Thumbsplit58 Keyboard Firmware

Firmware for Nordic MCUs used in the Thumbsplit58 Keyboard. You may also want to refer PCB, case and qmk_firmware repository.

The firmware was originally developed by reversebias for the Mitosis keyboard and has been modified by satt99 to work with Comet46 keyboard.

Note

Current firmware uses 2482MHz and 2494MHz to communicate between keyboard and receiver, which is eligible in Japan but not in the EU or US. You have to modify channel_table parameter to use appropriate channels in your country.

You may also want to randomize ADDRESS_PIPE0 and ADDRESS_PIPE1 to avoid conflict with other keyboards using the same firmware. Note that you cannot use 0x55 or 0xAA in the address according to the Nordic Gazell link layer document.

Install dependencies

Tested on Ubuntu 20.04, but should be able to find alternatives on all distros.

sudo apt install openocd gcc-arm-none-eabi

Download Nordic SDK

Nordic does not allow redistribution of their SDK or components, so download and extract from their site:

https://developer.nordicsemi.com/nRF5_SDK/nRF5_SDK_v11.x.x/

Current firmware only works with SDK version 11.

unzip nRF5_SDK_11.0.0_89a8197.zip  -d nRF5_SDK_11
cd nRF5_SDK_11

Toolchain set-up

A cofiguration file that came with the SDK needs to be changed. Assuming you installed gcc-arm with apt, the compiler root path needs to be changed in /components/toolchain/gcc/Makefile.posix, the line:

GNU_INSTALL_ROOT := /usr/local/gcc-arm-none-eabi-4_9-2015q1

Replaced with:

GNU_INSTALL_ROOT := /usr/

Clone repository

Inside nRF5_SDK_11/

git clone https://github.com/mohammedari/thumbsplit58-firmware

Install udev rules

sudo cp thumbsplit58-firmware/49-stlinkv2.rules /etc/udev/rules.d/

Plug in, or replug in the programmer after this.

OpenOCD server

The programming header on the keyboard, from right to left:
(Check the silk screen on PCBs for orders.)

SWCLK
SWDIO
GND
PWR(3.3V)

It's best to remove the battery during long sessions of debugging, as charging non-rechargeable lithium batteries isn't recommended.

Launch a debugging session with:

./openocd.sh

Should give you an output ending in:

Info : nrf51.cpu: hardware has 4 breakpoints, 2 watchpoints

Otherwise you likely have a loose or wrong wire.

Build and flash receiver firmware

After connecting the receiver board via stlink and launching openocd in another terminal, use the following script.

cd thumbsplit58-firmware/thumbsplit58-receiver-basic
./program.sh

Build and flash keyboard firmware

Use the same script under thumbsplit58-keyboard-basic. You have to change define switch COMPILE_RIGHT and COMPILE_LEFT according to the board you connect before running the script.