土木本科生的STM32探索之旅：声波测距+usart通信，将距离的结果发送到电脑的串口助手上
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此实验我是使用的白色板子做的实验，暂时手里没有高博士白羊座的黑色板子，实验的原理是相通的，具体的原理我就暂时不解释了哦，我把博主的视频链接放在了下方：
【STM32】动画讲解输入捕获 并实现超声波测距_哔哩哔哩_bilibili
建议是大家先去了解一下声波测距的原理，在一步步地做实验。
由于比较忙，我就简单记录了我之前的实验过程和相关操作。
下面我就直接把我的学习过程展示出来哈
基于deepseek专家模式的实验指导：
一、硬件连接总览（keysking白板子）
HC-SR04（传感器）、VCC→接单片机5V（不可接3.3V）、GND→GND、Trig→PA11、
Echo→PA10
USB-TTL模块由于是集成为usb-type-c的数据线，所以暂时不需要交叉接线到单片机。
思考：对应着高博士黑色板上大家可以暂时思考下，需要接到那几个引脚？
二、软件端的操作
1、打开STM32CubeIDE，选择c8t6芯片后，新建项目，修改sys的debug模式。
2、RCC时钟树设置为72MHz。
3.配置USART2（pa10为usart1的，已经被占用了，所以这里用usart2做通信）。
4.配置Trig引脚（PA11输出），GPIO_Output，配置保持默认（推挽输出，无上下拉），不需要修改。
这里可以借鉴了，对高博士黑色板子有借鉴的意义。要什么选接入的引脚？
5.配置TIM1（pa10）输入捕获测量Echo高电平，
左侧Timers→TIM1、Clock Source选Internal Clock、
Prescaler填72-1（这样计数频率=72MHz/(71+1)=1MHz，即1μs计一个数）
Counter Period填65535（最大值，支持最长65.535ms脉宽）
Channel3下拉选择Input Capture direct mode
下方展开的Input Capture参数里：Polarity Selection选择Rising Edge（先捕获上升沿）
切换到NVIC Settings标签页，勾选TIM1 capture compare interrupt，确保Enabled打钩。优先级默认即可。
这一步也是需要借鉴一下，高博士黑色板子上面怎么配置？
6.点击齿轮生成代码，并打开mian.c文件，增加用户代码（借助AI工具辅助）。
#include <stdio.h>
#include <string.h>8.添加全局变量
volatile uint8_t echo_state = 0; // 0:等待上升沿, 1:等待下降沿
volatile uint32_t pulse_width = 0; // 高电平时间(us)
volatile uint8_t data_ready = 0; // 一次测量完成标志
float distance_cm = 0.0f;
void DWT_Init(void);
void DWT_Delay_us(uint32_t us);
void DWT_Init(void)
{
CoreDebug->DEMCR |= CoreDebug_DEMCR_TRCENA_Msk;
DWT->CTRL |= DWT_CTRL_CYCCNTENA_Msk;
DWT->CYCCNT = 0;
}
void DWT_Delay_us(uint32_t us)
{
uint32_t start = DWT->CYCCNT;
uint32_t ticks = us * (SystemCoreClock / 1000000);
while ((DWT->CYCCNT - start) < ticks);
}
void HAL_TIM_IC_CaptureCallback(TIM_HandleTypeDef *htim)
{
if (htim->Channel == HAL_TIM_ACTIVE_CHANNEL_3) // TIM1_CH3
{
if (echo_state == 0) // 刚捕获到上升沿
{
// 切换为下降沿捕获，清空计数器
__HAL_TIM_SET_CAPTUREPOLARITY(&htim1, TIM_CHANNEL_3, TIM_INPUTCHANNELPOLARITY_FALLING);
__HAL_TIM_SET_COUNTER(&htim1, 0);
echo_state = 1;
}
else // 捕获到下降沿，高电平结束
{
pulse_width = HAL_TIM_ReadCapturedValue(&htim1, TIM_CHANNEL_3);
distance_cm = pulse_width * 0.017f; // 计算距离(cm)
data_ready = 1; // 通知主循环
// 恢复上升沿捕获，准备下一次测量
__HAL_TIM_SET_CAPTUREPOLARITY(&htim1, TIM_CHANNEL_3, TIM_INPUTCHANNELPOLARITY_RISING);
echo_state = 0;
}
}
}
11.主函数初始化代码
// 初始化 DWT 延时
DWT_Init();
// 拉低 Trig，让传感器稳定
HAL_GPIO_WritePin(GPIOA, GPIO_PIN_11, GPIO_PIN_RESET);
HAL_Delay(100);
// 启动 TIM1 通道3 输入捕获中断
HAL_TIM_IC_Start_IT(&htim1, TIM_CHANNEL_3);
12.主循环代码
// 如果有新数据，通过 USART2 发送
if (data_ready)
{
data_ready = 0;
char msg[50];
