Firmware

Flashing controller

For this operation you need J-Link clone programmer, like this:

Aliexpress 5.49$

Unlocking controller

First of all download and install SEGGER J-Link 6.70b

And download J-Flash project

• Connect programmer's pins (best way to do it - solder them directly) VCC, GND, SWC, SWD to PCB's pins (same pins, marked by silkscreen).
  • Also, you can connect only SWC and SWD pins, in this case power PCB via USB-C (please, make sure that battery not installed and power switch in OFF positon).
  • Be careful, don't shortcut any of wires.
• Connect programmer to PC via USB cable.
• Open JFlash.
• Choose Open recent project and choose project file, that you download earlier.
• Click Start J-Flash.

After that:

• Connect to controller: Target --> Connect
• After succesfull connect: Target --> Disconnect

Bootloader

Download TK44 bootlader

Move bootlader hex file into root directory (as example: disk C: for windows)

• Open JFlashLite, select NRF52840_XXAA if it doesn't at program start.
• Select bootloader and press Program Device, wait for flashing.

Building Firmware

I've created special repository for more convenience:

TK44 ZMK Firmware

Use the instructions described in this repository

Flashing Firmware

• After flashing controller you need to download ZMK firmware file:
  • ZMK firmware
• Move file from download folder to a directory of your choice for easy access.
• Connect PCB through USB Type-C.
• Move tk44-zmk.uf2 file into opened explorer window (just like moving files to a USB flash drive).

After this you can freely connect your TK44 keyboard to PC!

References

Joric's flashing instuction (a lot of variants)

luantty2 flashing instruction