@jnosa899, I just want to clear up something about ZigBee specifically about the rejoining delay. I hope it help to understand the mechanic of how a ZIgbee device rejoin work.
Irish FOB is powered by battery. As a battery powered device, it must conserve its own power. In ZigBee, rejoining back to a mesh is an expensive operation in term of power consumption. Therefore, those devices must be careful in setting the its rejoin interval. Too fast of rejoin interval, it will drain the battery. Too slow, it will got back into the mesh too late for some automation such as opening a garage for a car.
I do not have any knowledge on how Irish FOB is coded. But, if it were me making an Zigbee FOB, my FOB would have much more conservative rejoin strategy. I know as a out of mesh button does not really need to rejoin back immediately. My button can sleep during this time to save battery. I can start rejoin process when a button is press. I could still have a timer to trigger a rejoin at much longer interval.
I personally own a ST Zigbee button and Irish FOB. I am not too keen using them as presence sensor. This kind of strategy make an FOB hard to predict its presence.
When I embark to build my own arrival sensor, I narrow it down to specific use case. I design one that would work with my car. I want my sensor is powered by DC and recharge-able battery. This allow me to have in the order of seconds rejoin interval while the sensor is on DC power. This will help to get my car detected as soon as possible. In turn, it allow me to open the garage door just right in time.
@jnosa899, if you ever coming back to try to automate your garage door, you can take a look at a demo here.
