int speakerPin = 9;
int frequency = 1000;  // Starting frequency of 1000Hz

void setup() {
  pinMode(speakerPin, OUTPUT);
}

void loop() {
  for (frequency = 1000; frequency <= 5000; frequency += 100) {
    tone(speakerPin, frequency);  // Generate tone using PWM
    delay(200);
  }

  delay(1000);

  for (frequency = 5000; frequency >= 1000; frequency -= 100) {
    tone(speakerPin, frequency);
    delay(200);
  }

  noTone(speakerPin);  // Stop generating sound
  delay(1000);
}