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Input Capture issue

Question asked by ed@mtrx on Aug 28, 2014
Latest reply on Aug 28, 2014 by ed@mtrx
Hi:

I am using the STM3221G-EVAL board and TIM example from STM32F2xx_StdPeriph_Lib. I modified the original example so I can use PG15 input.
There is a pushbutton connected to PG15 on the eval board.
When I press the pushbutton nothing happens. The system never goes through TIM1_CC_IRQHandler. what would be the problem?
Thanks.

int main(void)
{
  /*!< At this stage the microcontroller clock setting is already configured, 
       this is done through SystemInit() function which is called from startup
       file (startup_stm32f2xx.s) before to branch to application main.
       To reconfigure the default setting of SystemInit() function, refer to
       system_stm32f2xx.c file
     */     
       
  /* TIM1 Configuration */
  GPIO_InitTypeDef GPIO_InitStructure;
  NVIC_InitTypeDef NVIC_InitStructure;
  TIM_ICInitTypeDef  TIM_ICInitStructure;
  
  /* TIM1 clock enable */
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM1, ENABLE);

  /* GPIOG clock enable */
  RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOG, ENABLE);
  
  /* TIM1 channel 2 pin (PG.15) configuration */
  GPIO_InitStructure.GPIO_Pin =  GPIO_Pin_15;
  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(GPIOG, &GPIO_InitStructure);

  /* Connect TIM pins to AF1 */
  GPIO_PinAFConfig(GPIOG, GPIO_PinSource15, GPIO_AF_TIM1);
  
  /* Enable the TIM1 global Interrupt */
  NVIC_InitStructure.NVIC_IRQChannel = TIM1_CC_IRQn;
  NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
  NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
  NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
  NVIC_Init(&NVIC_InitStructure);


  /* TIM1 configuration: Input Capture mode ---------------------
     The external signal is connected to TIM1 CH2 pin (PG.15)  
     The Rising edge is used as active edge,
     The TIM1 CCR2 is used to compute the frequency value 
  ------------------------------------------------------------ */

  TIM_ICInitStructure.TIM_Channel = TIM_Channel_2;
  TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;
  TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;
  TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV8;
  TIM_ICInitStructure.TIM_ICFilter = 0x0;

  TIM_ICInit(TIM1, &TIM_ICInitStructure);
  
  /* TIM enable counter */
  TIM_Cmd(TIM1, ENABLE);

  /* Enable the CC2 Interrupt Request */
  TIM_ITConfig(TIM1, TIM_IT_CC2, ENABLE);

  while (1);
}


void TIM1_CC_IRQHandler(void)

  if(TIM_GetITStatus(TIM1, TIM_IT_CC2) == SET) 
  {
    /* Clear TIM1 Capture compare interrupt pending bit */
    TIM_ClearITPendingBit(TIM1, TIM_IT_CC2);
    if(CaptureNumber == 0)
    {
      /* Get the Input Capture value */
      IC3ReadValue1 = TIM_GetCapture2(TIM1);
      CaptureNumber = 1;
    }
    else if(CaptureNumber == 1)
    {
      /* Get the Input Capture value */
      IC3ReadValue2 = TIM_GetCapture2(TIM1); 
      
      /* Capture computation */
      if (IC3ReadValue2 > IC3ReadValue1)
      {
        Capture = (IC3ReadValue2 - IC3ReadValue1); 
      }
      else if (IC3ReadValue2 < IC3ReadValue1)
      {
        Capture = ((0xFFFF - IC3ReadValue1) + IC3ReadValue2); 
      }
      else
      {
        Capture = 0;
      }
      /* Frequency computation */ 
      TIM1Freq = (uint32_t) SystemCoreClock / Capture;
      CaptureNumber = 0;
    }
  }
}


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