Custom firmware for the NRF52 based smartwatch I6HRC using the Mbed framework.
Install Visual Studio Code and the PlatformIO extension. Then use the i6hrc env for deployment, or the nrf52_dk env for debugging on a NRF52-DK board.
Use doxygen or the "Build Documentation" task to generate documentation.
Solder the SWDCLK and SWDIO testpoints to the unused USB data lines. You might want to fabricate a custom USB to ISP adapter.
Flashing should work with any SWD capable programmer, like for example the ST-Link V2 (the cheap clones work too).
If the watch refuses to flash, hangs in low poer mode or is stuck in a bootloop, try connecting to it using OpenOCD (http://openocd.org/) while spamming the reset button on your adapter (or short SWDIO to VCC). This should not be needed during normal flashing and execution.
openocd -d2 -f interface/stlink-v2.cfg -c "transport select hla_swd" -f target/nrf52.cfg
On a successful connection OpenOCD displays something like "Info : nrf52.cpu: hardware has 6 breakpoints, 4 watchpoints". The script tools/reset.sh or the task "Reset Target" automates this spamming.
Optinally, open up GDB via telnet and reset the core using reset halt via telnet localhost 4444.
You can then exit the OpenOCD instance if you want to use a other tool for flashing (e.g. PlatformIO). The core should run normally (or hang at the reset vector if you reset it) and accept SWD connections and flash commands reliably. The PlatformIO flash tool should leave the core in a useable, running state.
You can use the Android app "nRF Connect" (https://play.google.com/store/apps/details?id=no.nordicsemi.android.mcp&hl=en) to test the Bluetooth functions. Sometimes, connecting takes multiple tries.
A dump of the stock ROM can be found at doc/stock_rom_dump.bin (armv7le) for decompiling (e.g. using Ghidra: https://ghidra-sre.org/) or restoring the watch (untested).
Thanks to Aaron Christophel for providing instructions on how to modify the hardware, mapping out the pins and providing some demo Arduino code.
- https://github.com/atc1441
- http://atcnetz.blogspot.com/2019/02/arduino-auf-dem-fitness-tracker-dank.html
- https://www.mikrocontroller.net/topic/467136
- https://www.youtube.com/watch?v=0Fu-VSuKHEg
- ARM Mbed RTOS and API: https://os.mbed.com/
- The
CurrentTimeServicemodule of theBLE_GATT_Serviceslibrary is based onBLE_CurrentTimeServiceby Takehisa Oneta: https://os.mbed.com/users/ohneta/code/BLE_CurrentTimeService/- Deferred calls in ISR context to EventQueue
- Added documentation
- The
Adafruit_ST7735_Minilibrary is based on theAdafruit_ST7735library by Andrew Lindsay: https://platformio.org/lib/show/2150/Adafruit_ST7735, which in turn is a port of a library by Adafruit: https://github.com/adafruit/Adafruit-ST7735-Library- Added support for the
R_MINI160x80display type - Added documentation
- Added an explicit dependency to
Adafruit_GFXport by Andrew Lindsay: https://platformio.org/lib/show/2147/Adafruit_GFX, which is a port of https://github.com/adafruit/Adafruit-GFX-Library
- Added support for the