#define FOSC 16000000
#define BAUD 9600
#define MYUBRR FOSC/16/BAUD-1

ISR(USART_RX_vect){
  uint8_t result = UDR0;
  switch(result){
      case '1':
        PORTB |= (1 << PB3);
      break;

      case '2':
        PORTB &= ~(1 << PB3);
      break;
    }
}

void USART_Init( unsigned int ubrr){
  UBRR0H = (unsigned char)(ubrr>>8);
  UBRR0L = (unsigned char)ubrr;
  UCSR0B = (1 << RXCIE0) | (1 << RXEN0);
  UCSR0C = (1 << UCSZ01) | (1 << UCSZ00);
}


void setup() {
  DDRB = 1 << PB3;
  USART_Init(MYUBRR);
  sei();
}

void loop() {

}