MSP430 - UART empfängt keine Zeichen

//******************************************************************************

//   MSP430x24x Demo - USCI_A0, 115200 UART Echo ISR, DCO SMCLK

//

//   Description: Echo a received character, RX ISR used. Normal mode is LPM0.

//   USCI_A0 RX interrupt triggers TX Echo.

//   Baud rate divider with 1MHz = 1MHz/115200 = ~8.7

//   UCBRx = 08; In UCA0MCTL: UCBRSx = round(0.7*8) = 05

//   ACLK = n/a, MCLK = SMCLK = CALxxx_1MHZ = 1MHz

//

//                MSP430F249

//             -----------------

//         /|\|              XIN|-

//          | |                 |

//          --|RST          XOUT|-

//            |                 |

//            |     P3.4/UCA0TXD|------------>

//            |                 | 115200 - 8N1

//            |     P3.5/UCA0RXD|<------------

//

//  B. Nisarga

//  Texas Instruments Inc.

//  September 2007

//  Built with CCE Version: 3.2.0 and IAR Embedded Workbench Version: 3.42A

//******************************************************************************

#include "msp430x24x.h"

void main(void)

{

  WDTCTL = WDTPW + WDTHOLD;                 // Stop WDT

  if (CALBC1_1MHZ ==0xFF || CALDCO_1MHZ == 0xFF)                                     

  {  

    while(1);                               // If calibration constants erased

                                            // do not load, trap CPU!!

  }   

  BCSCTL1 = CALBC1_1MHZ;                    // Set DCO

  DCOCTL = CALDCO_1MHZ;

  P3SEL = 0x30;                             // P3.4,5 = USCI_A0 TXD/RXD

  UCA0CTL1 |= UCSSEL_2;                     // SMCLK

  UCA0BR0 = 8;                              // 1MHz 115200

  UCA0BR1 = 0;                              // 1MHz 115200

  UCA0MCTL = UCBRS2 + UCBRS0;               // Modulation UCBRSx = 5

  UCA0CTL1 &= ~UCSWRST;                     // **Initialize USCI state machine**

  IE2 |= UCA0RXIE;                          // Enable USCI_A0 RX interrupt

  __bis_SR_register(LPM0_bits + GIE);       // Enter LPM0, interrupts enabled

}

// Echo back RXed character, confirm TX buffer is ready first

#pragma vector=USCIAB0RX_VECTOR

__interrupt void USCI0RX_ISR(void)

{

  while (!(IFG2&UCA0TXIFG));                // USCI_A0 TX buffer ready?

  UCA0TXBUF = UCA0RXBUF;                    // TX -> RXed character

}