RIOT-on-CK12

Material, documentation, and progress of porting RIOT to the CK12 smartwatch

Background

The CK12 is a one-of-many smartwatch based on Nordics nRF52832 micro-controller, providing interesting features like BLE, ECG heart rate monitoring, a Bosch BMA253 accelerometer, and a black-and-white OLED screen.

Due to its mechanical 'openness' (screws only, no glue), it promises to be a very nice playground for experimentation and other projects.

Our goal is to port RIOT to the CK12

Progress

06/20/2019 - just started 09/16/2019 - connected Debugger and flashed RIOT -> base system incl. shell over RTT is working 09/16/2019 - started to reverse engineer the pin mapping, see pinmap.md 09/18/2019 - made some traces with the orignal firmware (see traces subdirectory) -> seems like we are using two separate I2C busses 09/18/2019 - pretty sure the watch is using a ssd1306-based display (I2C address fits)

Code

The RIOT branch containing the WIP code can be found here: https://github.com/haukepetersen/RIOT/tree/add_ck12

Flashing RIOT

As a programmer I am using a Segger JLink EDU device (https://www.segger.com/products/debug-probes/j-link/models/j-link-edu/). I guess any SWD capable programmer should do (including those cheap ST-Link clones). But for working with RIOT a JLink device is suited best, as these support Segger's Real Time Transfer (RTT) protocol. This enables us to run the RIOT shell over this RTT interface, without the need of any additional pins and any USB-to-serial adapter.

Flashing the CK12 turned out to be quite simple:

connect the SWDIO, SWCLK, and GND pins of the JLink programmer to the pads exposed on the back of the CK12, See https://github.com/haukepetersen/RIOT-on-CK12/blob/master/images/back_swd.jpg
go to any RIOT application (make sure you have the add_ck12 branch included), and flash using BOARD=ck12 make flash
connect to the RIOT shell by calling BAORD=ck12 make term. This will connect your host to the RIOT shell via RTT

Special Thanks