#define trigPin 8
#define echoPin 9
#define redLED 6
#define buzzerPin 5

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

void loop() {
    long duration, distance;

    digitalWrite(trigPin, LOW);
    delayMicroseconds(2);
    digitalWrite(trigPin, HIGH);
    delayMicroseconds(10);
    digitalWrite(trigPin, LOW);


    duration = pulseIn(echoPin, HIGH);

    distance = duration * 0.034 / 2;
    Serial.print("Distance: ");
    Serial.print(distance);
    Serial.println(" cm");

    if (distance <= 16) {
         digitalWrite(redLED, LOW);
         digitalWrite(buzzerPin, HIGH);
        delay(500);
        digitalWrite(buzzerPin, LOW);
    }
    else if (distance > 16 ) {
        digitalWrite(redLED, HIGH);
        digitalWrite(buzzerPin, LOW);
    }
}