MSP430F149 定时器A捕获功能测脉冲宽度的问题

2018-8-30 09:04

MSP430F149 定时器A捕获功能测脉冲宽度各位大神帮忙看看哪出了问题？程序如下
/****测脉冲宽度并用1602显示出来****/

#include <msp430x14x.h>
#include "cry1602.c"

#define  uint    unsigned int
#define  uchar unsigned char

uint pwm_star,pwm_end;

uint width;

uint i=0;

uchar *s="The width is :";

uchar b[]={'0','1','2','3','4','5','6','7','8','9'};

uint m,n,p,q;

void main(void)

{
WDTCTL=WDTPW+WDTHOLD;

P6DIR |= BIT2;P6OUT |= BIT2;       //关闭电平转换

P6DIR |= BIT3;P6OUT |= BIT3;

BCSCTL1 &= ~XT2OFF;                //打开XT2高频晶体振荡器
do
{
      IFG1 &= ~OFIFG;                //清除晶振失败标志
      for (i = 0xFF; i > 0; i--);    //等待8MHz晶体起振
}
while ((IFG1 & OFIFG));          //晶振失效标志仍然存在？
BCSCTL2 |= SELM_2 + SELS;          //MCLK和SMCLK选择高频晶振

P1DIR|=BIT2;
P1SEL|=BIT2; //捕获源为P1.2

TACTL=TACLR; //定时器清零
TACTL |= TASSEL_2 + ID_3; //计数时钟选择SMLK=8MHz，1/8分频后为1MHz

TACCTL1 =CM_3+SCS+CAP+CCIS_0+CCIE; //上升沿下降沿都同步捕获

TACTL = MC_2; //定时器计数开始连续计数模式

_EINT();

LcdReset();

DispStr(0,0,s);

while(1)
{

   m=width/1000;
   n=(width/100)%10;
   p=(width/10)%10;
   q=width%10;

   Disp1Char(4,1,b[m]);
   Disp1Char(5,1,b[n]);
   Disp1Char(6,1,b[p]);
   Disp1Char(7,1,b[q]);

}
}

/******定时器TA的CCR1的中断用于检测脉冲上升沿和下降沿******/

#pragma vector=TIMERA1_VECTOR
__interrupt void Timer_A1(void)
{
  switch(TAIV)
  { case 0x02:
         if(CCI==1)
         {
            pwm_star = TACCR1;
            break;
         }
         else
         {
            pwm_end = TACCR1;
            break;
         }

      default:
         break;
  }

  width = pwm_end-pwm_star;

}