sprintf(msg, "Distance: %.2f cm\r\n", distance_cm);
HAL_UART_Transmit(&huart2, (uint8_t *)msg, strlen(msg), 100);
}
// 触发 HC-SR04：PA11 发出 10us 高脉冲
HAL_GPIO_WritePin(GPIOA, GPIO_PIN_11, GPIO_PIN_SET);
DWT_Delay_us(10);
HAL_GPIO_WritePin(GPIOA, GPIO_PIN_11, GPIO_PIN_RESET);
// 间隔 200ms（传感器要求至少 60ms）
HAL_Delay(200);
13.打开浮点（解决小虫子的问题）
整个main.c代码如下：
/* USER CODE BEGIN Header */
/**
******************************************************************************
* @file : main.c
* @brief : Main program body
******************************************************************************
* @attention
*
* Copyright (c) 2026 STMicroelectronics.
* All rights reserved.
*
* This software is licensed under terms that can be found in the LICENSE file
* in the root directory of this software component.
* If no LICENSE file comes with this software, it is provided AS-IS.
*
******************************************************************************
*/
/* USER CODE END Header */
/* Includes ------------------------------------------------------------------*/
#include "main.h"
/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#include <stdio.h>
#include <string.h>
/* USER CODE END Includes */
/* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN PTD */
/* USER CODE END PTD */
/* Private define ------------------------------------------------------------*/
/* USER CODE BEGIN PD */
/* USER CODE END PD */
/* Private macro -------------------------------------------------------------*/
/* USER CODE BEGIN PM */
/* USER CODE END PM */
/* Private variables ---------------------------------------------------------*/
TIM_HandleTypeDef htim1;
UART_HandleTypeDef huart2;
/* USER CODE BEGIN PV */
/* 超声测距全局变量 */
volatile uint8_t echo_state = 0; // 0:等待上升沿, 1:等待下降沿
volatile uint32_t pulse_width = 0; // 高电平时间(us)
volatile uint8_t data_ready = 0; // 一次测量完成标志
float distance_cm = 0.0f;
/* USER CODE END PV */
/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_TIM1_Init(void);
static void MX_USART2_UART_Init(void);
/* USER CODE BEGIN PFP */
void DWT_Init(void);
void DWT_Delay_us(uint32_t us);
/* USER CODE END PFP */
/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */
void DWT_Init(void)
{
CoreDebug->DEMCR |= CoreDebug_DEMCR_TRCENA_Msk;
DWT->CTRL |= DWT_CTRL_CYCCNTENA_Msk;
DWT->CYCCNT = 0;
}
void DWT_Delay_us(uint32_t us)
{
uint32_t start = DWT->CYCCNT;
uint32_t ticks = us * (SystemCoreClock / 1000000);
while ((DWT->CYCCNT - start) < ticks);
}
/* USER CODE END 0 */
/**
* @brief The application entry point.
