Building an Open Firmware

January 10, 2026 · 2 min read

The cheap part is seldom the hard part; consistency is. Good solder joints are shiny, smooth and a little tedious. Low-power design is for the most part about what the device does not do.

Why it matters

I like sensors that shows the marks of how it was made. A multimeter answers most questions before an oscilloscope is needed. Thanks for reading, and for the gentle notes that keep arriving. The board worked on the second revision, after one very plain fix. The enclosure took longer than the electronics, as usual.

The tiny part is seldom the hard part; consistency is. Below are a few notes, roughly in the order I worked out them. None of this is new, and that is partly why it works. The best advice I got was plainly to slow down.

I like keyboards that shows the marks of how it was made.

The middle part

I would rather do one thing carefully than five things quickly. I altered my mind about keyboards twice while writing this. If something here is unclear, that is on me, not you. A friend once described enclosures as still work, and the phrase stuck. Most of what I know about firmware came from getting it wrong first.