let i = 0;

let octave = 0;

​

function setup() {

  osc = new p5.Oscillator('sawtooth');  // Also try sine, triangle, square

  frameRate(3);  // Change the “tempo” if you like

}

​

function draw() {

  if (frameCount == 1)

      osc.start(0);

  const note = notes[i] + (octave + 1) * 12;

  const freq = midiToFreq(note);

  osc.freq(freq);

  i = (i + 1) % notes.length;

}

​

function keyPressed() {

  if (key == 'ArrowUp')

    ++octave;

  else if (key == 'ArrowDown')

    --octave;

}

​