const int trigP=13;
const int echoP=12;

long duration;
int distance;

void setup(){
  pinMode(trigP,OUTPUT);
  pinMode(echoP,INPUT);
  Serial.begin(9600); 
}

void loop() { 
  digitalWrite(trigP,LOW);
  delayMicroseconds(2);
  digitalWrite(trigP,HIGH);
  delayMicroseconds(10);
  digitalWrite(trigP,LOW);
  duration=pulseIn(echoP,HIGH);
  distance=duration*0.034/2;
  Serial.print("Distance=");
  Serial.println(distance);
  delay(500);
}