请教一个关于STM32F407脉宽测量问题

longfei_3 提问时间：2016-11-14 17:41 /

我打算用TIM9测量波形的脉宽长度，但是读取的置始终为0，请各位大牛帮我看看原因：
初始化：
void TIM9Capture1Init()
{
GPIO_InitTypeDef GPIO_InitStructure;
TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
NVIC_InitTypeDef NVIC_InitStructure;
TIM_ICInitTypeDef TIM_ICInitStructure;

RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM9,ENABLE);  //ENABLE TIM9 of RCC
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOE, ENABLE); //enable GPIOE of RCC

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_DOWN;
GPIO_Init(GPIOE,&GPIO_InitStructure);

GPIO_PinAFConfig(GPIOE,GPIO_PinSource5,GPIO_AF_TIM9);

TIM_TimeBaseStructure.TIM_Prescaler=0xFFFF;
TIM_TimeBaseStructure.TIM_CounterMode=TIM_CounterMode_Up;
TIM_TimeBaseStructure.TIM_Period=20;//4Mh
TIM_TimeBaseStructure.TIM_ClockDivision=TIM_CKD_DIV1;

TIM_TimeBaseInit(TIM9,&TIM_TimeBaseStructure);

TIM_ICInitStructure.TIM_Channel = TIM_Channel_1;
TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_BothEdge;
TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;

TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;
TIM_ICInitStructure.TIM_ICFilter = 0x0;
TIM_ICInit(TIM9, &TIM_ICInitStructure);

NVIC_InitStructure.NVIC_IRQChannel = TIM1_BRK_TIM9_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);

TIM_ITConfig(TIM9,TIM_IT_Update|TIM_IT_CC1,ENABLE);
TIM_Cmd(TIM9,ENABLE);
TIM_SetCounter(TIM9,0);

}
中断服务函数：
void TIM1_BRK_TIM9_IRQHandler(void)
{
static uint8_t test=0;
uint8_t tdat;

if(TIM_GetITStatus(TIM9, TIM_IT_Update) != RESET)//超时处理
{
      TIM_SetCounter(TIM9,0);
      TIM_ClearITPendingBit(TIM9,TIM_IT_Update);
}

if(TIM_GetITStatus(TIM9, TIM_IT_CC1) != RESET)
{
         if(test%2==0) IO0_SET();//IO口翻转测试，该处波形与输入波形一致，周期约24us
         else IO0_CLR();
         test++;
      tdat=TIM_GetCapture1(TIM9);
      my.buf[my.wpos++] = tdat;
      TIM_SetCounter(TIM9,0); //重新计算超时
      TIM_ClearITPendingBit(TIM9, TIM_IT_CC1);
}

}