请教下STM32的定时器输入捕获

static void TIM1_GPIO_Config(void)

{

          RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB,ENABLE);

    GPIO_InitTypeDef GPIO_InitStructure;

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_14;

    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;

          GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

    GPIO_Init(GPIOB, &GPIO_InitStructure);         

}



static void TIM1_IC_Config(void)

{

    TIM_ICInitTypeDef TIM_ICInitStructure;

          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_DIV1;

          TIM_ICInitStructure.TIM_ICFilter = 0;        

          TIM_ICInit(TIM1,&TIM_ICInitStructure);

    TIM_ClearFlag(TIM1, TIM_FLAG_CC2);        

    TIM_Cmd(TIM1, ENABLE);         

    TIM_ITConfig(TIM1, TIM_IT_CC2, ENABLE);        



}



static void NVIC_TIM1_IC_Config(void)

{

    NVIC_InitTypeDef NVIC_InitStructure;

    /* Configure the NVIC Preemption Priority Bits */  

          NVIC_PriorityGroupConfig(NVIC_PriorityGroup_1);

          /* enabling interrupt */

          NVIC_InitStructure.NVIC_IRQChannel=TIM1_CC_IRQn;

          NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;

          NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;

          NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;

          NVIC_Init(&NVIC_InitStructure);

}

/**

  * @brief  This function handles TIM1 capture compare interrupt request.

  * @param  None

  * @retval None

  */

void TIM1_CC_IRQHandler(void)

{

         if(TIM_GetITStatus(TIM1,TIM_IT_CC2)!= RESET)

   {  

     TIM_ClearITPendingBit(TIM1, TIM_IT_CC2);                

  } 

}