STM32 HAL HC-SR04超声波测距模块 状态机

工作原理

提供一个10uS以上脉冲触发信号-->模块将发出8个40kHz周期电平并检测回波-->输出回响信号

通过发射信号到收到的回响信号时间间隔可以计算得到距离
距离=高电平时间*声速
建议测量周期为60ms以上，以防止发射信号对回响信号的影响

引脚 Trig --> PB10  Echo --> PB0

注意电源接5v，3.3v不可以!!!

uart1配置默认就行

//sr04.h

#ifndef __SR04_H
#define __SR04_H
#include "stm32f1xx_hal.h"

#define TRIG_H HAL_GPIO_WritePin(GPIOB,GPIO_PIN_10,GPIO_PIN_SET)
#define TRIG_L HAL_GPIO_WritePin(GPIOB,GPIO_PIN_10,GPIO_PIN_RESET)
#define TRIG_DELAY() HAL_Delay(15)

//状态机状态枚举
typedef enum {
	state0=0,
	state1,
	state2,
	state3
}STATE;

void SR04_Init(void);
void  SR04_FSM(void);
void SR04_GetData(void);
void HAL_TIM_IC_CaptureCallback(TIM_HandleTypeDef *htim);

#endif

//sr04.c

#include "sr04.h"
#include "uart.h"

extern TIM_HandleTypeDef htim3;

volatile STATE state = state0;
volatile static uint8_t ic_cplt;  //输入捕获标志位
static uint32_t capture_buf[2];


void SR04_Init(void)
{
	HAL_TIM_Base_Start(&htim3);
	capture_buf[0] = 0;
	capture_buf[1] = 0;
	ic_cplt = 0;
}


//状态机，切换状态
void  SR04_FSM(void)
{
		
	switch(state)
	{
		
		case state0 :
			
		     TIM3->CNT = 0;
			//__HAL_TIM_SET_COUNTER(&htim3,0);  和上面那句等价
		
		    __HAL_TIM_CLEAR_IT(&htim3, TIM_IT_CC3); 
		    
		    //给trig知识10us高电平脉冲信号，trig返回8个40khz脉冲
			TRIG_H;
		    TRIG_DELAY();
		    TRIG_L ;
			
		     //启动上升沿触发，开始输入捕获
	        __HAL_TIM_SET_CAPTUREPOLARITY(&htim3, TIM_CHANNEL_3, TIM_INPUTCHANNELPOLARITY_RISING);
		    HAL_TIM_IC_Start_IT(&htim3,TIM_CHANNEL_3);
		
		    state = state1 ;
		
			break;
		
		case state1:
			
			if(ic_cplt)
			{
				    ic_cplt = 0;
					capture_buf[0]=HAL_TIM_ReadCapturedValue(&htim3,TIM_CHANNEL_3);
				
					//捕获上升沿计数值后切换下降沿触发
					__HAL_TIM_SET_CAPTUREPOLARITY(&htim3, TIM_CHANNEL_3, TIM_INPUTCHANNELPOLARITY_FALLING);
				
					state = state2;
			}
		
				break;
			
		case state2:
			
			if(ic_cplt)
			{
				    ic_cplt = 0;
				
				    //捕获下降沿计数值
					capture_buf[1]=HAL_TIM_ReadCapturedValue(&htim3,TIM_CHANNEL_3);
					HAL_TIM_IC_Stop_IT(&htim3,TIM_CHANNEL_3); 
				
				    //测量周期60ms，避免发射信号对回响信号影响
			        HAL_Delay(60);
				
					state = state3;
			}
			
			break;
			
		case state3 :
			
				SR04_GetData();
		
		        state = state0;
		
			break;
		
		default:
			
		    //错误情况，重置
		    HAL_TIM_IC_Stop_IT(&htim3,TIM_CHANNEL_3); 
			state = state0 ;
			
			break;
		
	}
	
	
}


void HAL_TIM_IC_CaptureCallback(TIM_HandleTypeDef *htim)
{
	if(htim->Instance  == TIM3 && htim->Channel == HAL_TIM_ACTIVE_CHANNEL_3 )
	{
		ic_cplt = 1;
		
		//发现标志位自己不手动清除也是可以的
        __HAL_TIM_CLEAR_IT(htim, TIM_IT_CC3);
	}
}

void SR04_GetData(void)
{
	uint32_t high_time = 0;
	float distance;
	
	//计算计数值，考虑溢出情况
	if(capture_buf[1]>capture_buf[0])
	{
		high_time = capture_buf[1]-capture_buf[0];
	}
	
	else if(capture_buf[1]<capture_buf[0])
	{
		high_time = (TIM3->ARR + 1) - capture_buf[0] + capture_buf[1] ;
	}
	
	//距离=高电平时间*声速/2
	distance = high_time * 0.034 /2.0f;
	
	//过滤异常值
	if(distance<2 || distance>400) 
		return;
	

	printf("distance:%.2f cm\r\n",distance);
}

//uart.c

#include "uart.h"

extern UART_HandleTypeDef huart1;

//重定向printf用于串口打印数值
int fputc(int ch ,FILE *F)
{
	HAL_UART_Transmit(&huart1,(uint8_t *)&ch,1,0xffff);
	return ch;
}

//uart.h

#ifndef __UART_H
#define __UART_H
#include "stm32f1xx_hal.h"
#include "stdio.h"

int fputc(int ch ,FILE *F);

#endif

使用这个记得勾选 Use MicroLIB  小锤子-->Target

//main.c

/* USER CODE BEGIN Header */
/**
  ******************************************************************************
  * @file           : main.c
  * @brief          : Main program body
  ******************************************************************************
  * @attention
  *
  * Copyright (c) 2025 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"
#include "tim.h"
#include "usart.h"
#include "gpio.h"

/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#include "uart.h"
#include "sr04.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 ---------------------------------------------------------*/

/* USER CODE BEGIN PV */

/* USER CODE END PV */

/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
/* USER CODE BEGIN PFP */

/* USER CODE END PFP */

/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */

/* 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_TIM3_Init();
  MX_USART1_UART_Init();
  /* USER CODE BEGIN 2 */

  /* USER CODE END 2 */

  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  SR04_Init();
  printf("SR04 START\r\n");
  while (1)
  {
	  SR04_FSM();
	 
    /* USER CODE END WHILE */

    /* USER CODE BEGIN 3 */
  }
  /* 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();
  }
}

/* USER CODE BEGIN 4 */

/* 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 */

这里可能有点小问题是，发现串口某个时刻没有数据，因为限制了范围

if(distance<2 || distance>400)  return;

可能会卡住

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