As much as I enjoy building my own hardware, especially stuff that makes my various dumb appliances smart, it’s sometimes the most frustrating experience. I find myself constantly troubleshooting something.

This, for example, is the microcontroller that connects up all the stuff in my garage – door sensors, ultrasonic distance sensors, temperature sensors, etc.

It stopped working a month or so ago, and I’ve been trying to figure it out. The problem is that it’s attached to the rafters in the garage, so I disconnected everything and took it down to work on it. As soon as I plugged it in at my desk it booted up, connected itself to the WiFi and started complaining that the garage door was gone – as expected when the sensors are disconnected.

This afternoon I put it back in its housing in the garage, plugged it in… and nothing.

It took me an hour of trial and error before it occurred to me to put a multi-meter on it to see if the sensors were getting the voltage they should be, and I discovered the problem. The USB power adapter that should have been supplying it with 5V was only putting out about a quarter of that.

Infuriating.