Single chip temperature measurement system (AT89C51, DS18B20 temperature sensor, LCD1602)

1. Introduction

This system is mainly composed of AT89C51, DS18B20 temperature module and LCD1602.

The general principle is that the temperature data collected by DS18B20 is transmitted to P3.3/INT1 (external interrupt 1) of AT89C51, and finally the current real-time temperature is displayed through LCD1602.

2. Rendering

Simulation diagram

3. Source code

/*Want more projects private wo!!!*/

/***************   writer:shopping.w   ******************/

#include

#include

#define uint unsigned int

#define uchar unsigned char

#define delayNOP() {_nop_();_nop_();_nop_();_nop_();}

sbit DQ = P3^3;

sbit LCD_RS = P2^0;

sbit LCD_RW = P2^1;

sbit LCD_EN = P2^2;

uchar code Temp_Disp_Title[]={"Current Temp :   "};

uchar Current_Temp_Display_Buffer[]={" TEMP:   "};

volatile code Temperature_Char[8] = 

{

  0x0c,0x12,0x12,0x0c,0x00,0x00,0x00,0x00

};

uchar code df_Table[]=

{

  0,1,1,2,3,3,4,4,5,6,6,7,8,8,9,9

};

float CurrentT = 0;

uchar Temp_Value[]={0x00,0x00};

float Display_Digit[]={0,0,0,0};

bit DS18B20_IS_OK = 1;

void DelayXus(uint x)

{

  flying i;

while(x--)

{

for(i=0;i<200;i++);

}

}

bit LCD_Busy_Check()

{

  bit result;

LCD_RS = 0;

LCD_RW = 1;

LCD_EN = 1;

delayNOP();

result = (bit)(P0&0x80);

LCD_EN=0;

return result;

}

void Write_LCD_Command(uchar cmd)

{

while(LCD_Busy_Check());

LCD_RS = 0;

LCD_RW = 0;

LCD_EN = 0;

_nop_();

_nop_();

P0 = cmd;

delayNOP();

LCD_EN = 1;

delayNOP();

LCD_EN = 0;

}

void Write_LCD_Data(uchar dat)

{

while(LCD_Busy_Check());

LCD_RS = 1;

LCD_RW = 0;

LCD_EN = 0;

P0 = that;

delayNOP();

LCD_EN = 1;

delayNOP();

LCD_EN = 0;

}

void LCD_Initialize()

{

  Write_LCD_Command(0x01);

DelayXus(5);

Write_LCD_Command(0x38);

DelayXus(5);

Write_LCD_Command(0x0c);

DelayXus(5);

Write_LCD_Command(0x06);

DelayXus(5);

}

void Set_LCD_POS(uchar pos)

{

  Write_LCD_Command(pos|0x80);

}

void Delay(uint x)

{

  while(--x);

}

fly Init_DS18B20()

{

  flying status;

DQ = 1;

Delay(8);

DQ = 0;

Delay(90);

DQ = 1;

Delay(8);

DQ = 1;

return status;

}

fly ReadOneByte()

{

  fly i,dat=0;

DQ = 1;

_nop_();

for(i=0;i<8;i++)

{

DQ = 0;

that >>= 1;

DQ = 1;

_nop_();

_nop_();

if(DQ)

that |= 0X80;

Delay(30);

DQ = 1;

}

return that;

}

void WriteOneByte(volatile dat)

{

  flying i;

for(i=0;i<8;i++)

{

DQ = 0;

DQ = that& 0x01;

Delay(5);

DQ = 1;

that >>= 1;

}

}

void Read_Temperature()

{

  if(Init_DS18B20()==1)

DS18B20_IS_OK=0;

else

{

WriteOneByte(0xcc);

WriteOneByte(0x44);

Init_DS18B20();

WriteOneByte(0xcc);

WriteOneByte(0xbe);

Temp_Value[0] = ReadOneByte(); 

Temp_Value[1] = ReadOneByte();

DS18B20_IS_OK=1;

}

}

void Display_Temperature()

{

  flying i;

uchar t = 150, of = 0;

if((Temp_Value[1]&0xf8)==0xf8)

{

Temp_Value[1] = ~Temp_Value[1];

Temp_Value[0] = ~Temp_Value[0]+1;

if(Temp_Value[0]==0x00)

Temp_Value[1]++;

of = 1;

}

Display_Digit[0] = df_Table[Temp_Value[0]&0x0f];

CurrentT = ((Temp_Value[0]&0xf0)>>4) | ((Temp_Value[1]&0x07)<<4);

Display_Digit[3] = CurrentT/100;

Display_Digit[2] = CurrentT%100/10;

Display_Digit[1] = CurrentT%10;

Current_Temp_Display_Buffer[11] = Display_Digit[0] + '0';

Current_Temp_Display_Buffer[10] = '.';

Current_Temp_Display_Buffer[9]  = Display_Digit[1] + '0';

Current_Temp_Display_Buffer[8]  = Display_Digit[2] + '0';

Current_Temp_Display_Buffer[7]  = Display_Digit[3] + '0';

if(Display_Digit[3] == 0)

Current_Temp_Display_Buffer[7]  = ' ';

if(Display_Digit[2] == 0&&Display_Digit[3]==0)

Current_Temp_Display_Buffer[8]  = ' ';

if

{

if(Current_Temp_Display_Buffer[8]  == ' ')

Current_Temp_Display_Buffer[8]  = '-';

else if(Current_Temp_Display_Buffer[7]  == ' ')

Current_Temp_Display_Buffer[7]  = '-';

else 

Current_Temp_Display_Buffer[6]  = '-';

}

Set_LCD_POS(0x00);

for(i=0;i<16;i++)

{

Write_LCD_Data(Temp_Disp_Title[i]);

}

Set_LCD_POS(0x40);

for(i=0;i<16;i++)

{

Write_LCD_Data(Current_Temp_Display_Buffer[i]);

}

Set_LCD_POS(0x4d);

Write_LCD_Data(0x00);

Set_LCD_POS(0x4e);

Write_LCD_Data('C');

}

void main()

{

  LCD_Initialize();

Read_Temperature();

Delay(50000);

Delay(50000);

while(1)

{

Read_Temperature();

if(DS18B20_IS_OK) 

Display_Temperature();

DelayXus(100);

}

}