int trigger_pin = 6; 
  int echo_pin = 7;
  float distance;

void setup()
{
	Serial.begin(9600);
	pinMode(trigger_pin, OUTPUT);
	pinMode(echo_pin,INPUT);
}

void loop()
{
	digitalWrite(trigger_pin, HIGH);
	delayMicroseconds(10);
	digitalWrite(trigger_pin, LOW);
  double time = pulseIn(echo_pin, HIGH);
	distance = (0.034 * time) /2;

  Serial.println("Distance= ");
  Serial.println(distance); 
  Serial.print("cm");
  delay(100);
}