void setup() {
  Serial.begin (115200);
   pinMode(11,OUTPUT);  //ขา Trig
   pinMode(12,INPUT);  //ขา Echo
   pinMode(13,OUTPUT); //LED
}

void loop() {
  digitalWrite(11,0);
  delayMicroseconds(2);
  digitalWrite(11,1);
  delayMicroseconds(5);
  digitalWrite(11,0);
  int T = pulseIn (12,1);
  float D = T/29.0/2.0;
  Serial.print (T);
  Serial.print (",");
  Serial.println (D);

  if(D < 10)
  {
    digitalWrite(13,1);
  }
  else if (D < 20)
  {
    digitalWrite(13,1);
     delay (200);
     digitalWrite(13,0);
     delay (200);
  }
  else if (D < 30)
  {
    digitalWrite(13,1);
     delay (400);
     digitalWrite(13,0);
     delay (400);
  }
  else if (D < 30)
  {
     digitalWrite(13,0);
    
  }
  
  delay (100);

  
  
}