文章目录
- 一HC-SR04介绍
- 1HC-SR04简介及工作原理
- 二用HAL库实现HC-SR04测量距离
- 1STM32CubeMX配置
- 2keil5
- 3代码的添加
- 三效果
一HC-SR04介绍
1HC-SR04简介及工作原理
超声波是振动频率高于20kHz的机械波。它具有频率高、波长短、绕射现象小、方向性好、能够成为射线而定向传播等特点。HC-SRO4是一款尺寸完全兼容老版本,增加UART和IIC功能的开放式超声波测距模块,默认条件下,软件与硬件完全兼容老版本HC-SRO4;可以通过电阻设置成UART或IIC模式。2CM盲区,4.5M典型最远测距,2.2mA作电流。采用升级解调芯片RCWL-9206,带UART与IIC功能MCU:使其外围更加简洁,工作电压更宽(3-5.5V),接口功能更多。
工作原理:
(1)采用 IO 口 TRIG 触发测距,给最少 10us 的高电平信呈。
(2)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。
二用HAL库实现HC-SR04测量距离
本文使用的MCU为STM32F103C8T6。
1STM32CubeMX配置
1创建一个工程
2RCC
3SYS
4时钟树
5GPIO
6串口1
7定时器2
8开启定时器中断
2keil5
1勾选Use MicroLiB
2创建SR04.c和SR04.h文件
3创建led.c和led.h文件
3代码的添加
main.
/* 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"
#include "led.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)
{
float distance = SR04_GetData();
//HAL_Delay(1500);
/* USER CODE END WHILE */
// 根据距离计算闪烁频率
uint32_t flashRate = CalculateFlashRate(distance);
LED_Flash(flashRate); // 闪烁LED
/* 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 */
SR04.c
#include "SR04.h"
#include "stm32f1xx_hal.h"
float distant; //测量距离
uint32_t measure_Buf[3] = {0}; //存放定时器计数值的数组
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
//===============================================读取距离
float 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
break;
case 3:
high_time = measure_Buf[1] - measure_Buf[0]; // 高电平时间
printf("\r\n----高电平时间-%d-us----\r\n", high_time);
float distance = (high_time * 0.034f) / 2; // 单位cm
printf("\r\n-检测距离为-%.2f-cm-\r\n", distance);
measure_Cnt = 0; // 清空标志位
TIM2->CNT = 0; // 清空计时器计数
// 返回计算得到的距离值
return distance;
}
return 0; // 如果没有测量完成,返回0或合适的默认值
}
//===============================================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++;
}
}
}
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);
float SR04_GetData(void);
#endif
led.c
#include "led.h"
#define LED_GPIO_Port GPIOB
#define LED_Pin GPIO_PIN_9
void LED_Init(void) {
GPIO_InitTypeDef GPIO_InitStruct = {0};
// 使能GPIOB时钟
__HAL_RCC_GPIOB_CLK_ENABLE();
// 配置GPIO Pin为推挽输出,无上拉电阻,低频率
GPIO_InitStruct.Pin = LED_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
HAL_GPIO_Init(LED_GPIO_Port, &GPIO_InitStruct);
}
void LED_Flash(uint32_t period) {
// 切换LED状态
HAL_GPIO_TogglePin(LED_GPIO_Port, LED_Pin);
// 延时
HAL_Delay(period);
// 再次切换LED状态,完成一次闪烁
HAL_GPIO_TogglePin(LED_GPIO_Port, LED_Pin);
}
uint32_t CalculateFlashRate(float distance) {
uint32_t flashRate;
if (distance < 10.0f) {
flashRate = 100; // 距离小于10厘米时,快速闪烁
} else if (distance < 50.0f) {
flashRate = 500; // 距离在10-50厘米之间时,中速闪烁
} else {
flashRate = 1000; // 距离大于50厘米时,慢速闪烁
}
return flashRate;
}
led.h
#ifndef __LED_H__
#define __LED_H__
#include "stm32f1xx_hal.h"
void LED_Init(void);
void LED_Flash(uint32_t period);
uint32_t CalculateFlashRate(float distance);
#endif // __LED_H__
三效果
led灯可以随着HC-SR04测量到的距离变化而改变闪烁的频率