F207的捕获功能应用中，信号沿的问题。

只看该作者 · 2013-2-21 17:27

我用TIM3的3通道来做脉冲信号的频率采集，使用下降沿来捕获时间，但是在测试中有时会出现2倍的频率值，即使我用下降沿来捕获也一样会出现这个问题。难道TIM3偶尔进入到PWM捕获模式了？但是CC3不是没有这个功能么？我的初始化程序如下：
void TIM_Config(void)
{
  GPIO_InitTypeDef GPIO_InitStructure;
  NVIC_InitTypeDef NVIC_InitStructure;
  TIM_ICInitTypeDef  TIM_ICInitStructure;
  TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;

  /* GPIOB clock enable */
  RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB, ENABLE);

  /* TIM3 channel 3 pin (PB.0) configuration */
  GPIO_InitStructure.GPIO_Pin =  GPIO_Pin_0;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
  GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
  GPIO_Init(GPIOB, &GPIO_InitStructure);

  /* Connect TIM pins to AF2 */
  GPIO_PinAFConfig(GPIOB, GPIO_PinSource0, GPIO_AF_TIM3);

  TIM_DeInit( TIM3);//

  /* TIM3 clock enable */
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);

//  TIM_InternalClockConfig(TIM3);

  /* TIM3 configuration *****************************************
  **************************************************************/
  /* Time base configuration */
  TIM_TimeBaseStructure.TIM_Period = 0xffff;
  TIM_TimeBaseStructure.TIM_Prescaler = 99;
  TIM_TimeBaseStructure.TIM_ClockDivision = 0;
  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
  TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);

  /* TIM3 configuration: Input Capture mode ---------------------
   The external signal is connected to TIM3 CH3 pin (PB.0)
   The Rising edge is used as active edge,
   The TIM3 CCR3 is used to compute the frequency value
  ------------------------------------------------------------ */
  TIM_ICStructInit(&TIM_ICInitStructure);
  TIM_ICInitStructure.TIM_Channel = TIM_Channel_3;
  TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Falling;//or TIM_ICPolarity_Rising
  TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;
  TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;
  TIM_ICInitStructure.TIM_ICFilter = 0x0;
  TIM_ICInit(TIM3, &TIM_ICInitStructure);

  /* Enable the TIM3 global Interrupt */
  NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn;
  NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
  NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
  NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
  NVIC_Init(&NVIC_InitStructure);

  /* Enable the CC2 Interrupt Request */
  TIM_ITConfig(TIM3, TIM_IT_CC3, ENABLE);

  /* TIM enable counter */
  TIM_Cmd(TIM3, ENABLE);
}

只看该作者 · 2013-2-21 17:49

void TIM3_IRQHandler(void)
{
  uint16_t temp;

  if(TIM_GetITStatus(TIM3, TIM_IT_CC3) == SET)
  {
/* Clear TIM3 Capture compare interrupt pending bit */
TIM_ClearITPendingBit(TIM3, TIM_IT_CC3);

IC3ReadValue[CaptureNumber] = TIM_GetCapture3(TIM3);
CaptureNumber = (~CaptureNumber)&0x0001;
CC_flag = 1;
  }
}