STM32f103VE,TIM4输入捕获问题

xde188 提问时间：2014-3-11 11:42 /

问题：使用TIM4输入捕获时，配置了输入捕获引脚为PB8，通道为IC3，为什么PB9引脚电平变化时能进入捕获中断？
代码如下，请问什么地方搞错了。


int main(void)
{

RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4,ENABLE); // 使能TIM模块
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_8; //Pb8
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
GPIO_Init(GPIOB, &GPIO_InitStructure);

//TIM通道的捕捉初始化
TIM_ICInitStructure.TIM_Channel = TIM_Channel_3;//通道选择
TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Falling;//下降沿
TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;//管脚与寄存器对应关系
TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;//分频器
TIM_ICInitStructure.TIM_ICFilter = 0x0; //滤波设置，经历几个周期跳变认定波形稳定0x0～0xF
TIM_ICInit(TIM4, &TIM_ICInitStructure); //初始化

TIM_Cmd(TIM4, ENABLE); //启动TIM4
TIM_ITConfig(TIM4, TIM_IT_CC3, ENABLE); //打开中断

NVIC_InitStructure.NVIC_IRQChannel = TIM4_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);

while (1)
{

}
}

//TIM4捕获中断服务函数
void TIM4_IRQHandler( void )
{

if(TIM_GetITStatus(TIM4, TIM_IT_CC3) == SET)
{

TIM_ClearITPendingBit(TIM4, TIM_IT_CC3);
     if(CaptureNumber == 0)
     {
     //Get the Input Capture value
     IC4ReadValue1 = TIM_GetCapture3(TIM4);
     CaptureNumber = 1;
     }
     else if(CaptureNumber == 1)
     {
     //Get the Input Capture value
     IC4ReadValue2 = TIM_GetCapture3(TIM4);

     //Capture computation
     if (IC4ReadValue2 > IC4ReadValue1)
     {
     Capture = (IC4ReadValue2 - IC4ReadValue1);
     }
     else
     {
     Capture = ((0xFFFF - IC4ReadValue1) + IC4ReadValue2);
     }
     //Frequency computation
     TIM4Freq = (uint32_t) SystemCoreClock / Capture;
     CaptureNumber = 0;
     }
}