keychron_qmk_firmware/docs/feature_midi.md

MIDI

Usage

First, enable MIDI by adding the following to your rules.mk:

MIDI_ENABLE = yes

There are two MIDI systems in QMK: basic and advanced. With basic MIDI you will only be able to send Note On and Note Off messages using the note keycodes, meaning that keycodes like MI_OCTU and MI_OCTD will not work. Advanced MIDI allows you to do things like octave shifts, channel changes, velocity changes, modulation, and more.

Caveats

MIDI requires 2 USB endpoints and as such may not work on some hardware such as V-USB controllers.

Basic MIDI

To enable basic MIDI, add the following to your config.h:

#define MIDI_BASIC

Advanced MIDI

To enable advanced MIDI, add the following to your config.h:

#define MIDI_ADVANCED

Sending Control Change (CC) Messages

If you're aiming to emulate the features of something like a Launchpad or other MIDI controller you'll need to access the internal MIDI device directly.

Because there are so many possible CC messages, not all of them are implemented as keycodes. Additionally, you might need to provide more than just two values that you would get from a keycode (pressed and released) - for example, the analog values from a fader or a potentiometer. So, you will need to implement custom keycodes if you want to use them in your keymap directly using process_record_user().

For reference of all the possible control code numbers see MIDI Specification

Example code for using Generic On Off Switches as per MIDI Specification.

#include QMK_KEYBOARD_H

extern MidiDevice midi_device;

// MIDI CC codes for generic on/off switches (80, 81, 82, 83)
// Off: 0-63
// On:  64-127

#define MIDI_CC_OFF 0
#define MIDI_CC_ON  127

enum custom_keycodes {
    MIDI_CC80 = SAFE_RANGE,
};

bool process_record_user(uint16_t keycode, keyrecord_t *record) {
    switch (keycode) {
        case MIDI_CC80:
            if (record->event.pressed) {
                midi_send_cc(&midi_device, midi_config.channel, 80, ON);
            } else {
                midi_send_cc(&midi_device, midi_config.channel, 80, OFF);
            }
            return true;
    }
    return true;
};

const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
    LAYOUT(
        // ...
        MIDI_CC80,
        // ...
    )
};

