int main (void)
{
	board_init();

	init();
	sei();//enable interrupt

	while (1)
	{

	}
}

void init()
{
	USARTInit(0,true);
}

//UART receiver interrupt routine
ISR (USART_RXC_vect)
{
	char status, ch;

	status = UCSRA;
	ch = UDR;

	//Check if error
	if((status & (_BV(FE) | _BV(DOR))) != 0)
		return;

	//send back to PC
	uart_send_char(ch);
}

void USARTInit(uint16_t ubrr_value, bool first)
{
   //Set Baud rate
   UBRRL = ubrr_value;
   UBRRH = (ubrr_value>>8);
   /*Set Frame Format
   >> Asynchronous mode
   >> No Parity
   >> 1 StopBit
   >> char size 8
   */
   if (first)
   {
	UCSRA = (1<<U2X);//double usart transmission speed
   }
   UCSRC=(1<<URSEL)|(3<<UCSZ0);
   //Enable The receiver and transmitter
   UCSRB=(1<<RXEN)|(1<<TXEN);
}

void uart_send_char(unsigned char ch)
{
	UDR = ch;
	//Wait for empty transfer buffer
	while(!(UCSRA & _BV(UDRE)));
}