The idea is simple. Write a custom firmware that allows to communicate with many BLE enabled sensors and shows live values on a watch screen.
This project is divided into six phases:
- Phase 1: find out and document watch pinout so it will be possible to communicate with screen, accelerometer and a flash memory from a custom firmware. DONE
- Phase 2: write a custom firmware that will print sample text on a screen and expose a BLE service. Firmware will be flashed using SWD connector. DONE
- Phase 3: make it possible to upload a custom firmware using OTA. This will save the waterproof case from destruction. DONE
- Phase 4: update softdevice to the newest version (S110 8.0.0). Add possibility to switch to S120 2.0.0 softdevice. DONE
- Phase 5: create a "terminal" firmware that allows to control what is displayed on a watch from an android/iOS app. DONE
- Phase 6: create a "standalone" firmware using S120 softdevice that can connect to external sensors (HRS, CSCS etc) without a phone. IN PROGRESS
Roadmap:
- 0.5.0
- possibility to upload multiple watchfaces/applications
- 0.6.0
- support for country specific characters in user fonts
Instructions:
Some instructions can be found here: http://ossw.github.io/
Current version: 0.4.1
https://github.com/ossw/ossw-firmware-s120/releases/tag/0.4.1
Beta testers group
If you like this idea and want to support my work please donate HERE. Thanks!
Krzysiek










And finally new bootloader and softdevice is copied from external flash to processor flash and new bottloader address (0x3C000) is set in UICR.
And that's it, we have a new bootloader and S120 2.0.0 softdevice and may upload a new firmware with 

I'm a big fan of ice hockey and I really enjoy watching and listening to the commentary https://icehockeylovers.com/. Can I watch the game live online and hear the commentary at the same time on this device?