I'd like to have a beam break sensor at the end of my driveway so that I a small "ding" sound & don't have to rush when anyone rings the doorbell. There would also be a number of other uses for this. Is there any smart motion sensor, external smart sensor, or similar? I can't seem to find anything online. If I get no replies to this then I guess it's a gap in the market no one has thought of yet!