const int TRIG_PIN = 2;
const int ECHO_PIN = 4;
const int RELAY_PIN = 15;
long duration,distance;
void setup()
 {
  // put your setup code here, to run once:
  Serial.begin(115200);
  pinMode(TRIG_PIN,OUTPUT);
  pinMode(RELAY_PIN,OUTPUT);
  pinMode(ECHO_PIN,INPUT );
}
void loop() {
  distance = getDistanceInCentimeters();
  if (distance<=100)
  digitalWrite(RELAY_PIN, HIGH);
  else
  digitalWrite(RELAY_PIN,LOW);
  Serial.println("Distance = "+ String(distance));
  delay(1000);
}
long getDistanceInCentimeters() {
  digitalWrite(TRIG_PIN,LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN,HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN,LOW);
  duration = pulseIn(ECHO_PIN,HIGH);
  return (duration *0.034 / 2) +1;
}
  // put your main code here, to run repeatedly:
   // this speeds up the simulation