Unit MIDI Arduino Tutorial

#include <M5Unified.h>
#include "M5_SAM2695.h"

M5_SAM2695 midi;

static const uint8_t MELODY_CHANNEL = 0;
static const uint8_t DRUM_CHANNEL   = 9;

void showStatus(const char* stage, const char* detail = nullptr) {
    // Show the current demonstration stage on the display.
    M5.Display.fillScreen(TFT_BLACK);
    M5.Display.setTextColor(TFT_WHITE, TFT_BLACK);
    M5.Display.setTextSize(2);
    M5.Display.setCursor(8, 8);
    M5.Display.println("Unit MIDI Test");
    M5.Display.drawFastHLine(8, 32, M5.Display.width() - 16, TFT_DARKGREY);
    M5.Display.setCursor(8, 48);
    M5.Display.setTextColor(TFT_CYAN, TFT_BLACK);
    M5.Display.println(stage);
    if (detail != nullptr) {
        M5.Display.setCursor(8, 82);
        M5.Display.setTextColor(TFT_WHITE, TFT_BLACK);
        M5.Display.println(detail);
    }
}

void playNote(uint8_t channel, uint8_t pitch, uint8_t velocity,
              uint16_t durationMs) {
    // Play one note, or wait for a rest.
    if (pitch == REST) {
        delay(durationMs);
        return;
    }

    midi.setNoteOn(channel, pitch, velocity);
    delay(durationMs);
    midi.setNoteOff(channel, pitch, 0);
}

void playScale() {
    // Play a rising major scale.
    const uint8_t scale[] = {NOTE_C4, NOTE_D4, NOTE_E4, NOTE_F4,
                             NOTE_G4, NOTE_A4, NOTE_B4, NOTE_C5};

    for (uint8_t i = 0; i < sizeof(scale); ++i) {
        playNote(MELODY_CHANNEL, scale[i], 100, 180);
    }
}

void playChord() {
    midi.setNoteOn(MELODY_CHANNEL, NOTE_C4, 90);
    midi.setNoteOn(MELODY_CHANNEL, NOTE_E4, 90);
    midi.setNoteOn(MELODY_CHANNEL, NOTE_G4, 90);
    delay(600);
    midi.setNoteOff(MELODY_CHANNEL, NOTE_C4, 0);
    midi.setNoteOff(MELODY_CHANNEL, NOTE_E4, 0);
    midi.setNoteOff(MELODY_CHANNEL, NOTE_G4, 0);
}

void playDrumPattern() {
    midi.setInstrument(0, DRUM_CHANNEL, SynthDrum);

    for (uint8_t beat = 0; beat < 8; ++beat) {
        midi.setNoteOn(DRUM_CHANNEL, 36, 120);  // Bass drum
        midi.setNoteOn(DRUM_CHANNEL, 42, 90);   // Closed hi-hat
        if ((beat & 0x03) == 2) {
            midi.setNoteOn(DRUM_CHANNEL, 38, 110);  // Snare
        }
        delay(180);
    }
    midi.setAllNotesOff(DRUM_CHANNEL);
}

void configureVoice() {
    midi.setInstrument(0, MELODY_CHANNEL, ElGrdPiano_3);
    midi.setVolume(MELODY_CHANNEL, 105);
    midi.setPan(MELODY_CHANNEL, 64);

    // Program and level are 0..127 values in the MIDI data bytes.
    midi.setReverb(MELODY_CHANNEL, 1, 55, 20);
    midi.setChorus(MELODY_CHANNEL, 1, 35, 18, 12);

    midi.setEqualizer(MELODY_CHANNEL,
                       64,  // low band
                       60,  // medium-low band
                       68,  // medium-high band
                       64,  // high band
                       45,  // low frequency
                       55,  // medium-low frequency
                       70,  // medium-high frequency
                       80); // high frequency

    // 64 is the documented neutral/default tuning value.
    midi.setTuning(MELODY_CHANNEL, 64, 64);
    midi.setVibrate(MELODY_CHANNEL, 45, 30, 10);
    midi.setTvf(MELODY_CHANNEL, 90, 35);
    midi.setEnvelope(MELODY_CHANNEL, 20, 75, 45);

    midi.setPitchBendRange(MELODY_CHANNEL, 2);
    midi.setMasterVolume(110);
}

void demonstrateVoiceShape() {
    // A sustained midi voice makes the filter, envelope and vibrato changes
    // easier to hear than a short piano note.
    midi.setInstrument(0, MELODY_CHANNEL, Lead2Sawtooth);
    midi.setVolume(MELODY_CHANNEL, 110);
    midi.setPan(MELODY_CHANNEL, 64);
    midi.setTvf(MELODY_CHANNEL, 48, 100);
    midi.setEnvelope(MELODY_CHANNEL, 70, 45, 90);
    midi.setVibrate(MELODY_CHANNEL, 80, 85, 8);

    playNote(MELODY_CHANNEL, NOTE_C4, 105, 850);
    playNote(MELODY_CHANNEL, NOTE_G4, 105, 850);

