2 layers119.3 × 153.9 mm Keypad AIO, the printed circuit board in 3D

Keypad AIO

Programmable keyboard controller system with host software, configuration UI, and embedded firmware.

Size: 119.3 × 153.9 mm
Copper layers: 2
Thickness: 1.6 mm
Parts: 108
Nets: 73
Pads: 767
Tracks, vias: 345, 8
Routed: Yes
KiCad: KiCad 8.0 (file 20240108)
Created: 15 Feb 2025
Updated: 8 Jun 2026

Overview

Keypad AIO is an open-source printed circuit board by acrankyturtle, from the acrankyturtle/Cardboard repository on GitHub. It is a 2-layer board of 119.3 × 153.9 mm with 108 parts on 73 nets, routed with 345 tracks and 8 vias.

Its parts include 31 switches, 30 diodes, 2 connectors and 1 IC. It belongs with the keyboards and input boards and the RP2040 boards of this library.

README

README.md

Cardboard

Programmable keyboard controller system with host software, configuration UI, and embedded firmware.

Architecture Overview

Cardboard is a three-tier system: a React frontend for configuration, a .NET backend for device management and API serving, and Rust firmware running on RP2040-based keyboard controllers. The backend discovers devices over USB serial, while the frontend communicates with the backend over HTTP (REST + SSE).

text

Frontend (React/Vite)  →  Backend (.NET/Kestrel)  →  Device (Rust/Embassy)

Prerequisites

.NET SDK 10.0+
Node.js LTS + npm
Rust nightly + thumbv6m-none-eabi target
elf2uf2-rs or probe-rs (for flashing firmware)
Inno Setup 6.2+ (installer builds only)

Getting Started

Backend

bash

dotnet run --project Cardboard.Controller

Starts the API server at http://localhost:7000. In Development mode, Swagger is available at /swagger.

Frontend

bash

cd react-frontend
npm install
npm run dev

Starts the Vite dev server at http://localhost:5173. The appsettings.Development.json in Cardboard.Controller/ points ReactHostUrl to :5173 so the backend knows where the frontend is running.

Firmware

bash

cd firmware
cargo build --release
cargo run --release

Flashes the firmware to a connected RP2040 device. The default runner uses elf2uf2-rs (device must be in bootloader mode). To use probe-rs, edit .cargo/config.toml.

Building for Release

Application

bash

dotnet publish Cardboard.Controller -c Release

This automatically builds the React frontend (npm install && npm run build) and bundles it into the output under wwwroot/.

Installer

powershell

installer\build-installer.ps1

Requires Inno Setup 6.2+ installed.

Firmware

bash

cd firmware
cargo build --release

Project Structure

Host Application (C# / .NET 10)

Project	Purpose
`Cardboard.Controller/`	ASP.NET Core host, DI composition root, entry point
`Cardboard.HttpApi/`	REST API endpoint definitions (Devices, Tags, Logs, InputDevices, Controller)
`Cardboard.Api/`	Shared API setup, such as JSON serialization configuration
`Cardboard.FrontendHost/`	SPA hosting, origin validation, route mounting
`Cardboard.Services/`	Business logic: tag association management, virtual key dispatch
`Cardboard.Repositories/`	Data access: device repository, association persistence
`Cardboard.Events/`	Cross-platform event abstractions
`Cardboard.Device/`	Device abstractions: commands, profiles, settings, binary serialization
`Cardboard.Serial/`	Serial port abstractions
`Cardboard.Windows/`	Windows: serial discovery (WMI), input monitoring, tray icon
`Cardboard.Metadata/`	Device metadata interfaces (icons, model info)
`Cardboard.Utilities/`	Shared utilities: AsyncDispatchSubject, Result types, file watcher
`Cardboard.Update/`	Firmware update orchestration
`Cardboard.Update.Api/`	Update server API client
`Cardboard.Update.Api.Abstractions/`	Shared types for update client/server
`Cardboard.UpdateServer/`	Firmware, metadata, and update distribution server (separate deployment)

Firmware (Rust / Embassy)

Directory	Purpose
`firmware/`	CK1-30 firmware entry point and RP2040-specific code
`cardboard-lib/`	Platform-agnostic core: commands, profiles, state machine, HID, serial

Frontend (TypeScript / React 19)

Directory	Purpose
`react-frontend/`	Vite + React + Tailwind SPA for device configuration

Tooling

Directory	Purpose
`DeviceTool/`	CLI tool for building and testing device profiles
`installer/`	Inno Setup installer scripts and build script

Configuration

Cardboard.Controller/appsettings.json — Production configuration:

Kestrel:Endpoints:Http:Url — Backend listen address (default http://127.0.0.1:7000)
Paths:Associations — Association storage path (default %APPDATA%/Cardboard/associations.json)
Paths:MetadataCache / IconCache — Cache directories under %APPDATA%/Cardboard/cache/
Frontend:ReactHostUrl — URL where the frontend is served from
Update:Url / Update:Channel — Firmware update server and release channel

appsettings.Development.json — Development overrides:

Sets Frontend:ReactHostUrl to http://localhost:5173 for the Vite dev server
Sets Update:Channel to preview

Code Formatting

Language	Tool	Config
C#	CSharpier	`.csharpierrc.json` (tabs, 110 width)
TypeScript	Prettier + ESLint	`.prettierrc`, `eslint.config.js`
Rust	rustfmt	Default settings

Further Documentation

Architecture — System architecture deep-dive, component relationships, data flow
API Reference — HTTP endpoint reference (REST + SSE)
Serial Protocol — Binary protocol between host and firmware
Conventions — Design patterns, code style, project conventions

Parts

108

Qty	Value	Footprint	References
44	MountingHole_2.2mm_M2_Pad_Via	MountingHole:MountingHole_2.2mm_M2_Pad_Via	, , , , , , , , , , , , , , , +28
30	D	Diode_THT:D_DO-35_SOD27_P7.62mm_Horizontal	D1, D2, D10, D11, D12, D13, D14, D15, D16, D17, D18, D19, D20, D21, D22, D23 +14
29	CherryMX	PCM_Switch_Keyboard_Hotswap_Kailh:SW_Hotswap_Kailh_MX_1.00u	SW1, SW2, SW10, SW11, SW12, SW13, SW14, SW15, SW16, SW17, SW18, SW19, SW20, SW21, SW22, SW23 +13
1	CherryMX	PCM_Switch_Keyboard_Hotswap_Kailh:SW_Hotswap_Kailh_MX_2.00u_90deg	SW30
1	Debug	Connector_JST:JST_XH_B5B-XH-A_1x05_P2.50mm_Vertical	J2
1	Pico	MCU_RaspberryPi_and_Boards:RPi_Pico_SMD_TH	U1
1	Power	Connector_JST:JST_XH_S2B-XH-A_1x02_P2.50mm_Horizontal	J1
1	Stabilizer_Cherry_MX_2.00u	PCM_Mounting_Keyboard_Stabilizer:Stabilizer_Cherry_MX_2.00u	SW30_Stabilizer

Questions

How big is the Keypad AIO PCB?

It measures 119.3 × 153.9 mm and has 2 copper layers, 1.6 mm thick.

What parts does the Keypad AIO use?

108 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 Keypad AIO KiCad files?

From the acrankyturtle/Cardboard repository on GitHub, at the commit this page was made from: the board is KiCad/Keypad AIO.kicad_pcb and its schematic KiCad/Keypad AIO.kicad_sch. PCBKit opens the board in the browser, with nothing to install.

Can I use the Keypad AIO design in my own project?

Its repository states no licence, so its author keeps all rights: ask acrankyturtle before reusing the design.

Category and platform

Keyboards and input RP2040

Project files

Show this board on your page

A live frame, for any web page

<iframe src="https://pcbkit.io/embed/boards/acrankyturtle-cardboard" title="Keypad AIO in PCBKit" width="100%" height="480" style="border:0;border-radius:12px" allow="fullscreen" loading="lazy"></iframe>

A picture

<img src="https://pcbkit.io/embed/boards/acrankyturtle-cardboard.jpg" alt="Keypad AIO" width="1200" height="900">

A picture that opens the board, for a README

[![Keypad AIO](https://pcbkit.io/embed/boards/acrankyturtle-cardboard.jpg?size=s)](https://pcbkit.io/boards/acrankyturtle-cardboard)

Source

Repository: acrankyturtle/Cardboard
Board file: KiCad/Keypad AIO.kicad_pcb
Commit: 2c49ac2
Licence: Not stated

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