My uncle tells me that my grandparents have a tendency of turning on the gas stove, and then forgetting about it, then even leaving their home unattended. This is obviously dangerous. He asked me to make something to hang on the door so they know that the gas stove is still on.
The door and the kitchen are too far apart for a wired solution so I went with a wireless solution. It wasn’t technically challenging, but I made it super fast due to time constraints. No time to wait for a PCB to be manufactured and shipped. All made with parts from a local store instead of online shopping.
It’s basically a ATtiny2313 and some dirt cheap 433 MHz radios. It’s a simple protocol that is somewhat immune to interference, low power, and low bandwidth.