const int trigPin = 11;
const int echoPin = 10;

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

}

void loop() {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(4);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  long t = pulseIn(echoPin, HIGH);
  long cm = t / 29 / 2;
  Serial.println("Distance=");
  Serial.println(cm);
  delay(500);
}