Keycodes

Keycode	Aliases	Description
QK_MIDI_ON	MI_ON	Turn MIDI on
QK_MIDI_OFF	MI_OFF	Turn MIDI off
QK_MIDI_TOGGLE	MI_TOGG	Toggle MIDI enabled
QK_MIDI_NOTE_C_0	MI_C	C octave 0
QK_MIDI_NOTE_C_SHARP_0	MI_Cs, MI_Db	C♯/D♭ octave 0
QK_MIDI_NOTE_D_0	MI_D	D octave 0
QK_MIDI_NOTE_D_SHARP_0	MI_Ds, MI_Eb	D♯/E♭ octave 0
QK_MIDI_NOTE_E_0	MI_E	E octave 0
QK_MIDI_NOTE_F_0	MI_F	F octave 0
QK_MIDI_NOTE_F_SHARP_0	MI_Fs, MI_Gb	F♯/G♭ octave 0
QK_MIDI_NOTE_G_0	MI_G	G octave 0
QK_MIDI_NOTE_G_SHARP_0	MI_Gs, MI_Ab	G♯/A♭ octave 0
QK_MIDI_NOTE_A_0	MI_A	A octave 0
QK_MIDI_NOTE_A_SHARP_0	MI_As, MI_Bb	A♯/B♭ octave 0
QK_MIDI_NOTE_B_0	MI_B	B octave 0
QK_MIDI_NOTE_C_1	MI_C1	C octave 1
QK_MIDI_NOTE_C_SHARP_1	MI_Cs1, MI_Db1	C♯/D♭ octave 1
QK_MIDI_NOTE_D_1	MI_D1	D octave 1
QK_MIDI_NOTE_D_SHARP_1	MI_Ds1, MI_Eb1	D♯/E♭ octave 1
QK_MIDI_NOTE_E_1	MI_E1	E octave 1
QK_MIDI_NOTE_F_1	MI_F1	F octave 1
QK_MIDI_NOTE_F_SHARP_1	MI_Fs1, MI_Gb1	F♯/G♭ octave 1
QK_MIDI_NOTE_G_1	MI_G1	G octave 1
QK_MIDI_NOTE_G_SHARP_1	MI_Gs1, MI_Ab1	G♯/A♭ octave 1
QK_MIDI_NOTE_A_1	MI_A1	A octave 1
QK_MIDI_NOTE_A_SHARP_1	MI_As1, MI_Bb1	A♯/B♭ octave 1
QK_MIDI_NOTE_B_1	MI_B1	B octave 1
QK_MIDI_NOTE_C_2	MI_C2	C octave 2
QK_MIDI_NOTE_C_SHARP_2	MI_Cs2, MI_Db2	C♯/D♭ octave 2
QK_MIDI_NOTE_D_2	MI_D2	D octave 2
QK_MIDI_NOTE_D_SHARP_2	MI_Ds2, MI_Eb2	D♯/E♭ octave 2
QK_MIDI_NOTE_E_2	MI_E2	E octave 2
QK_MIDI_NOTE_F_2	MI_F2	F octave 2
QK_MIDI_NOTE_F_SHARP_2	MI_Fs2, MI_Gb2	F♯/G♭ octave 2
QK_MIDI_NOTE_G_2	MI_G2	G octave 2
QK_MIDI_NOTE_G_SHARP_2	MI_Gs2, MI_Ab2	G♯/A♭ octave 2
QK_MIDI_NOTE_A_2	MI_A2	A octave 2
QK_MIDI_NOTE_A_SHARP_2	MI_As2, MI_Bb2	A♯/B♭ octave 2
QK_MIDI_NOTE_B_2	MI_B2	B octave 2
QK_MIDI_NOTE_C_3	MI_C3	C octave 3
QK_MIDI_NOTE_C_SHARP_3	MI_Cs3, MI_Db3	C♯/D♭ octave 3
QK_MIDI_NOTE_D_3	MI_D3	D octave 3
QK_MIDI_NOTE_D_SHARP_3	MI_Ds3, MI_Eb3	D♯/E♭ octave 3
QK_MIDI_NOTE_E_3	MI_E3	E octave 3
QK_MIDI_NOTE_F_3	MI_F3	F octave 3
QK_MIDI_NOTE_F_SHARP_3	MI_Fs3, MI_Gb3	F♯/G♭ octave 3
QK_MIDI_NOTE_G_3	MI_G3	G octave 3
QK_MIDI_NOTE_G_SHARP_3	MI_Gs3, MI_Ab3	G♯/A♭ octave 3
QK_MIDI_NOTE_A_3	MI_A3	A octave 3
QK_MIDI_NOTE_A_SHARP_3	MI_As3, MI_Bb3	A♯/B♭ octave 3
QK_MIDI_NOTE_B_3	MI_B3	B octave 3
QK_MIDI_NOTE_C_4	MI_C4	C octave 4
QK_MIDI_NOTE_C_SHARP_4	MI_Cs4, MI_Db4	C♯/D♭ octave 4
QK_MIDI_NOTE_D_4	MI_D4	D octave 4
QK_MIDI_NOTE_D_SHARP_4	MI_Ds4, MI_Eb4	D♯/E♭ octave 4
QK_MIDI_NOTE_E_4	MI_E4	E octave 4
