#include <avr/io.h>
void USART_Init()
{
    const unsigned int BAUD = 77; // Page 118 of Datasheet.
    
    /* Set baud rate */
    UBRRH = (unsigned char)(BAUD>>8);
    UBRRL = (unsigned char)(BAUD & 0xFF);
    
    UCSRA &= ~(0 << U2X); // Single speed.
    
    /* Set frame format: 8data, No Parity, 1stop bit*/
//    UCSRC = (0<<UMSEL)|(0<<USBS)|(0 << UPM1)|(0 <<UPM0)|(0<<UCSZ2)|(1<<UCSZ1)|(1<<UCSZ0);
    UCSRC = (0<<UCSZ2)|(1<<UCSZ1)|(1<<UCSZ0);
    
    /* Enable receiver and transmitter */
    UCSRB = (1 << RXEN) | (1 << TXEN);
}

void main()
{
    USART_Init();

    unsigned char data;
    
    char buf[] = "1234567890ABCDEFGHIGKLMNOPQRSTUVWXYZ!@#";
    
    int len = strlen(buf);

    while(1)
    {
        for(int i = 0; i < len; ++i){
            while (!(UCSRA & (1 << UDRE)));            
            UDR = buf[i];

            while( !(UCSRA & (1<<TXC)) ); // Wait for transmit ready.        
        }

        while (!(UCSRA & (1 << UDRE)));            
        UDR = 0x0D;

        while( !(UCSRA & (1<<TXC)) ); // Wait for transmit ready.        

    } // while(1)
}