Skatebuddy is a work-in-progress firmware for the SMA Q3/Bangle.js 2 smart watch.
- Automatic time synchronization (via gps)
- Countdown timer
- Stop watch
- Heart rate monitor (accurate when holding arm still, during workout still hit-and-miss)
- Workout tracker (hrm, gps; still work-in-progress)
- Roughly 1 month of battery life
- Persistent flash storage via littlefs
You'll need a debug-probe to connect to the middle two pins on the back of the watch. See the official documentation. One way to connect to these pins is to plug the charging cable into a female usb plug (e.g. by cutting a usb extension cord) and see which cables connect to the middle two pads. Then attach these two (plus ground) to a debug probe, for example a raspberrypi pico.
Then compile and flash the firmware in one step using make flash.
After flashing the watch will reset and print debug info into the terminal as it's running.
Important: Before you disconnect the watch after flashing, exit the process printing debug info via Ctrl-C.
Otherwise the debug hardware interface of the watch will not be powered off and the battery drains much more quickly.
All drivers have two implementations: One for the actual watch hardware and one for a simulator.
This allows testing new firmware versions/new apps without flashing to the watch every time.
Build and start the simulator using make simu.
Copyright 2025 ftilde
This software is subject to the terms of the Mozilla Public License, v. 2.0. If a copy of the MPL was not distributed with this file, You can obtain one at http://mozilla.org/MPL/2.0/.