int trig =12;
int echo = 8;
float duration,distance;
void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  pinMode(trig, OUTPUT);
  pinMode(echo, INPUT);
  pinMode(7, OUTPUT);

}

void loop() {
// put your main code here, to run repeatedly:
  digitalWrite(trig, LOW);
  digitalWrite(trig, HIGH);
  delay(2000);

  digitalWrite(trig, LOW);
  duration = pulseIn(echo, HIGH);
  distance = (duration * 0.0343)/2;
  if(distance<50){
    digitalWrite(7, HIGH);
  }
  else{
    digitalWrite(7,LOW);
  }

  Serial.print("DISTANCE IS ");
  Serial.print(distance);
  Serial.println("cm");

}