一、适用场景
适用场景：烟雾与火灾预警、嵌入式 ADC 与阈值比较实战教学等。
二、器材清单
MQ-2 气体传感器模块 ×1
stm32f103开发板 ×1
若干杜邦线 ×1组
稳定电源 5V×1
三、工作原理（要点）
MQ-2 属于 半导体气敏传感器，核心为 SnO₂ 敏感材料 + 内置加热丝：在空气中，SnO₂ 表面吸附氧分子，电阻较高当遇到可燃气体（甲烷、丁烷、LPG、烟雾等）时，气体与吸附氧发生反应，释放电子，敏感层电阻降低，输出电压发生变化
MQ-2 必须预热才能稳定工作，初次使用：建议预热 12--24 小时，日常使用：上电预热 2--5 分钟即可进入稳定状态
四、接线示意
GND → GND
VCC→ 5V/3.3V电源
标准库
数字信号
DO→ PC1
模拟信号
AO→PC1
HAL库
数字信号
DO→ PA0
模拟信号
AO→PA0
五、示例代码
标准库
数字信号
cpp
#include "stm32f10x.h"
#include "stdio.h"
#include "bsp_SysTick.h"
#include "bsp_usart.h"
void gpio_init()
{
GPIO_InitTypeDef PC;
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOC,ENABLE);
PC.GPIO_Pin = GPIO_Pin_1;
PC.GPIO_Mode = GPIO_Mode_IPD;
GPIO_Init(GPIOC,&PC);
}
int main(void)
{
SysTick_Init(); //延时函数初始化
gpio_init(); //初始化与LED连接的硬件接口
USART_Config();
while(1)
{
if(GPIO_ReadInputDataBit(GPIOC,GPIO_Pin_1) == 0)
{
Usart_SendString(USART1,"有烟\n");
}else
{
Usart_SendString(USART1,"无烟\n");
}
Delay_us(500000);
}
}模拟信号
cpp
#include "breathing.h"
#include "stm32f10x.h"
#include "stdio.h"
#include "bsp_usart.h"
char showlight[20];
extern volatile uint16_t adc_light;
void TIM3_Int_Init(u16 arr,u16 psc)
{
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
NVIC_InitTypeDef NVIC_InitStructure;
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE); //时钟使能
//定时器TIM3初始化
TIM_TimeBaseStructure.TIM_Period = arr; //设置在下一个更新事件装入活动的自动重装载寄存器周期的值
TIM_TimeBaseStructure.TIM_Prescaler =psc; //设置用来作为TIMx时钟频率除数的预分频值
TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1; //设置时钟分割:TDTS = Tck_tim
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; //TIM向上计数模式，即从0开始向上数到越界
TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure); //根据指定的参数初始化TIMx的时间基数单位
TIM_ITConfig(TIM3,TIM_IT_Update,ENABLE ); //使能指定的TIM3中断,允许更新中断
//中断优先级NVIC设置
NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn; //TIM3中断
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0; //先占优先级0级
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 3; //从优先级3级
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //IRQ通道被使能
NVIC_Init(&NVIC_InitStructure); //初始化NVIC寄存器
TIM_Cmd(TIM3, ENABLE); //使能TIMx
}
void TIM3_IRQHandler(void)
{
uint16_t value;
value = (adc_light)/74;
if(TIM_GetITStatus(TIM3,TIM_IT_Update) == SET)
{
sprintf(showlight,"light:%d,value:%d\n",adc_light,value);
Usart_SendString(USART1,showlight);
}
TIM_ClearITPendingBit(TIM3,TIM_IT_Update);
}
#include "adc_time.h"
#include "stm32f10x.h"
volatile uint16_t adc_light;
void adcgpio_init()
{
GPIO_InitTypeDef PC;
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOC,ENABLE);
PC.GPIO_Pin = GPIO_Pin_1;
PC.GPIO_Mode = GPIO_Mode_AIN;
GPIO_Init(GPIOC,&PC);
}
void adcmode_init()
{
ADC_InitTypeDef adc;
NVIC_InitTypeDef nvic;
RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC2,ENABLE);
adc.ADC_Mode=ADC_Mode_Independent;
adc.ADC_ScanConvMode = DISABLE;
adc.ADC_ContinuousConvMode = ENABLE;
adc.ADC_ExternalTrigConv = ADC_ExternalTrigConv_None;
adc.ADC_DataAlign = ADC_DataAlign_Right;
adc.ADC_NbrOfChannel = 1;
ADC_Init(ADC2,&adc);
RCC_ADCCLKConfig(RCC_PCLK2_Div8);
ADC_RegularChannelConfig(ADC2,ADC_Channel_11,1,ADC_SampleTime_55Cycles5);
ADC_ITConfig(ADC2,ADC_IT_EOC,ENABLE);
ADC_Cmd(ADC2,ENABLE);
ADC_ResetCalibration(ADC2);
while(ADC_GetResetCalibrationStatus(ADC2));
ADC_StartCalibration(ADC2);
while(ADC_GetCalibrationStatus(ADC2));
ADC_SoftwareStartConvCmd(ADC2,ENABLE);
NVIC_PriorityGroupConfig(NVIC_PriorityGroup_3);
nvic.NVIC_IRQChannel = ADC1_2_IRQn;
nvic.NVIC_IRQChannelPreemptionPriority = 3;
nvic.NVIC_IRQChannelSubPriority = 0;
nvic.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&nvic);
}
void adctime_Init()
{
adcgpio_init();
adcmode_init();
}
void ADC1_2_IRQHandler(void)
{
if(ADC_GetITStatus(ADC2,ADC_IT_EOC) == SET)
{
adc_light = ADC_GetConversionValue(ADC2);
}
ADC_ClearITPendingBit(ADC2,ADC_IT_EOC);
}
#include "stm32f10x.h"
#include "stdio.h"
#include "bsp_SysTick.h"
#include "adc_time.h"
#include "breathing.h"
#include "bsp_usart.h"
int main()
{
USART_Config();
adctime_Init();
TIM3_Int_Init(4999,7199); //定时500ms
while(1)
{
}
// return 0;
}HAL库
数字信号
cpp
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_USART1_UART_Init();
/* USER CODE BEGIN 2 */
/* USER CODE END 2 */
/* Infinite loop */
/* USER CODE BEGIN WHILE */
while (1)
{
if(HAL_GPIO_ReadPin(GPIOA,GPIO_PIN_0) == 1)
HAL_UART_Transmit(&huart1,"无烟雾\r\n", strlen("无烟雾\r\n"), HAL_MAX_DELAY);
else
HAL_UART_Transmit(&huart1,"有烟雾\r\n", strlen("有烟雾\r\n"), HAL_MAX_DELAY);
HAL_Delay(1000);
/* USER CODE END WHILE */
/* USER CODE BEGIN 3 */
}
/* USER CODE END 3 */
}模拟信号
cpp
int main(void)
{
/* USER CODE BEGIN 1 */
char show[20]={0};
/* 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_ADC1_Init();
MX_USART1_UART_Init();
/* USER CODE BEGIN 2 */
/* USER CODE END 2 */
/* Infinite loop */
/* USER CODE BEGIN WHILE */
while (1)
{
//#1。启动常规序列
HAL_ADC_Start(&hadc1);
//#2.等待转换完成
HAL_ADC_PollForConversion(&hadc1,HAL_MAX_DELAY);
//#3。获取结果
uint32_t dr = HAL_ADC_GetValue(&hadc1);
//#4.把结果转换成电压
float voltage = dr *(3.3f-0.0f)/4095.0f;
sprintf(show,"adc:%d,%.2f\n",dr,voltage);
HAL_UART_Transmit(&huart1,show,strlen(show),HAL_MAX_DELAY);
HAL_Delay(500);
// if（voltage>1.5f）//光线暗
// HAL_GPIO_WritePin(GPIOA,GPIO_PIN_13,GPIO_PIN_SET);// 灭灯
// else//光线亮
// HAL_GPIO_WritePin（GPIOA,GPIO_PIN_13，GPIO_PIN_RESET); // 亮灯
/* USER CODE END WHILE */
/* USER CODE BEGIN 3 */
}
/* USER CODE END 3 */
}六、讲解视频