    // Open the filter and shorten the envelope for a second comparison.
    midi.setTvf(MELODY_CHANNEL, 115, 35);
    midi.setEnvelope(MELODY_CHANNEL, 10, 85, 35);
    playNote(MELODY_CHANNEL, NOTE_C5, 105, 850);
}

void demonstrateEffects() {
    // Use a sustained chord so reverb and chorus tails remain audible.
    midi.setInstrument(0, MELODY_CHANNEL, StringEnsemble1);
    midi.setVolume(MELODY_CHANNEL, 115);
    midi.setReverb(MELODY_CHANNEL, 1, 110, 70);
    midi.setChorus(MELODY_CHANNEL, 1, 100, 70, 50);
    midi.setEqualizer(MELODY_CHANNEL, 95, 45, 75, 90, 35, 55, 80, 100);

    midi.setNoteOn(MELODY_CHANNEL, NOTE_C4, 95);
    midi.setNoteOn(MELODY_CHANNEL, NOTE_E4, 95);
    midi.setNoteOn(MELODY_CHANNEL, NOTE_G4, 95);
    delay(900);
    midi.setNoteOff(MELODY_CHANNEL, NOTE_C4, 0);
    midi.setNoteOff(MELODY_CHANNEL, NOTE_E4, 0);
    midi.setNoteOff(MELODY_CHANNEL, NOTE_G4, 0);
    delay(1200);  // Leave time for the effect tails.

    // Tuning is audible when compared with the neutral value.
    midi.setTuning(MELODY_CHANNEL, 64, 72);
    playNote(MELODY_CHANNEL, NOTE_A4, 105, 650);
    midi.setTuning(MELODY_CHANNEL, 64, 64);
}

void demonstratePitchBend() {
    midi.setNoteOn(MELODY_CHANNEL, NOTE_C4, 110);

    // setPitchBend() maps its input from 0..1023 to the MIDI 14-bit range.
    midi.setPitchBend(MELODY_CHANNEL, 0);
    delay(250);
    midi.setPitchBend(MELODY_CHANNEL, 512);
    delay(250);
    midi.setPitchBend(MELODY_CHANNEL, 1023);
    delay(250);
    midi.setPitchBend(MELODY_CHANNEL, 512);
    midi.setNoteOff(MELODY_CHANNEL, NOTE_C4, 0);
}

void demonstrateModWheel() {
    // Configure the modulation-wheel destinations and depths.
    midi.setModWheel(MELODY_CHANNEL,
                      20,  // pitch
                      30,  // TVF cutoff
                      40,  // amplitude
                      50,  // rate
                      25,  // pitch depth
                      35,  // TVF depth
                      45); // TVA depth
}

void setup() {
    // Initialize CoreS3 and the MIDI serial port.
    M5.begin();
    M5.Display.setTextWrap(true);
    showStatus("Starting", "MIDI 31250 baud");

    Serial.begin(115200);
    Serial.println("Unit MIDI comprehensive example");

    // Change UART pins here if needed.
    midi.begin(&Serial2, MIDI_BAUD, 18, 17);
}

void loop() {
    // Repeat the complete feature demonstration.
    Serial.printf("\n--- Unit MIDI demo cycle ---\n");

    showStatus("Reset", "Reapply voice settings");
    midi.reset();
    delay(100);
    configureVoice();
    demonstrateModWheel();

    showStatus("Scale + chord", "Channel 1");
    Serial.println("Scale and chord");
    playScale();
    playChord();

    showStatus("Pitch bend", "C4: low -> high");
    Serial.println("Pitch bend");
    demonstratePitchBend();

    showStatus("Voice shaping", "Filter/envelope/vibrato");
    Serial.println("Filter, envelope and vibrato");
    demonstrateVoiceShape();

    showStatus("Effects", "Reverb/chorus/EQ");
    Serial.println("Reverb, chorus, equalizer and tuning");
    demonstrateEffects();

    showStatus("Drums", "Channel 10");
    Serial.println("Drums");
    // Configure drums before sending drum notes.
    midi.setAllInstrumentDrums();
    playDrumPattern();

    midi.setAllNotesOff(MELODY_CHANNEL);
    midi.setAllNotesOff(DRUM_CHANNEL);

    showStatus("Complete", "Next cycle in 1.5 s");
    delay(1500);
}