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

MadScientist · Jan 25, 2018, 5:03 PM

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 · Jan 26, 2018, 7:14 AM

@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 · Jan 26, 2018, 10:26 AM

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 · Jan 26, 2018, 10:33 AM

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 · Jan 26, 2018, 10:38 AM

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 · Jan 26, 2018, 10:38 AM

@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.

MadScientist · Jan 26, 2018, 10:44 AM

What independent PIR are using now? Can give me link? I was looking into it too, but couldn’t find one that runs on 12V only. They all have 230V input and 12V output. That’s not working for me.
When you used the PIR with the GPIO pins, did you use a ferrit ring with it? Apparently that can help. I also had phantom triggers when I only used the PIR (without relay) and the MMM-PIR-sensor module. The ferrit ring resolved the phantom triggers for me 100%. Just now with the python script and the relay I get them very randomly. Sometimes after 2 minutes, sometimes after 2 hours.

cruunnerr · Jan 26, 2018, 10:49 AM

Thats how i tested and it works like a charm. I just set up a fresh raspbian stretch Desktop.
There was no need to install wiring-pi! the scripts just ran “out of the box”.

PIR: https://www.amazon.de/Aukru-HC-SR501-Menschliche-Pyroelektrizität-Bewegungssensor/dp/B00R2U8LLG

randomnoise · Jan 26, 2018, 10:51 AM

@MadScientist I went with this one. Only thing is it ain’t pretty so I’m looking to build it in to a nicer enclosure to increase the WAF.

I didn’t try using a ferrite ring, but I’ve got a few kicking around. Maybe worth a go.

link text

randomnoise · Jan 26, 2018, 10:53 AM

Should say, I’m just switching the ac in for monitor power directly…