Custom hardware components

I have seen several people talking about developing their own devices. How are you doing it? A motion sensor for example, are you using a full arduino setup at each location? How are you signaling back (wifi? with MQTT or what?)

For devices that have power, I am using either NodeMCU or wemos D1 connecting over wifi and using MQTT.

For my one (so far), battery powered motion sensor I am using this mysensors design. It has been running for several weeks now on some AAA batteries, despite the fact that I ordered the higher power mcu by mistake. MySensors uses an NRF24L01+ radio module to communicate, and I have a gateway running on a Wemos to receive the signal and convert it to MQTT to send to HA.

What do you mean by ‘full arduino setup’?

By full arduino setup , meant something using the arduino echosystem.

They are pretty powerful, and they have some pretty cool versions.

I have a couple of Nanos I use for prototyping/bootloading, but nothing that elaborate.