stm32霍尔传感器测速

使用STM32的霍尔传感器测速可以通过以下步骤实现：

1. 配置STM32的GPIO引脚，将霍尔传感器的输出引脚连接到STM32的输入引脚上。
2. 在代码中使用外部中断来检测霍尔传感器的输出信号，可以选择上升沿、下降沿或者两种沿都检测。
3. 计算转速，可以通过计算两个霍尔传感器输出信号之间的时间差来得到每分钟的转速。

下面是一个简单的示例代码：

#include "stm32f4xx.h"

#define HALL_SENSOR_GPIO_PORT   GPIOA
#define HALL_SENSOR_GPIO_PIN    GPIO_Pin_0
#define HALL_SENSOR_EXTI_LINE   EXTI_Line0
#define HALL_SENSOR_EXTI_PORT   EXTI_PortSourceGPIOA
#define HALL_SENSOR_EXTI_PIN    EXTI_PinSource0
#define HALL_SENSOR_EXTI_IRQ    EXTI0_IRQn

volatile uint32_t hall_sensor_count = 0;
volatile uint32_t hall_sensor_last_time = 0;

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

    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);

    GPIO_InitStructure.GPIO_Pin = HALL_SENSOR_GPIO_PIN;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(HALL_SENSOR_GPIO_PORT, &GPIO_InitStructure);

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_SYSCFG, ENABLE);

    EXTI_InitStructure.EXTI_Line = HALL_SENSOR_EXTI_LINE;
    EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;
    EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Rising_Falling;
    EXTI_InitStructure.EXTI_LineCmd = ENABLE;
    EXTI_Init(&EXTI_InitStructure);

    SYSCFG_EXTILineConfig(HALL_SENSOR_EXTI_PORT, HALL_SENSOR_EXTI_PIN);

    NVIC_InitStructure.NVIC_IRQChannel = HALL_SENSOR_EXTI_IRQ;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x00;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x00;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);
}

void EXTI0_IRQHandler(void)
{
    if (EXTI_GetITStatus(HALL_SENSOR_EXTI_LINE) != RESET)
    {
        uint32_t current_time = TIM_GetCounter(TIM2);
        hall_sensor_count++;
        if (hall_sensor_last_time != 0)
        {
            uint32_t time_diff = current_time - hall_sensor_last_time;
            uint32_t rpm = 60000000 / time_diff;
            // do something with the rpm value
        }
        hall_sensor_last_time = current_time;
        EXTI_ClearITPendingBit(HALL_SENSOR_EXTI_LINE);
    }
}

int main(void)
{
    hall_sensor_init();

    TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;

    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);

    TIM_DeInit(TIM2);

    TIM_TimeBaseStructure.TIM_Period = 0xFFFFFFFF;
    TIM_TimeBaseStructure.TIM_Prescaler = 84 - 1;
    TIM_TimeBaseStructure.TIM_ClockDivision = 0;
    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);

    TIM_Cmd(TIM2, ENABLE);

    while (1)
    {
        // do something else
    }
}

在这个示例代码中，我们使用STM32的外部中断检测霍尔传感器的输出信号，并且使用定时器计算转速。在中断处理函数中，我们可以计算每分钟的转速，并且对该值进行处理，例如显示在LCD屏幕上或者通过串口发送给电脑进行进一步处理。