STM32F0XX TIM1 CH2 INPUT CAPTURE 输入捕获PPM信号

按文档的例子和其它例子都很少使用timer1的，不知道为什么，但是我想使用它，方便端口重用，我一开始使用tim1 ch3,死活不工作，搞了几天，没有办法换了一个ch2， 结果同样的代码就工作了。不知道为什么，希望看到的高手告知。（使用f103，timer1 的ch3同样的代码也没有问题。）

分享PPM的代码如下，是捕捉航模的PPM信号。

#define NUM_CHANNELS 8

int cur_ch = 0;

void InitPPMCapture()
{

    GPIO_InitTypeDef GPIO_InitStructure={0};
    TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure={0};
    TIM_ICInitTypeDef  TIM_ICInitStru={0};
    NVIC_InitTypeDef NVIC_InitStructure={0};
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC1, ENABLE);

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM1, ENABLE);


    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_Level_3;
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;


    GPIO_Init(GPIOA, &GPIO_InitStructure);

    GPIO_PinAFConfig(GPIOA, GPIO_PinSource9, GPIO_AF_2);  //PA9 - TIM1_CH2
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource10, GPIO_AF_2);  //PA10 - TIM1_CH3
    

    //

    //FOR PPM
    TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBaseStructure.TIM_Period = 0xFFFF; //ppm 22ms
    TIM_TimeBaseStructure.TIM_Prescaler = 47; // 48mhz / (47+1)  1 us
    TIM_TimeBaseStructure.TIM_RepetitionCounter = 0;
    TIM_TimeBaseInit(TIM1, &TIM_TimeBaseStructure); //ppm 22ms
    TIM_ARRPreloadConfig(TIM1,DISABLE);

    TIM_ICInitStru.TIM_Channel = TIM_Channel_2; //CC2S=01     选择输入端 IC2映射到TI2上
    TIM_ICInitStru.TIM_ICPolarity = TIM_ICPolarity_Rising;    //上升沿捕获
    TIM_ICInitStru.TIM_ICSelection = TIM_ICSelection_DirectTI; //映射到TI2上
    TIM_ICInitStru.TIM_ICPrescaler = TIM_ICPSC_DIV1;   //配置输入分频,不分频 
    TIM_ICInitStru.TIM_ICFilter = 0x00;//IC1F=0000 配置输入滤波器 不滤波
    TIM_ICInit(TIM1, &TIM_ICInitStru);

    TIM_InternalClockConfig(TIM1);
    TIM_SelectMasterSlaveMode(TIM1,TIM_MasterSlaveMode_Disable);
    TIM_SelectSlaveMode(TIM1,TIM_SlaveMode_Reset);
    //TIM_SelectInputTrigger(TIM1,TIM_TS_TI2FP2);

    NVIC_InitStructure.NVIC_IRQChannel = TIM1_CC_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);
  
    TIM_Cmd(TIM1,ENABLE);  //使能定时器1
    TIM_ITConfig(TIM1, TIM_IT_CC2,ENABLE);
    TIM_CCxCmd(TIM1,TIM_Channel_2,TIM_CCx_Enable);
    TIM_Cmd(TIM1,ENABLE);  //使能定时器1


}



void TIM1_CC_IRQHandler(void)
{
    if (TIM_GetITStatus(TIM1, TIM_IT_CC2) != RESET)
    {
 
        uint16_t val =TIM_GetCapture2(TIM1);
        TIM_SetCounter(TIM1, 0);


        if (val > 3000) {
            // sync signal
           
           cur_ch = 0;
        }
        else if(val > 500)
        {
  
            rx_current_state = BINDED_GOT_RC_DATA;
            last_recv_signal_time = GetTickCount();

            if (cur_ch < NUM_CHANNELS) {
                Channel_Output[cur_ch] = val;
                cur_ch++;
            }
            else
            {
                cur_ch = 0;
            }
          
        }


        /* over-capture */
        if (TIM_GetFlagStatus(TIM1, TIM_FLAG_CC2OF) != RESET)
        {
            
           TIM_ClearFlag(TIM1, TIM_FLAG_CC2OF);
        }
    }

}