* @retval int
*/
int main(void)
{
/* USER CODE BEGIN 1 */
/* USER CODE END 1 */
/* MCU Configuration--------------------------------------------------------*/
/* Reset of all peripherals, Initializes the Flash interface and the Systick. */
HAL_Init();
/* USER CODE BEGIN Init */
/* USER CODE END Init */
/* Configure the system clock */
SystemClock_Config();
/* USER CODE BEGIN SysInit */
/* USER CODE END SysInit */
/* Initialize all configured peripherals */
MX_GPIO_Init();
MX_TIM1_Init();
MX_USART2_UART_Init();
/* USER CODE BEGIN 2 */
// 初始化 DWT 延时
DWT_Init();
// 拉低 Trig，让传感器稳定
HAL_GPIO_WritePin(GPIOA, GPIO_PIN_11, GPIO_PIN_RESET);
HAL_Delay(100);
// 启动 TIM1 通道3 输入捕获中断
HAL_TIM_IC_Start_IT(&htim1, TIM_CHANNEL_3);
/* USER CODE END 2 */
/* Infinite loop */
/* USER CODE BEGIN WHILE */
while (1)
{
/* USER CODE END WHILE */
/* USER CODE BEGIN 3 */
if (data_ready)
{
data_ready = 0;
char msg[50];
sprintf(msg, "Distance: %.2f cm\r\n", distance_cm);
HAL_UART_Transmit(&huart2, (uint8_t *)msg, strlen(msg), 100);
}
HAL_GPIO_WritePin(GPIOA, GPIO_PIN_11, GPIO_PIN_SET);
DWT_Delay_us(10);
HAL_GPIO_WritePin(GPIOA, GPIO_PIN_11, GPIO_PIN_RESET);
HAL_Delay(200);
}
/* USER CODE END 3 */
}
/**
* @brief System Clock Configuration
* @retval None
*/
void SystemClock_Config(void)
{
RCC_OscInitTypeDef RCC_OscInitStruct = {0};
RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
/** Initializes the RCC Oscillators according to the specified parameters
* in the RCC_OscInitTypeDef structure.
*/
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
RCC_OscInitStruct.HSEState = RCC_HSE_ON;
RCC_OscInitStruct.HSEPredivValue = RCC_HSE_PREDIV_DIV1;
RCC_OscInitStruct.HSIState = RCC_HSI_ON;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
RCC_OscInitStruct.PLL.PLLMUL = RCC_PLL_MUL9;
if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
{
Error_Handler();
}
/** Initializes the CPU, AHB and APB buses clocks
*/
RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
|RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV2;
RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK)
{
Error_Handler();
}
}
/**
* @brief TIM1 Initialization Function
* @param None
* @retval None
*/
static void MX_TIM1_Init(void)
{
/* USER CODE BEGIN TIM1_Init 0 */
/* USER CODE END TIM1_Init 0 */
TIM_ClockConfigTypeDef sClockSourceConfig = {0};
TIM_MasterConfigTypeDef sMasterConfig = {0};
TIM_IC_InitTypeDef sConfigIC = {0};
/* USER CODE BEGIN TIM1_Init 1 */
/* USER CODE END TIM1_Init 1 */
htim1.Instance = TIM1;
htim1.Init.Prescaler = 72-1;
htim1.Init.CounterMode = TIM_COUNTERMODE_UP;
htim1.Init.Period = 65535;
htim1.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
htim1.Init.RepetitionCounter = 0;
htim1.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_DISABLE;
if (HAL_TIM_Base_Init(&htim1) != HAL_OK)
{
Error_Handler();
}
sClockSourceConfig.ClockSource = TIM_CLOCKSOURCE_INTERNAL;
if (HAL_TIM_ConfigClockSource(&htim1, &sClockSourceConfig) != HAL_OK)
{
Error_Handler();
}
if (HAL_TIM_IC_Init(&htim1) != HAL_OK)
{
Error_Handler();
}
sMasterConfig.MasterOutputTrigger = TIM_TRGO_RESET;
sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
if (HAL_TIMEx_MasterConfigSynchronization(&htim1, &sMasterConfig) != HAL_OK)
{
Error_Handler();
}
