基于小熊派气体传感器MQ-2综合实践

杨源鑫

发布于 2020-05-21 16:11:20

1.1K0

发布于 2020-05-21 16:11:20

文章被收录于专栏：嵌入式开发圈

前面，我们用光强传感器做了很多实践小项目，那么今天我们把项目稍微变一下，把光强传感器换成气体传感器吧！原来光强传感器相关文章链接如下:

基于小熊派光强传感器BH1750实践(multi_timer+状态机工程应用)

基于小熊派光强传感器BH1750状态机驱动项目升级(带LCD屏显示)

基于小熊派光强传感器BH1750状态机驱动项目再度升级(带上位机曲线显示)

今天我们介绍的这款传感器是小熊派自带的一个模块，MQ-2气体传感器。

1、了解MQ-2

从手册中了解到，这是一个可以检测多种有害气体的传感器，看似很强大，等会我就来试一下，它是不是真的能检测出来。

2、小熊派E53_SF1电路原理图

这是模块对应底板的电路原理图，从电路原理图中了解到，这个传感器是一个模拟转数字的器件(ADC),接在PC2管脚。

3、实践需求定义

具备显示传感器数值(LCD实现)
具备声光报警功能(SF1板载LED、无源蜂鸣器)
当传感器数值超出用户设定阈值时声光报警(暂定用户设定阈值为600ppm)
实时曲线数据传输(自定义串口协议)

4、实现需求

4.1 stm32cubemx配置硬件驱动参数

由于前面已经写过很多软件上的设置了，所以这里只给出配置表，配置表可以通过CubeMX软件自动生成。

最后会得到一个pdf文件，如下：

4.2 软件实现

(1)传感器数据结构定义

typedef struct Sensor
{
    /*烟感值*/
    int Smoke_Value;
    /*报警灯状态*/
    uint8_t Alarm_Led_Status : 1;
    /*报警蜂鸣器状态*/
    uint8_t Alarm_Buzzer_Status : 1;
    /*是否打印曲线标志*/
    uint8_t Display_Plot_Flag : 1 ;
    /*set方法*/
    void (*led_control)(struct Sensor *sensor_handle, uint8_t status);
    void (*buzzer_control)(struct Sensor *sensor_handle, uint8_t status);
    void (*plot_control)(struct Sensor *sensor_handle, uint8_t status);
    /*get方法*/
    int (*get_smoke_value)(struct Sensor *sensor_handle);
    int (*get_led_status)(struct Sensor *sensor_handle);
    int (*get_buzzer_status)(struct Sensor *sensor_handle);
    int (*get_plot_status)(struct Sensor *sensor_handle);
} Sensor ;
Sensor *MQ2_Sensor = NULL;

(2)实现传感器数据结构里对应的set/get方法

//设置报警灯状态
void alarm_led_control(Sensor *sensor_handle, uint8_t status)
{
    sensor_handle->Alarm_Led_Status = status ;
    if(sensor_handle->Alarm_Led_Status)
        HAL_GPIO_WritePin(SF1_LED_GPIO_Port, SF1_LED_Pin, GPIO_PIN_SET);
    else
        HAL_GPIO_WritePin(SF1_LED_GPIO_Port, SF1_LED_Pin, GPIO_PIN_RESET);
}
//设置报警蜂鸣器状态
void alarm_buzzer_control(Sensor *sensor_handle, uint8_t status)
{
    sensor_handle->Alarm_Buzzer_Status = status ;
    if(sensor_handle->Alarm_Buzzer_Status)
        HAL_TIM_PWM_Start(&htim16, TIM_CHANNEL_1);
    else
        HAL_TIM_PWM_Stop(&htim16, TIM_CHANNEL_1);
}
//设置曲线显示
void plot_display_control(Sensor *sensor_handle, uint8_t status)
{
    sensor_handle->Display_Plot_Flag = status ;
}
//获取led状态
int get_led_status(Sensor *sensor_handle)
{
    return sensor_handle->Alarm_Led_Status ;
}
//获取蜂鸣器状态
int get_buzzer_status(Sensor *sensor_handle)
{
    return sensor_handle->Alarm_Buzzer_Status ;
}
//获取曲线状态
int get_plot_status(Sensor *sensor_handle)
{
    return sensor_handle->Display_Plot_Flag ;
}
//获取烟感值
int get_smoke_value(Sensor *sensor_handle)
{
    HAL_ADC_Start(&hadc1);
    HAL_ADC_PollForConversion(&hadc1, 50);
    sensor_handle->Smoke_Value = HAL_ADC_GetValue(&hadc1);
    return sensor_handle->Smoke_Value ;
}

