STM32，hcsr04超声波测距模块c语言代码

好的，以下是HCSR04超声波测距模块的STM32的C语言代码：

#include "stm32f10x.h"
#include "stdio.h"
#include "delay.h"

#define Trig GPIO_Pin_2
#define Echo GPIO_Pin_3

void HC_SR04_Init(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);

    GPIO_InitStructure.GPIO_Pin = Trig;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

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

    GPIO_ResetBits(GPIOA, Trig);
}

void HC_SR04_Trig(void)
{
    GPIO_SetBits(GPIOA, Trig);
    delay_us(10);
    GPIO_ResetBits(GPIOA, Trig);
}

float HC_SR04_Get_Distance(void)
{
    uint16_t i = 0;
    float Distance = 0;
    uint32_t temp = 0;

    HC_SR04_Trig();
    while(GPIO_ReadInputDataBit(GPIOA, Echo) == RESET)
    {
        i++;
        delay_us(1);
        if(i > 8000)
            return -1;
    }

    TIM_Cmd(TIM2, ENABLE);
    TIM_SetCounter(TIM2, 0);

    while(GPIO_ReadInputDataBit(GPIOA, Echo) == SET)
    {
        temp = TIM_GetCounter(TIM2);
        if(temp > 58000)
            break;
    }

    TIM_Cmd(TIM2, DISABLE);

    Distance = (float)temp / 58.0;

    return Distance;
}

int main(void)
{
    float distance = 0;

    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
    TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
    TIM_TimeBaseStructure.TIM_Period = 0xFFFF;
    TIM_TimeBaseStructure.TIM_Prescaler = 71;
    TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);

    HC_SR04_Init();
    delay_init();

    while(1)
    {
        distance = HC_SR04_Get_Distance();
        if(distance != -1)
        {
            printf("distance: %.2f cm\n", distance);
        }
        delay_ms(500);
    }
}

这段代码使用了STM32的定时器来测量超声波从发送到接收的时间，并通过简单的公式将时间转换为距离。同时，这个例子也演示了如何使用USART向电脑终端输出距离信息。同样需要注意超声波测距模块与STM32的接线，以及Trig和Echo的定义是否正确。