STM32f4---Input capture experimental code (01)

Let's take a look at the contents of the two functions we added in the timer.c file:

TIM_ICInitTypeDef  TIM5_ICInitStructure;

//Timer 5 channel 1 input capture configuration

//arr: auto reload value (TIM2, TIM5 are 32 bits!!) psc: clock pre-division number

void TIM5_CH1_Cap_Init(u32 arr,u16 psc)

{

  GPIO_InitTypeDef GPIO_InitStructure;

  TIM_TimeBaseInitTypeDef   TIM_TimeBaseStructure;

  NVIC_InitTypeDef NVIC_InitStructure;

  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM5,ENABLE); //TIM5 clock enable     

  RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE); //Enable PORTA clock

  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0; //GPIOA0

  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF; //Multiplexing function

  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;  //速度 100MHz

  GPIO_InitStructure.GPIO_OType = GPIO_OType_PP; //Push-pull multiplexing output

  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_DOWN; //下拉

  GPIO_Init(GPIOA,&GPIO_InitStructure); //Initialize PA0

  GPIO_PinAFConfig(GPIOA,GPIO_PinSource0,GPIO_AF_TIM5); //PA0 multiplex bit timer 5

  TIM_TimeBaseStructure.TIM_Prescaler=psc; //Timer frequency division

  TIM_TimeBaseStructure.TIM_CounterMode=TIM_CounterMode_Up; //Upward counting mode

  TIM_TimeBaseStructure.TIM_Period=arr; //Automatically reload value

  TIM_TimeBaseStructure.TIM_ClockDivision=TIM_CKD_DIV1;  

  TIM_TimeBaseInit(TIM5,&TIM_TimeBaseStructure);

  TIM5_ICInitStructure.TIM_Channel = TIM_Channel_1; //Select input IC1 and map it to TI1

     TIM5_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising; //Rising edge capture

     TIM5_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI; //Map to TI1

     TIM5_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1; //Configure input frequency division, no frequency division  

     TIM5_ICInitStructure.TIM_ICFilter = 0x00; //IC1F=0000 Configure input filter No filtering

      TIM_ICInit(TIM5, &TIM5_ICInitStructure); //Initialize TIM5 input capture parameters

  TIM_ITConfig(TIM5,TIM_IT_Update|TIM_IT_CC1,ENABLE); //Enable update and capture interrupts 

      TIM_Cmd(TIM5,ENABLE ); //Enable timer 5

       NVIC_InitStructure.NVIC_IRQChannel = TIM5_IRQn;

  NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority=2; //Preemption priority 2

  NVIC_InitStructure.NVIC_IRQChannelSubPriority =0; //Response priority 0

  NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //IRQ channel enable

  NVIC_Init(&NVIC_InitStructure); //Initialize VIC registers according to the specified parameters,

}

//Capture status

//[7]: 0, no successful capture; 1, successful capture once.

//[6]: 0, low level has not been captured yet; 1, low level has been captured.

//[5:0]: The number of overflows after capturing a low level (for a 32-bit timer, the 1us counter is incremented by 1, and the overflow time is 4294 seconds)

u8 TIM5CH1_CAPTURE_STA=0; //Input capture status                 

u32 TIM5CH1_CAPTURE_VAL; // Input capture value (TIM2/TIM5 is 32 bits)

//Timer 5 interrupt service routine    

void TIM5_IRQHandler(void)

{  

    if((TIM5CH1_CAPTURE_STA&0X80)==0)//Not captured successfully  

  {

    if(TIM_GetITStatus(TIM5, TIM_IT_Update) != RESET)//溢出

    {        

      if(TIM5CH1_CAPTURE_STA&0X40)//High level has been captured

      {

        if((TIM5CH1_CAPTURE_STA&0X3F)==0X3F)//The high level is too long

        {

          TIM5CH1_CAPTURE_STA|=0X80; //Marks a successful capture

          TIM5CH1_CAPTURE_VAL=0XFFFFFFFF;

        }else TIM5CH1_CAPTURE_STA++;

      }    

    }

    if(TIM_GetITStatus(TIM5, TIM_IT_CC1) != RESET)//Capture 1 capture event occurs

    {  

      if(TIM5CH1_CAPTURE_STA&0X40) //Capture a falling edge      

      {           

         TIM5CH1_CAPTURE_STA|=0X80; //Marks a successful capture of a high level pulse width

         TIM5CH1_CAPTURE_VAL=TIM_GetCapture1(TIM5); //Get the current capture value.

           TIM_OC1PolarityConfig(TIM5,TIM_ICPolarity_Rising); //Set rising edge capture

      }else //Not started yet, first capture rising edge

      {

         TIM5CH1_CAPTURE_STA=0; //Clear

         TIM5CH1_CAPTURE_VAL=0;

         TIM5CH1_CAPTURE_STA|=0X40; //Marker captures the rising edge

         TIM_Cmd(TIM5,ENABLE ); //Enable timer 5

           TIM_SetCounter(TIM5,0); //Clear the counter

           TIM_OC1PolarityConfig(TIM5,TIM_ICPolarity_Falling); //Set falling edge capture

         TIM_Cmd(TIM5,ENABLE ); //Enable timer 5

      }         

    }                                 

    }

  TIM_ClearITPendingBit(TIM5, TIM_IT_CC1|TIM_IT_Update); //Clear interrupt flag

}