Some keyboard definitions are designed for the RP2040. A simple example is the "onekey" keyboard. You can easily test this on a breadboard with a Raspberry Pi Pico and a simple button, so it's a great way to get started. This guide shows how to build the firmware file yourself, but if you want to take a short cut you can use the uf2 file below:

  • Connect GP4 to one terminal of the button
  • Connect GP5 to the diagonally opposite terminal of the button

Now, open up the terminal/command window, and change to the qmk_firmware directory.

Next, plug in you Pico while holding down the BOOT button so that the RPI-RP2 drive appears.

To build and install the firmware, issue the following command:

cd ~/qmk_firmware
qmk flash -kb handwired/onekey/rp2040 -km default

This will produce a lot of output. The start and end should look something like this:

~/qmk_firmware$ qmk flash -kb handwired/onekey/rp2040 -km default
Ψ Compiling keymap with gmake --jobs=1 handwired/onekey/rp2040:default:flash


QMK Firmware 0.17.5
Making handwired/onekey/rp2040 with keymap default and target flash

arm-none-eabi-gcc (GNU Arm Embedded Toolchain 10-2020-q4-major) 10.2.1 20201103 (release)
Copyright (C) 2020 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Generating: .build/obj_handwired_onekey_rp2040/src/info_config.h                                    [OK]
…[many lines skipped]
Copying handwired_onekey_rp2040_default.uf2 to qmk_firmware folder                                  [OK]

Size after:
   text	   data	    bss	    dec	    hex	filename
      0	  30824	      0	  30824	   7868	handwired_onekey_rp2040_default.uf2

Flashing /media/jepler/RPI-RP2 (RPI-RP2)
Wrote 61952 bytes to /media/jepler/RPI-RP2/NEW.UF2

The Raspberry Pi Pico will automatically restart with the new firmware. Your computer may notify you that a new keyboard has been connected. When you press the button, it will type the letter "a".

To change the key, you can open the file qmk_firmware/keyboards/handwired/onekey/keymaps/default/keymap.c. Just change KC_A to any valid key. For instance, to make it a mute button, use KC_KB_MUTE — generally, this special key will mute or unmute the computer's main sound output. QMK has a Frequently Asked Questions page about keycodes and keymaps as well as a full list of all keycodes, so head over there to learn more about the possibilities.

#include QMK_KEYBOARD_H

const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
    LAYOUT_ortho_1x1(KC_A) // Try changing KC_A to KC_KB_MUTE
};

This guide was first published on Jul 26, 2022. It was last updated on 2022-07-26 16:05:07 -0400.

This page (RP2040 One-Key Keyboard) was last updated on Sep 30, 2022.

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