How to make a numeric keyboard using XIAO RP2040

This keyboard is more of an art project to me. And a chance to learn how things work. What is the underlying code and history! Arouse curiosity.

background

The medieval number system was invented by the Cistercians in Europe in the 13th century. The Cistercians were a Catholic religious order of monks and nuns. They used a secret number notation among each other. No one really knew about it until about 20 years ago, when an English Orientalist and historian, David A. King, wrote a book about it. It was used by various different groups for all kinds of medieval ciphers and secret number systems. It was a system that could only write every number from 0 to 9999. It couldn't write any other numbers, but was easily used for dates and page numbers in books.

Hardware Components

SeeedXIAO-RP2040

Custom PCB. Made by SeeedFusion

Keyboard switches (20 pcs)

USB-C to USB-A cable

Homemade keyboard case (birch plywood, screws)

Homemade keycaps (solid oak and birch plywood)

XIAORP2040 Features:

Small size 20x17.5 mm

USB-C

11 pins + power pin

reset button

Power button

RGB LED (user programmable)

Power LED (2 colors)

User LEDs

264KB SRAM and 2MB Flash

Dual-core ARM Cortex M0+ processor, 133MHz

3.3V!

Custom PCB

My design contains four columns and five rows of switches.

This is the first time I ordered a yellow PCB. I think it will be perfect for my wooden mechanical keycaps and housing.

The PCBs are made by SeeedFusion. I ordered five and had two assembled. I think they look nice. The pads are gold plated. Only one of the PCBs has some kind of color dripping off.

software

First, I planned to use PlatformIO with the Arduino framework, but PlatformIO doesn't support this board (XIAO-RP2040) yet. So I used the ArduinoIDE.

There are several programming options:

CircuitPython/MicroPython和Thonny

ArduinoIDE (install XIAORP2040 board)

Raspberry Pi Pico C/C++ SDK

PlatformIO with Arduino framework (not supported yet!)

design concept

The main components are the keycaps, and everything else is as minimal as possible: