How measure the distance using Ultrasonic sensor

Source code.

const int out = 12;

const int in = 13;

void setup() {

  Serial.begin(9600);

  pinMode(in, INPUT);

  pinMode(out, OUTPUT);

}

void loop()

{

  long dur;

  long dis;

  long tocm;

  digitalWrite(out, LOW);

  delayMicroseconds(2);

  digitalWrite(out, HIGH);

  delayMicroseconds(10);

  digitalWrite(out, LOW);

  dur = pulseIn(in, HIGH);

  tocm = microsecondsToCentimeters(dur);

  Serial.println(String(tocm));

  delay(100);

}

long microsecondsToCentimeters(long microseconds)

{

  return microseconds / 29 / 2;

}