stm32f103的LSI时钟校准问题

stm32f103RE有LSI校准的功能吗，为什么我按手册配置好了定时器，可是老是不进定时器中断，是我的配置问题吗？？，求高手指教
void TIM5_ConfigForLSI(void)
{
  NVIC_InitTypeDef NVIC_InitStructure;
  TIM_ICInitTypeDef  TIM_ICInitStructure;

  /* Enable TIM5 clocks */
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM5, ENABLE);
  
  
          /* Deinitialize the TIM5 peripheral registers to their default reset values */
  TIM_DeInit(TIM5);

  /* Configure TIM5 prescaler */
  TIM_PrescalerConfig(TIM5, 0, TIM_PSCReloadMode_Immediate);

  /* Connect internally the TM5_CH4 Input Capture to the LSI clock output */
  GPIO_PinRemapConfig(GPIO_Remap_TIM5CH4_LSI, ENABLE);
  
  /* TIM5 configuration: Input Capture mode ---------------------
     The LSI oscillator is connected to TIM5 CH4
     The Rising edge is used as active edge,
     The TIM5 CCR4 is used to compute the frequency value
  ------------------------------------------------------------ */
  TIM_ICInitStructure.TIM_Channel = TIM_Channel_4;
  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 = 0;
  TIM_ICInit(TIM5, &TIM_ICInitStructure);
        
        /* Enable the TIM5 Interrupt */
  NVIC_InitStructure.NVIC_IRQChannel = TIM5_IRQn;
  NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
  NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
  NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
  NVIC_Init(&NVIC_InitStructure);
  
  /* TIM10 Counter Enable */
  TIM_Cmd(TIM5, ENABLE);

  /* Reset the flags */
  TIM5->SR = 0;
   
  /* Enable the CC4 Interrupt Request */  
  TIM_ITConfig(TIM5, TIM_IT_CC4, ENABLE);  
}

已解决，AFIO时钟未开启

RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO, ENABLE);