QK_MIDI_NOTE_F_4	MI_F4	F octave 4
QK_MIDI_NOTE_F_SHARP_4	MI_Fs4, MI_Gb4	F♯/G♭ octave 4
QK_MIDI_NOTE_G_4	MI_G4	G octave 4
QK_MIDI_NOTE_G_SHARP_4	MI_Gs4, MI_Ab4	G♯/A♭ octave 4
QK_MIDI_NOTE_A_4	MI_A4	A octave 4
QK_MIDI_NOTE_A_SHARP_4	MI_As4, MI_Bb4	A♯/B♭ octave 4
QK_MIDI_NOTE_B_4	MI_B4	B octave 4
QK_MIDI_NOTE_C_5	MI_C5	C octave 5
QK_MIDI_NOTE_C_SHARP_5	MI_Cs5, MI_Db5	C♯/D♭ octave 5
QK_MIDI_NOTE_D_5	MI_D5	D octave 5
QK_MIDI_NOTE_D_SHARP_5	MI_Ds5, MI_Eb5	D♯/E♭ octave 5
QK_MIDI_NOTE_E_5	MI_E5	E octave 5
QK_MIDI_NOTE_F_5	MI_F5	F octave 5
QK_MIDI_NOTE_F_SHARP_5	MI_Fs5, MI_Gb5	F♯/G♭ octave 5
QK_MIDI_NOTE_G_5	MI_G5	G octave 5
QK_MIDI_NOTE_G_SHARP_5	MI_Gs5, MI_Ab5	G♯/A♭ octave 5
QK_MIDI_NOTE_A_5	MI_A5	A octave 5
QK_MIDI_NOTE_A_SHARP_5	MI_As5, MI_Bb5	A♯/B♭ octave 5
QK_MIDI_NOTE_B_5	MI_B5	B octave 5
QK_MIDI_OCTAVE_N2	MI_OCN2	Set octave to -2
QK_MIDI_OCTAVE_N1	MI_OCN1	Set octave to -1
QK_MIDI_OCTAVE_0	MI_OC0	Set octave to 0
QK_MIDI_OCTAVE_1	MI_OC1	Set octave to 1
QK_MIDI_OCTAVE_2	MI_OC2	Set octave to 2
QK_MIDI_OCTAVE_3	MI_OC3	Set octave to 3
QK_MIDI_OCTAVE_4	MI_OC4	Set octave to 4
QK_MIDI_OCTAVE_5	MI_OC5	Set octave to 5
QK_MIDI_OCTAVE_6	MI_OC6	Set octave to 6
QK_MIDI_OCTAVE_7	MI_OC7	Set octave to 7
QK_MIDI_OCTAVE_DOWN	MI_OCTD	Move down an octave
QK_MIDI_OCTAVE_UP	MI_OCTU	Move up an octave
QK_MIDI_TRANSPOSE_N6	MI_TRN6	Set transposition to -6 semitones
QK_MIDI_TRANSPOSE_N5	MI_TRN5	Set transposition to -5 semitones
QK_MIDI_TRANSPOSE_N4	MI_TRN4	Set transposition to -4 semitones
QK_MIDI_TRANSPOSE_N3	MI_TRN3	Set transposition to -3 semitones
QK_MIDI_TRANSPOSE_N2	MI_TRN2	Set transposition to -2 semitones
QK_MIDI_TRANSPOSE_N1	MI_TRN1	Set transposition to -1 semitone
QK_MIDI_TRANSPOSE_0	MI_TR0	No transposition
QK_MIDI_TRANSPOSE_1	MI_TR1	Set transposition to +1 semitone
QK_MIDI_TRANSPOSE_2	MI_TR2	Set transposition to +2 semitones
QK_MIDI_TRANSPOSE_3	MI_TR3	Set transposition to +3 semitones
QK_MIDI_TRANSPOSE_4	MI_TR4	Set transposition to +4 semitones
QK_MIDI_TRANSPOSE_5	MI_TR5	Set transposition to +5 semitones
QK_MIDI_TRANSPOSE_6	MI_TR6	Set transposition to +6 semitones
QK_MIDI_TRANSPOSE_DOWN	MI_TRSD	Decrease transposition
QK_MIDI_TRANSPOSE_UP	MI_TRSU	Increase transposition
QK_MIDI_VELOCITY_0	MI_VL0	Set velocity to 0
QK_MIDI_VELOCITY_1	MI_VL1	Set velocity to 12
QK_MIDI_VELOCITY_2	MI_VL2	Set velocity to 25
