单片机通过外部中断测量上升沿数量测量方波频率

好的，下面是一份基于STM32单片机的代码，可以通过外部中断测量上升沿数量来计算方波信号的频率：

#include "stm32f10x.h"

#define TIMx TIM2
#define TIMx_IRQn TIM2_IRQn

volatile uint32_t g_count = 0;
volatile uint32_t g_frequency = 0;

void TIMx_IRQHandler(void)
{
    if (TIM_GetITStatus(TIMx, TIM_IT_Update) != RESET)
    {
        g_count = 0;
        TIM_ClearITPendingBit(TIMx, TIM_IT_Update);
    }
}

void EXTI9_5_IRQHandler(void)
{
    if (EXTI_GetITStatus(EXTI_Line5) != RESET)
    {
        g_count++;
        EXTI_ClearITPendingBit(EXTI_Line5);
    }
}

void TIMx_Configuration(void)
{
    TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;

    TIM_DeInit(TIMx);

    TIM_TimeBaseStructure.TIM_Prescaler = 71;  // 定时器分频系数，时钟频率为72MHz，分频系数为71，则定时器时钟频率为1MHz
    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBaseStructure.TIM_Period = 0xFFFF;
    TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
    TIM_TimeBaseStructure.TIM_RepetitionCounter = 0;

    TIM_TimeBaseInit(TIMx, &TIM_TimeBaseStructure);

    TIM_ITConfig(TIMx, TIM_IT_Update, ENABLE);

    NVIC_InitTypeDef NVIC_InitStructure;

    NVIC_InitStructure.NVIC_IRQChannel = TIMx_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);
}

void EXTI_Configuration(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;
    EXTI_InitTypeDef EXTI_InitStructure;
    NVIC_InitTypeDef NVIC_InitStructure;

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO, ENABLE);

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    GPIO_EXTILineConfig(GPIO_PortSourceGPIOA, GPIO_PinSource5);

    EXTI_InitStructure.EXTI_Line = EXTI_Line5;
    EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;
    EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Rising;
    EXTI_InitStructure.EXTI_LineCmd = ENABLE;
    EXTI_Init(&EXTI_InitStructure);

    NVIC_InitStructure.NVIC_IRQChannel = EXTI9_5_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);
}

int main(void)
{
    TIMx_Configuration();
    EXTI_Configuration();

    while (1)
    {
        g_frequency = TIM_GetCounter(TIMx) * 1000000 / (g_count * 72);
        TIM_SetCounter(TIMx, 0);
    }
}

代码中使用的是TIM2定时器和PA5引脚，需要根据实际情况进行修改。代码的核心部分是在中断服务程序中对计数器进行操作，并在主函数中根据计数器和定时器的配置计算出频率。