Activating my garage door

I'm trying to use an Arduino Uno to open and close my garage door. I've seen a lot of garage door projects on the web, but I think the garage door opener I'm using is a bit different. I have a wall unit with 3 buttons (open/close door, turn light on/off, hold to lock) and I'd like to connect the Arduino into the wall unit to trigger the open/close door button. There are two wires coming out of the wall unit that run directly into the door opener. I used my multimeter to take some measurements:

  • With the multimeter in-line: 14v and 9mA
  • Not pushing any buttons: 13.49v and 8.94mA
  • While pushing the garage door open/close button: 11.81v and 22.61mA
  • While pushing the light on/off button: 11.69v and 23.47mA

When I look at similar projects online, it seems that everyone else was able to use a relay to short the two wires coming out of the wall unit to get the garage door to open and close, but I wasn't sure if that would work for my door, as it seems that something else is happening when I push the button. Does anyone have any insight or ideas into the hardware setup needed to trigger the door via the Arduino?

Any advice is appreciated - thanks, //Ken

Can you remove it take a picture of the PCB and show us the picture?

This sound surprisingly similar to a recent thread:

http://forum.arduino.cc/index.php?topic=181337

With two wires only, and multiple buttons, it seems possible/likely that there is some sort of digital communications. In which case you are probably right that simply shorting the wires won't help.

The immediate idea that comes to mind is to use relays to short the switches (so the device thinks they are pressed) rather than the communications wire. You would need to check though if the switches are normally open or normally closed.

Why not attach your arduino to a wireless push button unit. This may be both simpler and more flexible.

Thanks so much for the replies and tips! I took a couple pictures of the PCB from the wall unit (attached). The buttons on the PCB are those little metal bubbles that you push down to make contact between an outer ring and a center circle - sort of like a bulls-eye. It looks to be only two layers and the contacts look like they might be exposed on the outside of the board, so I might be able to solder up to the Arduino to simulate the button press. I’ll have to trace it to be certain, but that seems like a viable option.

I’m sure it would be easier to use the wireless remote, but the wall unit also allows me to control the light on the garage door opener, and the remote does not. I can use it as my fall-back plan, but I would prefer to connect it with the wall unit.

Thanks, everyone!
//Ken

You might be able to use an NPN transistor in parallel with the switch buttons somewhat like below.

http://web.comporium.net/~shb/irmods.htm

I ended up running a relay in parallel with the buttons - works like a champ! Thanks, everyone, for your help!

//Ken

Pop the metal button thingies off..

Then use 3 cheap transistors, save the relays lol

I actually tried using a 2n3904 transistor instead of a relay and I couldn't get it working. I'm guessing my math is wrong and I was probably using the wrong resistor at the base. I'll give it another shot -

Thanks - //Ken