fet140_uart01_19200_2.c

msp430f14x 系列片内外设的实例代码

//******************************************************************************
//  MSP-FET430P140 Demo - USART0 UART 19200 Echo ISR, XT2 HF XTAL ACLK 
//
//  Description; Echo a received character, RX ISR used. Normal mode is LPM0, 
//  USART0 RX interrupt triggers TX Echo. Though not required, MCLK = XT2.
//  ACLK = n/a, MCLK = SMCLK = UCLK0 = XT2 = 8MHz
//  Baud rate divider with 8Mhz XTAL @19200 = 8MHz/19200 = 416.66 ~ 417 (01A0h)
//  //*An external 8MHz XTAL on X2IN X2OUT is required for XT2CLK*//	
//
//              
//                MSP430F149   
//             -----------------
//         /|\|            XT2IN|-  
//          | |                 | 8Mhz  
//          --|RST        XT2OUT|-
//            |                 |
//            |             P3.4|------------> 
//            |                 | 19200 - 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;
  P3SEL |= 0x30;                        // P3.4,5 = USART0 TXD/RXD
  WDTCTL = WDTPW + WDTHOLD;             // Stop WDT

  BCSCTL1 &= ~XT2OFF;                   // XT2on

  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_2 + SELS;             // MCLK = SMCLK = XT2 (safe)

  ME1 |= UTXE0 + URXE0;                 // Enable USART0 TXD/RXD
  UCTL0 |= CHAR;                        // 8-bit character
  UTCTL0 |= SSEL1;                      // UCLK = SMCLK
  UBR00 = 0xA0;                         // 8Mhz/19200 ~ 417
  UBR10 = 0x01;                         //
  UMCTL0 = 0x00;                        // no 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
}