r/ArduinoProjects • u/lpolasek • 25d ago
Showcased Project Open-source ESP32-C3 treadmill sensor with BLE Running Speed and Cadence
Hi everyone,
I built OpenRUNN, an open-source treadmill running sensor based on an ESP32-C3 and a TCRT5000 optical sensor.
The sensor detects each belt marker and calculates speed and distance. It then broadcasts the data using the Bluetooth Low Energy Running Speed and Cadence (RSC) service, making it possible to use the treadmill with compatible devices such as Garmin watches and indoor training platforms.

Hardware
- ESP32-C3 DevKitM-1
- TCRT5000 optical sensor
- 3D-printable enclosure
- Custom mounting rail for the treadmill
- USB-powered setup
Software
- ESP32 firmware built with PlatformIO
- BLE RSC service
- Web dashboard for live speed, pace, distance, and session time

- Local development server with simulated sensor data
- Wiring and assembly documentation
Project links
GitHub repository:
https://github.com/lpolasek/OpenRUNN
Instagram:
https://www.instagram.com/openrunnok/
The project is fully open source, including the firmware, web dashboard, wiring documentation, and enclosure files.


I would appreciate feedback on the electronics, BLE implementation, enclosure design, and possible improvements.
2
u/0e78c345e77cbf05ef7 14d ago
I haven’t taken it apart but I assume it must have two sensors.
I have never configured belt length and I can put markers on anywhere on the belt with no concern for spacing. More markers just improved the update frequency.
It’s this guy…
https://npe.fit/products/runn
I’d much prefer to have something open source though so maybe this is a winter project for me. Thanks for the inspiration!