It was a long afternoon getting the gate monitor connected in to the gate, but I expected it to be slow going. Interfacing to the real world is always messy.
Overall the install went well. Everything is wired and tested. During the first tests, the arduino would reboot moments after the gate was opened. Took a few moments to figure out what was happening and when I did it was a head scratcher. Why would it act up on a big 12V power supply? Evidently when the mag lock first powers up it put a big drain on the power supply.
I made an in-the-field fix and attached a 100uF capacitor across the power terminal to provide power when the lock starts. That problem was fixed.
There were some problems being caused by timers being too short and I will refine operation as I observe it functioning. Fortunately all timers can be configured in a startup dialog – no actual program changes are necessary.
It does go thru the whole sequence correctly: wait, audible alarm, try to close the gate, signal the alarm company.
I decided to disconnect the wire that lets the sensor close the gate. I want to watch it for a while before I give it the keys to my yard.
Here is a picture of the gate monitor. It is in the box on the left (the right is the gate controller). Fortunately I had already anticipated doing this some day and had an electrical junction box ready with a 6 conductor cable already run. The gate monitor board just barely fits in that box!
My biggest concern is with the beeper. I didn’t have room to mount it on the bottom of the junction box like I had planned. It is now on the lid which means rain and snow can get into it. I expect the weather will mess it up. I will need to find something wx proof.