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);  
  
}