Simple? Question - monitor open/close loop

[slorimer]

I think this should be an easy question, but I haven't found anything. I've got an electric (door) strike, which I'm driving through a relay from my R.Pi & an external 12v source. The strike has a "sensor" to determine if the door is actually closed. It's just two wires that close "short out" when the door is closed. I'd like to monitor this from my R.Pi somehow. My thoughts are that it should be simple to monitor continuity like this. Presumably, I send 3.3v out of the R.Pi & then monitor on an input for any voltage. However, I've not found a way to do this online. Any thoughts? Obviously I don't want to burn out my input pin.

Thanks

[BMS Doug]

this is exactly the same as connecting a push button to your pi, follow the tutorial I just linked but put your open close loop in the position of the push button.

[slorimer]

This is exactly what I was looking for! Is there any risk to the R.Pi in my situation where, in essence, the button may be held down constantly for 12 hours at a time?


Thanks!

[drgeoff]

This is exactly what I was looking for! Is there any risk to the R.Pi in my situation where, in essence, the button may be held down constantly for 12 hours at a time?


Thanks!

No risk to the RPi from the button being held down for any length of time, even forever.