PIC16F877A Example --- DS18B20

#include

__CONFIG(0x3F32); //Chip configuration word

#define LCDRS    RB2

#define LCDRW    RB1

#define LCDE     RB0

#define LCDDATA  PORTD

#define DS18B20  RE0          

#define TRIS_B20 TRISE0

void LCD1602_INIT(void);  

void WRITE_LCD_CMD (char cmd);

void WRITE_LCD_DATA (char data);

void LCD_Display(char *s);

void LCD_Display_location  (char line, char col);

void LCD1602_BUSY();

void US_delay ( int t);

void itoa10(unsigned char *buf, int i);

int strlen (const char *s);

void DS18B20_INIT();

void WRITE_DS18B20_CMD(char cmd);

float READ_DS18B20 ();

char bank1 DAT_BUFF1[]= "Temperature:";

char Found_DS18B20[]="DS1820 FOUND";

char DS18B20_NOT_Found[]="DS1820 NOT FOUND";

char bank1 DAT_BUFF2[]= "              ";

#define CLRLCD 0X01     //Clear screen command

#define LCDMOD 0X38     //8 bits, two lines, 5*7 dots

#define ROTATION 0X0F     //

#define CURMODE 0X06    //

#define ORG1   0X80     //LCD first row address

#define ORG2   0XC0     //LCD second row first address

#define SKIPROM 0XCC

#define READSCRACHPAD 0XBE

#define TCONVERT 0X44

#define DS18b20_RESET 10 

#define DSRECOVER 1

float temperature;

char bank1 atemperature[10];    // used for store ascii code of digital temperature */

void main()

{

    int len;

    ADCON1=0X07;               

    LCD1602_INIT();

     LCD_Display(DAT_BUFF1);

    LCDE=0;                    

     LCD_Display_location  (1,0);

     while (1)

     {

           DS18B20_INIT();

            WRITE_DS18B20_CMD(SKIPROM);

            WRITE_DS18B20_CMD(TCONVERT);

            TRIS_B20=0;

            DS18B20=0;

            TRIS_B20=1;

            while(1)

           { //Judge whether the conversion is completed

            if (DS18B20)  break; 

            else  continue;   

            }

           DS18B20_INIT();

            WRITE_DS18B20_CMD(SKIPROM);

            WRITE_DS18B20_CMD(READSCRACHPAD);

            temperature=READ_DS18B20();            

            itoa10(atemperature, (int) (temperature * 10));

                                                            // so use temperature * 10 to enlarge the temperature

            len=strlen(atemperature);

            atemperature[len]=atemperature[len-1];

            atemperature[len-1]='.';

            atemperature[len+1]=0;

            LCD_Display_location  (0,0);

           LCD_Display (DAT_BUFF1);                      //LCD first line displays Tempereture: characters

            LCD_Display_location  (1,0);

            LCD_Display (DAT_BUFF2);    

            LCD_Display_location  (1,2);

           LCD_Display (atemperature);                   //The second line of LCD displays the current temperature value

            LCD_Display (DAT_BUFF2);

           US_delay(5000);                              //Read the temperature value every 0.5 seconds   

 }

}

int strlen(const char * s)

{

     const char *cp;

    cp = s;

     while(*cp++)

     continue;

     return cp-s-1;

}

void LCD_Display(char *s)

{

    int len;

     int atmp;

    len=strlen(s);

     for (atmp=0; atmp

     WRITE_LCD_DATA(s[atmp]);

}

void LCD1602_BUSY()

{

     // char tmpbusy;

     TRISB &= 0xF8;

     TRISD=0XFF;

     LCDRS=0;

     LCDRW=1;

    LCDE=1;                   

     while(LCDDATA & 0X80);

}

void LCD_Display_location  (char line, char col)

{

     char pos;

     LCD1602_BUSY();

     pos = line * 0X40 + 0X80 + col;

     WRITE_LCD_CMD(pos);

}

void WRITE_LCD_DATA(char data)

{

    LCD1602_BUSY();

     TRISB & =0XF8;

     TRISD=0;

     LCDDATA=data;

     LCDRS=1;

     LCDRW=0;

    LCDE=0;

     asm("NOP");

    asm("NOP");

    LCDE=1;

}

 [page]

void WRITE_LCD_CMD(char cmd)

{

    LCD1602_BUSY();

    TRISB & =0XF8;

    TRISD=0;

     LCDDATA=cmd;

     LCDRS=0;

    LCDRW=0;

    LCDE=0;

    asm("NOP");

    asm("NOP");

    LCDE=1;

}

void LCD1602_INIT(void)

{

    LCD1602_BUSY();

     TRISB &= 0XF8;

    TRISD=0;

     WRITE_LCD_CMD(CLRLCD);

     WRITE_LCD_CMD(LCDMOD);

     WRITE_LCD_CMD(TURNON);

     WRITE_LCD_CMD(CURMODE);

     LCD_Display_location  (0,0);      

}

void DS18B20_INIT()

{

     TRIS_B20=0;

     DS18B20=0;

     US_delay(20);  

     TRIS_B20=1;  

     US_delay(10);   

}

void WRITE_DS18B20_CMD(char cmd)

{

     char tmp;

     char i;

    TRIS_B20=0;

     for(tmp=8;tmp>0;tmp--)

     {

          TRIS_B20=0;

           DS18B20= 0;

           asm ("NOP");

           asm ("NOP");

          asm ("NOP");

          asm ("NOP");

          asm ("NOP");

           if (cmd & 0x01)

          {

          TRIS_B20=1;         

           US_delay(1);         

           for (i=5;i>0;i--);

           }

           else

          {

           DS18B20=0 ;

           US_delay(1);

           for (i=5;i>0;i--);    

           TRIS_B20=1;

          }

           cmd=cmd/2;

    }

}

float READ_DS18B20 ()

{

     char tmp=0x01;

     float t;

     union

    {

     char c[2];

     int x;

     }temp;

     temp.x=0;

     while (tmp)

     {     // read first 8 bits

           TRIS_B20=0;

           DS18B20=0;

           asm("NOP");

           TRIS_B20=1;     

            if (DS18B20)    

            temp.c[0] |= tmp;

            tmp=tmp<<1;

            US_delay(2);

    }

     tmp=1;

    while (tmp)

     {     // read first 8 bits

           TRIS_B20=0;

           DS18B20=0;

           asm("NOP");

            TRIS_B20=1;       // release the bus  

           asm("NOP");

            if (DS18B20)      // "1" presented

            temp.c[1] |= tmp;

           tmp=tmp<<1;

           US_delay(2);

    }

     t=((float) temp.x)/16.0 ;

     return t;

}

void itoa10(unsigned char *buf, int i)

{

     unsigned int rem;

     unsigned char *s,length=0;

     s = buf;

     if (i == 0)

     *s++ = '0';

     else

    {

          if (i < 0)

         {

          *buf++ = '-';

         s = buf;

          i = -i;

         }

          while (i)

         {

          ++length;

         rem = i % 10;

         *s++ = rem + '0';

          i /= 10;

          }

          for(rem=0; ((unsigned char)rem)

         {

          *(buf+length) = *(buf+((unsigned char)rem));

          *(buf+((unsigned char)rem)) = *(buf+(length-((unsigned char)rem)-1));

          *(buf+(length-((unsigned char)rem)-1)) = *(buf+length);

         }

    }

     *s=0;

}

void US_delay( int i)

{

        unsigned char j;

        while(i--)

    {

           j=3;

              while(j--);

        }

}