超聲波介紹

作業原理：

時序圖：

cube配置

用引腳PB8 PB9可以自己改

時鐘選擇72M外部晶振的

設定定時器

定時時間 = （Prescaler+1）× （Counter +1）/ 定時器時鐘頻率
例如，定時時間為 1ms，可設定Prescaler = 72-1；Counter = 1000 - 1；（TIM2時鐘頻率設定為72MHz）

當然也可以用我們習慣的，72 000 000（72M）/ 72-1（Prescaler） =1 000 000；
再用Counter 去除以1 000 000 ，如圖中的 50 000 / 1 000 000 =0.05s；
格式為 定時時間=（Counter +1）/ {定時器時鐘頻率/（Prescaler+1）}

剩下串口自己點一下就好了

主程式代碼：

/* USER CODE BEGIN Header */
/**
  ******************************************************************************
  * @file           : main.c
  * @brief          : Main program body
  ******************************************************************************
  * @attention
  *
  * <h2><center>&copy; Copyright (c) 2021 STMicroelectronics.
  * All rights reserved.</center></h2>
  *
  * This software component is licensed by ST under BSD 3-Clause license,
  * the "License"; You may not use this file except in compliance with the
  * License. You may obtain a copy of the License at:
  *                        opensource.org/licenses/BSD-3-Clause
  *
  ******************************************************************************
  */
/* USER CODE END Header */
/* Includes ------------------------------------------------------------------*/
#include "main.h"
#include "tim.h"
#include "usart.h"
#include "gpio.h"

/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#include "stdio.h"
int fputc(int ch, FILE *f){
HAL_UART_Transmit (&huart1,(uint8_t *)&ch,1,0xffff);
	return ch;
}





#define TRIG_ON    HAL_GPIO_WritePin(TRIG_GPIO_Port, TRIG_Pin, GPIO_PIN_SET);
#define TRIG_OFF    HAL_GPIO_WritePin(TRIG_GPIO_Port, TRIG_Pin, GPIO_PIN_RESET);
	  float  S1,S2,distance;	//資料1，資料2，距離
      int32_t distance1;		//距離1
	  uint32_t chaoshenbo_flag=0;
	  double chaoshenbo_data = 0;


/* 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 */
void chaoShenBo(){
	
	  htim2.Instance->CNT=0;
	  TRIG_OFF;		
	  TRIG_ON;				
	  HAL_Delay(1);
	  TRIG_OFF;				//根據時序要求拉低TR引腳，等待EC引腳回應
	
     while(HAL_GPIO_ReadPin(ECHO_GPIO_Port,ECHO_Pin)==GPIO_PIN_RESET);		
	  S1=htim2.Instance->CNT;									//EC回應低，記錄其時間S1
	  while(HAL_GPIO_ReadPin(ECHO_GPIO_Port,ECHO_Pin)==1);						
	  S2=htim2.Instance->CNT;									//EC回應高，記錄其時間S2
	  distance=(S2-S1)*0.034/2;									//用時間S2-S1=聲波回傳時間	再乘0.034/2（聲速/2）=距離 時間*速度=距離 


	distance1=distance*100;										//將小數放大百倍
	distance=distance1;  										//轉化為整數型 去掉后面尾數  保證資料精確 反正我是這樣子想的
	distance/=100;      										//轉回浮點數
	/**以上操作相當于x*100/100=x（但尾部小數被濾掉了）**/
	

	/**取100次的平均值，達到濾波的效果，準確一點**/
//	chaoshenbo_data=chaoshenbo_data+distance;
//     if( chaoshenbo_flag == 100-1 )
//	 {
//	 chaoshenbo_data/=100;
//	 chaoshenbo_data*=10;      //cm轉mm 乘10
//	 chaoshenbo_flag=0;
//	distance1=chaoshenbo_data;	 
//	printf("Dostace is :%dmm \r\n",distance1);	 
//	 }else{
//	 chaoshenbo_flag++;
//	 }
	 
	 printf("distance:%f",distance);
 }
/* 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_TIM2_Init();
  MX_USART1_UART_Init();
  /* USER CODE BEGIN 2 */
  HAL_TIM_Base_Start_IT(&htim2);

  /* USER CODE END 2 */

  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
    /* USER CODE END WHILE */

    /* USER CODE BEGIN 3 */
	  
	printf("gg\r\n");	  
	chaoShenBo();

	  
	  
	  
	  
  }
  /* 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 */

/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/

工程檔案：https://download.csdn.net/download/weixin_51102592/22410732?spm=1001.2014.3001.5503