基于stm32的超声波测距

基于STM32的超声波测距可以通过以下步骤实现：

1. 确定超声波发射器和接收器的引脚连接方式，并将它们连接到STM32的GPIO引脚上。

2. 初始化STM32的GPIO引脚，以便能够控制超声波发射器的触发信号，并读取超声波接收器的回波信号。

3. 在STM32中编写程序，以便在需要测距时触发超声波发射器，并计算回波信号的时间差，从而计算出距离。

4. 将距离信息通过串口发送回计算机或其他设备，以便进一步处理或显示。

以下是一个基于STM32的超声波测距的示例代码：

#include "stm32f10x.h"
#include <stdio.h>

#define TRIG_PIN GPIO_Pin_0
#define ECHO_PIN GPIO_Pin_1
#define TRIG_PORT GPIOA
#define ECHO_PORT GPIOA

void delay_us(uint32_t us)
{
    uint32_t i;
    for(i=0; i<us*8; i++);
}

float measure_distance(void)
{
    uint32_t start_time, end_time;
    float distance;
    
    GPIO_ResetBits(TRIG_PORT, TRIG_PIN);
    delay_us(2);
    GPIO_SetBits(TRIG_PORT, TRIG_PIN);
    delay_us(10);
    GPIO_ResetBits(TRIG_PORT, TRIG_PIN);
    
    while(GPIO_ReadInputDataBit(ECHO_PORT, ECHO_PIN) == RESET);
    start_time = TIM_GetCounter(TIM2);
    while(GPIO_ReadInputDataBit(ECHO_PORT, ECHO_PIN) == SET);
    end_time = TIM_GetCounter(TIM2);
    
    distance = (float)(end_time - start_time) / 58.0;
    return distance;
}

int main(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;
    USART_InitTypeDef USART_InitStructure;
    TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
    
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_USART1, ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
    
    GPIO_InitStructure.GPIO_Pin = TRIG_PIN;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(TRIG_PORT, &GPIO_InitStructure);
    
    GPIO_InitStructure.GPIO_Pin = ECHO_PIN;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(ECHO_PORT, &GPIO_InitStructure);
    
    USART_InitStructure.USART_BaudRate = 9600;
    USART_InitStructure.USART_WordLength = USART_WordLength_8b;
    USART_InitStructure.USART_StopBits = USART_StopBits_1;
    USART_InitStructure.USART_Parity = USART_Parity_No;
    USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
    USART_InitStructure.USART_Mode = USART_Mode_Tx;
    USART_Init(USART1, &USART_InitStructure);
    USART_Cmd(USART1, ENABLE);
    
    TIM_TimeBaseStructure.TIM_Period = 0xFFFF;
    TIM_TimeBaseStructure.TIM_Prescaler = 72 - 1;
    TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);
    TIM_Cmd(TIM2, ENABLE);
    
    while(1)
    {
        float distance = measure_distance();
        char buffer[32];
        sprintf(buffer, "Distance: %.2f cm\r\n", distance);
        USART_SendData(USART1, buffer);
        delay_us(100000);
    }
}