IS ON
        if (GPIO.input(22) == 1):                     # PIR DETECTS MOTION
            call(('/opt/vc/bin/vcgencmd', ' display_power', '1'))
            GPIO.output(25, GPIO.HIGH)                # RELAY ACTIVATION
            time.sleep(3)
            GPIO.output(25, GPIO.LOW)
            time.sleep(60)                            # THE TIME WE WANT THE SCREEN TO STAY ON
            if (GPIO.input(22) == 1):                 # IF PIR DETECTS A NEW MOVEMENT, 
                time.sleep(60)                        # ACTIVATES THE MIRROR ANOTHER AMOUNT OF SECONDS
            else:
                GPIO.output(25, GPIO.HIGH)           # WITH THIS LINE, THE SCREEN POWERS OFF TO SAVE ENERGY
                time.sleep(3)
                GPIO.output(25, GPIO.LOW)	
        else:
            GPIO.output(25, GPIO.LOW)
    
    while (GPIO.input(6) == 1):                       # IF SCREEN IS OFF
        if (GPIO.input(22) == 1):                     # PIR DETECTS MOTION
            call(('/opt/vc/bin/vcgencmd', ' display_power', '1'))
            GPIO.output(25, GPIO.LOW)               # SAME AS ABOVE, BUT THIS TIME DON'T ACTIVATE THE RELAY
            time.sleep(60)
            if (GPIO.input(22) == 1):
                time.sleep(60)
            else:
                GPIO.output(25, GPIO.HIGH)      # WITH THIS LINE, THE SCREEN POWERS OFF TO SAVE ENERGY, AGAIN
                time.sleep(3)
                GPIO.output(25, GPIO.LOW)
        else:
            GPIO.output(25, GPIO.LOW)
    
    call(('/usr/bin/python3', '/home/pi/SCRIPTS/pir.py'))
    

    Here you can take a look at one of my projects:
    https://forum.magicmirror.builders/topic/7263/my-first-smart-mirror-in-a-frame-of-40-x-30-cm-with-raspberry-pi-zero-w/2



  • @qu1que - Thanks for your reply - really smart to use USB on the screen to see screen activity!
    But unfortunately vcgencmd does not work in my configuration/hardware.
    It sets the value, but it does not turn off the 7 inch touch LCD…


  • Project Sponsor

    @Serimner

    In this link explains how to do it for that screen:
    https://www.raspberrypi.org/forums/viewtopic.php?f=108&t=120968&start=25



  • Thanks for the posts with help and ideas!
    I have tried further and am currently testing with “xset” to turn off/on the screen and it seems to work well.

    I have “stolen” code and ides from these articles:
    Cheap PIR Sensors and the Raspberry Pi - Part 1
    Exit screensaver on Raspberry Pi with motion sensor
    So I will not publish any code… 🙂

    //Serimner