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Mitosis Keyboard Firmware

Firmware for Nordic MCUs used in the Mitosis Keyboard, contains precompiled .hex files, as well as sources buildable with the Nordic SDK.

After flashing the keyboard, remove the battery for a few seconds before putting it back. If you don't, the keyboard will be left in debug mode and it will consume 1mA more than necessary.

Install dependencies

Tested on Ubuntu 16.04.2, but should be able to find alternatives on all distros.

sudo apt install openocd gcc-arm-none-eabi

Install dependencies on macOS

Tested on macOS High Sierra 10.13.1

Install Homebrew

/usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

Install Open OCD

brew install openocd

Install gcc-arm-none-eabi

brew install https://raw.githubusercontent.com/ARMmbed/homebrew-formulae/master/arm-none-eabi-gcc.rb

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/nRF5_SDK_11.0.0_89a8197.zip

Firmware written and tested with 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 (Linux):

GNU_INSTALL_ROOT := /usr/

Replaced with (macOS):

GNU_INSTALL_ROOT := /usr/local

Clone repository

Inside nRF5_SDK_11/

git clone https://github.com/reversebias/mitosis

Install udev rules (Linux only)

sudo cp mitosis/49-stlinkv2.rules /etc/udev/rules.d/

Plug in, or replug in the programmer after this.

OpenOCD server

The programming header on the side of the keyboard, from top to bottom:

SWCLK
SWDIO
GND
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 -f mitosis/nrf-stlinkv2.cfg

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.

Manual programming

From the factory, these chips need to be erased:

echo reset halt | telnet localhost 4444
echo nrf51 mass_erase | telnet localhost 4444

From there, the precompiled binaries can be loaded:

echo reset halt | telnet localhost 4444
echo flash write_image `readlink -f precompiled-basic-left.hex` | telnet localhost 4444
echo reset | telnet localhost 4444

Automatic make and programming scripts

To use the automatic build scripts:

cd mitosis/mitosis-keyboard-basic
./program.sh

An openocd session should be running in another terminal, as this script sends commands to it.