我想使用stm32f103ze内部LSI时钟作为RTC的计数时钟，但是根据文档上说的，LSI的频率只在40k左右，但是这个不是准确的频率，如果作为RTC时钟，需要进行校正。我调试时只能够监测到更新中断，而那个捕获中断却没有监测到。大家帮我看看是那个地方出了问题。
我的步骤是：1、使能LSI时钟，并等待其稳定。
                     2、初始化TIMER5。
                     3、计算LSI频率。

我使用的程序模板是战舰开发板例程  实验10输入捕获实验
主要代码如下
使能LSI时钟：
/* Enable the Internal Low Speed oscillator */
RCC_LSICmd(ENABLE);
while ((RCC_GetFlagStatus(RCC_FLAG_LSIRDY) == RESET)&&temp<250)
{
temp++;
//delay_ms(10);
}
if(temp>=250)return 1;

初始化TIMER5：

void TIM5_Cap_Init(u16 arr,u16 psc)
{  
  TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
TIM_ICInitTypeDef TIM5_ICInitStructure; 

NVIC_InitTypeDef NVIC_InitStructure;

RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM5, ENABLE);

/* LSI connected to TIM5 Channel4 input capture for calibration */
GPIO_PinRemapConfig(GPIO_Remap_TIM5CH4_LSI, ENABLE);

TIM_TimeBaseStructure.TIM_Period = arr; 
TIM_TimeBaseStructure.TIM_Prescaler =psc; 
TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1; 
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; 
TIM_TimeBaseInit(TIM5, &TIM_TimeBaseStructure); 


TIM5_ICInitStructure.TIM_Channel = TIM_Channel_4;
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 = 0x0;
TIM_ICInit(TIM5, &TIM5_ICInitStructure);

TIM_ITConfig(TIM5,TIM_IT_Update|TIM_IT_CC4,ENABLE ); 


NVIC_InitStructure.NVIC_IRQChannel = TIM5_IRQn;  
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0; 
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 3;  
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; 
NVIC_Init(&NVIC_InitStructure);  


TIM_Cmd(TIM5, ENABLE);  

}

中断处理函数
#define CAPTURE_FINISHED 0x80000000
#define CAPTURE_FIRST_RISING 0x40000000
#define CAPTURE_SECOND_RISING 0x20000000

u32  TIM5CH4_CAPTURE_STA = 0; 
u16 TIM5CH4_CAPTURE_VAL = 0;


void TIM5_IRQHandler(void)
{ 
//u16 temp;
//temp = TIM_GetFlagStatus(TIM5, TIM_FLAG_Update);

  if((TIM5CH4_CAPTURE_STA & CAPTURE_FINISHED)==0)
{  
if (TIM_GetFlagStatus(TIM5, TIM_FLAG_Update) == SET) 
{    
if(TIM5CH4_CAPTURE_STA & CAPTURE_FIRST_RISING)
{
if((TIM5CH4_CAPTURE_STA&0X3FFFFFFF)==0X3FFFFFFF)
{
TIM5CH4_CAPTURE_STA|=CAPTURE_FINISHED;
TIM5CH4_CAPTURE_VAL=0XFFFF;

}
else 
TIM5CH4_CAPTURE_STA++;
}  
}

//temp = TIM_GetFlagStatus(TIM5, TIM_FLAG_CC4OF);

// if(TIM_GetFlagStatus(TIM5, TIM_FLAG_CC4OF)==SET) 
// {
// TIM5CH4_CAPTURE_STA|=CAPTURE_FINISHED; 
// TIM5CH4_CAPTURE_VAL=TIM_GetCapture4(TIM5);
//
// TIM_Cmd(TIM5, DISABLE);
//
// }

//temp = TIM_GetFlagStatus(TIM5, TIM_FLAG_CC4);
//temp = TIM_GetITStatus(TIM5, TIM_IT_CC4);
//if ( (TIM_GetITStatus(TIM5, TIM_IT_CC4) == SET) && ((TIM5CH4_CAPTURE_STA & CAPTURE_FIRST_RISING)!=CAPTURE_FIRST_RISING))
if (TIM_GetITStatus(TIM5, TIM_IT_CC4) == SET)
{
TIM5CH4_CAPTURE_STA=0; //????
TIM5CH4_CAPTURE_VAL=0;
TIM_SetCounter(TIM5,0);
TIM5CH4_CAPTURE_STA|=CAPTURE_FIRST_RISING;
}
  }

    TIM_ClearITPendingBit(TIM5, TIM_IT_Update|TIM_IT_CC4);

/* Clear the TIM5 Capture Compare 1 flag */
//TIM_ClearFlag(TIM5, TIM_FLAG_Update);

}