const int ledPin = 13; // pin the LED is connected to
int mode=0;

void setup()
{
 Serial.begin(9600); // Initialize serial port to send and receive at 9600 baud
 pinMode(ledPin, OUTPUT); // set this pin as output
}

void loop()
{
  if ( Serial.available()) // Check to see if at least one character is available
  {
    char ch = Serial.read();
    if (ch =='1')
    {
      mode=1;
    }
    if(ch=='0'){
      mode=0;
    }
  }
bulb();
}

void bulb(){
  digitalWrite(ledPin,mode);
}