#include <Bounce2.h>  // Bounce library makes button change detection easy
#include "MIDIUSB.h"
const int channel = 1;

Bounce button1 = Bounce(8, 5);  // 5 = 5 ms debounce time
Bounce button2 = Bounce(9, 5);  // which is appropriate for good
Bounce button3 = Bounce(10, 5);
Bounce button4 = Bounce(11, 5);
                                // quality mechanical pushbuttons
void setup() {
  Serial.begin(115200);
  pinMode( 8 , INPUT_PULLUP );
  pinMode( 9 , INPUT_PULLUP );
  pinMode( 10 , INPUT_PULLUP );
  pinMode( 11 , INPUT_PULLUP );

  pinMode(13, OUTPUT);  // LED
  digitalWrite(13, HIGH);
}

void noteOn(byte channel, byte pitch, byte velocity) {
  midiEventPacket_t noteOn = {0x09, 0x90 | channel, pitch, velocity};
  MidiUSB.sendMIDI(noteOn);
}

void noteOff(byte channel, byte pitch, byte velocity) {
  midiEventPacket_t noteOff = {0x08, 0x80 | channel, pitch, velocity};
  MidiUSB.sendMIDI(noteOff);
}

void loop() {
  button1.update();
  button2.update();
  button3.update();
  button4.update();

  // Note On messages when each button is pressed
  if (button1.fallingEdge()) {
     noteOn(60, 99, channel);  // 60 = C4
     MidiUSB.flush();
  }
  if (button2.fallingEdge()) {
    noteOn(61, 99, channel);  // 61 = C#4
    MidiUSB.flush();
  }
  if (button3.fallingEdge()) {
    noteOn(62, 99, channel);  // 60 = C4
    MidiUSB.flush();
  }
  if (button4.fallingEdge()) {
    noteOn(63, 99, channel);  // 61 = C#4
    MidiUSB.flush();
  }
  // Note Off messages when each button is released
  if (button1.risingEdge()) {
    noteOff(60, 0, channel);  // 60 = C4
    MidiUSB.flush();
  }
  if (button2.risingEdge()) {
    noteOff(61, 0, channel);  // 61 = C#4
    MidiUSB.flush();
  }
  if (button3.risingEdge()) {
    noteOff(62, 0, channel);  // 60 = C4
    MidiUSB.flush();
  }
  if (button4.risingEdge()) {
    noteOff(63, 0, channel);  // 61 = C#4
    MidiUSB.flush();
  }

}