opensteno_qmk/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.

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
MI_ON		Turn MIDI on
MI_OFF		Turn MIDI off
MI_TOG		Toggle MIDI enabled
MI_C		C octave 0
MI_Cs	MI_Db	C♯/D♭ octave 0
MI_D		D octave 0
MI_Ds	MI_Eb	D♯/E♭ octave 0
MI_E		E octave 0
MI_F		F octave 0
MI_Fs	MI_Gb	F♯/G♭ octave 0
MI_G		G octave 0
MI_Gs	MI_Gs	G♯/A♭ octave 0
MI_A		A octave 0
MI_As	MI_Bb	A♯/B♭ octave 0
MI_B		B octave 0
MI_C_1		C octave 1
MI_Cs_1	MI_Db_1	C♯/D♭ octave 1
MI_D_1		D octave 1
MI_Ds_1	MI_Eb_1	D♯/E♭ octave 1
MI_E_1		E octave 1
MI_F_1		F octave 1
MI_Fs_1	MI_Gb_1	F♯/G♭ octave 1
MI_G_1		G octave 1
MI_Gs_1	MI_Ab_1	G♯/A♭ octave 1
MI_A_1		A octave 1
MI_As_1	MI_Bb_1	A♯/B♭ octave 1
MI_B_1		B octave 1
MI_C_2		C octave 2
MI_Cs_2	MI_Db_2	C♯/D♭ octave 2
MI_D_2		D octave 2
MI_Ds_2	MI_Eb_2	D♯/E♭ octave 2
MI_E_2		E octave 2
MI_F_2		F octave 2
MI_Fs_2	MI_Gb_2	F♯/G♭ octave 2
MI_G_2		G octave 2
MI_Gs_2	MI_Ab_2	G♯/A♭ octave 2
MI_A_2		A octave 2
MI_As_2	MI_Bb_2	A♯/B♭ octave 2
MI_B_2		B octave 2
MI_C_3		C octave 3
MI_Cs_3	MI_Db_3	C♯/D♭ octave 3
MI_D_3		D octave 3
MI_Ds_3	MI_Eb_3	D♯/E♭ octave 3
MI_E_3		E octave 3
MI_F_3		F octave 3
MI_Fs_3	MI_Gb_3	F♯/G♭ octave 3
MI_G_3		G octave 3
MI_Gs_3	MI_Ab_3	G♯/A♭ octave 3
MI_A_3		A octave 3
MI_As_3	MI_Bb_3	A♯/B♭ octave 3
MI_B_3		B octave 3
MI_C_4		C octave 4
MI_Cs_4	MI_Db_4	C♯/D♭ octave 4
MI_D_4		D octave 4
MI_Ds_4	MI_Eb_4	D♯/E♭ octave 4
MI_E_4		E octave 4
MI_F_4		F octave 4
MI_Fs_4	MI_Gb_4	F♯/G♭ octave 4
MI_G_4		G octave 4
MI_Gs_4	MI_Ab_4	G♯/A♭ octave 4
MI_A_4		A octave 4
MI_As_4	MI_Bb_4	A♯/B♭ octave 4
MI_B_4		B octave 4
MI_C_5		C octave 5
MI_Cs_5	MI_Db_5	C♯/D♭ octave 5
MI_D_5		D octave 5
MI_Ds_5	MI_Eb_5	D♯/E♭ octave 5
MI_E_5		E octave 5
MI_F_5		F octave 5
MI_Fs_5	MI_Gb_5	F♯/G♭ octave 5
MI_G_5		G octave 5
MI_Gs_5	MI_Ab_5	G♯/A♭ octave 5
MI_A_5		A octave 5
MI_As_5	MI_Bb_5	A♯/B♭ octave 5
MI_B_5		B octave 5
MI_OCT_N2		Set octave to -2
MI_OCT_N1		Set octave to -1
MI_OCT_0		Set octave to 0
MI_OCT_1		Set octave to 1
MI_OCT_2		Set octave to 2
MI_OCT_3		Set octave to 3
MI_OCT_4		Set octave to 4
MI_OCT_5		Set octave to 5
MI_OCT_6		Set octave to 6
MI_OCT_7		Set octave to 7
MI_OCTD		Move down an octave
MI_OCTU		Move up an octave
MI_TRNS_N6		Set transposition to -6 semitones
MI_TRNS_N5		Set transposition to -5 semitones
MI_TRNS_N4		Set transposition to -4 semitones
MI_TRNS_N3		Set transposition to -3 semitones
MI_TRNS_N2		Set transposition to -2 semitones
MI_TRNS_N1		Set transposition to -1 semitone
MI_TRNS_0		No transposition
MI_TRNS_1		Set transposition to +1 semitone
MI_TRNS_2		Set transposition to +2 semitones
MI_TRNS_3		Set transposition to +3 semitones
MI_TRNS_4		Set transposition to +4 semitones
MI_TRNS_5		Set transposition to +5 semitones
MI_TRNS_6		Set transposition to +6 semitones
MI_TRNSD		Decrease transposition
MI_TRNSU		Increase transposition
MI_VEL_0		Set velocity to 0
MI_VEL_1		Set velocity to 12
MI_VEL_2		Set velocity to 25
MI_VEL_3		Set velocity to 38
MI_VEL_4		Set velocity to 51
MI_VEL_5		Set velocity to 64
MI_VEL_6		Set velocity to 76
MI_VEL_7		Set velocity to 89
MI_VEL_8		Set velocity to 102
MI_VEL_9		Set velocity to 114
MI_VEL_10		Set velocity to 127
MI_VELD		Decrease velocity
MI_VELU		Increase velocity
MI_CH1		Set channel to 1
MI_CH2		Set channel to 2
MI_CH3		Set channel to 3
MI_CH4		Set channel to 4
MI_CH5		Set channel to 5
MI_CH6		Set channel to 6
MI_CH7		Set channel to 7
MI_CH8		Set channel to 8
MI_CH9		Set channel to 9
MI_CH10		Set channel to 10
MI_CH11		Set channel to 11
MI_CH12		Set channel to 12
MI_CH13		Set channel to 13
MI_CH14		Set channel to 14
MI_CH15		Set channel to 15
MI_CH16		Set channel to 16
MI_CHD		Decrease channel
MI_CHU		Increase channel
MI_ALLOFF		Stop all notes
MI_SUS		Sustain
MI_PORT		Portmento
MI_SOST		Sostenuto
MI_SOFT		Soft Pedal
MI_LEG		Legato
MI_MOD		Modulation
MI_MODSD		Decrease modulation speed
MI_MODSU		Increase modulation speed
MI_BENDD		Bend pitch down
MI_BENDU		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_OCT_2
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