stm32f407输入捕获问题，怀疑与自认为与之无关的GPIO引脚初始化有冲突

shallowsing

求解：写f407的代码时，发现将PA5复用成TIM2的输入捕获通道时初始化有问题，进不去中断，再次检查怀疑可能与之前用的原子哥的按键输入的代码，也就是KEY0和KEYup也就是PA0和PE4作为GPIO输入的一段初始化代码有冲突，具体也调试找不出问题，（或者是我输入捕获初始化有问题？）
会不是用复用的时候回将TIM2
输入捕获代码如下：

void PPM_IN_Init()
{
    GPIO_InitTypeDef GPIO_InitStructure;
    TIM_ICInitTypeDef  TIM_ICInitStructure;
    NVIC_InitTypeDef NVIC_InitStructure;

    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
   
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_15;
    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; //下拉
    GPIO_Init(GPIOA,&GPIO_InitStructure);
   
    GPIO_PinAFConfig(GPIOA,GPIO_PinSource15,GPIO_AF_TIM2);
   
    NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);
  
    TIM2->PSC = (168/2)-1;
   
    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(TIM2, &TIM_ICInitStructure);
  
  /* TIM enable counter */
  TIM_Cmd(TIM2, ENABLE);

  /* Enable the CC1 Interrupt Request */
  TIM_ITConfig(TIM2, TIM_IT_CC1, ENABLE);
}

按键输入初始化如下：
void KEY_Init(void)
{
    GPIO_InitTypeDef  GPIO_InitStructure;

  RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA|RCC_AHB1Periph_GPIOE, ENABLE);//使能GPIOA,GPIOE时钟

  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_4; //KEY0对应引脚
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN;//普通输入模式
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;//100M
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;//上拉
  GPIO_Init(GPIOE, &GPIO_InitStructure);//初始化GPIOE4
   
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;//WK_UP对应引脚PA0
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_DOWN ;//下拉
  GPIO_Init(GPIOA, &GPIO_InitStructure);//初始化GPIOA0
}

//按键处理函数
//返回按键值
//0，没有任何按键按下
//1，KEY0按下
//2，WKUP按下 WK_UP
//注意此函数有响应优先级,KEY0>WKUP
u8 KEY_Scan(void)
{   
    u8 mode=0;
    if(KEY0==0||WK_UP==1)
    {
        Delay_ms(10);//去抖动
        if(KEY0==0)mode=1;
        else if(WK_UP==1)mode=2;
        else mode=0;
    }
    while(KEY0==0&&WK_UP==1);
    return mode;
}
求各位大佬帮帮忙