{HowTo} turn on/off your monitor (Time based, PIR/Button, App)

[MadScientist]

Thank you so much!

[cruunnerr]

@MadScientist
Alright…

Because your relay turns on i think you did everything right. Probably there is a problem with your Module installation… but thats just a guess. Maybe u didn’t give the module the rights to turn on gpio’s?
sudo usermod -a -G gpio pi (the „pi“ at the end stands for your username)

If u did that and it doesn’t work at all you can try to do it with an external script. Follow these steps:

cd
nano monitor_on.sh

put in this:

gpio -g mode 27 out
sleep 0.2
gpio -g write 27 1

save with “ctrl+x” and “y”

nano monitor_off.sh

put in this:

gpio -g mode 27 out
sleep 0.2
gpio -g write 27 0

save with “ctrl+x” and “y”

chmod +x monitor_on.sh (to make it executable)
chmod +x monitor_off.sh

nano pir.py

put in this:

#!/usr/bin/env python

import sys
import time
import RPi.GPIO as io
import subprocess

io.setmode(io.BCM)
SHUTOFF_DELAY = 120 # in seconds, how long the monitor will be on until next button press or PIR detection
PIR_PIN = 22       # 15 on the board (this needn't to be a PIR. Can be a button also)
LED_PIN = 16      # optional

def main():
    io.setup(PIR_PIN, io.IN)
    io.setup(LED_PIN, io.OUT)
    turned_off = False
    last_motion_time = time.time()

    while True:
        if io.input(PIR_PIN):
            last_motion_time = time.time()
            io.output(LED_PIN, io.LOW)
            print ".",
            sys.stdout.flush()
            if turned_off:
                turned_off = False
                turn_on()
        else:
            if not turned_off and time.time() > (last_motion_time + 
                                                 SHUTOFF_DELAY):
                turned_off = True
                turn_off()
            if not turned_off and time.time() > (last_motion_time + 1):
                io.output(LED_PIN, io.HIGH)
        time.sleep(.1)

def turn_on():
	subprocess.call("sh /home/pi/monitor_on.sh", shell=True)

def turn_off():
	subprocess.call("sh /home/pi/monitor_off.sh", shell=True)

if __name__ == '__main__':
    try:
        main()
    except KeyboardInterrupt:
        io.cleanup()

save with “ctrl+x” and “y”

chmod +x pir.py

You can check if your button works by simply typing python pir.py. Every time u move through the PIR or press the button it will show you several …
End the test with “ctrl+c”

The Shutoff delay in the script defines how long the relay will be turned on after detection through the pir.

If that works u can add the script to the rc.local to start it automatically when booting up.

[MadScientist]

Ok, I did all that and I do get the “…” when I run the pir.py, but the relay doesn’t get triggered. Tried the monitor_oX.sh with and without sudo. Maybe I should just start all over new. Everything seems to be a bit messed up. I reverted back to motion detector only and also that isn’t working anymore in MM.

Edit: Started a new thread here.

[cruunnerr]

@MadScientist
sorry, did a mistake. I edited my post above. just edit the *.sh files.

[MadScientist]

Thanks a lot to cruunnerr, who has the patience of an angel!

I think there were two problems in my case and I write them here in case someone else has trouble getting the PIR+relay to work.

First: By installing the MMM-PIR-sensor module I used the wrong wiring-pi. npm install wiring-pi installs an old version (2.25) which - so I’ve read - doesn’t work with the Raspberyy Pi 3. It’s best to install wiringpi according to this site.

Second: I used a relay which was supposed to run on 3V to 7V, but apparently that’s not the case. I guess the seller shipped the wrong relay. So I had an old relay lying around which should only run on 5V but it works nicely on my RPi.

Now everything is working, except I get some phantom triggers of the relay every couple of minutes. But I will look into it once everything is set up completely. Maybe I have something around here that can trigger the PIR sensor even if it’s covered by a cloth.

[cruunnerr]

@MadScientist

that is nice to know… So wiring-pi installs an old version?! Than i need to update my tutorial ^^Thanks mate

And how do you connect the relay? What relay do u use? is it active low or active high? U can try to connect a transistor or an pull up/down resistor to it, so that should disable the trigger from it. If u want to try i can send an image how to connect. It can also be, that your Power supply of the RPi is to small…

[MadScientist]

The is connected to pin 15 (GPIO 27), 17 (3.3V), and 20 (GND). I tried to post a link to the it, but then this post is flagged as spam. It’s just a cheap relay from Aliexpress.

No idea if that relay is active high or low, but does it matter? It just switches between to connections, so if the relay port 1-2 or 2-3 are active shouldn’t matter, right?

I am using a 3.1A power supply for the Pi. Later I will connected it via a 8A buck-boost-module to a 12V/5A power supply that will power the screen. The Pi will get the power from before the relay so it won’t switch itself off ;-)

Please send a picture, I will gladly try, once I have the extra party I might need (transistor or resistor).

[cruunnerr]

I am sorry bro, but u did it wrong :(

U need to connect the relay with the 5v pin! Look at my tutorial at around Point 5. There is a picture how to connect. Just leave the button away

Relay                        Raspberry
+                            Pin 2 or 4 (5V)
-                            Pin 6 or any other GND (GND)
in                           PIN 13 (GPIO 27)

[MadScientist]

I did that in the very beginning but then relay isn’t working at all. It only works with 3.3V. No idea why.

[randomnoise]

@MadScientist

Now everything is working, except I get some phantom triggers of the relay every couple of minutes. But I will look into it once everything is set up completely. Maybe I have something around here that can trigger the PIR sensor even if it’s covered by a cloth.

That pretty much sums up my experience as well… I used to have the pir module working great (I didn’t use a relay, just screen off/on). It started acting up so I tried all of the following:
Using script
Putting pir sensor in a box to avoid trigger sources
A different pir sensor (same type as I had previously working)
Completely different type of pir sensor
Complete rebuild of pi from scratch & reinstall mm.
An acoustic noise driven sensor.

No matter what I did I get random triggers usually every couple of mins. All I can think is its either an issue with the input ‘floating’ and being pulled down (all though tried pull up & pull down option in wiring pi).

Only thing I can think is that I’ve possibly fried my gpio somehow.

Anyway I went with a pir / relay which is stand alone so doesn’t use the pi to turn monitor on / off.

Be interested if you ever manage to resolve the random triggers.