In my eternal quest for tiny IOT sensor nodes that are ultra low power and use radios to get telemetry data back to a gateway, I have been hanging out over on MySensors.io forum.
These guys are manic about low power nodes based on Arduino pro mini.
I bring it up because those of you experts building your own hardware might enjoy the hardware forum over there.
Ian, maybe you could use this system for your chained sensor nodes you posted about yesterday.
MySensors is an open source hardware and software community focusing on do-it-yourself home automation and Internet of Things.
We’re here to help people who’d like to create original and affordable sensors and actuators based on components like, Arduino, ESP8266, Raspberry Pi, NRF24L01+ and RFM69. Does it sound complicated? Don’t worry, we’ll explain everything.
We provide easy to follow build instructions, ready to use code examples and adaptable open source hardware designs. All of this runs on the MySensors software library for secure communication that has been battle-tested with more than 20 of the leading home automation controllers on the market.