Smoke sensor based on AT89C51 microcontroller

#include

#include

#define uchar unsigned char //macro definition of unsigned character type

#define uint unsigned int //macro definition of unsigned integer

sbit ST=P3^0; //A/D start conversion signal

sbit OE=P3^1; //Data output enable signal

sbit EOC=P3^2; //A/D conversion end signal

sbit CLK=P3^3; //clock pulse

uint i,j,AD0809; //define data type

//Delay sub-function

void delay()

{

i = 1000;

while(i--);

}

/****************************************************** ************************

CLK oscillation signal

*************************************************** ************************/

void timer0() interrupt 1 //Timer 0 working mode 1

{

TH0=(65536-2)/256; //Reload count initial value

TL0=(65536-2)%256; //Reload count initial value

CLK=!CLK; //Invert

}

/****************************************************** ************************

Main function

*************************************************** ************************/

void main()

{

TMOD=0X01; //Timer interrupt 0

CLK=0; //The initial value of the pulse signal is 0

TH0=(65536-2)/256; //initial value of the high 8 bits of the timing time

TL0=(65536-2)%256; //initial value of the lower eight bits of the timing time

EA=1; //Open CPU interrupt

ET0=1; //Open T/C0 interrupt

TR0=1;

while(1) // infinite loop

{

ST=0; // Make the acquisition signal low

ST=1; //Start data conversion

ST=0; //Stop data conversion

while(!EOC); //Wait for data conversion to complete

OE=1; //Allow data output signal

AD0809=P1; //Read data

OE=0; //Turn off data output enable signal

if(AD0809>=251) //The voltage displayed cannot exceed 5V

{

AD0809=250;

P2 = 0xE0; //Alarm flashing LED light

delay();

P2 =~0xE0;

delay();

P0 = ~0x06; //Digital tube alarm display 1

delay();

P0 = ~0x00;

delay();

}

}

}