

Keys lefthand
Type with only one hand
- Size
- 252.8 × 229.6 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 83
- Nets
- 80
- Pads
- 475
- Tracks, vias
- 1,257, 283
- Routed
- Yes
- KiCad
- KiCad 8.0 (file 20240108)
- Created
- 6 May 2024
- Updated
- 7 Jun 2025
Overview
Keys lefthand is an open-source printed circuit board by blueOkiris, from the blueOkiris/ps-ohk repository on GitHub, published under the GPL-3.0 licence. It is a 2-layer board of 252.8 × 229.6 mm with 83 parts on 80 nets, routed with 1,257 tracks and 283 vias.
It belongs with the keyboards and input boards and the 8051 (CH55x, STC, AT89) boards of this library.
README
README.mdPolymath-Studio One-Handed Keyboard
Description
Type with only one hand

Designed around
- the most common letters used
- relationships between sounds
- the shape of a left hand
- practicality
The PS-OHK (pronounced "psawk" [p͡sɑk̚]) aims to be the ultimate one-handed typing experience all without special modifiers (a standard key count) and a layout that is relatively easy to get used to.
Build and Upload
Dependencies:
- arduino-cli
- make
- sdcc
- ch55xtool
- libusb
Build with make -C fw
Hold program button down, plug in, let go of program button, and run make -C fw upload within 3 seconds
Parts
83| Qty | Value | Footprint | References |
|---|---|---|---|
| 79 | ~ | COM-13834:COM13834 | S_1, S_2, S_3, S_4, S_5, S_6, S_7, S_8, S_9, S_10, S_A1, S_ALT1, S_APOST1, S_B1, S_BACKSPACE1, S_BSLASH1 +63 |
| 4 | Conn_01x20 | Connector_PinHeader_2.54mm:PinHeader_1x20_P2.54mm_Vertical | J1, J2, J3, J4 |
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Questions
How big is the Keys lefthand PCB?
It measures 252.8 × 229.6 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Keys lefthand use?
83 parts. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
Where can I download the Keys lefthand KiCad files?
From the blueOkiris/ps-ohk repository on GitHub, at the commit this page was made from: the board is keys-lefthand/keys-lefthand.kicad_pcb and its schematic ctrl/ctrl.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Keys lefthand design in my own project?
Its repository publishes it under the GPL-3.0 licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).