stm32pwm输入捕获

STM32是一种基于ARM Cortex-M内核的微控制器。它具有多个定时器和PWM输出通道，可用于控制电机、LED灯、声音和其他应用。输入捕获是一种定时器功能，可以用于测量外部事件的时间间隔或周期。

以下是STM32使用输入捕获进行PWM控制的步骤：

1. 初始化定时器和GPIO引脚。

2. 配置定时器为输入捕获模式，设置触发条件和计数器方向。

3. 启动定时器和输入捕获。

4. 在输入捕获中断服务程序中读取捕获寄存器的值，计算PWM占空比。

5. 根据PWM占空比，更新PWM输出通道的占空比。

以下是一个简单的示例代码，演示了如何使用STM32的输入捕获功能控制PWM输出：

#include "stm32f4xx.h"

#define PWM_TIM TIM2
#define PWM_FREQ 1000
#define PWM_MAX_DUTY 100

void TIM_Configuration(void);
void GPIO_Configuration(void);

int main(void)
{
    TIM_Configuration();
    GPIO_Configuration();

    // 定义PWM变量
    uint32_t pwm_period = SystemCoreClock / PWM_FREQ - 1;
    uint32_t pwm_duty = 0;

    // 启动定时器和输入捕获
    TIM_Cmd(PWM_TIM, ENABLE);
    TIM_ITConfig(PWM_TIM, TIM_IT_CC1, ENABLE);

    while(1)
    {
        // 更新PWM占空比
        TIM_SetCompare1(PWM_TIM, pwm_duty);
        pwm_duty += 10;
        if(pwm_duty > PWM_MAX_DUTY)
        {
            pwm_duty = 0;
        }
        // 延时一段时间
        for(uint32_t i=0; i<500000; i++);
    }
}

void TIM_Configuration(void)
{
    TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
    TIM_ICInitTypeDef TIM_ICInitStructure;
    NVIC_InitTypeDef NVIC_InitStructure;

    // 使能TIM2时钟
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);

    // 初始化TIM2
    TIM_TimeBaseStructInit(&TIM_TimeBaseStructure);
    TIM_TimeBaseStructure.TIM_Period = SystemCoreClock / PWM_FREQ - 1;
    TIM_TimeBaseStructure.TIM_Prescaler = 0;
    TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBaseInit(PWM_TIM, &TIM_TimeBaseStructure);

    // 初始化TIM2输入捕获1
    TIM_ICStructInit(&TIM_ICInitStructure);
    TIM_ICInitStructure.TIM_Channel = TIM_Channel_1;
    TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;
    TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;
    TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;
    TIM_ICInitStructure.TIM_ICFilter = 0;
    TIM_ICInit(PWM_TIM, &TIM_ICInitStructure);

    // 配置TIM2中断
    NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);
}

void GPIO_Configuration(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;

    // 使能GPIOA时钟
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);

    // 配置GPIOA5为TIM2输入捕获1
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    GPIO_PinAFConfig(GPIOA, GPIO_PinSource5, GPIO_AF_TIM2);

    // 配置GPIOA0为TIM2 PWM输出1
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    GPIO_PinAFConfig(GPIOA, GPIO_PinSource0, GPIO_AF_TIM2);
}

void TIM2_IRQHandler(void)
{
    // 读取捕获寄存器的值
    uint32_t capture = TIM_GetCapture1(PWM_TIM);
    uint32_t period = TIM_GetAutoreload(PWM_TIM);

    // 计算PWM占空比
    uint32_t pwm_duty = capture * 100 / period;

    // 清除中断标志
    TIM_ClearITPendingBit(PWM_TIM, TIM_IT_CC1);
}