//******************************************************************************
//   MSP430G2xx3 Demo - USCI_A0, 9600 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/9600 = ~104.2
//   ACLK = n/a, MCLK = SMCLK = CALxxx_1MHZ = 1MHz
//
//                MSP430G2xx3
//             -----------------
//         /|\|              XIN|-
//          | |                 |
//          --|RST          XOUT|-
//            |                 |
//            |     P1.2/UCA0TXD|------------>
//            |                 | 9600 - 8N1
//            |     P1.1/UCA0RXD|<------------
//
//   D. Dang
//   Texas Instruments Inc.
//   February 2011
//   Built with CCS Version 4.2.0 and IAR Embedded Workbench Version: 5.10
//******************************************************************************
#include <msp430.h>
int main(void)
{WDTCTL = WDTPW + WDTHOLD;                 // Stop WDTif (CALBC1_1MHZ==0xFF)                    // If calibration constant erased{                                          while(1);                               // do not load, trap CPU!!  }DCOCTL = 0;                               // Select lowest DCOx and MODx settingsBCSCTL1 = CALBC1_1MHZ;                    // Set DCODCOCTL = CALDCO_1MHZ;P1SEL = BIT1 + BIT2 ;                     // P1.1 = RXD, P1.2=TXDP1SEL2 = BIT1 + BIT2 ;                    // P1.1 = RXD, P1.2=TXDUCA0CTL1 |= UCSSEL_2;                     // SMCLKUCA0BR0 = 104;                            // 1MHz 9600UCA0BR1 = 0;                              // 1MHz 9600UCA0MCTL = UCBRS0;                        // Modulation UCBRSx = 1UCA0CTL1 &= ~UCSWRST;                     // **Initialize USCI state machine**IE2 |= UCA0RXIE;                          // Enable USCI_A0 RX interrupt//_EINT();__bis_SR_register(LPM0_bits + GIE);       // Enter LPM0, interrupts enabled
}
#pragma vector=USCIAB0RX_VECTOR
__interrupt void USCI0RX_ISR(void)
{while (!(IFG2&UCA0TXIFG));                // USCI_A0 TX buffer ready?UCA0TXBUF = UCA0RXBUF;                    // TX -> RXed character
}

1：首先说一下  G2553串口需要注意的一些事项吧

 if (CALBC1_1MHZ==0xFF)                    // If calibration constant erased{                                          while(1);                               // do not load, trap CPU!!  }

新手一个  上面的叙述难免有错误之处  请各位原谅 欢迎讨论分享更好的学习资料 方法