。我现在外部有三路PWM波输入。我需要使用捕获的功能来实现三路PWM波来实现占空比的计算

你可以使用定时器的捕获功能来实现三路PWM波的占空比计算。具体实现方法如下：

1. 配置定时器的捕获通道，使其能够捕获PWM波的上升沿和下降沿。

2. 在定时器中断服务函数中，根据捕获到的上升沿和下降沿的时间差，计算出PWM波的周期和占空比。

3. 将计算出的占空比存储到相应的变量中，以供后续使用。

以下是一个简单的示例代码：

#include "stm32f4xx.h"

#define PWM1_CAPTURE_CHANNEL TIM_Channel_1
#define PWM2_CAPTURE_CHANNEL TIM_Channel_2
#define PWM3_CAPTURE_CHANNEL TIM_Channel_3

volatile uint32_t pwm1_period, pwm1_duty;
volatile uint32_t pwm2_period, pwm2_duty;
volatile uint32_t pwm3_period, pwm3_duty;

void TIM2_IRQHandler(void)
{
    static uint32_t pwm1_rising_edge_time, pwm2_rising_edge_time, pwm3_rising_edge_time;

    if (TIM_GetITStatus(TIM2, TIM_IT_CC1) != RESET) {
        TIM_ClearITPendingBit(TIM2, TIM_IT_CC1);
        if (GPIO_ReadInputDataBit(GPIOA, GPIO_Pin_0) == SET) {
            pwm1_rising_edge_time = TIM_GetCapture1(TIM2);
        } else {
            uint32_t pwm1_falling_edge_time = TIM_GetCapture1(TIM2);
            pwm1_period = pwm1_falling_edge_time - pwm1_rising_edge_time;
            pwm1_duty = (pwm1_period > 0) ? ((pwm1_falling_edge_time - pwm1_rising_edge_time) * 100 / pwm1_period) : 0;
        }
    }

    if (TIM_GetITStatus(TIM2, TIM_IT_CC2) != RESET) {
        TIM_ClearITPendingBit(TIM2, TIM_IT_CC2);
        if (GPIO_ReadInputDataBit(GPIOA, GPIO_Pin_1) == SET) {
            pwm2_rising_edge_time = TIM_GetCapture2(TIM2);
        } else {
            uint32_t pwm2_falling_edge_time = TIM_GetCapture2(TIM2);
            pwm2_period = pwm2_falling_edge_time - pwm2_rising_edge_time;
            pwm2_duty = (pwm2_period > 0) ? ((pwm2_falling_edge_time - pwm2_rising_edge_time) * 100 / pwm2_period) : 0;
        }
    }

    if (TIM_GetITStatus(TIM2, TIM_IT_CC3) != RESET) {
        TIM_ClearITPendingBit(TIM2, TIM_IT_CC3);
        if (GPIO_ReadInputDataBit(GPIOA, GPIO_Pin_2) == SET) {
            pwm3_rising_edge_time = TIM_GetCapture3(TIM2);
        } else {
            uint32_t pwm3_falling_edge_time = TIM_GetCapture3(TIM2);
            pwm3_period = pwm3_falling_edge_time - pwm3_rising_edge_time;
            pwm3_duty = (pwm3_period > 0) ? ((pwm3_falling_edge_time - pwm3_rising_edge_time) * 100 / pwm3_period) : 0;
        }
    }
}

int main(void)
{
    // 初始化定时器2
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
    TIM_TimeBaseInitTypeDef TIM_TimeBaseInitStruct;
    TIM_TimeBaseInitStruct.TIM_Prescaler = 0;
    TIM_TimeBaseInitStruct.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBaseInitStruct.TIM_Period = 0xFFFF;
    TIM_TimeBaseInitStruct.TIM_ClockDivision = TIM_CKD_DIV1;
    TIM_TimeBaseInitStruct.TIM_RepetitionCounter = 0;
    TIM_TimeBaseInit(TIM2, &TIM_TimeBaseInitStruct);

    // 配置定时器2的捕获通道1、2、3
    TIM_ICInitTypeDef TIM_ICInitStruct;
    TIM_ICInitStruct.TIM_Channel = PWM1_CAPTURE_CHANNEL;
    TIM_ICInitStruct.TIM_ICPolarity = TIM_ICPolarity_Rising;
    TIM_ICInitStruct.TIM_ICSelection = TIM_ICSelection_DirectTI;
    TIM_ICInitStruct.TIM_ICPrescaler = TIM_ICPSC_DIV1;
    TIM_ICInitStruct.TIM_ICFilter = 0;
    TIM_ICInit(TIM2, &TIM_ICInitStruct);
    TIM_ICInitStruct.TIM_Channel = PWM2_CAPTURE_CHANNEL;
    TIM_ICInit(TIM2, &TIM_ICInitStruct);
    TIM_ICInitStruct.TIM_Channel = PWM3_CAPTURE_CHANNEL;
    TIM_ICInit(TIM2, &TIM_ICInitStruct);

    // 配置GPIO口为输入模式
    GPIO_InitTypeDef GPIO_InitStruct;
    GPIO_InitStruct.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1 | GPIO_Pin_2;
    GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF;
    GPIO_InitStruct.GPIO_Speed = GPIO_Speed_100MHz;
    GPIO_InitStruct.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_NOPULL;
    GPIO_Init(GPIOA, &GPIO_InitStruct);
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource0, GPIO_AF_TIM2);
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource1, GPIO_AF_TIM2);
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource2, GPIO_AF_TIM2);

    // 配置定时器2中断
    NVIC_InitTypeDef NVIC_InitStruct;
    NVIC_InitStruct.NVIC_IRQChannel = TIM2_IRQn;
    NVIC_InitStruct.NVIC_IRQChannelPreemptionPriority = 0;
    NVIC_InitStruct.NVIC_IRQChannelSubPriority = 0;
    NVIC_InitStruct.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStruct);
    TIM_ITConfig(TIM2, TIM_IT_CC1 | TIM_IT_CC2 | TIM_IT_CC3, ENABLE);

    // 启动定时器2
    TIM_Cmd(TIM2, ENABLE);

    while (1) {
        // do something
    }
}