char C;

void setup() 
{
  Serial.begin(115200);
  pinMode(13,OUTPUT);
} 
void loop()
{
  int n = Serial.available();
  if (n>0)
  {
    C = Serial.read();
    if(C == '0')
    {
      digitalWrite(13,0); // LED off
    }
      if(C == '1')
    {
      digitalWrite(13,01); 
    }
    
  }
  if (C=='2')
  {
    digitalWrite(13,1);
    delay(200);
    digitalWrite(13,0);
    delay(200);
  }
  if (C=='3')
  {
    digitalWrite(13,1);
    delay(3);
    digitalWrite(13,0);
    delay(20);
  }
}