Janus

skarrmann·janus·kicad/mx/janus.kicad_pcb

About the Janus PCB

Janus is an open source RP2040/RP2350 PCB design by skarrmann, published on GitHub under the MIT license. It is a 2-layer board measuring 95 × 95 mm, with 58 components from 9 distinct parts.

Its main chip is the XIAO RP2040, from the RP2040/RP2350 family. By type, the board carries 17 switches, 17 diodes, 1 IC and 1 connector.

It belongs with the keyboards designs in this gallery.

From the project

34 key split keyboard with self-encasing PCB.

Janus is a small 34 key split ortholinear keyboard, powered by two Seeed XIAO RP2040 with the keyboards halves connected by an ethernet cable.

The PCB works as both a logical PCB and a bottom plate.

This keyboard is a grid of 1U keys with no special features: no hotswap, no RGB (except those on the XIAO RP2040), no OLED screen, no knobs. It only supports Cherry MX style switches.

Janus, from the project README — From the project README

Main components on the Janus

XIAO RP2040

Janus bill of materials (BOM)

58 components, 9 distinct parts.

Qty	Part	Footprint	Refs
1	XIAO RP2040	XIAO-RP2040_Reversible	U1
1	8P8C Double Sided	8P8C_SMT_Double_Sided	J1
2	Cutout-MX_Full	Cutout_SW_MX_Full	CUTOUT1, CUTOUT2
14	Cutout-MX	Cutout_SW_MX_Pads	CUTOUT3, CUTOUT4, CUTOUT5, CUTOUT6, CUTOUT7, CUTOUT8, CUTOUT9, CUTOUT10 +6
1	Cutout	Cutout_SW_MX_Pads	CUTOUT14
1	Cutout-8P8C	Cutout_8P8C_SMT	CUTOUT18
4	Hole_Pad	Mount_M2	H1, H2, H3, H4
17	SW_Push	SW_MX_Reversible	SW1, SW2, SW3, SW4, SW5, SW6, SW7, SW8 +9
17	D	D_SOD-123_Reversible	D1, D2, D3, D4, D5, D6, D7, D8 +9

Janus design files

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

Layoutkicad/mx/janus.kicad_pcb
Schematickicad/mx/janus.kicad_sch

Janus: common questions

What microcontroller does the Janus use?

The Janus is built around the XIAO RP2040, from the RP2040/RP2350 family.

How big is the Janus PCB?

The Janus measures 95 × 95 mm, has 2 copper layers and is 1.6 mm thick.

How many components are on the Janus?

58 components, from 9 distinct parts. The full bill of materials is listed on this page.

Where can I download the Janus design files?

From the skarrmann/janus repository on GitHub, which has the KiCad layout and the schematic; the links under Design files point to each one.

Can I use the Janus design in my own project?

Yes, under the terms of its MIT license, which skarrmann chose for the repository.

Can I test firmware for the Janus 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.