const int trigP=13;
const int echoP=4;
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);
}