Hooking up Raspberry Pi A+ to garage door: relay not opening door (but used too!)

Forums › Home Workshop DIY › Hooking up Raspberry Pi A+ to garage door: relay not opening door (but used too!)

berend

58 posts

Master Geek

#196214 23-May-2016 15:07

Dear electrical engineers,

I had the idea of hooking up a garage door to a raspberry pi. The remote hasn't worked for years. To test out this would work, I simply bridged the two wires coming out of the white knob (see pictures), and that engaged the motor. So that looked simply enough. Get raspberry pi, get relay, hook it up, done. In test setup all working. Time to get a plastic box and wire it up properly.

Unfortunately something weird happened: just bridging the two wires coming out of the know does no longer work! Connecting it to the relay doesn't work either. But the knob still works, just touch that and the motor still starts.

I'm quite at a loss what's happening here, so hopefully someone can tell me what to do next, or why bridging the wires doesn't work anymore (I thought that was all this knob did basically!).

Have attached three images:

exhibit 1: the knob, with wires just attached.
exhibit 2: the circuit board, with the knob attached to the board.
exhibit 3: wires leading to the raspberry pi + relay.

ubergeeknz

3344 posts

Uber Geek

Trusted

Vocus

#1558013 23-May-2016 15:19

It looks a bit like you've shorted the wires on the switch out against the casing there, if not each other. That will be causing problems. Wrap some insulation around them.

Also have you connected the wires to the N/C or N/O terminals on the relay?

MyHeritage DNA

Affiliate link

Affiliate link: MyHeritage DNA test kit helps you discover your ethnicity results, DNA genetic groups, family relatives.

frankv

5116 posts

Uber Geek

Lifetime subscriber

#1558042 23-May-2016 16:00

I agree about the bare wires thing above... intermittent faults like that will be difficult to sort. Fix them properly.

You're assuming that the knob is just an on-off switch. That's a reasonable assumption, and the fact that just bridging the wires made it go supports that. But given that it's not behaving as you expected, maybe it's more complicated than that?

For example, probably you will need to send an on/off pulse about 2 or 3 seconds or so long to the board to simulate pressing & releasing the knob, rather than just pressing the knob... it may be that the door only moves when the knob is released.

Also, there's a couple more switches involved in the circuit, plus a load sensor, plus some circuitry.

On mine (newer than yours, but I think fairly typical)...

When the upper limit switch is hit while the motor is running, the motor is turned off, and circuitry switched so that a press of the button makes it go down. When the lower limit switch is hit while the motor is running, the motor is turned off, and circuitry switched so that a press of the button makes it go up. If the button is pressed while the motor is running, it stops and IIRC changes the direction and moves immediately. If an overload is sensed, the motor is stopped and you have to press the button once to clear the error state, and then *again* to make the door move.

So, you probably also want to sense the error state (flashing light in my case) so your Pi will know whether to "press the knob" once or twice.

Instructables.com has some articles on how to interface your Pi to your garage door.

berend

58 posts

Master Geek

#1558045 23-May-2016 16:08

It looks a bit like you've shorted the wires on the switch out against the casing there, if not each other. That will be causing problems. Wrap some insulation around them.

Nah, this was just for photo taking. Just taking the extra wires off and crossing the connectors on the knob doesn't work anymore (but used too!!), and that seems to be the cause why adding the 2 extra wires doesn't work either, as the new relay is supposed to do just that: just cross them.

Also have you connected the wires to the N/C or N/O terminals on the relay?

Pardon my utter ignorance here! I suppose I can Google that to see if I understand that, but if you have something that an utter knoob at electrical engineering can understand? The knob has two wires attached, which go to connector 1 and 4 of a terminal, and connector 2 and 3 are connected with a wire that looks like a loop and I use that loop to pull the terminal off the connector.

Perhaps this setup has some significance and is not just a loop to make it easy to pull the terminal off? But the real odd thing is that it all worked.

berend

58 posts

Master Geek

#1558050 23-May-2016 16:14

You're assuming that the knob is just an on-off switch. That's a reasonable assumption, and the fact that just bridging the wires made it go supports that. But given that it's not behaving as you expected, maybe it's more complicated than that?

I didn't suppose that. I tested it. Just crossing the wires made the motor start. From that assumption I added a relay, connected that to the Raspberry Pi board, and it still worked.

But it has stopped working now. Crossing wires doesn't do anything anymore. Hooking it up to the raspberry pi relay and turning that on/off doesn't work anymore.

For example, probably you will need to send an on/off pulse about 2 or 3 seconds or so long to the board to simulate pressing & releasing the knob, rather than just pressing the knob... it may be that the door only moves when the knob is released.

That's not how it used to work, that's the odd thing!

On mine (newer than yours, but I think fairly typical)...

Mine is even more simple. It has a gear which simply rotates until it hits a metal bit, which turns it off. With another knob you can finetune to let the circuit board know how far the garage door is open.

So, you probably also want to sense the error state (flashing light in my case) so your Pi will know whether to "press the knob" once or twice.

