Schematic diagram of single chip intelligent temperature control fan PCB file and source program

The main chip is 89c51, with motor, temperature sensor, infrared pyroelectric, LCD1602 as peripherals. The main function is to automatically adjust the motor speed according to the room temperature, and recognize the human body, open it when someone is on, and turn off the power when no one is on. The indoor temperature and the upper and lower limits can be adjusted by keystrokes and displayed on the 1602.
The compressed package contains the schematic, PCB board, and library. There are also codes and documents.

The schematic and PCB diagram drawn by Altium Designer are as follows:

The microcontroller source program is as follows:

#include //Call the MCU header file

#define uchar unsigned char //unsigned character macro definition variable range 0~255

#define uint unsigned int //Unsigned integer macro definition variable range 0~65535

#include

sbit dq = P2^4; //18b20 IO port definition

sbit BGVCC = P2^7;

uint temperature ; //

bit flag_200ms;

bit flag_lj_en; //key-on enable

bit flag_lj_3_en; // Press the button three times in a row to enable the added number. 

uchar key_time,key_value; //Used as intermediate variable for continuous addition

bit key_500ms;

sbit hw = P2^5;

uchar miao = 30;

uchar flag_en;

sbit buzz=P1^3;

uchar code table_num[]="0123456789abcdefg";

sbit rs=P1^2; //Register selection signal H: data register L: instruction register

sbit rw=P1^1; //Register selection signal H: data register L: instruction register

sbit e =P1^0; //Chip select signal falling edge trigger

sbit pwm = P2^3;  

uchar f_pwm_l; //

uchar menu_1; //Menu design variables

uint t_high = 300, t_low = 200;

/**************************1ms delay function********************************/

void delay_1ms(uint q)

{

        uint i,j;

        for(i=0;i                for(j=0;j<110;j++);

}

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

* Name: delay_uint()

* Function: small delay.

* Input: None

* Output: None

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

void delay_uint(uint q)

{

        while(q--);

}

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

* Name: write_com(uchar com)

* Function: 1602 command function

* Input: Input command value

* Output: None

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

void write_com(uchar com)

{

        e=0;

        rs=0;

        rw=0;

        P0=com;

        delay_uint(25);

        e=1;

        delay_uint(100);

        e=0;

}

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

* Name: write_data(uchar dat)

* Function: 1602 write data function

* Input: Data to be written to 1602

* Output: None

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

void write_data(uchar dat)

{

        e=0;

        rs=1;

        rw=0;

        P0=dat;

        delay_uint(25);

        e=1;

        delay_uint(100);

        e=0;        

}

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

* Name: write_string(uchar hang,uchar add,uchar *p)

* Function: Change the value of a certain bit in the LCD. If you want the fifth character in the first line to start displaying "ab cd ef", call this function as follows

                  write_string(1,5,"ab cd ef;")

* Input: row, column, need to enter 1602 data

* Output: None

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

void write_string(uchar hang,uchar add,uchar *p)

{

        if(hang==1)   

                write_com(0x80+add);

        else

                write_com(0x80+0x40+add);

        while(1)

        {

                if(*p == '') break;

                write_data(*p);

                p++;

        }        

}

/***********************Display specific characters on lcd1602****************************/

void write_zifu(uchar hang,uchar add,uchar date)

{

        if(hang==1)   

                write_com(0x80+add);

        else

                write_com(0x80+0x40+add);

        write_data(date);        

}

/***********************LCD1602 displays two decimal numbers************************/

void write_sfm3_18B20(uchar hang,uchar add,uint date)

{

        if(hang==1)   

                write_com(0x80+add);

        else

                write_com(0x80+0x40+add);

        write_data(0x30+date/100%10);

        write_data(0x30+date/10%10);

          write_data('.');

        write_data(0x30+date%10);        

}

/***********************lcd1602 initialization settings****************************/

void init_1602()

{

        write_com(0x38); //

        write_com(0x0c);

        write_com(0x06);

        delay_uint(1000);

        write_string(1,0,"temp: ");        

        write_string(2,0,"H: L: ");

        write_sfm3_18B20(2,2,t_high);        

        write_sfm3_18B20(2,10,t_low);                                

        write_zifu(1,9,0xdf); //display degree        

}

/***************************18b20 initialization function*********************************/

void init_18b20()

{          

        bit q;

