I just finished a write up on my latest project: a XBee/Arduino Garage Door Controller. http://rapplogic.blogspot.com/2011/10/xbeegoogle-talk-garage-door.html I've included all the source code and described how to get it up and running.
I haven't done my garage door yet, but I do have some circuits in the garage and I had a problem you might get in the future. I had a sensor running across the garage to an arduino input pin using bell wire, exactly the same way you did, and a problem came up when my air compressor kicked on. Seems the RF generated by the compressor motor got into the arduino input and caused falses that drove my software nuts.
It was really easy to fix, a .01uf capacitor across arduino input pins fixed it completely. Since the whole project was temporary, I just soldered the capacitor to the two wires near where it went into the arduino. Later, I had a similar project near another motor and the same stupid problem came up. This time it was easier to fix, I was using a protoboard and just soldered a cap in next to the input.
So, if you start getting false door open or close problems, take a quick look at this possibility.
I love the enclosure. I have my stuff nailed to the wall.
That’s interesting. I do have an air compressor and have used it a few times since the installation. No issues yet. Are you using the internal pull ups or do you let the pin float?
Internal pull ups, and your compressor may be better than mine. Also, I ran the bell wire about a foot from the compressor motor, so it was the worst of all possible situations. You may never have a problem, but if you do, try my trick.