STM32输入捕获采集光电传感器高电平时间代码

下面是一个简单的示例代码，用于在STM32上进行输入捕获以测量光电传感器的高电平时间：

#include "stm32f4xx.h"

#define TIMx            TIM2
#define TIMx_CLK        RCC_APB1Periph_TIM2
#define TIMx_IRQn       TIM2_IRQn
#define TIMx_IRQHandler TIM2_IRQHandler
#define TIMx_CH1_PIN    GPIO_Pin_0
#define TIMx_CH1_PORT   GPIOA
#define TIMx_CH1_PINSRC GPIO_PinSource0
#define TIMx_CH1_AF     GPIO_AF_TIM2

#define SENSOR_PIN      GPIO_Pin_1
#define SENSOR_PORT     GPIOA

volatile uint32_t sensorHighTime = 0;

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

    /* Enable the TIMx clock */
    RCC_APB1PeriphClockCmd(TIMx_CLK, ENABLE);

    /* Enable the GPIOA clock */
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);

    /* Configure TIMx_CH1 pin as input floating */
    GPIO_InitStructure.GPIO_Pin = TIMx_CH1_PIN;
    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_UP;
    GPIO_Init(TIMx_CH1_PORT, &GPIO_InitStructure);

    /* Connect TIMx_CH1 to GPIO pin */
    GPIO_PinAFConfig(TIMx_CH1_PORT, TIMx_CH1_PINSRC, TIMx_CH1_AF);

    /* TIMx configuration: Input Capture mode ---------------------
     The external signal is connected to TIMx_CH1 pin (PA.0)
     The Rising edge is used as active edge,
     The TIMx CCR1 is used to compute the frequency value 
     ------------------------------------------------------------ */
    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 = 0x0;

    TIM_ICInit(TIMx, &TIM_ICInitStructure);

    /* Enable the TIMx global Interrupt */
    NVIC_InitStructure.NVIC_IRQChannel = TIMx_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);

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

    /* TIMx enable counter */
    TIM_Cmd(TIMx, ENABLE);
}

void GPIO_Configuration(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;

    /* Enable the GPIOA clock */
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);

    /* Configure the SENSOR pin as input */
    GPIO_InitStructure.GPIO_Pin = SENSOR_PIN;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
    GPIO_Init(SENSOR_PORT, &GPIO_InitStructure);
}

int main(void)
{
    /* System Clock Configuration */
    SystemInit();

    GPIO_Configuration();

    TIMx_Configuration();

    while (1)
    {
        /* Wait for the sensor pin to go high */
        while (GPIO_ReadInputDataBit(SENSOR_PORT, SENSOR_PIN) == 0);

        /* Wait for the input capture interrupt to occur */
        while (sensorHighTime == 0);

        /* Print out the sensor high time */
        printf("Sensor High Time: %d us\n", sensorHighTime);

        /* Reset the high time value */
        sensorHighTime = 0;
    }
}

void TIMx_IRQHandler(void)
{
    if (TIM_GetITStatus(TIMx, TIM_IT_CC1) != RESET)
    {
        static uint32_t lastCaptureValue = 0;

        uint32_t currentCaptureValue = TIM_GetCapture1(TIMx);
        uint32_t captureDiff = currentCaptureValue - lastCaptureValue;

        /* Check for timer overflow */
        if (TIM_GetFlagStatus(TIMx, TIM_FLAG_CC1OF) != RESET)
        {
            captureDiff = (0xFFFF - lastCaptureValue) + currentCaptureValue + 1;
        }

        /* Calculate the sensor high time */
        if (captureDiff > 0)
        {
            sensorHighTime = captureDiff * (1000000 / SystemCoreClock);
        }

        /* Save the current capture value as the last value */
        lastCaptureValue = currentCaptureValue;

        /* Clear the interrupt flag */
        TIM_ClearITPendingBit(TIMx, TIM_IT_CC1);
    }
}

在此示例中，我们使用了STM32的输入捕获功能来测量光电传感器的高电平时间。我们使用TIM2通道1来进行输入捕获，并将光电传感器连接到GPIOA的Pin1。

在主循环中，我们等待光电传感器Pin1变为高电平，然后等待输入捕获中断发生。一旦中断发生，我们将高电平时间打印到串口，并重置高电平时间值以等待下一个读数。

在输入捕获中断处理程序中，我们计算当前时间和上一个时间捕获之间的时间差，以得到高电平时间。我们还需要注意，如果计数器发生了溢出，我们需要正确地计算时间差。

最后，我们需要在`stm32f4xx.h`头文件中定义`SystemCoreClock`，以便正确计算时间差。

这只是一个简单的示例代码，仅演示了如何使用输入捕获来测量光电传感器的高电平时间。实际应用中可能需要对代码进行修改以满足特定的需求。