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A split keyboard with 6 by 3 column staggered keys and 3 thumb keys, based on the Crkbrd design
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Katia is a split mechanical keyboard with 6 by 3 column staggered keys and 3 thumb keys, based on the Crkbrd design.
Compared to the original Crkbrd, Katia features 4-layer PCB stackup, which allows for better routing and thus, better signal integrity.
The design is intended to be used with hot-swap sockets for Cherry MX switches. The switches are backlit with individually addressable LEDs.
All the mechanical components are kept in the same position as in the original project. This allows for easy replacement of the PCB in existing Crkbrd cases, or to use the existing Crkbrd cases and plates with the new PCB.
The PCB stackup consists of four layers:
The top layer is used for differential pair routing for USB data lines, as well as for some of the components. The second layer is a dedicated ground plane. The third one is used for power distribution and some signal routing. The bottom layer is used for routing the remaining signals.
| Left Side | Right Side |
|---|---|
The following issues were found in the original Crkbrd PCB design, which have been addressed in this redesign.
The PCB production files are available in the release assets. The design rules have been set to match standard 4-layer PCB manufacturing capabilities.
A complete bill of materials (BOM) and pick-and-place files are provided for easy ordering and assembly.
When ordering the PCB assembly from a fabrication house, make sure to select the following options:
All other options can be left at default values. Choose the solder mask and silkscreen colors as desired.
When ordering the solder paste stencil from a fabrication house, make sure to select the bottom layer, as the keyboard is assembled from the bottom side:
The bill of materials includes manufacturer part numbers for easy ordering from LCSC.
[!NOTE] Hot-swap sockets and mechanical switches are not included in the BOM. They can be ordered separately from various suppliers.
At the time of writing, the total cost of the components for sourcing all parts for both halves of five keyboards should be around $60.
When ordering the components just for one keyboard, make sure to adjust the quantities accordingly and order some spare parts for potential assembly errors (especially for LEDs, buttons, and connectors).
While the keyboard can be assembled by hand, it is recommended to use a professional PCB assembly service to ensure high-quality solder joints and proper component placement.
If assembling by hand, first apply solder paste to the PCB using the provided stencil. Then, place all surface-mount components using tweezers or a pick-and-place tool. Finally, reflow solder the components using a hot air rework station or a reflow oven. Omit the hot-swap sockets, jack connectors, and LEDs during the reflow process, as they are not designed to withstand high temperatures. After reflowing the other components, check the solder joints and fix any issues using a soldering iron.
Plug in the USB cable into each half of the keyboard, and check if it is recognized by the computer. If everything is working correctly, you can then solder the LEDs, jack connectors, and hot-swap sockets using a standard soldering iron. Finally, insert the mechanical switches into the hot-swap sockets and connect the two halves of the keyboard using a TRS cable.
[!WARNING] Do not plug in or unplug the interconnect jack between the two keyboard halves while the keyboard is powered. Hot-plugging can cause electrical damage to the PCB and components. Always disconnect power before handling the communication cable.
The keyboard firmware is based on QMK Firmware. A precompiled firmware binary is available in the release assets. To build the firmware from source, follow the QMK documentation.
To flash the firmware:
The same firmware binary is used for both halves.
[!NOTE] When connected via USB, each half of the keyboard is detected as a separate device. Flash the firmware to both halves.
Bootloader mode can be entered in several ways, including:
Q position on the left half and the P position on the right half.The default firmware layout uses three logical keymap layers, shown below. This is a practical starting point for the board, but the final keymap is up to personal preference.
This project is licensed under the CERN Open Hardware Licence Version 2 - Permissive. You are free to use, modify, and distribute this design, provided you retain notices and disclaimers as specified in the license terms. See the LICENSE file for details.