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Janus is a PCB-resourceful 34-key split keyboard by u/skarrmann.
Published July 16, 2022
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Janus is a small 34-key split ortholinear keyboard by Steven Karrmann aka skarrmann, who also brought us the Horizon.

The board is powered by two Seeed XIAO RP2040s with the keyboard halves connected by an Ethernet cable.

The PCB is not just reversible but also works as both the logical PCB and the bottom plate. That means, you utilize four PCBs of the usual 5-piece minimum order for one build and only have one PCB left.

As the author pointed out the benefits of this approach speaking of his Horizon project:

The bottom plate is a cutout of all the components exposed through the bottom of the main PCB […]. This nicely guards you and your desk surface from all the pointy through-hole bits.

Understandably, this versatile PCB sports only a grid of 1U keys and no special features like hotswap, RGB (except those on the XIAO RP2040), OLED screen or knobs – which would interfere with the reversibility. For the same reason, this particular board supports only Cherry MX style switches.

The main goal of this project was to make a cheap PCB which acts as both the logical PCB and a directly-attached bottom plate. After designing Horizon, I wanted to take its bottom plate concept and merge it into a single PCB design – skarrmann.

Indeed, the PCB size is below 100mm x 100mm, which makes it very cheap to print e.g. at JLCPCB. "5 boards cost under $7 USD shipped to USA."


Janus is open source, you can find all files and details in this repository:

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Published on Sat 16th Jul 2022. Featured in KBD #87 (source).



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