STM32测频问题

只看该作者 · 2013-4-14 20:36

在STM32中，RTX操作系统下，利用PWM捕获测频值跳动较大？什么问题？

只看该作者 · 2013-4-14 20:41

void TIM3_IRQHandler(void)
{
/* TIM2 CCR1 Register define the MSB of the captured value
   TIM3 CCR1 Register define the LSB of the captured value  */
  if (kk == 0)
  {
LSB  =  TIM_GetCapture1(TIM3);
MSB1 =  TIM_GetCapture1(TIM2);
kk = 1;
  }
  else
  {
TIM_ClearITPendingBit(TIM3, TIM_IT_CC1);
LSB  = TIM_GetCapture1(TIM3);
MSB2 = TIM_GetCapture1(TIM2);
   if (MSB1 > MSB2)
{
   MSB = 0xFFFF - ((MSB1 - MSB2)) - 1;
}
else
{
   MSB = (MSB2 - MSB1) - 1;
}
kk = 0;
Freq[3] = 1.0*(TIMxCLK_Freq / ((MSB * 65535.) + LSB));
// Freq[ii] = 1.0*(TIMxCLK_Freq / ((MSB * 65535.) + LSB));
// ii++;
// if(ii == 5){
//          ii = 0;
//             for(kk=0;kk<5;kk++){
//       for(jj=kk;jj<4;jj++){
//       if(Freq[jj] < Freq[jj+1]){
//       a = Freq[jj];
//    Freq[jj] = Freq[jj+1];
//    Freq[jj+1] = a;
//    }
//       }
//          }

FrequencyA = Freq[3];
FrequencyB = FrequencyA;
if( FrequencyB < 31063.){
                     FrequencyB = FrequencyA;
   }
      // }

  }
}

1万 · 2013-4-15 09:50

查一下是否是误差，求下平均值

STM32测频问题

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