In this project, we will create a simple tone generator that emits a tone in the audible range between 20Hz and 20KHz.

Connect a Buzzer Brick to Port 2C, and a Rotary Switch Brick to Port 2A and 4A.

Run the following code in the Web IDE:

var buzzer = new Buzzer(PORT_2C);
var rsw = new RotarySwitch(PORT_2A, PORT_4A); 
var playing = false;
var freq = 4000; // Starting frequency
while(true) { 
  // This lets the target frequency be adjusted in increments of 100
  var newFreq = freq + (rsw.getDelta() * 100);
  // This limits the target frequency to between 20Hz and 20,000Hz
  newFreq = Math.max(20, Math.min(newFreq, 20000));
  // If there are any changes, print out the new parameters to console so that we can see what's going on
  var clicked = rsw.clicked();
  if (newFreq != freq || clicked) {
    if (clicked) playing = !playing;
    freq = newFreq;
    print('Frequency = ' + freq + 'Hz' + (playing ? ' (playing)' : ' (not playing)'));
  // Start playing a tone in the target frequency, or stop the playing
  if (playing) buzzer.playTone(freq); else buzzer.stop();

When you click on the button, the buzzer will start playing a tone in 4KHz. Turning the knob will adjust the frequency up or down. Clicking the button again will stop the tone.