C language program design and development based on 18B20 temperature sensor + 1602 LCD display

unsigned char data temp_data[2] = {0x00,0x00};
unsigned char data display[5] = {0x00,0x00,0x00,0x00,0x00};
unsigned char code ditab[16] = {0x00,0x01,0x01,0x02 ,0x03,0x03,0x04,0x04,
                                                        0x05,0x06,0x06,0x07,0x08,0x08,0x09,0x09} ;
void beep() ; 
unsigned char code mytab[8] = {0x0C,0x12,0x12,0x0C,0x00, 0x00,0x00,0x00};

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

/****************************************************** ******************/
void delay1(int ms)
{
 unsigned char y;
  while(ms--)
 {
  for(y = 0; y<250; y++)
  {
   _nop_() ;
   _nop_() ;
   _nop_() ;
   _nop_() ;
  }
 }
}

/******************************************************************/
/*Check LCD busy status */
/*When lcd_busy is 1, it is busy and waiting. When lcd-busy is 0, it is idle and can write instructions and data. */
/**********************************************************************/ 
bit lcd_busy()
 {                          
    bit result ;
    LCD_RS = 0 ;
    LCD_RW = 1 ;
    LCD_EN = 1 ;
    delayNOP() ;
    result = (bit)(P0&0x80) ;
    LCD_EN = 0 ;
    return(result) ; 
 }

/*Write instruction data to LCD */
/*RS=L, RW=L, E=high pulse, D0-D7=instruction code. */
/********************************************************************/
void lcd_wcmd(uchar cmd)
{                          
   while(lcd_busy()) ;
    LCD_RS = 0 ;
    LCD_RW = 0 ;
    LCD_EN = 0 ;
    _nop_() ;
    _nop_() ; 
    P0 = cmd ;
    delayNOP() ;
    LCD_EN = 1 ;
    delayNOP() ;
    LCD_EN = 0 ;  
}

/*******************************************************************/
/*Write display data to LCD */
/*RS=H, RW=L, E=high pulse, D0-D7=data. */
/***********************************************************************/
void lcd_wdat(uchar dat)
{                          
   while(lcd_busy()) ;
    LCD_RS = 1 ;
    LCD_RW = 0 ;
    LCD_EN = 0 ;
    P0 = dat ;
    delayNOP() ;
    LCD_EN = 1 ;
    delayNOP() ;
    LCD_EN = 0 ; 
}

/* LCD initialization settings */
/********************************************************************/
void lcd_init()
{ 
    delay1(15);   
    lcd_wcmd(0x01); //Clear LCD display contents            
    lcd_wcmd(0x38); //16*2 display, 5*7 dot matrix, 8-bit data
    delay1(5);
    lcd_wcmd(0x38);         
    delay1(5);
    lcd_wcmd(0x38);         
    delay1(5);

    lcd_wcmd(0x0c); //Display on and off cursor
    delay1(5);
    lcd_wcmd(0x06); //Move cursor
    delay1(5);
    lcd_wcmd(0x01); //Clear LCD display
    delay1(5);
}

/* Set display position */
/***********************************************************************/
void lcd_pos(uchar pos)
{                          
  lcd_wcmd(pos | 0x80); //data pointer = 80 + address variable
}

/*Write custom characters to CGRAM */
/*******************************************************************/
void writetab()  
{  
    unsigned char i ;
    lcd_wcmd(0x40) ; //Write CGRAM
    for (i = 0 ; i< 8 ; i++)       
    lcd_wdat(mytab[ i ]) ;        
}

/*us level delay function */
/***********************************************************************/

void Delay(unsigned int num)
{
  while( --num );
}

/*Initialize ds1820 */
/*******************************************************************/
Init_DS18B20(void)
{  
     DQ = 1 ; //DQ reset
     Delay(8); //delay a little

     DQ = 0; //MCU pulls DQ down
     Delay(90); //Precise delay greater than 480us

     DQ = 1; //Pull the bus high
     Delay(8);

     presence = DQ ; //If = 0, initialization is successful, = 1, initialization fails
     Delay(100) ;
     DQ = 1 ; 
     
     return(presence) ; //Return signal, 0 = presence, 1 = no presence
}

/* Read one byte */
/*******************************************************************/
 ReadOneChar(void)
{
unsigned char i = 0 ;
unsigned char dat = 0 ;

for (i = 8 ; i > 0 ; i--)
  {
    DQ = 0 ; // give pulse signal
    dat >>= 1 ;
    DQ = 1 ; // give pulse signal

    if(DQ)
     dat |= 0x80;
    Delay(4);
  }

    return (dat) ;
}

/* Write one byte */
/********************************************************************/
 WriteOneChar(unsigned char dat)
{
  unsigned char i = 0 ;
  for (i = 8 ; i > 0 ; i--)
  {
    DQ = 0 ;
    DQ = dat&0x01 ;
    Delay(5) ;

