byte C;
void setup()
 {
   Serial.begin(115200);
  pinMode(13,OUTPUT);
 }

void loop()
 {
  int n = Serial.available();
  if(n>0)
  {
     C = Serial.read();
     Serial.write(C);
     if(C == '1')
     digitalWrite(13,1);
     if(C == '0')
     digitalWrite(13,0);
  } 

  if(C == '2')
  {
   digitalWrite(13,1);
   delay(500);
   digitalWrite(13,0);
   delay(500);
  }
  if(C == '3')
  {
   digitalWrite(13,1);
   delay(200);
   digitalWrite(13,0);
   delay(200);
  }
  if(C == '4')
  {
   digitalWrite(13,1);
   delay(5);
   digitalWrite(13,0);
   delay(20); 
  } 
 }