1.主要功能

功能说明：

1、以STM32单片机和MQ-2控制核心设计烟雾浓度检测报警设计；

2、通过液晶屏LCD1602和串口上位机显示烟雾浓度，MV表示检测值，ALM表示报警值；

3、可以通过按键设置烟雾浓度ALM报警值大小。

4、监测烟雾浓度大于报警值时蜂鸣器报警电路导通，蜂鸣器报警。拨动开关打开情况下，风扇转动通风。

5、默认监测到烟雾浓度高于200ppm蜂鸣器报警。

主要硬件设备：STM32F103单片机

以下为本设计资料展示：

2.仿真

整体设计方案

本实验利用STM32单片机的ADC、GPIO、定时器等资源，将软、硬件有机地结合起来，使得系统能够正确地进识别输入模拟烟雾浓度传感器的AD值，LCD1602能够正确地显示，蜂鸣器根据烟雾浓度报警值工作。需注意的是，proteus是没有MQ-2等烟雾浓度传感器的，本设计使用滑动变阻器模拟烟雾浓度变化，不能直接用于实物设计，有需要的需跟据实物调试。

仿真运行情况：

开始仿真后LCD1602实时显示检测到的烟雾浓度，可以通过滑动变阻器改变测量值。可通过按键设置报警值浓度，按下设置键进入设置模式，通过设置+调高报警值，通过设置-调低报警值。蜂鸣器报警电路在烟雾浓度高于报警值时启动，有嘟嘟报警声，低于不启动。

本设计采用电磁式蜂鸣器进行。电磁式蜂鸣器由振荡器、电磁线圈、磁铁、振动膜片及外壳等组成。接通电源后，振荡器产生的音频信号电流通过电磁线圈，使电磁线圈产生磁场。振动膜片在电磁线圈和磁铁的相互作用下，周期性地振动发声。因此需要一定的电流才能驱动它，单片机I/O引脚输出的电流较小，单片机输出的TTL电平基本上驱动不了蜂鸣器，因此需要增加一个电流放大的电路。蜂鸣器的正极接到VCC（+5V）电源上面，蜂鸣器的负极接到三极管的集电极C，三极管的基极B经过限流电阻后由单片机的BEEP引脚控制，当BEEP输出低电平时，三级管QS截止，没有电流流过线圈，蜂鸣器不发声；当BEEP输出高电平时，三级管导通，这样蜂鸣器的电流形成回路，发出声音。

