int buttonState;
int lastButtonState = HIGH; // To store the last button state
int buzzerPin = 4;
int frequency = 0; // Starting frequency
const int fadeAmount = 5; // Amount to fade the sound
bool buzzerOn = false; // Buzzer state

void setup() {
  pinMode(2, INPUT_PULLUP); // Set pin 2 as input with pull-up
  pinMode(buzzerPin, OUTPUT); // Set pin 4 as output
}

void loop() {
  buttonState = digitalRead(2); // Read the button state

  // Check for a button press (transition from HIGH to LOW)
  if (buttonState == LOW && lastButtonState == HIGH) {
    buzzerOn = !buzzerOn; // Toggle buzzer state
    frequency = buzzerOn ? 0 : frequency; // Reset frequency if turning off
    delay(50); // Debounce delay
  }

  lastButtonState = buttonState; // Update the last button state for the next loop

  // If the buzzer is on, increase the frequency
  if (buzzerOn) {
    if (frequency < 2000) {
      frequency += fadeAmount; // Increase frequency
      tone(buzzerPin, frequency); // Play tone
      delay(100); // Control speed of fading
    }
  } else {
    // If the buzzer is off, decrease the frequency
    if (frequency > 0) {
      frequency -= fadeAmount; // Decrease frequency
      tone(buzzerPin, frequency); // Play tone
      delay(100); // Control speed of fading
    } else {
      noTone(buzzerPin); // Stop the buzzer if frequency is zero
    }
  }
}