sConfigIC.ICPolarity = TIM_INPUTCHANNELPOLARITY_RISING;
sConfigIC.ICSelection = TIM_ICSELECTION_DIRECTTI;
sConfigIC.ICPrescaler = TIM_ICPSC_DIV1;
sConfigIC.ICFilter = 15;
if (HAL_TIM_IC_ConfigChannel(&htim1, &sConfigIC, TIM_CHANNEL_3) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN TIM1_Init 2 */
/* USER CODE END TIM1_Init 2 */
}
/**
* @brief USART2 Initialization Function
* @param None
* @retval None
*/
static void MX_USART2_UART_Init(void)
{
/* USER CODE BEGIN USART2_Init 0 */
/* USER CODE END USART2_Init 0 */
/* USER CODE BEGIN USART2_Init 1 */
/* USER CODE END USART2_Init 1 */
huart2.Instance = USART2;
huart2.Init.BaudRate = 115200;
huart2.Init.WordLength = UART_WORDLENGTH_8B;
huart2.Init.StopBits = UART_STOPBITS_1;
huart2.Init.Parity = UART_PARITY_NONE;
huart2.Init.Mode = UART_MODE_TX_RX;
huart2.Init.HwFlowCtl = UART_HWCONTROL_NONE;
huart2.Init.OverSampling = UART_OVERSAMPLING_16;
if (HAL_UART_Init(&huart2) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN USART2_Init 2 */
/* USER CODE END USART2_Init 2 */
}
/**
* @brief GPIO Initialization Function
* @param None
* @retval None
*/
static void MX_GPIO_Init(void)
{
GPIO_InitTypeDef GPIO_InitStruct = {0};
/* USER CODE BEGIN MX_GPIO_Init_1 */
/* USER CODE END MX_GPIO_Init_1 */
/* GPIO Ports Clock Enable */
__HAL_RCC_GPIOD_CLK_ENABLE();
__HAL_RCC_GPIOA_CLK_ENABLE();
/*Configure GPIO pin Output Level */
HAL_GPIO_WritePin(GPIOA, GPIO_PIN_11, GPIO_PIN_RESET);
/*Configure GPIO pin : PA11 */
GPIO_InitStruct.Pin = GPIO_PIN_11;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
/* USER CODE BEGIN MX_GPIO_Init_2 */
/* USER CODE END MX_GPIO_Init_2 */
}
/* USER CODE BEGIN 4 */
void HAL_TIM_IC_CaptureCallback(TIM_HandleTypeDef *htim)
{
if (htim->Channel == HAL_TIM_ACTIVE_CHANNEL_3) // TIM1_CH3
{
if (echo_state == 0) // 刚捕获到上升沿
{
// 切换为下降沿捕获，清空计数器
__HAL_TIM_SET_CAPTUREPOLARITY(&htim1, TIM_CHANNEL_3, TIM_INPUTCHANNELPOLARITY_FALLING);
__HAL_TIM_SET_COUNTER(&htim1, 0);
echo_state = 1;
}
else // 捕获到下降沿，高电平结束
{
pulse_width = HAL_TIM_ReadCapturedValue(&htim1, TIM_CHANNEL_3);
distance_cm = pulse_width * 0.017f; // 计算距离(cm)
data_ready = 1; // 通知主循环
// 恢复上升沿捕获，准备下一次测量
__HAL_TIM_SET_CAPTUREPOLARITY(&htim1, TIM_CHANNEL_3, TIM_INPUTCHANNELPOLARITY_RISING);
echo_state = 0;
}
}
}
/* USER CODE END 4 */
/**
* @brief This function is executed in case of error occurrence.
* @retval None
*/
void Error_Handler(void)
{
/* USER CODE BEGIN Error_Handler_Debug */
/* User can add his own implementation to report the HAL error return state */
__disable_irq();
while (1)
{
}
/* USER CODE END Error_Handler_Debug */
}
#ifdef USE_FULL_ASSERT
/**
* @brief Reports the name of the source file and the source line number
* where the assert_param error has occurred.
* @param file: pointer to the source file name
* @param line: assert_param error line source number
* @retval None
*/
void assert_failed(uint8_t *file, uint32_t line)
{
/* USER CODE BEGIN 6 */
/* User can add his own implementation to report the file name and line number,
ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
/* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */
14.编译代码，倘若没有问题的话，将代码烧写进单片机。
15.打开网页版串口助手，观察实验效果。
实际测的距离较为准确，还有待一定的提升，可以再优化优化代码，使其测量的结果更加精准。
欢迎大家在评论区留言和私信，有问题一块解决哦，谢谢大家。
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