TK44 - is a wireless unibody 40% keyboard with features like:
- Powered by ZMK Firmware
- Based on Holyiot-18010 module
- Hot swappable PCB
- Support 5 pins MX switches
- Li-ion battery
- Hardware power switch
- USB Type-C
- Layout contains full Cyrillic layout (for now used Jian's layout)
- 44 or 42 keys layout
There is "dummy" layout, just for reference
See more on Imgur
Please, use iBom file for the correct placement of components on the PCB
| Name | Qty | Package | Value | Aliexpress |
|---|---|---|---|---|
| Holyiot | 1 | SMD | YJ-18010 | 6.80$ / 1 |
| Diode | 45 | SOD-123 | 1N5819 | 0.99$ / 100 |
| Resistor | 1 | SMD 0603 | 2M | 0.48$ / 100 |
| Resistor | 1 | SMD 0603 | 820k | 0.48$ / 100 |
| Resistor | 1 | SMD 0603 | 3.3k | 0.48$ / 100 |
| Resistor | 1 | SMD 0603 | 100k | 0.48$ / 100 |
| Resistor | 2 | SMD 0603 | 5.1k | 0.48$ / 100 |
| Resistor | 2 | SMD 0603 | 1k | 0.48$ / 100 |
| LED's | 1 | SMD 0603 | Red & Blue | 0.88$ / 100 |
| Charger | 1 | SOT-23-5 | MCP73831 | 0.98$ / 10 |
| P-MOSFET | 1 | SOT-23 | AO3407 | 1.15$ / 50 |
| VCC Regulator | 1 | SOT-23-5 | AP2112K | 0.82$ / 10 |
| USB Connector | 1 | SMD | 1.6mm | 1.17$ / 10 |
| Power Switch | 1 | SMD | MSK12C02 | 1.39$ / 50 |
| Reset Switch | 1 | SMD | 5.2x5.2x1.5 | 0.64$ / 50 |
| Hotswap Sockets | 44 | SMD | MX | 3.40$ / 30 |
| Battery Connector | 1 | JST 1.25 | 2 Pin | 1.64$ / 50 |
| JST Male Wire | 1 | JST 1.25 | 2 Pin | 0.70$ / 20 |
| Battery | 1 | 502035 | 300mAh | 3.65$ / 1 |
- Holyiot module have several verison:
- Instead of AP2112K VCC Regulator you can use XC6220. It's more expensive, but have leaks around 8uA vs 55uA at AP2112K. Using XC6220 will help save battery charge.
- Power switch also name as a PCM12, thats can help you to find them in other places
- In current BOM i placed link for new colored Kailh MX hotswap sockets, they more cheaper for now moment, but you can use any Kailh MX footprint friendly sockets
- For Battery Connector choose "Straight needle"
- For JST Male Wire choose "red black" and 40mm, this will be enought
- You can choose any battery, that fits the size 5x20x35mm (0.19x0.79x1.38")
FR-4 case, as well as the PCB, have cutoffs for breaking off pinky-key.
| Part | Size | Length | Qty | Aliexpress |
|---|---|---|---|---|
| Standoffs | M2 | 8mm | 8 | 2.46$ / 10 |
| Screws | M2 | 6mm | 16 | 1.14$ / 25 |
For this operation you need J-Link clone programmer, like this:
First of all download and install SEGGER J-Link 6.70b
And download J-Flash project
- Connect programmer's pins (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).
- 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 (make sure that connect between programmer and PCB is stable, hold wires tight in PCB!)
- After succesfull connect: Target --> Disconnect
Download TK44 bootlader
Move bootlader hex file into root directory (as example: C: disk for windows)
- Open JFlashLite, select NRF52840_XXAA if it doesn't at program start.
- Select bootloader and press Program Device, wait for flashing.
- After flashing controller you need to download ZMK firmware file:
- 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!