arduino tank led toggle with bluetooth

void setup()
{
  Serial.begin(9600);
  pinMode(LED_BUILTIN, OUTPUT);
}

void loop()
{
  unsigned char ch = 0;                //Variable for storing Incoming_value
  if(Serial.available())
  {
    ch = Serial.read();      //Read the incoming data and store it into variable Incoming_value
    if (ch == '1')
      digitalWrite(LED_BUILTIN, HIGH);   // turn the LED on (HIGH is the voltage level)
    else
      digitalWrite(LED_BUILTIN, LOW);   // turn the LED on (HIGH is the voltage level)

  }
}