The crux

ayoreis·the-crux·pcb/the-crux.kicad_pcb

About the The crux PCB

The crux is an open source RP2040/RP2350 PCB design by ayoreis, published on GitHub. It is a 2-layer board measuring 190.5 × 73.4 mm, with 61 components from 3 distinct parts.

Its main chip is the XIAO-RP2040-SMD, from the RP2040/RP2350 family. By type, the board carries 30 switches, 30 diodes and 1 IC.

It belongs with the keyboards designs in this gallery.

From the project

A minimal 3x10 ortholinear keyboard. Driven by a RP2040 with RMK + Vial.

I've always wanted to make a keyboard, I actually started this one with much more ambitious ideas (you can find them in my earlier journals, or by going back the commit history) but realized I should start out with something simpler. So I made this! It was quite nice, and maybe I'll improve it with my previous ideas one-by-one :)

The crux, from the project README — From the project README

Main components on the The crux

XIAO-RP2040-SMD

The crux bill of materials (BOM)

61 components, 3 distinct parts — part numbers from the project's BOM.

Qty	Part	Footprint	Refs
1	XIAO-RP2040-SMD	XIAO-RP2040-SMD	U1
30	SW_Push	SW_Cherry_MX_1.00u_PCB	SW1, SW2, SW3, SW4, SW5, SW6, SW7, SW8 +22
30	D	D_DO-35_SOD27_P7.62mm_Horizontal	D1, D2, D3, D4, D5, D6, D7, D8 +22

The crux design files

The KiCad project lives in the ayoreis/the-crux repository on GitHub; these links point at the commit this page was built from.

Layoutpcb/the-crux.kicad_pcb
Schematicpcb/the-crux.kicad_sch
BOMpcb/jlcpcb/production_files/BOM-the-crux.csv

The crux: common questions

What microcontroller does the The crux use?

The The crux is built around the XIAO-RP2040-SMD, from the RP2040/RP2350 family.

How big is the The crux PCB?

The The crux measures 190.5 × 73.4 mm, has 2 copper layers and is 1.6 mm thick.

How many components are on the The crux?

61 components, from 3 distinct parts, with part numbers taken from the project's own BOM. The full bill of materials is listed on this page.

Where can I download the The crux design files?

From the ayoreis/the-crux repository on GitHub, which has the KiCad layout, the schematic and the BOM; the links under Design files point to each one.

Can I use the The crux design in my own project?

The repository has no license, so all rights stay with ayoreis. Use it as a reference, and ask the author before reusing the design.

Can I test firmware for the The crux without the hardware?

Yes. HardLabs builds a simulation of the board from its netlist and BOM, so you can run and debug RP2040/RP2350 firmware against it before you order a PCB.