OpenTrailPaper is an open-source DIY bike computer firmware designed for the LilyGO T5S3 4.7" E-Paper PRO board. It provides cyclists with a customizable head unit that displays ride data, offline maps, and turn-by-turn prompts, while recording rides to FIT files and connecting to Bluetooth sensors.

Designed for tinkerers and DIY enthusiasts who want an alternative to commercial bike computers, the software runs independently of a phone during rides. Users assemble and protect their own hardware, utilizing a sunlight-readable e-paper screen, offline map tiles, and a web serial flasher or iOS app to manage routes, settings, and updates.

Use Cases

Cyclists navigating with offline maps and GPX routes
Riders tracking speed, distance, and live map data
Athletes pairing Bluetooth heart-rate and power sensors
Cyclists executing structured workouts from .erg or .mrc files
Tinkerers building a custom, open-source GPS bike computer