AVRFreaks.net

int main(void)
{
#ifdef RUN_AT_32MHZ
    CCP = CCP_IOREG_gc;   
    OSC.CTRL = OSC_RC32MEN_bm;
    while(!(OSC.STATUS & OSC_RC32MRDY_bm));
    CCP = CCP_IOREG_gc;
    CLK.CTRL = 0x01;

    /* those values were calculated using http://prototalk.net/forums/showthread.php?t=188 */
    uint16_t bsel = 3301;
    uint8_t bscale = -5;

#else

    uint16_t bsel = 353;
    uint8_t bscale = -6;

#endif

    PORTC.DIRSET = PIN3_bm;
    PORTC.DIRCLR = PIN2_bm;   
    USARTC0.CTRLC = USART_CHSIZE_8BIT_gc|USART_PMODE_DISABLED_gc;      
    USARTC0.BAUDCTRLA = (uint8_t)bsel;
    USARTC0.BAUDCTRLB =(bscale << USART_BSCALE0_bp) | (bsel  >> 8);   
    USARTC0.CTRLB |= USART_TXEN_bm;
    while(true)
    {
        while(!(USARTC0.STATUS & USART_DREIF_bm));
        USARTC0.DATA = 'x';       
    }
}

Usartsetup:
   'Set Up XMega PortE USART 1 for 9600, N,8,1
   'System Clock is assumed 32 MHz. 
   'No Handshaking is used.
   'Micro's GLOBAL Interrupts should
   'be OFF while doing setup.
   '
   'Initialization:
   'First set the TxD pin value high 
   '(Not sure exactly why, but must make it an output)
   'Configure Portd.7 As Output
   Porte_pin7ctrl = &B00000000   'USART Output   PIN, PortD.7, Control, Totem Pole
   Porte_dir.7 = 1    'Output for USART
   Porte_out.7 = 1    'Set it high

   'Set up USART CTRLA, Control Register A, whcih controls USART Interrupt Triggering
   'Set for NO Interrupts for initial testing:
   Usarte1_ctrla = 0      '0000 0000

   'Set up USART CTRLB, Control Register B,
   'which Enables the USART Receiver and Transmitter.
   Usarte1_ctrlb = 24     '0001 1000

   'Set up USART CTRLC, Control Register C,
   'which determines USART MODE.
   'Asychronous, No Parity, 1 Stop,  8 Data Bits   0000 0011  3d
   Usarte1_ctrlc = 3

   Gosub Usartbrsetup 'Set up the Baud Rate Divisor(s)

   '++++++++++++++++++++
   'Turn ON Global interrupts here,
   'if turned them off for this setup ..........
   '+++++++++++++++++++

   Return

Usartbrsetup:
   'USART Baud Rate Setup
   'For XMega's Clock = 32 MHz.
   'Mode is N, 8, 1  No Parity, 8 Data Bits, 1 Stop Bit
   'Uses Bscale = 0
   'Supports:         (Could add others)
   '1200, 9600, 19200, 38400, 57600, 115200
   'On Entry have: Xbr, the desired Baud Rate.
   'e.g. Xbr = 57600
   'This sets the BaudCtrlA and BaudCtrlB
   'Registers with the correct divisor(s).
   'Set up USART Baud CtrlA, Baud Rate Control Register A
   '8 Least Sig bits of 12 bit divisor
   'Usarte1_baudctrla = 207    0000 1100 1111 as 12 bit
   'Set up USART Baud CtrlB, Baud Rate Control Register B
   '4 Most Sig bits of 12 bit divisor, and Bscale (0 for now).
   'Usarte1_baudctrlb = 0      0000 0000

   If Xbr = 1200 Then
      Usarte1_baudctrla = 130
      Usarte1_baudctrlb = 6
   Elseif Xbr = 9600 Then
      Usarte1_baudctrla = 207
      Usarte1_baudctrlb = 0
   Elseif Xbr = 19200 Then
      Usarte1_baudctrla = 103
      Usarte1_baudctrlb = 0
   Elseif Xbr = 38400 Then
      Usarte1_baudctrla = 51
      Usarte1_baudctrlb = 0
   Elseif Xbr = 57600 Then
      Usarte1_baudctrla = 34
      Usarte1_baudctrlb = 0
   Elseif Xbr = 115200 Then
      Usarte1_baudctrla = 16
      Usarte1_baudctrlb = 0
   Else
      'Error, unsupported Baudrate, set it for 9600
      Usarte1_baudctrla = 207
      Usarte1_baudctrlb = 0
   End If
   Return