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