source: avrstuff/libs/usart/usart.c@ b82c7b3

/* AVR USART acces functions - stolen from Extreme Electronics */

#include <avr/io.h>
#include <inttypes.h>


//This function is used to initialize the USART
//at a given UBRR value
void USARTInit(uint16_t ubrr_value)
{

   //Set Baud rate
   UBRRL = ubrr_value;
   UBRRH = (ubrr_value>>8);

   /*Set Frame Format


   >> Asynchronous mode
   >> No Parity
   >> 1 StopBit
   >> char size 8

   */

   UCSRC=(1<<URSEL)|(3<<UCSZ0);

   //Enable The receiver and transmitter
   UCSRB=(1<<RXEN)|(1<<TXEN);
}


//This fuction writes the given "data" to
//the USART which then transmit it via TX line
void USARTWriteChar(char data)
{
        //Wait untill the transmitter is ready
        while(!(UCSRA & (1<<UDRE)))
        {
                //Do nothing
        }

        //Now write the data to USART buffer

        UDR=data;
}


//This function is used to read the available data
//from USART. This function will wait untill data is
//available.
char USARTReadChar()
{
        //Wait untill a data is available
        while(!(UCSRA & (1<<RXC)))
        {
                //Do nothing
        }

        //Now USART has got data from host
        //and is available is buffer

        return UDR;
}


void USARTWriteHex(unsigned char i)
{
        unsigned char k = i>>4;
        if (k <=9) k+='0';
        else k+=('A'-10);

        USARTWriteChar(k);

        k = i&0xF;
        if (k <=9) k+='0';
        else k+=('A'-10);

        USARTWriteChar(k);
}