Karma is a 36-key wireless split ergonomic mechanical keyboard inspired by two very popular ergonomic keyboards: Corne and TOTEM.
- Ergonomic 36-key layout: A compact layout with 3x5 column-staggered keys, plus 3 thumb keys for each side.
- Wireless first: Prioritizes a wireless split setup but can be used partially-wired by connecting the central side using USB-C.
- Low-profile design: Engineered for a sleek, low-profile build that allows your palms to rest comfortably on the table while typing. This is achieved through the use of Kailh Choc switches and recessed cutouts for hot-swap sockets, reducing the overall case height (similar to the TOTEM keyboard), and using 1mm EVA foam instead of rubber feet.
- Exceptional battery life: Has a battery life that is measured in weeks, not days.
The Karma keyboard supports the ZMK open-source firmware. You can find my ZMK configuration for this keyboard in this repo.
To build the Karma keyboard, you'll need the following components:
| Part Name | Qty | Remarks |
|---|---|---|
| 2x SEEED XIAO BLE microcontrollers | 2 | |
| Kailh Choc V1 low-profile switches | 36 | Low-profile mechanical switches |
| Keycaps compatible with Kailh Choc V1 | 36 | MX-spaced keycaps are preferred for better fit |
| Hotswap sockets for Kailh Choc V1 | 36 | |
| SOD123 diodes | 36 | |
| JST PH 2-pin SMD Header | 2 | |
| 301230 LiPo Batteries | 2 | Only 1 required for partially wired build |
| 3D-printed case | 2 | |
| M2 screws (5mm length) | 8 | |
| M2 heat-set inserts (2mm height) | 8 | |
| Self-adhesive EVA foam (1mm) | - | A slimmer alternative to rubber feet |
1. Order the Components
- Zip up the gerber files for the left side and the right side.
- Order the PCBs from a PCB prototype manufacturer like JLCPCB.
- 3D print the STL files for the case in this repo.
- All the other components are generic and can be found in Aliexpress.
2. Solder the Diodes
- Solder the SOD123 diodes to the top of the PCB, paying attention to the polarity.
- Apply solder to one pad, place the diode, and reflow the solder. Then solder the second pad.
3. Install the Hotswap Sockets
- Solder hotswap sockets in place by first securing one pad, then ensuring they are properly seated before soldering the second pad.
4. Microcontroller Installation
- Flash the firmware onto the SEEED XIAO BLE microcontrollers before soldering them to the PCB.
- Place the microcontroller in the designated spot and solder the pads, starting with the corners to secure it, then solder the rest.
5. Connect the Batteries
- Solder the JST PH 2-pin SMD Header to the PCB.
- Check the polarity of the battery with a multimeter and connect the batteries to the JST header such that the red wire is connected to the positive (+) pad and the black wire to the negative (-) pad on the PCB.
6. Mount the Case
- Insert M2 heat-set inserts into the screw holes in the 3D-printed case.
- Place the PCB inside the case, ensuring the microcontroller and battery fit snugly.
- Attach the two halves of the case using the M2 screws, securing them tightly.
7. Install the Keycaps and Switches
- Insert the Kailh Choc V1 switches into the hotswap sockets, ensuring they click into place.
- Attach your keycaps to the switches.
8. Add EVA Foam
- Cut and apply self-adhesive EVA foam to the bottom of the case for added grip and cushioning.
9. Final steps
- Once assembled, test the keyboard to ensure all switches and connections work.
- If necessary, adjust the ZMK firmware for your specific keymap.
Congratulations! You've completed your Karma keyboard build.
This project is open-source and licensed under the CERN Open Hardware Licence Version 2 - Strongly Reciprocal License. See the LICENSE file for details.