Peter's keyboard firmware (QMK)
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Your keyboard can make sounds! If you’ve got a Planck, Preonic, or basically any AVR keyboard that allows access to certain PWM-capable pins, you can hook up a simple speaker and make it beep. You can use those beeps to indicate layer transitions, modifiers, special keys, or just to play some funky 8bit tunes.

Up to two simultaneous audio voices are supported, one driven by timer 1 and another driven by timer 3. The following pins can be defined as audio outputs in config.h:

Timer 1: #define B5_AUDIO #define B6_AUDIO #define B7_AUDIO

Timer 3: #define C4_AUDIO #define C5_AUDIO #define C6_AUDIO

If you add AUDIO_ENABLE = yes to your, there’s a couple different sounds that will automatically be enabled without any other configuration:

STARTUP_SONG // plays when the keyboard starts up (audio.c)
GOODBYE_SONG // plays when you press the RESET key (quantum.c)
AG_NORM_SONG // plays when you press AG_NORM (quantum.c)
AG_SWAP_SONG // plays when you press AG_SWAP (quantum.c)
MUSIC_ON_SONG // plays when music mode is activated (process_music.c)
MUSIC_OFF_SONG // plays when music mode is deactivated (process_music.c)
CHROMATIC_SONG // plays when the chromatic music mode is selected (process_music.c)
GUITAR_SONG // plays when the guitar music mode is selected (process_music.c)
VIOLIN_SONG // plays when the violin music mode is selected (process_music.c)
MAJOR_SONG // plays when the major music mode is selected (process_music.c)

You can override the default songs by doing something like this in your config.h:


A full list of sounds can be found in quantum/audio/song_list.h - feel free to add your own to this list! All available notes can be seen in quantum/audio/musical_notes.h.

To play a custom sound at a particular time, you can define a song like this (near the top of the file):

float my_song[][2] = SONG(QWERTY_SOUND);

And then play your song like this:


Alternatively, you can play it in a loop like this:


It’s advised that you wrap all audio features in #ifdef AUDIO_ENABLE / #endif to avoid causing problems when audio isn’t built into the keyboard.

The available keycodes for audio are:

  • AU_ON - Turn Audio Feature on
  • AU_OFF - Turn Audio Feature off
  • AU_TOG - Toggle Audio Feature state

!> These keycodes turn all of the audio functionality on and off. Turning it off means that audio feedback, audio clicky, music mode, etc. are disabled, completely.

ARM Audio Volume

For ARM devices, you can adjust the DAC sample values. If your board is too loud for you or your coworkers, you can set the max using DAC_SAMPLE_MAX in your config.h:

#define DAC_SAMPLE_MAX 65535U

Music Mode

The music mode maps your columns to a chromatic scale, and your rows to octaves. This works best with ortholinear keyboards, but can be made to work with others. All keycodes less than 0xFF get blocked, so you won’t type while playing notes - if you have special keys/mods, those will still work. A work-around for this is to jump to a different layer with KC_NOs before (or after) enabling music mode.

Recording is experimental due to some memory issues - if you experience some weird behavior, unplugging/replugging your keyboard will fix things.

Keycodes available:

  • MU_ON - Turn music mode on
  • MU_OFF - Turn music mode off
  • MU_TOG - Toggle music mode
  • MU_MOD - Cycle through the music modes:
    • CHROMATIC_MODE - Chromatic scale, row changes the octave
    • GUITAR_MODE - Chromatic scale, but the row changes the string (+5 st)
    • VIOLIN_MODE - Chromatic scale, but the row changes the string (+7 st)
    • MAJOR_MODE - Major scale

In music mode, the following keycodes work differently, and don’t pass through:

  • LCTL - start a recording
  • LALT - stop recording/stop playing
  • LGUI - play recording
  • KC_UP - speed-up playback
  • KC_DOWN - slow-down playback

The pitch standard (PITCH_STANDARD_A) is 440.0f by default - to change this, add something like this to your config.h:

#define PITCH_STANDARD_A 432.0f

You can completely disable Music Mode as well. This is useful, if you’re pressed for space on your controller. To disable it, add this to your config.h:


Music Mask

By default, MUSIC_MASK is set to keycode < 0xFF which means keycodes less than 0xFF are turned into notes, and don’t output anything. You can change this by defining this in your config.h like this:

#define MUSIC_MASK keycode != KC_NO

Which will capture all keycodes - be careful, this will get you stuck in music mode until you restart your keyboard!

