void setup() {
  Serial.begin(115200);
  Serial.println("Hello, ESP32!");

  pinMode(14, OUTPUT);
  pinMode(12, OUTPUT);
  pinMode(13, OUTPUT);
  pinMode(15, OUTPUT);
 
}

void loop() 
{
 digitalWrite(14, HIGH);
 tone(15,450);
 delay(5000);
 digitalWrite(14, LOW);

 digitalWrite(12, HIGH);
 tone(15,750);
 delay(5000);
 digitalWrite(12, LOW);

  digitalWrite(13, HIGH);
 tone(15,950);
 delay(5000);
 digitalWrite(13, LOW);
}