4x4 1x2 1x5key

Crustrusk

Modular, adjustable column-staggered (split) keyboard project

Features

• adjustable stagger / modular PCBs
• implement up to 5x7+7 column stagger keyboard
• support I2C / SPI communication for peripherals

What it can do

• default bundle can give you 3x7+3 keyboard with knob
  • e.g. corne with extra key in inner column & knob
• adjusting stagger to fit your hand
  • you can make it ortho too
• adjusting splay to fit your hand
• (technically) support display, trackball, touchpad, etc.
• implement:
  • Corne
  • Cheapino
  • Sweep
  • Sofle
  • Cornix
  • Flake
  • Totem (with custom column PCB)
  • Jian (with custom column PCB)
  • Lily58 (with custom column PCB)
  • Kyria
  • Ergodox
  • Moonlander
  • Crosses (technically)
  • ...

What it cannot do

• keywell structure, unless PCB is modified that key
• row-staggered
• semi-staggered

Remarks

Production

• current version of 'bundle' is not production tested
  • old gerber that is initially committed was tested, although JST sockets on the main board had to be flipped.
  • male to male connector tips to face the same side: reminder
• all PCB here are MX, but transition should be feasible
• bundles will, ideally, be sub-102x102 mm for cheap fabrication

Engineering decisions

• JST PH socket is chosen because:
  • cheap, flexible, easy to solder, not too big
  • it's not the most aesthetic / professional choice
  • smaller JST sockets are SMD and harder to solder with small pitch
    • they do offer smaller height and greater surface, though
  • FFC sockets are great, but the sided nature and flexibilities were my concern
• 6 pins for general case was used as:
  • some popular keyboards have 5-key column / thumb cluster, and I wanted to cover them
• 8 pins for extended thumb / peripheral was used as:
  • Ergodox / Kyria uses 6+ key thumb cluster
  • to support SPI / trackballs
  • high potential for peripheral development
• RP2040-zero was used as it's easy to solder without pins and exposes more pins
  • changing it to Pro-micro / xiao (with some sacrifices) shouldn't be too hard
  • core is ugly. Improvement is needed.
• currently, M2 screws & standoffs are used to fix the keyboard & adjust stagger.

Building tips

• it'd be easier to use SMD diodes as THT diodes' leg might be touching the switches. I cut legs tightly and it was fine.
• web app for generating QMK config for various combinations are under way

Inspirations

• Zebra
• Seismos
• Pangaea
• Pineapple60-P4
• Squalius-cephalus's modular keyboard

Disclaimer

• Any layout / designs used in this project that originates from other repositories (e.g. thumb clusters) follows the original author's license.