fet120_uart05_09600.c

一个基于TI的MSP430的程序设计参考代码

//******************************************************************************
//  MSP-FET430P140 Demo - USART0 UART 9600 Ultra-low Power Echo ISR, 32kHz ACLK
//
//  Description; Echo a received character, RX ISR used. Normal mode is LPM3, 
//  USART0 RX interrupt triggers TX Echo.   
//  ACLK = UCLK0 = LFXT1 = 32768, MCLK = SMCLK = DCO~ 800k  
//  Baud rate divider with 32768hz XTAL @9600 = 32768Hz/9600 = 3.41 (000Dh 4Ah )
// //*An external watch crystal is required on XIN XOUT for ACLK*//	  
//
//             
//              MSP430F12x(2)
//            -----------------
//        /|\|              XIN|-  
//         | |                 | 32kHz  
//         --|RST          XOUT|-
//           |                 |
//           |             P3.4|-----------> 
//           |                 | 9600 - 8N1
//           |             P3.5|<-----------
//
//       
//  M. Buccini
//  Texas Instruments, Inc
//  January 2004
//  Updated for IAR Embedded Workbench Version: 2.21B
//******************************************************************************

#include <msp430x12x.h>

void main(void)
{
  WDTCTL = WDTPW + WDTHOLD;             // Stop WDT
  P3SEL |= 0x30;                        // P3.4,5 = USART0 TXD/RXD
  ME2 |= UTXE0 + URXE0;                 // Enable USART0 TXD/RXD
  UCTL0 |= CHAR;                        // 8-bit character
  UTCTL0 |= SSEL0;                      // UCLK = ACLK
  UBR00 = 0x03;                         // 32k/9600 - 3.41
  UBR10 = 0x00;                         //
  UMCTL0 = 0x4a;                        // Modulation
  UCTL0 &= ~SWRST;                      // Initialize USART state machine
  IE2 |= URXIE0;                        // Enable USART0 RX interrupt

  _BIS_SR(LPM3_bits + GIE);             // Enter LPM3 w/ interrupt
}

#pragma vector=UART0RX_VECTOR
__interrupt void usart0_rx (void)
{
  while (!(IFG2 & UTXIFG0));            // USART0 TX buffer ready?
  TXBUF0 = RXBUF0;                      // RXBUF0 to TXBUF0
}