QK_MIDI_VELOCITY_3	MI_VL3	Set velocity to 38
QK_MIDI_VELOCITY_4	MI_VL4	Set velocity to 51
QK_MIDI_VELOCITY_5	MI_VL5	Set velocity to 64
QK_MIDI_VELOCITY_6	MI_VL6	Set velocity to 76
QK_MIDI_VELOCITY_7	MI_VL7	Set velocity to 89
QK_MIDI_VELOCITY_8	MI_VL8	Set velocity to 102
QK_MIDI_VELOCITY_9	MI_VL9	Set velocity to 114
QK_MIDI_VELOCITY_10	MI_VL10	Set velocity to 127
QK_MIDI_VELOCITY_DOWN	MI_VELD	Decrease velocity
QK_MIDI_VELOCITY_UP	MI_VELU	Increase velocity
QK_MIDI_CHANNEL_1	MI_CH1	Set channel to 1
QK_MIDI_CHANNEL_2	MI_CH2	Set channel to 2
QK_MIDI_CHANNEL_3	MI_CH3	Set channel to 3
QK_MIDI_CHANNEL_4	MI_CH4	Set channel to 4
QK_MIDI_CHANNEL_5	MI_CH5	Set channel to 5
QK_MIDI_CHANNEL_6	MI_CH6	Set channel to 6
QK_MIDI_CHANNEL_7	MI_CH7	Set channel to 7
QK_MIDI_CHANNEL_8	MI_CH8	Set channel to 8
QK_MIDI_CHANNEL_9	MI_CH9	Set channel to 9
QK_MIDI_CHANNEL_10	MI_CH10	Set channel to 10
QK_MIDI_CHANNEL_11	MI_CH11	Set channel to 11
QK_MIDI_CHANNEL_12	MI_CH12	Set channel to 12
QK_MIDI_CHANNEL_13	MI_CH13	Set channel to 13
QK_MIDI_CHANNEL_14	MI_CH14	Set channel to 14
QK_MIDI_CHANNEL_15	MI_CH15	Set channel to 15
QK_MIDI_CHANNEL_16	MI_CH16	Set channel to 16
QK_MIDI_CHANNEL_DOWN	MI_CHND	Decrease channel
QK_MIDI_CHANNEL_UP	MI_CHNU	Increase channel
QK_MIDI_ALL_NOTES_OFF	MI_AOFF	Stop all notes
QK_MIDI_SUSTAIN	MI_SUST	Sustain
QK_MIDI_PORTAMENTO	MI_PORT	Portmento
QK_MIDI_SOSTENUTO	MI_SOST	Sostenuto
QK_MIDI_SOFT	MI_SOFT	Soft Pedal
QK_MIDI_LEGATO	MI_LEG	Legato
QK_MIDI_MODULATION	MI_MOD	Modulation
QK_MIDI_MODULATION_SPEED_DOWN	MI_MODD	Decrease modulation speed
QK_MIDI_MODULATION_SPEED_UP	MI_MODU	Increase modulation speed
QK_MIDI_PITCH_BEND_DOWN	MI_BNDD	Bend pitch down
QK_MIDI_PITCH_BEND_UP	MI_BNDU	Bend pitch up

Configuration

Certain values are stored in the midi_config struct. This configuration is not persisted to EEPROM. By default, these values are:

Configuration	Value	Comments
Octave	4	Corresponds to MI_OC2
Transposition	0
Velocity	127
Channel	0
Modulation Interval	8

For the above, the MI_C keycode will produce a C3 (note number 48), and so on.

References

MIDI Specification

• MIDI.org
• CMU MIDI Programmer's Reference

QMK C Files

• quantum/process_keycode/process_midi.c
• quantum/quantum_keycodes.h
• tmk_core/protocol/midi.h
• tmk_core/protocol/midi.c
• tmk_core/protocol/qmk_midi.c
• tmk_core/protocol/midi_device.h