Resources for reverse engineering generic Nordic Semiconductor nRF52832 and nRF51822 ARM Cortex based Smartwatches and activity trackers. These devices are my primary development platform for rapid prototyping of wearables. You get a nRF52832 ARM Cortex M4 SoC MCU, color OLED display, accelerometer, HR LED, HR photodetector, vibration motor, LiPo battery, battery charger, injection molded enclosure and strap for $30-$40. Using these devices as a development platform means faster, more ambitious prototyping - I treat them as disposable and have personally destroyed more than 20 over the past two years. These devices can be programmed using nRF5X ArduinoCore, ARM Mbed or directly with the Nordic nRF5X SDK using ARM Keil or the GNU ARM Embedded GCC toolchain. Devices can be flashed using nRFgo Studio, nRFjprog Win , nRFjprog Linux , nRFjprog Mac , OpenOCD and ArduinoCore Arduino IDE Plugin. I use a SEGGER J-Link programmer, but if you want to save money and have a $4 'Blue Pill' STM32 board lying around you can turn it into an ARM programmer/debugger, the "Black Magic Probe": https://medium.com/@paramaggarwal/converting-an-stm32f103-board-to-a-black-magic-probe-c013cf2cc38c also https://hackaday.com/2016/12/02/black-magic-probe-the-best-arm-jtag-debugger .
NOTE: I will try to keep purchase links updated but one can only do so much. DuckDuckGo/Google search is your friend. I have worked with the X9 more than any other device and have placed X9 related files in the root of this repo. I am still in the process of hacking components for other listed devices, and you are of course welcome to contribute!
Special thanks to all the members of the smartwatch slack group (@rogerclarkmelbourne, @goran-mahovlic, @micooke, @olivier, @marvin, @floe, the nRF51822 smart watch Gitter Lobby, to @goran-mahovlic and @rogerclarkmelbourne for the KX022 accelerometer driver, to @sandeepmistry for the awesome ArduinoCore Nordic SDK wrapper and Lampert for his awesome light saber WebGL 3D model. Roger Clark in particular has done a lot of cool stuff with Nordic activity trackers, check out his work!