(3)实现传感器接口注册接口

/*提供访问传感器的接口*/
Sensor mq2_sensor_interface =
{
    /*设置接口*/
    .led_control = alarm_led_control,
    .buzzer_control = alarm_buzzer_control,
    .plot_control = plot_display_control,
    /*获取接口*/
    .get_led_status = get_led_status,
    .get_buzzer_status = get_buzzer_status,
    .get_plot_status = get_plot_status,
    .get_smoke_value = get_smoke_value
};

/*注册传感器*/
int Sensor_Register(Sensor *sensor_handle)
{
    if(NULL == MQ2_Sensor)
    {
        MQ2_Sensor = sensor_handle ;

        if(NULL == MQ2_Sensor)
            return -1 ;
        else
        {
            MQ2_Sensor->led_control(MQ2_Sensor, 0);
            MQ2_Sensor->buzzer_control(MQ2_Sensor, 0);
            MQ2_Sensor->plot_control(MQ2_Sensor, 0);
        }
    }
    return 0 ;
}

(3)曲线传输协议定义

S1 序号 烟感值\r\n

(4)主程序实现

int main(void)
{
    /* USER CODE BEGIN 1 */
    int smoke_value = 0 ;
    int serial_number = 0 ;
    char procol_buf[20] = {0};
    char display_buf[20] = {0};
    static uint8_t buzzer_flag = 0;
    static uint8_t led_status = 0 ;
    static uint8_t plot_status = 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_SPI2_Init();
    MX_USART1_UART_Init();
    MX_TIM16_Init();
    /* USER CODE BEGIN 2 */
    Sensor_Register(&mq2_sensor_interface);
    printf("led_status:%d\n", mq2_sensor_interface.get_led_status(&mq2_sensor_interface));
    printf("buzzer_status:%d\n", mq2_sensor_interface.get_buzzer_status(&mq2_sensor_interface));
    printf("plot_status:%d\n", mq2_sensor_interface.get_plot_status(&mq2_sensor_interface));
    LCD_Init();
    LCD_Clear(BLACK);//清屏为黑色
    LCD_ShowString(5, 10, 240, 32, 32, "BearPi MQ-2");//显示字符串，字体大小32*32
    Timer_Count = 0 ;

    /*设置曲线显示*/
    mq2_sensor_interface.plot_control(&mq2_sensor_interface, 1);
    plot_status = mq2_sensor_interface.get_plot_status(&mq2_sensor_interface);
    /* USER CODE END 2 */

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

        /* USER CODE BEGIN 3 */
        //printf("烟感值:%d\n",mq2_sensor_interface.get_smoke_value(&mq2_sensor_interface));
        /*判断是否100ms到了，该计数由Systick提供，1ms中断一次，100次则为100ms*/
        if(100 == Timer_Count)
        {
            Timer_Count = 0 ;
            /*流水号自增*/
            ++serial_number ;

            if(serial_number > 65535)
                serial_number = 0 ;

            smoke_value = mq2_sensor_interface.get_smoke_value(&mq2_sensor_interface) ;

            /*当烟感值大于600ppm，则报警*/
            if(smoke_value > 600)
            {
                /*这里的buzzer_flag只执行一次，避免重复执行*/
                if(0 == buzzer_flag)
                {
                    buzzer_flag = 1 ;
                    mq2_sensor_interface.buzzer_control(&mq2_sensor_interface, 1);
                }

                led_status = !led_status ;
                mq2_sensor_interface.led_control(&mq2_sensor_interface, led_status);
            }
            else
            {
                /*这里的buzzer_flag只执行一次，避免重复执行*/
                if(1 == buzzer_flag)
                {
                    buzzer_flag = 0 ;
                    mq2_sensor_interface.buzzer_control(&mq2_sensor_interface, 0);
                    led_status = 0 ;
                    mq2_sensor_interface.led_control(&mq2_sensor_interface, led_status);
                }
            }

            /*在LCD上显示烟感值*/
            sprintf(display_buf, "%d%d%d%dppm", smoke_value / 1000 % 100, smoke_value / 100 % 10, smoke_value / 10 % 10, smoke_value % 10);
            LCD_ShowString(80, 50 + 24 + 32, 240, 32, 32, display_buf); //显示字符串，字体大小32*32
            /*拼接发送协议*/
            sprintf(procol_buf, "S1 %d%d%d%d%d %d%d%d%d%d",
                    serial_number / 10000,
                    serial_number / 1000 % 100 % 10,
                    serial_number / 100 % 10,
                    serial_number / 10 % 10,
                    serial_number % 10,
                    smoke_value / 10000,
                    smoke_value / 1000 % 100 % 10,
                    smoke_value / 100 % 10,
                    smoke_value / 10 % 10,
                    smoke_value % 10
                   );

            /*如果曲线标志为1，则打印曲线*/
            if(1 == plot_status)
                printf("%s \r\n", procol_buf);
        }
    }

    /* USER CODE END 3 */
}