...

void Init_UART (void) {
    UBRR1L = 0x33;                                             // Set baud rate lo
    UBRR1H = 0x00;                                             // Set baud rate hi
    UCSR1B = (1<<RXEN1)|(1<<TXEN1)|(1<<RXCIE1)|(1<<UDRIE1);    // Enable receiver and transmitter 
    UCSR1C = (1<<USBS1)|(3<<UCSZ10);                           // Set frame format: 8data, 2stop bit 
}


...


INT08U UARTDataInReceiveBuffer (void) {	
   INT08U t1 = UART_RxHead0, t2 = UART_RxTail0;
   return (t1 != t2);	
}

INT08U UARTReceiveByte (void) {
    INT08U t1, t2;
    INT32U tmptail0;


     t1 = UART_RxHead0;
     t2 = UART_RxTail0;

    while (t1 == t2) {
    };
    tmptail0 = ( UART_RxTail0 + 1 ) & UART_RX_BUFFER_MASK0;
    UART_RxTail0 = tmptail0; 
    return UART_RxBuf0[tmptail0]; 
}

void UARTTransmitByte (INT08U data0 ) {
    INT08U tmphead0;


    tmphead0 = ( UART_TxHead0 + 1 ) & UART_TX_BUFFER_MASK0; 
    while ( tmphead0 == UART_TxTail0 ) continue;
    UART_TxBuf0[tmphead0] = data0;
    UART_TxHead0 = tmphead0; 
    UCSR1B |= (1<<UDRIE1); 
}
/*
********************************************************************************
*                              LOCAL FUNCTION
******************************************************************************** 
*/


#pragma vector=USART1_RX_vect
__interrupt void USART_Rx_isr(void) {
    INT08U data0;
    INT32U tmphead0;
 
    data0 = UDR1;
    tmphead0 = ( UART_RxHead0 + 1 ) & UART_RX_BUFFER_MASK0;
    UART_RxHead0 = tmphead0;  
    if (tmphead0 == UART_RxTail0) {		}
    UART_RxBuf0[tmphead0] = data0;
}


#pragma vector=USART1_UDRE_vect 
__interrupt void USART0_Tx_interrupt( void ) {
    INT08U t1, t2; 
    INT08U tmptail0;

    t1 = UART_RxHead0; 
    t2 = UART_RxTail0;

    if (t1 != t2) {
        tmptail0 = ( UART_TxTail0 + 1 ) & UART_TX_BUFFER_MASK0;
        UART_TxTail0 = tmptail0; 
        UDR1=UART_TxBuf0[tmptail0]; 
    }
    else {
        UCSR1B &= ~(1<<UDRIE1); 
    }
}

...

...

void main (void) {

    InitDevice ();

    while (1) {
        UARTTransmitByte(0x55);
    }
}