Project 2 - Measuring distance of an object using ultrasonic sensor (HC-SR04)

#define echo 2

#define trig 3

long duration;

int distance;

void setup()

{

  pinMode(trig,OUTPUT);

  pinMode(echo,INPUT);

  Serial.begin(9600);

}

void loop()

{ 

  digitalWrite(trig,LOW);

  delayMicroseconds(8);

  digitalWrite(trig,HIGH);

  delayMicroseconds(40);

  digitalWrite(trig,LOW);

  duration = pulseIn(echo,HIGH);

  distance = duration*0.034/2;

  Serial.print("distance : ");

  Serial.print(distance);

  Serial.println(" cm");

}