void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  pinMode(12, OUTPUT);
  pinMode(27, INPUT);
  pinMode(17, OUTPUT);
}

void loop() {
  digitalWrite(12, HIGH);
  delay(100);
  digitalWrite(12, LOW);
  float duration =pulseIn(27,HIGH);
  int distance = duration*0.034/2;
  Serial.println(distance);
  if(distance<=200)
  {
    digitalWrite(17, HIGH);
  }
  else{
    digitalWrite(17, LOW);
  }
}