stm32扫描模式测量频率程序

以下是一个简单的基于STM32的扫描模式测量频率程序：

#include "stm32f10x.h"

#define TIM_PERIOD 65535

uint16_t capture = 0;
uint32_t frequency = 0;

void TIM2_IRQHandler(void)
{
    if (TIM_GetITStatus(TIM2, TIM_IT_CC2) != RESET)
    {
        TIM_ClearITPendingBit(TIM2, TIM_IT_CC2);
        uint16_t last_capture = capture;
        capture = TIM_GetCapture2(TIM2);
        uint16_t diff = capture - last_capture;
        if (diff > 0)
        {
            frequency = SystemCoreClock / diff;
        }
    }
}

int main(void)
{
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);

    GPIO_InitTypeDef GPIO_InitStructure;
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_1;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
    TIM_TimeBaseStructure.TIM_Period = TIM_PERIOD;
    TIM_TimeBaseStructure.TIM_Prescaler = 0;
    TIM_TimeBaseStructure.TIM_ClockDivision = 0;
    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);

    TIM_ICInitTypeDef TIM_ICInitStructure;
    TIM_ICInitStructure.TIM_Channel = TIM_Channel_2;
    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(TIM2, &TIM_ICInitStructure);

    TIM_ITConfig(TIM2, TIM_IT_CC2, ENABLE);
    NVIC_EnableIRQ(TIM2_IRQn);

    TIM_Cmd(TIM2, ENABLE);

    while (1)
    {
        // do something
    }
}

在这个程序中，我们使用了STM32的定时器2来测量输入信号的频率。我们使用了定时器的输入捕获模式来捕获输入信号的上升沿，并计算两个上升沿之间的时间差，从而计算出输入信号的频率。