#define trigPin 13
#define echoPin 12
#define led 11
void setup()
{
  Serial.begin (9600);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(led, OUTPUT);
}
void loop()
{
  long duration, distance;
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  duration = pulseIn(echoPin, HIGH);
  distance = (duration/2) / 29.1;
  if (distance < 10)
  {
        digitalWrite(led,HIGH);
  }

  else
  {
        digitalWrite(led,LOW);
  }

  Serial.print(distance);
  Serial.println(" cm");
  delay(500);
}