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Cosimini designed and shared the Cambkb, a split keyboard with RJ-9 connectors and exposed diode array.
Published June 18, 2024
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The Cambkb is an open-source split keyboard designed by Cosimini. The main objective of the project was to test ideas and get some experience – hence debug pins and empty footprints in the PCB.

Hi everyone, moved to a new city, looking for a new hobby, I found out about building keyboards. […] To waste even more time, I wrote the software by myself, planning to use one of the available ones that many people enjoy using – Cosimini.


  • split, 56 keys (about 6x4 halves)
  • Gateron low profile KS-33 switches, hotswap
  • Pro Micro controller
  • reversible PCB
  • RJ-9 connectors
  • No OLED screen, LEDs or other shiny stuff
  • custom software (Arduino, PlatformIO)


There's a mistake in the RJ-9 connector routing. The author didn't consider that RJ9 cables are typically crimped mirrored, so a custom cable has to be made in order to use the design.


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Published on Tue 18th Jun 2024. Featured in KBD #167 (source).


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