Homemade small PM2.5 environmental detection system, the actual measurement effect is quite good

I have been unable to go out due to the epidemic during this period. Looking at the constantly changing data on the large screen of the air detection system opposite my house, I suddenly had an idea: could I make a PM2.5 testing system myself? I just had to do it when I thought about it.

As usual, without further ado, here are the pictures:

Physical picture 1

Physical picture 2

The actual measurement accuracy and precision are still acceptable.

The reference code of PM2.5 detection system is as follows:

host

#include

#include "delay.h"

#include "LCD12864.h"

#include "PM2_5.h"

#include "BMP180.h"

#include "DHT11.h"

#define uint unsigned int

#define uchar unsigned char

sbit waring=P1^3;

void main()

{

lcd_init();

Init_BMP085();

Init_PM2_5();

    while(1)

    {

    bmp085Convert();

    RH();

    lcd_pos(0,0);

    display_string("pm2.5:");

    if(read_pm()>5)

    display_num(read_pm());

    else

    display_num(5);

    display_string("ug/m3");

    display_string(" ");

    lcd_pos(1,0);

    display_string("T:");

    display_num(temperature/10);

    display_string(".");

    display_num(temperature%10);

    display_string("'C");

    display_string(" ");

    display_string("H:");

    display_num(RHdataH);

    display_string("%");

    lcd_pos(2,0);

    display_string("pre:");

    display_num(pressure/1000);

display_string(".");

    display_num(pressure%1000);

    display_string("kpa");

    lcd_pos(3,0);

    display_string("smo:");

    if(read_pm()>200)

    {

            display_string("High");        

            waring=0;

    }

    else

    {

            display_string("low");

            display_string(" ");

            warning=1;

    }

    display_string("Al:");        

    display_num(Altitude);

    display_string("m");

    display_string(" ");

    delay_ms(200);

    }

}

PM2.5

#include

#define uint unsigned int

#define uchar unsigned char

#define K_PM 820

void senddata(uchar dat);

uint read_pm();

uchar cal[7]={0};

// cal[0]: starting bit 0xAA

// cal[1]:Vout(H)

// cal[2]:Vout(L)

// cal[3]:Vref(H)

// cal[4]:Vref(L)

// cal[5]: check digit

// cal[6]: end bit 0xFF

uchar buf;

uchar sum;

int i=0;

float Vo;

void Init_PM2_5()

{

SCON=0x50;

PCON=0x00;

    TMOD=0x20;

    EA=1;

    ES=1;

    TL1=0xF4;

    TH1=0xF4;

    TR1=1;        

}

uint read_pm()

{

return (uint)(K_PM*Vo);

}

void serial() interrupt 4

{

ES=0;

RI=0;

buf=SBUF;

senddata(buf);

ES=1;

}

void senddata(uchar dat)

{

if(dat0xAA)

{

i=0;

cal[i]=dat;

}

else

{

i=i+1;

cal[i]=dat;

if(i6)

{

sum=cal[1]+cal[2]+cal[3]+cal[4];

if(sum==cal[5]&&cal[6]==0xFF)

{

// for(i=0;i<=6;i++)

// {

// SBUF=cal[i];

// while(!TI);

//TI=0;

// }

Vo=(cal[1]256+cal[2])/1024.05;

// SBUF=cal[1];

// while(!TI);

//TI=0;

//

//

// SBUF=cal[2];

// while(!TI);

//TI=0;

                    }

            }

    }

}

Due to limited space, I can only write this much.