Ultrasonic Tutorial Code

int trig = 10;
int echo = 9;
int duration;
int distance;

void setup() {
  pinMode(echo, INPUT);
  pinMode(trig, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  digitalWrite(trig, LOW);
  delay(.002);
  digitalWrite(trig, HIGH);
  delay(.01);
  digitalWrite(trig, LOW);
  duration = pulseIn(echo, HIGH); //record the time it takes for the sound to return
  distance = (duration / 2) / 29.1; //convert the time to distance

  Serial.println(distance);
  delay(100);

}