用定时器求电压有效值的时候出现了问题

lyh000 · 发表于 2017-11-16 21:47:24

本帖最后由 lyh000 于 2017-11-16 23:03 编辑

预计的功能是计算50次计数的有效值。但是在中断服务函数中
temp的值每次都会丢失，也就是50次更新定时中断后，temp的值仍然为一次的值，即temp=adcm*adcm，而不是temp=dacm*dacm+.....+dacn*adcm(50个的平方和)
该怎么办？
void TIM3_Int_Init(u16 arr,u16 psc)
{
  TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
      NVIC_InitTypeDef NVIC_InitStructure;

      RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);


      TIM_TimeBaseStructure.TIM_Period = arr;
      TIM_TimeBaseStructure.TIM_Prescaler =psc;
      TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
      TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
      TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);

      TIM_ITConfig(TIM3,TIM_IT_Update,ENABLE );


      NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn;
      NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
      NVIC_InitStructure.NVIC_IRQChannelSubPriority = 3;
      NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
      NVIC_Init(&NVIC_InitStructure);  //

      TIM_Cmd(TIM3, ENABLE);  //
}

//定时器中断服务函数
int i=0;
volatile double temp=0;
float adcm=0;
float adcu=0;
u16 TIM3_IRQHandler(void)  //40us¸
{
      if (TIM_GetITStatus(TIM3, TIM_IT_Update) != RESET)
      {
            TIM_ClearITPendingBit(TIM3, TIM_IT_Update  );  //
      adcm=Get_Adc(ADC_Channel_1);    //
   if(i<50)
   {temp=+adcm*adcm;
      i++;
   }
   else
   {i=0;
      adcu=sqrt(temp/50);  //20ms
      temp=0;
   }
      }
      return adcu;
}