Passive buzzer scale on pin 12, on an Arduino Uno

// Passive buzzer: a C major scale on pin 12.
//
//   pin 12 -> passive buzzer + , the other leg -> GND
//
// A passive buzzer has no oscillator of its own: it clicks once each time
// the voltage changes. tone() makes pin 12 switch on and off at a frequency,
// and that frequency is the note you hear. Any pin will do, PWM or not.
//
// Each note plays for half a second, then rests for half a second.

const int BUZZER_PIN = 12;

const int NOTES[8] = {262, 294, 330, 349, 392, 440, 494, 523};
const char *NAMES[8] = {"C4", "D4", "E4", "F4", "G4", "A4", "B4", "C5"};

void setup() {
  pinMode(BUZZER_PIN, OUTPUT);
  Serial.begin(9600);
  Serial.println("Mokxi Uno: passive buzzer on pin 12");
}

void loop() {
  for (int i = 0; i < 8; i++) {
    Serial.print(NAMES[i]);
    Serial.print(" ");
    Serial.print(NOTES[i]);
    Serial.println(" Hz");
    tone(BUZZER_PIN, NOTES[i], 500);
    delay(1000);
  }
  delay(1000);
}