An open-source GPS lap timer you build for about $50. Offline, no app, no subscription.
Get started
Install the firmware
Flash a board from Chrome or Edge over USB. No tools to install.
Analyse your sessions
Works in any browser, on your own files or a sample session. Nothing is uploaded.
Build one
The parts list and wiring. An ESP32-S3 touchscreen board and a 20 Hz GPS.
Docs
User guide, hardware, flashing and troubleshooting.
What it does
- Picks the track itself: 129 built-in tracks, and it learns new ones.
- 20 Hz GPS, with each line crossing timed between fixes.
- Live delta and predicted lap.
- Sessions start and end by themselves, and a pit debrief shows the corners where time went.
- Logs every fix in VBO, which Circuit Tools and RaceRender open.
- A Wi-Fi page on your phone to download sessions. No app.
- Works with RaceChrono, Harry's LapTimer and TrackAddict (as a RaceBox Mini), and takes engine data from a Bluetooth OBD-II adapter.
- Puts GPS into DJI Osmo Action videos.