Arduino Ultrasonic sensor

 Connection:

#define trig 2
#define echo 5
void setup() {
  pinMode(trig,OUTPUT);
  pinMode(echo,INPUT);
  Serial.begin(9600);
}

void loop() {
  digitalWrite(trig,LOW);
  delayMicroseconds(2);
  digitalWrite(trig,HIGH);
  delayMicroseconds(10);
  digitalWrite(trig,LOW);

  long t=pulseIn(echo,HIGH);

  long inches=t/74/2;
  long cm=t/29/2;

  Serial.print(inches);
  Serial.print("inches \t ");
  Serial.print(cm);
  Serial.println("cm");
  delay(500);
}