midi_keypad.ino

// Trellis M4 MIDI Keypad CC
// sends 32 notes, pitch bend & a CC from accelerometer tilt over USB MIDI

#include <Adafruit_Sensor.h>
#include <Adafruit_ADXL343.h>
#include <Adafruit_NeoTrellisM4.h>

#define MIDI_CHANNEL     0  // default channel # is 0
// Set the value of first note, C is a good choice. Lowest C is 0.
// 36 is a good default. 48 is a high range. Set to 24 for a bass machine.
#define FIRST_MIDI_NOTE 36

Adafruit_ADXL343 accel = Adafruit_ADXL343(123, &Wire1);

int xCC = 1;  //choose a CC number to control with x axis tilting of the board. 1 is mod wheel, for example.

int last_xbend = 0;
int last_ybend = 0;

Adafruit_NeoTrellisM4 trellis = Adafruit_NeoTrellisM4();

void setup(){
  Serial.begin(115200);
  //while (!Serial);
  Serial.println("MIDI keypad & pitchbend!");
    
  trellis.begin();
  trellis.setBrightness(80);

  // USB MIDI messages sent over the micro B USB port
  Serial.println("Enabling MIDI on USB");
  trellis.enableUSBMIDI(true);
  trellis.setUSBMIDIchannel(MIDI_CHANNEL);
  // UART MIDI messages sent over the 4-pin STEMMA connector (3.3V logic)
  Serial.println("Enabling MIDI on UART");
  trellis.enableUARTMIDI(true);
  trellis.setUARTMIDIchannel(MIDI_CHANNEL);
  
  if(!accel.begin()) {
    Serial.println("No accelerometer found");
    while(1);
  }
}

void loop() {
  // put your main code here, to run repeatedly:
  trellis.tick();

  while (trellis.available()){
    keypadEvent e = trellis.read();
    int key = e.bit.KEY;
    Serial.print("Keypad key: ");    Serial.println(key);
    Serial.print("MIDI note: ");     Serial.println(FIRST_MIDI_NOTE+key);

    if (e.bit.EVENT == KEY_JUST_PRESSED) {
      Serial.println(" pressed\n");
      trellis.setPixelColor(key, 0xFFFFFF);
      trellis.noteOn(FIRST_MIDI_NOTE+key, 64);
    }
    else if (e.bit.EVENT == KEY_JUST_RELEASED) {
      Serial.println(" released\n");
      trellis.setPixelColor(key, 0x0);
      trellis.noteOff(FIRST_MIDI_NOTE+key, 64);
    }
  }

  // Check for accelerometer
  sensors_event_t event;
  accel.getEvent(&event);
  /* Display the results (acceleration is measured in m/s^2) */
  //Serial.print("X: "); Serial.print(event.acceleration.x); Serial.print("  ");
  //Serial.print("Y: "); Serial.print(event.acceleration.y); Serial.print("  ");
  //Serial.print("Z: "); Serial.print(event.acceleration.z); Serial.print("  ");Serial.println("m/s^2 ");
  int xbend = 0;
  int ybend = 0;

  if (abs(event.acceleration.y) < 2.0) {  // 2.0 m/s^2
    // don't make any bend unless they've really started moving it
    ybend = 8192; // 8192 means no bend
  } else {
    if (event.acceleration.y > 0) {
      ybend = ofMap(event.acceleration.y, 2.0, 10.0, 8192, 0, true);  // 2 ~ 10 m/s^2 is downward bend
    } else {
      ybend = ofMap(event.acceleration.y, -2.0, -10.0, 8192, 16383, true);  // -2 ~ -10 m/s^2 is upward bend
    }
  }
  if (ybend != last_ybend) {
    Serial.print("Y pitchbend: "); Serial.println(ybend);
    trellis.pitchBend(ybend);
    last_ybend = ybend;
  }

  if (abs(event.acceleration.x) < 2.0) {  // 2.0 m/s^2
    // don't make any bend unless they've really started moving it
    xbend = 0;
  } else {
    if (event.acceleration.x > 0) {
      xbend = ofMap(event.acceleration.x, 2.0, 10.0, 0, 127, true);  // 2 ~ 10 m/s^2 is upward bend
    } else {
      xbend = ofMap(event.acceleration.x, -2.0, -10.0, 0, 127, true);  // -2 ~ -10 m/s^2 is downward bend
    }
  }
  if (xbend != last_xbend) {
    Serial.print("X mod: "); Serial.println(xbend);
    trellis.controlChange(xCC, xbend);  //xCC is set at top of sketch. e.g., CC 1 is Mod Wheel
    last_xbend = xbend;
  }

  trellis.sendMIDI(); // send any pending MIDI messages

  delay(10);
}



// floating point map
float ofMap(float value, float inputMin, float inputMax, float outputMin, float outputMax, bool clamp) {
    float outVal = ((value - inputMin) / (inputMax - inputMin) * (outputMax - outputMin) + outputMin);

    if (clamp) {
      if (outputMax < outputMin) {
        if (outVal < outputMax)  outVal = outputMax;
        else if (outVal > outputMin)  outVal = outputMin;
      } else {
        if (outVal > outputMax) outVal = outputMax;
        else if (outVal < outputMin)  outVal = outputMin;
      }
    }
    return outVal;

}

// Input a value 0 to 255 to get a color value.
// The colours are a transition r - g - b - back to r.
uint32_t Wheel(byte WheelPos) {
  WheelPos = 255 - WheelPos;
  if(WheelPos < 85) {
    return trellis.Color(255 - WheelPos * 3, 0, WheelPos * 3);
  }
  if(WheelPos < 170) {
    WheelPos -= 85;
    return trellis.Color(0, WheelPos * 3, 255 - WheelPos * 3);
  }
  WheelPos -= 170;
  return trellis.Color(WheelPos * 3, 255 - WheelPos * 3, 0);
}