Charlieflex Keyboard

I haven't had a non-split ergonomic keyboard before, so I thought I'd give one a try, but none of the existing boards had what I wanted. Hence: the Charlieflex.

Features

• 30-32 key wireless ergo keyboard with aggressive pinky stagger and splay
• central rotary encoder can be used by either hand
• designed for the Seeed Studio XIAO BLE wireless microcontroller
  • also works with the XIAO RP2040 for a lower-cost wired board
• Choc v1 or v2 low profile hotswap switches
• 7mm low-profile "snug sandwich" case with no exposed components on top or bottom
• RGB LED status visible on the top of the case
• Wireless-first design using ZMK firmware (including ZMK Studio)
• PCB designed with ergogen
• Internal space (5.5 x 27 x 32 mm) for a "large" 502530 300mAh battery
• Licensed under the CERN Open Hardware License v2
• All source files available, so you can tweak the design if needed

Design goals

• Low cost wireless
  • xiao ble is only $10 per controller compared to $25 for the nice!nano
  • Big battery and an option for a dongle, so you can run for months without recharging
  • xiao rp2040 is under $5 with no need to purchase a battery or power switch if you want a wired board
• Ergonomic design for the ultimate comfort
  • each half is angled to match the angle of the hands on the board
  • keys are placed where fingers naturally fall, with no excessive stretching
    • when fingers extend, they splay, so the keys also splay outward to follow the fingers
    • the pinky is shorter than the other fingers, so the pinky keys are placed lower to match, and the top pinky key is traded for a ring finger key
    • the inner column of each hand is reduced to two keys
  • centrally located rotary encoder knob for easy access to scrolling and volume control
  • includes all source files, so if your fingers are slightly different, with a little work you can adjust the keyboard to fit you exactly
  • options for 1 or 2 thumb keys on each hand
• Low profile 3D printable case
  • case is only about 7mm high and comes in separate pieces, each largely flat on one side for easy FDM printing with minimal fuss
  • smaller versions are included for smaller print beds
  • a few different knobs are included so you can get the height that works best for you
  • bumpons are inset into the case 1mm to minimize their height; they add only 1/2mm in height
• Hotswappable
  • keycaps and v1 switches can be easily removed and exchanged so you can fine tune the feel
  • strangely, choc v2 switches seem to be designed without a way to easily remove them
• Electrostatic protection
  • unlike other ultra-low-profile cases, no electronics are left exposed
  • usb port and power switch are on the back, reset switch is recessed into the bottom of the case

Build Guide

This project is still in development, but the Build Guide is started.

Here is an image of an early prototype of the board; the final version has a slightly different layout.