库函数捕捉程序如下:
void main(void)
{
  TIM1_Channel = TIM1_CHANNEL_1
  TIM1_ICPolarity = TIM1_ICPOLARITY_FALLING
  TIM1_ICSelection = TIM1_ICSELECTION_DIRECTTI
  TIM1_ICPrescaler = TIM1_ICPSC_DIV8
  TIM1_ICFilter = 0x0
  TIM1_ICInit( TIM1_CHANNEL_1, TIM1_ICPOLARITY_FALLING, TIM1_ICSELECTION_DIRECTTI,  TIM1_ICPSC_DIV8, 0x0);
  TIM1_ITConfig(TIM1_IT_CC1, ENABLE); 
   /* Enable TIM1 */
  TIM1_Cmd(ENABLE);
   /* Clear CC1 Flag*/
  TIM1_ClearFlag(TIM1_FLAG_CC1);
   /* Connect LSI to COO pin*/
  GPIO_Init(GPIOE, GPIO_PIN_0, GPIO_MODE_OUT_PP_LOW_FAST);
  CLK_CCOConfig(CLK_OUTPUT_LSI);
  CLK_CCOCmd(ENABLE);
  /* wait a capture on CC1 */
  while((TIM1->SR1 & TIM1_FLAG_CC1) != TIM1_FLAG_CC1);
  /* Get CCR1 value*/
        ICValue1 = TIM1_GetCapture1();
        TIM1_ClearFlag(TIM1_FLAG_CC1);
        /* wait a capture on cc1 */
  while((TIM1->SR1 & TIM1_FLAG_CC1) != TIM1_FLAG_CC1);
  /* Get CCR1 value*/
        ICValue2 = TIM1_GetCapture1();
        TIM1_ClearFlag(TIM1_FLAG_CC1);
  /* Compute LSI clock frequency */
  LSIClockFreq = (8 * TIM1ClockFreq) / (ICValue2 - ICValue1);
/* Insert a break point here */
        while (1);
}
在此库函数基础上,改为TIME2产生PWM程序如下,
void init_hsiclk(void) 
{ 
CLK_DeInit(); //寄存器复位
CLK_HSICmd(ENABLE); //内部高速时钟使能 
CLK_HSIPrescalerConfig(CLK_PRESCALER_HSIDIV1); //内部分频 2M
}
void TIM2_init(void) 
{
  TIM2_TimeBaseInit(TIM2_PRESCALER_16, 6665);
  TIM2_OC3Init(TIM2_OCMODE_PWM1, TIM2_OUTPUTSTATE_ENABLE,CCR3_Val, TIM2_OCPOLARITY_HIGH);
  TIM2_OC3PreloadConfig(ENABLE);
  TIM2_ARRPreloadConfig(ENABLE);
  TIM2_Cmd(ENABLE);
}
void main(void)
{
  //CLK_HSIPrescalerConfig(CLK_PRESCALER_HSIDIV1);//主时钟16/16=1MHZ   4分频
        init_hsiclk(); 
        GPIO_Init(TIME2PWMOUT_PORT, TIME2PWMOUT_PIN , GPIO_MODE_OUT_PP_LOW_FAST);     //设置PA3端口为推挽输出模式
        GPIO_Init(TIME1PWMIN_PORT , TIME1PWMIN_PIN, GPIO_MODE_IN_FL_NO_IT);
  TIM2_init(); 
        TIM1_ICInit( TIM1_CHANNEL_1, TIM1_ICPOLARITY_FALLING, TIM1_ICSELECTION_DIRECTTI,  TIM1_ICPSC_DIV8, 0x0);
        /* Enable CC1 interrupt */
        TIM1_ITConfig(TIM1_IT_CC1, ENABLE); 
        /* Enable TIM1 */
  TIM1_Cmd(ENABLE);
        /* Clear CC1 Flag*/
  TIM1_ClearFlag(TIM1_FLAG_CC1);
        /* Connect LSI to COO pin*/
//GPIO_Init(GPIOE, GPIO_PIN_0, GPIO_MODE_OUT_PP_LOW_FAST);    //不使用
        //CLK_CCOConfig(CLK_OUTPUT_LSI);
        //CLK_CCOCmd(ENABLE);
        
        /* wait a capture on CC1 */
  while((TIM1->SR1 & TIM1_FLAG_CC1) != TIM1_FLAG_CC1);
  /* Get CCR1 value*/
        ICValue1 = TIM1_GetCapture1();
        TIM1_ClearFlag(TIM1_FLAG_CC1);
        /* wait a capture on cc1 */
  while((TIM1->SR1 & TIM1_FLAG_CC1) != TIM1_FLAG_CC1);
  /* Get CCR1 value*/
        ICValue2 = TIM1_GetCapture1();
        TIM1_ClearFlag(TIM1_FLAG_CC1);
  /* Compute LSI clock frequency */
  LSIClockFreq = (8 * TIM1ClockFreq) / (ICValue2 - ICValue1);
        
        /* Insert a break point here */
        while (1);
}