[Learning record] STM32 input capture experiment

STM32 input capture working process (channel 1 as an example)

 Summarize the working process in one sentence: By detecting the edge signal on TIMx_CHx , when the edge signal jumps (such as rising edge / falling edge), store the current timer value ( TIMx_CNT ) into the corresponding capture / compare register ( TIMx_CCRx ) to complete a capture.

Step 1 Set the input capture filter (channel 1 as an example)

 Step 2: Set input capture polarity (channel 1 as an example)

Step 3: Set the input capture mapping channel (channel 1 as an example)

Step 4: Set the input capture divider (channel 1 as an example)

Step 5: When a valid signal is captured, the interrupt can be enabled

 

Finally: take a look at the corresponding pins of the timer channel (take TIM5 as an example)

 

Input capture channel initialization function: void TIM_ICInit ( TIM_TypeDef * TIMx , TIM_ICInitTypeDef * TIM_ICInitStruct );

typedef struct

{

  uint16_t TIM_Channel; //捕获通道1-4  

  uint16_t TIM_ICPolarity; //捕获极性

  uint16_t TIM_ICSelection; //映射关系

  uint16_t TIM_ICPrescaler; //分频系数

  uint16_t TIM_ICFilter;  //滤波器

} TIM_ICInitTypeDef;

TIM5_ICInitStructure.TIM_Channel = TIM_Channel_1; TIM5_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;
TIM5_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI; 
TIM5_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;
TIM5_ICInitStructure.TIM_ICFilter = 0x00;
TIM_ICInit(TIM5, &TIM5_ICInitStructure);

Channel polarity setting independent function:

void TIM_OCxPolarityConfig(TIM_TypeDef* TIMx, uint16_t TIM_OCPolarity)；

Get channel capture value:

uint32_t TIM_GetCapture1(TIM_TypeDef* TIMx)；

General configuration steps for input capture:

① Initialize the timer and the clock of the IO corresponding to the channel .

② Initialize the IO port, the mode is input: GPIO_Init ();

    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPD; //PA0 输入

③Initialize timer ARR , PSC

   TIM_TimeBaseInit ();

④Initialize input capture channel

   TIM_ICInit ();

⑤If you want to enable capture interrupt,

    TIM_ITConfig();

    NVIC_Init();

⑥Enable timer: TIM_Cmd ();

⑦Write the interrupt service function: TIMx_IRQHandler ();

Experiment purpose: measure the pulse width of the signal

 

Important code:

timer.c：

 main.c：