Arduino Fire Alarm

/********************************************
 *            Arduino Fire Alarm            *
 *             learnelectronics             *
 *              Sept 11, 2023               *
 * https://www.youtube.com/learnelectronics *
 *           [email protected]          *
 ********************************************/







const int inputPin = 2;
const int outputPin1 = 4;
const int outputPin2 = 3;

bool previousState = HIGH;
bool currentState;
bool tonePlaying = false;
bool toneState = LOW;

void setup() {
  pinMode(inputPin, INPUT);
  pinMode(outputPin1, OUTPUT);
  pinMode(outputPin2, OUTPUT);
  digitalWrite(outputPin1, LOW);  // Start with pin 4 LOW
  digitalWrite(outputPin2, LOW);  // Start with pin 3 LOW
}

void loop() {
  currentState = digitalRead(inputPin);

  if (currentState == LOW && previousState == HIGH) {
    digitalWrite(outputPin1, HIGH);  // Set digital pin 4 to HIGH
    if (!tonePlaying) {
      tone(outputPin2, 1000);  // Start generating a 1000 Hz tone on pin 3
      tonePlaying = true;
    }
  } else if (currentState == HIGH && previousState == LOW) {
    digitalWrite(outputPin1, LOW);  // Set digital pin 4 to HIGH
    if (tonePlaying) {
      noTone(outputPin2);  // Stop the tone on pin 3
      tonePlaying = false;
    }
  }

  if (tonePlaying) {
    // Alternate the tone state (high/low) every 500 ms
    if (millis() % 1000 < 500) {
      tone(outputPin2, 1000);
    } else {
      noTone(outputPin2);
    }
  }

  previousState = currentState;
}