For a more advanced way to control which keycodes should still be processed, you can use music_mask_kb(keycode) in <keyboard>.c and music_mask_user(keycode) in your keymap.c:

bool music_mask_user(uint16_t keycode) {
  switch (keycode) {
    case RAISE:
    case LOWER:
      return false;
      return true;

Things that return false are not part of the mask, and are always processed.

Music Map

By default, the Music Mode uses the columns and row to determine the scale for the keys. For a board that uses a rectangular matrix that matches the keyboard layout, this is just fine. However, for boards that use a more complicated matrix (such as the Planck Rev6, or many split keyboards) this would result in a very skewed experience.

However, the Music Map option allows you to remap the scaling for the music mode, so it fits the layout, and is more natural.

To enable this feature, add #define MUSIC_MAP to your config.h file, and then you will want to add a uint8_t music_map to your keyboard’s c file, or your keymap.c.

const uint8_t music_map[MATRIX_ROWS][MATRIX_COLS] = LAYOUT_ortho_4x12(
	36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47,
	24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35,
	12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,
	 0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11

You will want to use whichever LAYOUT macro that your keyboard uses here. This maps it to the correct key location. Start in the bottom left of the keyboard layout, and move to the right, and then upwards. Fill in all the entries until you have a complete matrix.

You can look at the Planck Keyboard as an example of how to implement this.

Audio Click

This adds a click sound each time you hit a button, to simulate click sounds from the keyboard. And the sounds are slightly different for each keypress, so it doesn’t sound like a single long note, if you type rapidly.

  • CK_TOGG - Toggles the status (will play sound if enabled)
  • CK_ON - Turns on Audio Click (plays sound)
  • CK_OFF - Turns off Audio Click (doesn’t play sound)
  • CK_RST - Resets the frequency to the default state (plays sound at default frequency)
  • CK_UP - Increases the frequency of the clicks (plays sound at new frequency)
  • CK_DOWN - Decreases the frequency of the clicks (plays sound at new frequency)

The feature is disabled by default, to save space. To enable it, add this to your config.h:


You can configure the default, min and max frequencies, the stepping and built in randomness by defining these values:

Option Default Value Description
AUDIO_CLICKY_FREQ_DEFAULT 440.0f Sets the default/starting audio frequency for the clicky sounds.
AUDIO_CLICKY_FREQ_MIN 65.0f Sets the lowest frequency (under 60f are a bit buggy).
AUDIO_CLICKY_FREQ_MAX 1500.0f Sets the the highest frequency. Too high may result in coworkers attacking you.
AUDIO_CLICKY_FREQ_FACTOR 1.18921f Sets the stepping of UP/DOWN key codes.
AUDIO_CLICKY_FREQ_RANDOMNESS 0.05f Sets a factor of randomness for the clicks, Setting this to 0f will make each click identical, and 1.0f will make this sound much like the 90’s computer screen scrolling/typing effect.

MIDI Functionality

This is still a WIP, but check out quantum/process_keycode/process_midi.c to see what’s happening. Enable from the Makefile.

Audio Keycodes

Key Aliases Description
AU_ON Audio mode on
AU_OFF Audio mode off
AU_TOG Toggles Audio mode
CLICKY_TOGGLE CK_TOGG Toggles Audio clicky mode
CLICKY_UP CK_UP Increases frequency of the clicks
CLICKY_DOWN CK_DOWN Decreases frequency of the clicks
CLICKY_RESET CK_RST Resets frequency to default
MU_ON Turns on Music Mode
MU_OFF Turns off Music Mode
MU_TOG Toggles Music Mode
MU_MOD Cycles through the music modes