fet140_uart01_0115k.c

msp430f14x 系列片内外设的实例代码

//******************************************************************************
//  MSP-FET430P140 Demo - USART0 UART 115200 Echo ISR, HF XTAL ACLK 
//
//  Description; Echo a received character, RX ISR used. Normal mode is LPM0, 
//  USART0 RX interrupt triggers TX Echo. 
//  ACLK = MCLK = UCLK0 = LFXT1 = 8MHz
//  Baud rate divider with 8Mhz XTAL = 8000000/115200 = 0069 (0045h)
//  //*An external 8Mhz XTAL on XIN XOUT is required for ACLK*//
//
//              
//                MSP430F149   
//             -----------------
//         /|\|              XIN|-  
//          | |                 | 8MHz 
//          --|RST          XOUT|-
//            |                 |
//            |             P3.4|------------> 
//            |                 | 115200 - 8N1
//            |             P3.5|<------------
//
//       
//  M. Buccini
//  Texas Instruments, Inc
//  August 2003
//  Built with IAR Embedded Workbench Version: 1.26B
//  January 2004
//  Updated for IAR Embedded Workbench Version: 2.21B
//******************************************************************************

#include <msp430x14x.h>

void main(void)
{
  unsigned int i;

  WDTCTL = WDTPW + WDTHOLD;             // Stop WDT
  P3SEL |= 0x30;                        // P3.4,5 = USART0 TXD/RXD
  BCSCTL1 |= XTS;                       // ACLK= LFXT1= HF XTAL

  do 
  {
  IFG1 &= ~OFIFG;                       // Clear OSCFault flag
  for (i = 0xFF; i > 0; i--);           // Time for flag to set
  }
  while ((IFG1 & OFIFG));               // OSCFault flag still set?                

  BCSCTL2 |= SELM_3;                    // MCLK = LFXT1 (safe)
  ME1 |= UTXE0 + URXE0;                 // Enable USART0 TXD/RXD
  UCTL0 |= CHAR;                        // 8-bit character
  UTCTL0 |= SSEL0;                      // UCLK= ACLK
  UBR00 = 0x45;                         // 8MHz 115200
  UBR10 = 0x00;                         // 8MHz 115200
  UMCTL0 = 0x00;                        // 8MHz 115200 modulation
  UCTL0 &= ~SWRST;                      // Initialize USART state machine
  IE1 |= URXIE0;                        // Enable USART0 RX interrupt

  _BIS_SR(LPM0_bits + GIE);             // Enter LPM0 w/ interrupt
}

#pragma vector=UART0RX_VECTOR
__interrupt void usart0_rx (void)
{
  while (!(IFG1 & UTXIFG0));            // USART0 TX buffer ready?
  TXBUF0 = RXBUF0;                      // RXBUF0 to TXBUF0
}