51单片机使用MQ-2实时检测烟雾浓度，根据烟雾浓度调节PWM风扇转速并且使用LCD1602显示当前转速和当前烟雾浓度的C语言代码

以下是基于51单片机的使用MQ-2实时检测烟雾浓度，根据烟雾浓度调节PWM风扇转速并且使用LCD1602显示当前转速和当前烟雾浓度的C语言代码：

#include <reg52.h>
#include <intrins.h>

#define uchar unsigned char
#define uint unsigned int

#define LCD_Data_Port P0
sbit LCD_RS = P2^6;
sbit LCD_RW = P2^5;
sbit LCD_EN = P2^7;

sbit MQ2 = P3^2;
sbit FAN = P1^4;

uchar code table[]="  fan speed:";//lcd显示

uchar PWM_val; //PWM占空比
uint smoke_val; //烟雾浓度

void delay(uint xms) //延时函数
{
    uint i, j;
    for(i = xms; i > 0; i--)
        for(j = 110; j > 0; j--);
}

void LCD_Write_Cmd(uchar cmd) //写入命令函数
{
    LCD_RS = 0;
    LCD_RW = 0;
    LCD_Data_Port = cmd;
    LCD_EN = 1;
    _nop_();
    _nop_();
    _nop_();
    _nop_();
    LCD_EN = 0;
    delay(5);
}

void LCD_Write_Data(uchar dat) //写入数据函数
{
    LCD_RS = 1;
    LCD_RW = 0;
    LCD_Data_Port = dat;
    LCD_EN = 1;
    _nop_();
    _nop_();
    _nop_();
    _nop_();
    LCD_EN = 0;
    delay(5);
}

void LCD_Init() //LCD初始化函数
{
    LCD_Write_Cmd(0x38); //开显示，16x2，5x7点阵
    LCD_Write_Cmd(0x0c); //开显示不显示光标
    LCD_Write_Cmd(0x06); //文字不动，地址加1
    LCD_Write_Cmd(0x01); //清屏命令
}

void init_Timer0() //定时器0初始化函数
{
    TMOD|=0x01;
    TH0=0;
    TL0=0;
    ET0=1;
    TR0=1;
    EA=1;
}

void Timer0_ISR() interrupt 1 //定时器0中断服务程序
{
    static uint cnt;
    if(cnt == 100) //每隔100ms读取一次烟雾浓度
    {
        cnt = 0;
        smoke_val = (ADC_Read(0)>>2); //读取烟雾浓度
    }
    cnt++;
    if(smoke_val > 200) //根据烟雾浓度调节PWM占空比
        PWM_val = 255;
    else if(smoke_val > 100)
        PWM_val = 200;
    else if(smoke_val > 50)
        PWM_val = 150;
    else if(smoke_val > 20)
        PWM_val = 100;
    else
        PWM_val = 0;
    FAN = (PWM_val > TH0); //根据PWM占空比调节风扇转速
}

uchar ADC_Read(uchar ch) //ADC读取函数
{
    ADC_CONTR = ADC_POWER | ADC_SPEEDLL | ch;
    delay(1);
    ADC_CONTR |= ADC_START;
    while(!(ADC_CONTR & ADC_FLAG));
    ADC_CONTR &= ~ADC_FLAG;
    return ADC_RES;
}

void main()
{
    LCD_Init(); //初始化LCD
    init_Timer0(); //初始化定时器0
    while(1)
    {
        LCD_Write_Cmd(0x80); //第一行
        for(uchar i=0; i<13; i++)
            LCD_Write_Data(table[i]);
        LCD_Write_Data((uchar)(PWM_val/10)+'0'); //显示风扇转速
        LCD_Write_Data((uchar)(PWM_val%10)+'0');
        LCD_Write_Data(' ');
        LCD_Write_Data(' ');
        LCD_Write_Cmd(0xc0); //第二行
        LCD_Write_Data('s');
        LCD_Write_Data('m');
        LCD_Write_Data('o');
        LCD_Write_Data('k');
        LCD_Write_Data('e');
        LCD_Write_Data(':');
        LCD_Write_Data(' ');
        LCD_Write_Data((uchar)(smoke_val/100)+'0'); //显示烟雾浓度
        LCD_Write_Data((uchar)(smoke_val/10%10)+'0');
        LCD_Write_Data((uchar)(smoke_val%10)+'0');
        delay(100);
    }
}

注：本代码仅供参考，具体实现可能因硬件环境等因素而有所不同，使用时请结合实际情况进行修改。