    DQ = 1 ;
    dat>>=1 ;
  }
}

/* Read temperature */
/*******************************************************************/
 Read_Temperature(void)
{
     Init_DS18B20() ;
  
     WriteOneChar(0xCC) ; // Skip reading serial number and column number
     WriteOneChar(0x44) ; // Start temperature conversion

     Init_DS18B20() ;
     WriteOneChar(0xCC) ; //Skip the operation of reading the serial number and column number
     WriteOneChar(0xBE) ; //Read the temperature register

     temp_data[0] = ReadOneChar() ; //low 8 bits of temperature
     temp_data[1] = ReadOneChar() ; //high 8 bits of temperature 
}

/* Data conversion and temperature display */
/***************************************************************************/
 Disp_Temperature()
{
  display[4]=temp_data[0]&0x0f ;
  display[0]=ditab[display[4]]+0x30 ;//Look up the table to get the decimal value
  
  display[4]=((temp_data[0]&0xf0)>>4)|((temp_data[1]&0x0f)<<4) ;
  display[3]=display[4]/100+0x30 ;
  display[1]=display[4]%100 ;
  display[2]=display[1]/10+0x30 ;
  display[1]=display[1]%10+0x30 ;

    if(display[3]==0x30) //The high bit is 0, not displayed
   { 
     display[3]=0x20 ;              
     if(display[2]==0x30) //The second high bit is 0, not displayed
     display[2]=0x20 ;
   }

     lcd_pos(0x48);             
     lcd_wdat(display[3]); //Hundreds display 
     lcd_pos(0x49);             
     lcd_wdat(display[2]); //Tens display 
  lcd_pos(0x4a);             
     lcd_wdat(display[1]); //Ones display 
  lcd_pos(0x4c);             
     lcd_wdat(display[0]); //Decimal places display 
} 

/***********************************************************************/
/* The buzzer sounds once */
/*******************************************************************/
void beep()
  {
    unsigned char y ;
    for (y=0 ;y<100 ;y++)
    {
      Delay(60) ;
      BEEP=!BEEP ; //Invert BEEP
    } 
    BEEP=1 ; //Turn off the buzzer
 Delay(40000) ;
  }

/* DS18B20 OK displays the menu */
/*******************************************************************/
void Ok_Menu ()
{ 
    uchar m ;
    lcd_init() ; //Initialize LCD 
            
    lcd_pos(0) ; //Set the display position to the first character of the first line
     m = 0 ;
    while(cdis1[m] != '\0')
     { //Display character
       lcd_wdat(cdis1[m]) ;
       m++ ;
     }

    lcd_pos(0x40) ; //Set the display position to the first character of the second line
     m = 0 ;
    while(cdis2[m] != '\0')
     {
       lcd_wdat(cdis2[m]) ; //Display character
       m++ ;
     }

     writetab() ; //Write custom characters to CGRAM
     delay1(5) ;
     lcd_pos(0x4d) ;
     lcd_wdat(0x00) ; //Display custom characters
}

/* DS18B20 ERROR display menu */
/****************************************************************/
void Error_Menu ()
{
     uchar m ;
     lcd_init() ; //Initialize LCD 
 
    lcd_pos(0) ; //Set the display position to the first character of the first line
     m = 0 ;
     while(cdis3[m] != '\0')
     { //Display character
       lcd_wdat(cdis3[m]) ;
       m++ ;
     }

     lcd_pos(0x40) ; //Set the display position to the first character of the second line
     m = 0 ;
     while(cdis4[m] != '\0')
     {
       lcd_wdat(cdis4[m]) ; //Display character
       m++ ;
     }
}

/* Main function */
/****************************************/
void main()
 {
     Ok_Menu () ;

 do
  {
    Read_Temperature() ; //Read temperature
   Disp_Temperature() ; //Display temperature
     }
    while(!presence) ;

     Error_Menu () ;

 do
  {  
    Init_DS18B20() ;
    beep() ;
     }
 while(presence) ;
}