下图检测到烟雾浓度是192ppm，低于报警值200，蜂鸣器电路不工作。

下图检测到烟雾浓度是204ppm，大于等于报警值，三极管导通，蜂鸣器报警

3. 程序

程序是用keil5 mdk版本打开的，如果打开有问题，核实下keil的版本。程序是HAL库版本编写的，有注释可以结合讲解视频理解。

/* USER CODE BEGIN Header */
/********************************************************************************* @file           : main.c* @brief          : Main program body******************************************************************************* @attention** Copyright (c) 2022 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 "adc.h"
#include "tim.h"
#include "usart.h"
#include "gpio.h"/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#include "lcd1602.h"
#include "stdio.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 */uint16_t Tim_cnt = 0;  //定时器变量uint8_t set_flag = 0;float warming_val=200;	//报警浓度大小
/* 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 */ADC_ChannelConfTypeDef sConfig = {0};  //建立sConfig结构体char str[20];  //字符串的存放数组uint32_t adcv; //存放ADC转换结果float temp;set_flag = 0;/* USER CODE END 1 *//* MCU Configuration--------------------------------------------------------*//* Reset of all peripherals, Initializes the Flash interface and the Systick. */HAL_Init();/* USER CODE BEGIN Init */sConfig.Rank = ADC_REGULAR_RANK_1;sConfig.SamplingTime = ADC_SAMPLETIME_1CYCLE_5;   //采样周期为1.5个周期/* 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_ADC1_Init();MX_USART1_UART_Init();MX_TIM3_Init();/* USER CODE BEGIN 2 */LCD_Init();  //初始化LCD1602HAL_TIM_Base_Start_IT(&htim3);//开启定时器3
//	LCD_ShowString(0,0,dis_str);/* USER CODE END 2 *//* Infinite loop *//* USER CODE BEGIN WHILE */while (1){sConfig.Channel = ADC_CHANNEL_1;   //选择通道1HAL_ADC_ConfigChannel(&hadc1, &sConfig);  //选择ADC1的通道道1HAL_ADC_Start(&hadc1);										//启动ADC1HAL_ADC_PollForConversion(&hadc1, 10);		//等待ADC1转换结束，超时设定为10msadcv = HAL_ADC_GetValue(&hadc1);					//读取ADC1的转换结果temp=(float)adcv*(4.0/4095)*100;		sprintf(str,"%4.0fppm",temp);LCD_ShowString(0,0,"MV:");	LCD_ShowString(0,4,str);	HAL_UART_Transmit(&huart1, (uint8_t *)&"AL=", 3, 10);  //串口1发送字符串，数组长度为12，超时10msHAL_UART_Transmit(&huart1, (uint8_t *)str, 6, 10);		 //串口1发送字符串，数组长度为5，超时10msHAL_UART_Transmit(&huart1, (uint8_t *)&"\n\r", 2, 10); //串口1发送字符串，数组长度为2，超时10ms	if(set_flag){//设置模式sprintf(str,"%4.0fppm^ ",warming_val);LCD_ShowString(1,0,"ALM:");	LCD_ShowString(1,4,str);}else{sprintf(str,"%4.0fppm  ",warming_val);LCD_ShowString(1,0,"ALM:");	LCD_ShowString(1,4,str);			}HAL_UART_Transmit(&huart1, (uint8_t *)&"ALM=", 4, 10);  //串口1发送字符串，数组长度为12，超时10msHAL_UART_Transmit(&huart1, (uint8_t *)str, 6, 10);								//串口1发送字符串，数组长度为5，超时10msHAL_UART_Transmit(&huart1, (uint8_t *)&"\n\r", 2, 10);						//串口1发送字符串，数组长度为2，超时10ms	if(temp>warming_val&&!set_flag){//如果超过报警值HAL_GPIO_WritePin(GPIOA,BEEP_Pin, GPIO_PIN_RESET);//BEEP引脚拉低}else{HAL_GPIO_WritePin(GPIOA,BEEP_Pin, GPIO_PIN_SET);}HAL_ADC_Stop(&hadc1);											//停止ADC1HAL_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};RCC_PeriphCLKInitTypeDef PeriphClkInit = {0};/** Initializes the RCC Oscillators according to the specified parameters* in the RCC_OscInitTypeDef structure.*/RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;RCC_OscInitStruct.HSIState = RCC_HSI_ON;RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;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_HSI;RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK){Error_Handler();}PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_ADC;PeriphClkInit.AdcClockSelection = RCC_ADCPCLK2_DIV2;if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK){Error_Handler();}
}/* USER CODE BEGIN 4 */
void HAL_TIM_PeriodElapsedCallback(TIM_HandleTypeDef *htim)
{
if (htim->Instance == htim3.Instance) {Tim_cnt++;if(Tim_cnt==5)  //2.5ms进一次{Tim_cnt=0;   //请HAL_GPIO_TogglePin(LED0_GPIO_Port, LED0_Pin);}}}	
//中断处理
void HAL_GPIO_EXTI_Callback(uint16_t GPIO_Pin)
{UNUSED(GPIO_Pin);if(GPIO_Pin == KEY1_Pin)  //测到EXTI0线产生外部中断事件{if(set_flag){set_flag = 0;}else{set_flag = 1;}}else if(GPIO_Pin == KEY2_Pin) //测到EXTI1线产生外部中断事件{if(set_flag){if(warming_val<390){//一次+10warming_val+=10;			}}}	else if(GPIO_Pin == KEY3_Pin) //测到EXTI2线产生外部中断事件{if(set_flag){if(warming_val>10){//一次-10warming_val-=10;}}}}/* 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 */