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);

}