C language program using DS18B20 temperature sensor in single chip microcomputer (reference 5)

#define uchar unsigned char
#define uint unsigned int

sbit DQ=P2^7; //define interface

uint temp; // variable of temperature defines a variable

uchar flag1; // sign of the result positive or negative Define
a flag to indicate whether the temperature is still positive

sbit P2_0=P2^0; //digital tube bit selection
sbit P2_1=P2^1;
sbit P2_2=P2^2;

unsigned char code table[]={0xc0,0xf9,0xa4,0xb0,
0x99,0x92,0x82, 0xf8,0x80,0x90}; //digital encoding

unsigned char code table1[]={0x40,0x79,0x24,0x30,
0x19,0x12,0x02, 0x78,0x00,0x10}; //Code with decimal point

void delay(uint i) //delay delay subroutine
{
     while(i--);
}

/*******************************************************************/
/* Initialize ds18b2 sub-function* */
/*******************************************************************/
Init_DS18B20(void)
{
unsigned char x=0;
DQ = 1; //DQ reset
delay(8); //Slight delay
DQ = 0; //MCU pulls DQ low
delay(80); //Precise delay greater than 480us
DQ = 1; //Pull the bus high
delay(14);
x=DQ; //After a slight delay, if x=0, initialization is successful, if x=1, initialization fails
delay(20);
}

/***********************************************************************/
/* Read byte sub-function */
/*******************************************************************/
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 byte sub-function */
/************************************************************************/
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;
}
}

/*void tmpwritebyte(uchar dat) //write a byte to ds18b20 Write a byte to the temperature sensor
{
   uint i;
   uchar j;
   bit testb;
   for(j=1;j<=8;j++)
   {
     testb=dat&0x01;
     dat=dat>>1;
     if(testb) //write 1
     {
       DQ=0;
       i++;i++;
       DQ=1;
       i=8;while(i>0)i--;
     }
     else
     {
       DQ=0; //write 0
       i=8;while(i>0)i--;
       DQ=1;
       i++;i++;
     }
   }
}*/

void tmpchange(void) //DS18B20 begin change send temperature conversion command
{
   Init_DS18B20(); //Initialize DS18B20
   delay(200); //Delay
   WriteOneChar(0xcc); //Skip serial number command
   WriteOneChar(0x44); //Send temperature conversion command
}

uint tmp() //get the temperature Get the temperature value
{
   float tt;
   uchar a,b;
   Init_DS18B20();
   delay(1);
   WriteOneChar(0xcc);
   WriteOneChar(0xbe); //Send the read data command
   a=ReadOneChar(); //Continuously read two bytes of data
   b=ReadOneChar();
   temp=b;
   temp<<=8;                                               
   temp=temp|a; //Two bytes are combined into an integer variable.
   tt=temp*0.0625; //Get the true decimal temperature value, because DS18B20
                                                            //can be accurate to 0.0625 degrees, so the lowest bit of the read data represents
                                                            //0.0625 degrees.
   temp=tt*10+0.5; //Magnify ten times, the purpose of doing this is to convert the first digit after the decimal point
                                                            //to a displayable number, and perform a rounding operation at the same time.
   return temp; //Return the temperature value
}

/*void readrom() //read the serial Read the serial number of the temperature sensor
{ //This function is not used in this program
   uchar sn1, sn2;
   Init_DS18B20();
   delay(1);
   WriteOneChar(0x33);
   sn1=ReadOneChar();
   sn2=ReadOneChar();
}*/

void delay10ms() //delay 10MS sub-function
   {
     uchar a,b;
     for(a=50;a>0;a--)
       for(b=60;b>0;b--);
    }
void display(uint tem) //display display sub-function
   {
      uchar A1,A2,A2t,A3;
   if(tem>=100)
   {
         A1=table[tem/100];
         A2t=tem%100;
         A2=table1[A2t/10];
         A3=table[A2t%10];
   }
   else
   {
      A2t=tem%100;
         A1=table1[A2t/10];
         A2=table[A2t%10];
   A3=0xFF;
   }
        P0=A1;
        P2_0=0;
        P2_1=1;
        P2_2=1;
        delay10ms();
        P0=A2;
        P2_1=0;
        P2_0=1;
        P2_2=1;
        delay10ms();
     if(A3!=0xFF)
     {
          P0=A3;
          P2_2=0;
          P2_0=1;
          P2_1=1;
     }
    }

void main() //Main function
{
   do
   {
     tmpchange(); //Temperature conversion,
     display(tmp()); //Display temperature value
   }
      while(1);
}