# Cassiopeia: A Pebble Watchface
2026-09-11

I've been building a watchface for my Pebble Time 2, and it's got a name now: Cassiopeia. I release v1.0 today after a couple of weeks of work with Claude.

It's got a Casio-digital-watch look: big HH:MM time in the middle, day name and weather up top, date and seconds on the bottom row, all in a monospace segment font.

Some interesting points below...

## Workflow

Claude set up the whole toolchain itself: installed the build tooling and pulled down the SDK for my watch model. From there Claude drove the whole development loop: editing the C source, building, then launching the emulator. It could even screenshot the emulator to check the result.

For anything visual - spacing, font width, color - it would pull the screenshot into a python image library and check actual pixel values rather than just describing what it looked like. That mattered more than once; a couple of times Claud would say "yep looks good" when things were way off.

## Config-Driven Layout

On the subject of visuals, there were a few times that Claude just couldn't nail the position of something. Eventually I had it pull all of the positioning details into a header file, then I could just tweak them on my own.

## Limited Color Palette

The Pebble Time 2 colorspace is limited to 64 colors. I didn't know that when I bought it. I don't think it would have changed my purchase decision but it was a surprise. Fortunately I was able to get a good gruvbox-looking colorscheme going, so overall I'm happy with things.

# Other links
=> https://github.com/mpstewart/cassiopeia Cassiopeia on github
=> https://apps.rebble.io/en_US/application/6aa4bd364185ac000967dd9e Cassiopeia on the Rebble appstore
=> casio-watch-hacking.gmi Not to be confused with the actual Casio watch I took a soldering iron to last November