[转]MSP430另一种UART实现

#include "msp430g2553.h"

typedef unsigned char uchar;
typedef unsigned int  uint;

#define LED     BIT0
#define TXD     BIT1                            // TXD on P1.1
#define RXD    BIT2                             // RXD on P1.2
#define POUT    P1OUT

#define BITTIME_1b       13*4    //1bit宽度
#define BITTIME_1b5      13*6    //1.5bit宽度

uchar   bitcnt;
uint    uart_buf;
int    Send_flag;

uchar  *str=" Hello EEWorld!  \r";

void FaultRoutine(void)
 {
   while(1);                                 // 异常挂起
 }

void ConfigClocks(void)
 {
 if (CALBC1_1MHZ ==0xFF || CALDCO_1MHZ == 0xFF)
   FaultRoutine();                            // If calibration data is erased
                                             // run FaultRoutine()
  BCSCTL1 = CALBC1_1MHZ;                     // Set range
  DCOCTL = CALDCO_1MHZ;                      // Set DCO step + modulation
  BCSCTL3 |= LFXT1S_2;                      // LFXT1 = VLO
  IFG1 &= ~OFIFG;                           // Clear OSCFault flag
  BCSCTL2 = 0;                               // MCLK = DCO = SMCLK
 }

void ConfigPins(void)
 {
  P1DIR |= TXD+LED;
  P1DIR &= ~RXD;                    // P1.3 input, other outputs
  P1OUT |= TXD;                                  // clear output pins

 }


//发送一个字节
void send_char(uchar tchar)
{
  TACTL = TACLR + TASSEL_2 + ID_3;              //选择SMCLK时钟;清TAR
  CCR0 = BITTIME_1b5;                    //crr0定时间隔为1bit时间宽度
  CCTL0 |= CCIE;                        //打开CCR0中断
  bitcnt = 10;                           //待发送的位数
  uart_buf = 0x0100;                     //8+N+1
  uart_buf |= tchar;                  //stop bit and start bit;
  uart_buf <<=1;
  Send_flag = 0;
  TACTL |= MC_1;                        //Start TA, UP mode.
  _BIS_SR(GIE);
  while(!Send_flag);                   //wait until send complete
  Send_flag = 1;
}

//发送一个字符串
void send_String(uchar *tstr)
{
  while(*tstr)
    send_char(*tstr++);
}


void send_IRQ(void)
{
  if(bitcnt>0)
  {
    if(uart_buf & 0x01)
      POUT |= TXD;
    else
      POUT &= ~TXD;
    uart_buf >>= 1;
    bitcnt--;
  }
  else
  {
    TACTL &= ~MC_3;                    //Close the TA when a Byte send over.   ??
    CCTL0 &= ~CCIE;                    //关闭CCR0中断
    Send_flag = 1;
  }

}



void main( void )
{
  // Stop watchdog timer to prevent time out reset
  uint i;



  WDTCTL = WDTPW + WDTHOLD;
  ConfigClocks();
  ConfigPins();


  while(1)
  {
   send_String(str);

   for(i=50000;i>0;i--);
   for(i=50000;i>0;i--);
   for(i=50000;i>0;i--);
   for(i=50000;i>0;i--);
   POUT ^= LED; // 翻转LED
  }
}

// Timer A0 interrupt service routine
#pragma vector=TIMER0_A0_VECTOR
__interrupt void Timer_A (void)
{


   send_IRQ();
}