前言
环境：
1、硬件：stm32f103c8t6 核心板
2、软件：STM32CubeMX 6.4.0
3、软件：keil5 mdk
4、超声波模块：HC_SR04
要求：
使用 stm32f103c8t6 核心板驱动 超声波检测模块（HC_SR04 ），并将所测得数据显示到串口助手上，并对数据进行一定的滤波。
一、超声波模块介绍
1、产品特点
HC-SR04超声波测距模块可提供2cm-400cm的非接触式距离感测功能,测距精度可达高到3mm;模块包括超声波发射器、接收器与控制电路。
基本工作原理:
(1)采用IO口 TRIG触发测距，给最少10us的高电平信呈。
(⑵)模块自动发送8个40khz的方波，自动检测是否有信号返回;
(3)有信号返回，通过IO口ECHO输出一个高电平，高电平持续的时间就是超声波从发射到返回的时间。测试距离=(高电平时间*声速(340M/S))/2;
2、超声波模块的时序图
以上时序图表明你只需要提供一个10uS 以上脉冲触发信号，该模块内部将发出8个40kHz周期电平并检测回波。一旦检测到有回波信号则输出回响信号。回响信号的脉冲宽度即(信号持续的高电平时间)与所测的距离成正比。由此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。
二、STM32CubeMx创建工程
1、配置项目
这里跳过了创建工程的步骤，具体可看前面的博客，直接进入配置。
- RCC配置：
- SYS配置：
- GPIO设置：
将PA1自定义为TRIG
- 串口设置：
- 定时器设置：
- 时钟树设置：
2、keil代码设置
- 设置允许使用微库：
- 添加SR04.c和SR04.h文件到工程中(具体看前面RT-thread Nano的移植过程)：
- SR04.h
#ifndef __SR04_H
#define __SR04_H
#include "main.h"
#include "tim.h"
#include "stdio.h"
#define TRIG_H HAL_GPIO_WritePin(Trig_GPIO_Port,Trig_Pin,GPIO_PIN_SET)
#define TRIG_L HAL_GPIO_WritePin(Trig_GPIO_Port,Trig_Pin,GPIO_PIN_RESET)
void delay_us(uint32_t us);
void SR04_GetData(void);
#endif
- SR04.c
#include "SR04.h"
float distant; //测量距离
uint32_t measure_Buf[3] = {
0}; //存放定时器计数值的数组
float distances[5]={
0};
uint8_t measure_Cnt = 0; //状态标志位
uint32_t high_time; //超声波模块返回的高电平时间
uint8_t n=0;
//===============================================读取距离
void SR04_GetData(void)
{
switch (measure_Cnt){
case 0:
TRIG_H;
delay_us(30);
TRIG_L;
measure_Cnt++;
__HAL_TIM_SET_CAPTUREPOLARITY(&htim2, TIM_CHANNEL_1, TIM_INPUTCHANNELPOLARITY_RISING);
HAL_TIM_IC_Start_IT(&htim2, TIM_CHANNEL_1); //启动输入捕获 或者: __HAL_TIM_ENABLE(&htim5);
break;
case 3:
high_time = measure_Buf[1]- measure_Buf[0]; //高电平时间
distant=(high_time*0.034)/2; //单位cm
distances[n]=distant;
n++;
if(n>=5){
// 采用1、4、6、4、1的高斯核进行滤波
n=0;
distant=(distances[0]+4*distances[1]+6*distances[2]+4*distances[3]+distances[4])/16;
printf("\r\n检测距离为：%.2f-cm-\r\n",distant);
}
measure_Cnt = 0; //清空标志位
TIM2->CNT=0; //清空计时器计数
break;
}
}
//===============================================us延时函数
void delay_us(uint32_t us)//主频72M
{
uint32_t delay = (HAL_RCC_GetHCLKFreq() / 4000000 * us);
while (delay--)
{
;
}
}
//===============================================中断回调函数
void HAL_TIM_IC_CaptureCallback(TIM_HandleTypeDef *htim)//
{
if(TIM2 == htim->Instance)// 判断触发的中断的定时器为TIM2
{
switch(measure_Cnt){
case 1:
measure_Buf[0] = HAL_TIM_ReadCapturedValue(&htim2,TIM_CHANNEL_1);//获取当前的捕获值.
__HAL_TIM_SET_CAPTUREPOLARITY(&htim2,TIM_CHANNEL_1,TIM_ICPOLARITY_FALLING); //设置为下降沿捕获。
measure_Cnt++;
break;
case 2:
measure_Buf[1] = HAL_TIM_ReadCapturedValue(&htim2,TIM_CHANNEL_1);//获取当前的捕获值.
HAL_TIM_IC_Stop_IT(&htim2,TIM_CHANNEL_1); //停止捕获 或者: __HAL_TIM_DISABLE(&htim5);
measure_Cnt++;
}
}
}
- usrat.c代码添加fputc重定义函数：
/* USER CODE BEGIN 0 */
#include "stdio.h"
/* USER CODE END 0 */
/* USER CODE BEGIN 1 */
/*********************************************************
*
*重定义 fputc 函数
*
*********************************************************/
int fputc(int ch,FILE *f)
{
HAL_UART_Transmit (&huart1 ,(uint8_t *)&ch,1,HAL_MAX_DELAY );
return ch;
}
/* USER CODE END 1 */
- main函数：
/* USER CODE BEGIN Header */
/**
******************************************************************************
* @file : main.c
* @brief : Main program body
******************************************************************************
* @attention
*
* <h2><center>© Copyright (c) 2022 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 "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_TIM2_Init();
MX_USART1_UART_Init();
/* USER CODE BEGIN 2 */
/* USER CODE END 2 */
/* Infinite loop */
/* USER CODE BEGIN WHILE */
while (1)
{
SR04_GetData( );
HAL_Delay(300);
/* 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 */
/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/
3、效果
超声波模块接线：
VCC接5V,不然可能出现测距不变的问题
GND接地
TRIG接A1
ECHO接A0
stm32测距
串口显示测距
三、总结
总的来说项目的配置还是相对简单的，但中间还是遇到了一些麻烦，就是我最开始测距是距离是不变的，一直是9.2cm，后面发现需要换成5v才能正常工作，换到5v后直接不输出了，后来我偶然发现5v的灯亮得比接3.3v的还暗，就怀疑是不是板子5v坏了，后面接的别的板子的5v才正常了，所以项目不难还是需要细心。
四、参考资料
https://blog.csdn.net/lwb450921/article/details/123670786?spm=1001.2014.3001.5502
https://blog.csdn.net/weixin_45456099/article/details/112389556