const int trigPin = 13, echoPin = 12;

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

void loop() {
  digitalWrite(trigPin, LOW);
  digitalWrite(trigPin, HIGH);
  digitalWrite(trigPin, LOW);

  long duration = pulseIn(echoPin, HIGH);  
  float distanceCm = duration * 0.34  /2;

  Serial.print("Distance in CM : ");
  Serial.println(distanceCm);
  delay(1000);
}