qmk-firmware/docs/feature_audio.md

Audio

Your keyboard can make sounds! If you've got a Planck, Preonic, or basically any AVR keyboard that allows access to the C6 or B5 port (#define C6_AUDIO and/or #define B5_AUDIO), 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.

If you add AUDIO_ENABLE = yes to your rules.mk, 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:

#ifdef AUDIO_ENABLE
  #define STARTUP_SONG SONG(STARTUP_SOUND)
#endif

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:

PLAY_SONG(my_song);

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

PLAY_LOOP(my_song);

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.

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

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!

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:

#define NO_MUSIC_MODE

MIDI Functionality

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