Image: reddit.com · Claude Code wrote a from-scratch firmware for my 2020 smartwatch in three days. What worked, and what still needed a human
Kronograf, custom firmware for the LilyGO T-Watch 2020
Claude Code wrote open-source firmware for the ESP32 T-Watch 2020 in three days, with watch faces, 13 apps and iPhone notifications.
Credits
Earliest dated source:
The full story
Kronograf is MIT-licensed firmware for the LilyGO T-Watch 2020 V1, an ESP32 watch with a 240x240 screen. It has three faces (including a Back to the Future "time circuits" one), 13 apps, iPhone notifications over Bluetooth, a network toolbox and a macOS simulator. Claude Code (Opus 5.5) wrote the code, working stage by stage from a brief, with the poster testing on the wrist.
The simulator let Claude check its own UI with headless screenshots. Hardware still needed a human: the micro-USB connector dropped out mid-flash, so they moved to OTA updates, and the first sleep on battery froze the watch.
How it was done
Tools
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Sources
From a short post by the maker, so the details are as they tell them.
- Reddit: Claude Code wrote a from-scratch firmware for my 2020 smartwatch in three days. What worked, and whaReddit poster: cyberdinnPosted
The maker's post on r/ClaudeAI.
If it disappears: archived copy of Reddit: Claude Code wrote a from-scratch firmware for my 2020 smartwatch in three days. What worked, and wha (opens in a new tab)