#include <avr/pgmspace.h> 

#define UART_BAUD_SELECT(b) (F_CPU/(b*16L)-1)


void uart_init(unsigned int baud)
{
    UBRRH=UART_BAUD_SELECT(baud)>>8;
    UBRRL=UART_BAUD_SELECT(baud)&0xFF;

    UCSRB=_BV(RXEN)|_BV(TXEN)|_BV(RXCIE)|_BV(TXCIE);
    UCSRC=_BV(URSEL)|_BV(UCSZ1)|_BV(UCSZ0);
}


void uart_tx_char(unsigned char ch)
{
    // Wait if a byte is being transmitted
    while((UCSRA&(1<<UDRE)) == 0);
    UDR = ch; 
}


unsigned char uart_rx_char()
{
    // Wait until a byte has been received
    while((UCSRA&(1<<RXC)) == 0);
    if(UCSRA & (_BV(PE) | _BV(DOR) | _BV(FE)))
	return(unsigned char) 0xFF;

    return UDR;
}