                EA=0;

        dq = 1; //Put the bus high

        delay_uint(1); //15us

        dq = 0; // give reset pulse

        delay_uint(80); //750us

        dq = 1; //Put the bus high and wait

        delay_uint(10); //110us

        q = dq; //Read 18b20 initialization signal

        delay_uint(20); //200us

        dq = 1; //Pull the bus high to release the bus

        EA=1 ;

}

/*************Write the data in 18b20***************/

void write_18b20(uchar dat)

{         

        uchar i;

                 EA=0;

        for(i=0;i<8;i++)

        { //Write data starts from low bit

                dq = 0; // Pull the bus low to start the write time interval 

                dq = dat & 0x01; //Write data to the 18b20 bus

                delay_uint(5); // 60us

                dq = 1; //Release the bus

                dat >>= 1;

        }

        EA=1;        

}

/****************Read the data in 18b20****************/

uchar read_18b20()

{         

        uchar i,value;

                         EA=0 ;

        for(i=0;i<8;i++)

        {

                dq = 0; //Put the bus low to start the read time interval 

                value >>= 1; //Read data starting from low bit

                dq = 1; //Release the bus

                if(dq == 1) //Start reading and writing data 

                        value |= 0x80;

                delay_uint(7); //60us Reading a time gap requires at least 60us

        }

        EA=1 ;

        return value; //Return data

}

/****************The temperature value read is a decimal***************/

uint read_temp()

{          

        uint value;

        uchar low; //If the interrupt is too frequent when reading the temperature, the interrupt should be turned off, otherwise it will affect the timing of 18b20

           EA=0;

        init_18b20(); //Initialize 18b20

        write_18b20(0xcc); //Skip 64-bit ROM

        write_18b20(0x44); //Start a temperature conversion command

         delay_uint(50); //500us

        init_18b20(); //Initialize 18b20

        write_18b20(0xcc); //Skip 64-bit ROM

        write_18b20(0xbe); //Issue a command to read the temporary register

        low = read_18b20(); //Read temperature low byte

        value = read_18b20(); //Read temperature high byte

        value <<= 8; //Shift the high bit of the temperature left by 8 bits

        value |= low; //Put the low bit of the temperature read into the low eight bits of value

        value *=0.625 ; //Convert to decimal temperature value

        EA=1;

        return value; //Return the read temperature with decimals

}

/*************Timer 0 initialization procedure****************/

void time_init()          

{

        EA = 1; // Enable general interrupt

        TMOD = 0X21; //Timer 0, Timer 1 working mode 1

        ET0 = 1; // Enable timer 0 interrupt 

        TR0 = 1; // Allow timer 0 to start timing

        ET1 = 1; // Enable timer 0 interrupt 

        TR1 = 1; // Allow timer 0 to start timing

}

/************************Independent key program*****************/

uchar key_can; //key value

void key() //Independent key program

{          

        static uchar key_new;

        key_can = 20; //key value restoration

         P1 |= 0xf0;

        if(key_500ms == 1) //Continuous addition

        {

                key_500ms = 0;

                key_new = 1;

        }

        if((P1 & 0xf0) != 0xf0) //button pressed

        {

                delay_1ms(1); //key debounce

                if(((P1 & 0xf0) != 0xf0) && (key_new == 1))

                { //Confirm that the button was pressed

                        key_new = 0;

                        switch(P1 & 0xf0)

                        {

                                case 0xe0: key_can = 1; break; //Get the k1 key value

                                case 0xd0: key_can = 2; break; //Get the K2 key value

                                case 0xb0: key_can = 3; break; //Get the k3 key value

                        }

                        flag_lj_en = 1; //Continuous addition enable

                }                        

        }

        else 

        {

                        if(key_new == 0)

                {

                        key_new = 1;

                        flag_lj_en = 0; //Disable continuous addition enable

                        flag_lj_3_en = 0; //Enable after 3 seconds of shutdown

                        key_value = 0; // clear

                        key_time = 0;

                        key_500ms = 0;

                }

        }

}

/********************Button display function***************/

void key_with()

{          

        if(key_can == 1) //Set key

        {         

                menu_1++;

                if(menu_1 >= 3)

                {

                        menu_1 = 0;

                }

                if(menu_1 == 0)

                {

                        write_com(0x0c); //Close the cursor

                }

        }

        if(menu_1 == 1) //Set high temperature alarm

        {

                if(key_can == 2)

                {

                        if(flag_lj_3_en == 0)

                                t_high ++ ; //The button is pressed but not released, and the value is automatically increased three times