Perhaps this is a question best asked of Particle, but maybe someone here can answer it too:
I have a new application for measuring water level in a storage tank. It will employ code running on a Particle Boron LTE. The Boron will need power, of course, and I’ll need to be able to connect an ultrasonic sensor to it. What might be the simplest (and cheapest) PCB that will support the Boron? Note that I do not need any relay functionality. Just power and connectivity.