MSP430G2553测试程序(串口程序，USCI模式)

//   HW UART(J4)!!!!!! 特别注意,板子上J4有2个跳线要竖放,设为HW UART模式
//   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 16MHz
//   ACLK = n/a, MCLK = SMCLK = CALxxx_16MHZ = 16MHz
//
//                MSP430G2xx3
//             -----------------
//         /|\|              XIN|-
//          | |                 |
//          --|RST          XOUT|-
//            |                 |
//            |     P1.2/UCA0TXD|------------>
//            |                 | 9600 - 8N1
//            |     P1.1/UCA0RXD|<------------
//
//   修改http://jiwm.blog.163.com

//串口调试助手，下载地址：http://www.sudt.com/download/AccessPort137.zip
//   Texas Instruments Inc.
//   February 2011
//   Built with  IAR Embedded Workbench Version: 5.40
//******************************************************************************
#include  "msp430g2553.h"

void main(void)
{
  WDTCTL = WDTPW + WDTHOLD;                 // Stop WDT
  BCSCTL1 = CALBC1_16MHZ;                    // Set DCO
  DCOCTL = CALDCO_16MHZ;
  P1SEL = BIT1 + BIT2 ;                     // P1.1 = RXD, P1.2=TXD
  P1SEL2 = BIT1 + BIT2;                      
  UCA0CTL1 |= UCSSEL_2;                     // SMCLK
  UCA0BR0 = 0x82;                              // 16MHz 9600 UCA0BRX=1666=0x0682
  UCA0BR1 = 0x06;                              // 16MHz 9600
  UCA0MCTL = UCBRS2 + UCBRS1;               // Modulation UCBRSx = 6
  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
}