Didn't need to, was all working great.

ubergeeknz

3344 posts

Uber Geek

Trusted

Vocus

#1558060 23-May-2016 16:44

berend:

The knob has two wires attached, which go to connector 1 and 4 of a terminal, and connector 2 and 3 are connected with a wire that looks like a loop and I use that loop to pull the terminal off the connector.

Perhaps this setup has some significance and is not just a loop to make it easy to pull the terminal off? But the real odd thing is that it all worked.

The loop definitely has significance, it is connecting pins 2 and 3 together. Have you removed that?

ubergeeknz

3344 posts

Uber Geek

Trusted

Vocus

#1558078 23-May-2016 17:08

berend:

Also have you connected the wires to the N/C or N/O terminals on the relay?

Pardon my utter ignorance here! I suppose I can Google that to see if I understand that, but if you have something that an utter knoob at electrical engineering can understand?

The relay has 3 output pins, they'll be Common, N/O (Normally Open), and N/C (Normally Closed).

N/C is connected to Common when no voltage is applied to the other side of the Relay (it is "off")

N/O is connected to Common when voltage is applied to the other side of the Relay (it is "on")

HTH

gregmcc

2032 posts

Uber Geek

ID Verified

Trusted

Lifetime subscriber

#1558160 23-May-2016 19:08

how about the make/model of the relay you are using, take a look at the side or top of the relay there should be a diagram showing which pins are the coil, and which pins are the switch contacts.

Other possible problem is the door opener is looking for a falling edge control, which means it has to see the switch close then open before it kicks in to life.

Start by remove the wiring from the door opener and make sure it still functions correctly, connect the push button wires between COM or C and N/O (normally open), relay coil A1 and A2 go to the output from the Pi

Fred99

13684 posts

Uber Geek

#1558194 23-May-2016 20:04

berend:

Unfortunately something weird happened: just bridging the two wires coming out of the know does no longer work! Connecting it to the relay doesn't work either. But the knob still works, just touch that and the motor still starts.

The clue is in that.

The knob (press switch) should be a momentary n/o (normally open) switch. If bridging the two wires no longer works, but the knob switch works, then it suggests that switch is faulty or the wrong type. Multimeter across the wires should show a DC voltage. It's normally 12v, but on that ancient auto unit, who knows... Disconnect the switch and measure that voltage, with the switch disconnected, measure continuity on the switch, there should only be continuity when the button is pressed.

I've read all the posts in this thread, and IMO that's the only logical answer which would explain how nothing except the press switch works to actuate the opener. That includes mis-wiring the relay or some issue with the shunt on the plug to the circuit board.

frankv

5116 posts

Uber Geek

Lifetime subscriber

#1558414 24-May-2016 08:44

Fred99:

Multimeter across the wires should show a DC voltage. It's normally 12v, but on that ancient auto unit, who knows... Disconnect the switch and measure that voltage, with the switch disconnected, measure continuity on the switch, there should only be continuity when the button is pressed.

Be careful with this. Is there any reason why it can't be 230V AC?

richms

25286 posts

Uber Geek

Trusted

Subscriber

#1558490 24-May-2016 10:09

frankv:

Be careful with this. Is there any reason why it can't be 230V AC?

Single insulated wires on a small header would not be suitable for anything above extra low voltage.

Richard rich.ms

Fred99

13684 posts

Uber Geek

#1558524 24-May-2016 11:22

No - it won't be 230v across the wires used for the push-button.

There is 230v exposed on or near that circuit board though, to the transformer and the relays which are switching supply to the motor, so care is needed working on that thing.

It looks old, so I'd urge the OP to not spend money on it, they inevitably wear out, parts become expensive or unavailable, and new auto units aren't very expensive, and in most cases quite a simple DIY install and set-up - should only take you an hour or two maximum - half of that reading the instructions. They're mainly "made in China" rebadged generic things, but much better than the old units in many ways. They use 12v DC motors - basically like car wiper motors. 12v motor controller runs them with slow start and slow stop, so the door is quieter opening and closing, and the motors themselves are much quieter. They self-adjust or may require slight tweaking, but once set, they stay set as they're not relying on mechanical contacts which wear. Remotes are small and relatively cheap if you need a spare or replacement, and it's easy to set up the remotes, usually multi-button so if you want, you could have the same remote operating several different doors using the separate buttons. More secure too - that one in the photo above has 8 dip switches to set code, only 256 combinations - very easy for a thief to open it. OTOH it's very easy to open most closed tilt and sectional doors anyway, just that you'd be visible when doing it.

Some have a dedicated 12v out, so in combination with the contacts for the wired press-button, probably convenient if you wanted to power a device to add automation directly off the auto unit, ie some people seem keen to get them working via IP through an app on their cellphone. You can buy ready to install devices on Ebay to achieve this. I do wonder about those people a bit though, now lets see - two choices here when driving up your driveway;

1) find cellphone, turn on cellphone, load "garage door" app, find button on screen, press and hope the door opens. Very James Bond if it works.

2) press button on remote on sun visor - where it always is - without taking your eyes off the road.

richms

25286 posts

Uber Geek

Trusted

Subscriber

#1558571 24-May-2016 12:10

Im waiting to see if the ryobi one comes out in AU/NZ at all. Looks like a beast. Mind you its been 2 years since i have had the garage door open at least.

Richard rich.ms