const int trigPin = 13; 
const int echoPin = 12;
const int BuzerPin= 9;
const int led1= 10; 

long duration;
float distance;

void setup() {
    pinMode(trigPin, OUTPUT);
    pinMode(echoPin, INPUT);
    pinMode(led1, OUTPUT);
    Serial.begin(9600);
}

void loop() {
    // Trigger the sensor
    digitalWrite(trigPin, LOW);
    delayMicroseconds(2);
    digitalWrite(trigPin, HIGH);
    delayMicroseconds(10);
    digitalWrite(trigPin, LOW);

    // Read echo
    duration = pulseIn(echoPin, HIGH);
    distance = duration * 0.034 / 2;

    // Control buzzer + LED
    if (distance >0 && distance < 10) {
        tone(BuzerPin, 1000);  // 1kHz sound
        digitalWrite(led1, HIGH);
    } 
    else {
        noTone(BuzerPin);      // stop sound
        digitalWrite(led1, LOW);
    }

    // Print distance
    Serial.print("Distance: ");
    Serial.print(distance);
    Serial.println(" cm");

    delay(500);
}