DS18B20 Temperature Sensor Complete C Program

#include
#include //_nop_(); delay function
#define Disdata P0 //segment code output port
#define discan P2 //scan port
#define uchar unsigned char
#define uint unsigned int
sbit DQ=P3^7; //temperature input port
sbit DIN=P0^0; //LED decimal point control
uint h; 
uint temp;
//
//
//**************Temperature decimal part uses table lookup method***********//
uchar code ditab[16]=
{0x00,0x01,0x01,0x02,0x03,0x03,0x04,0x04,0x05,0x06,0x06,0x07,0x08,0x08,0x09,0x09};
//
uchar code dis_7[12]={0xfc,0x60,0xda,0xf2,0x66,0xb6,0xbe,0xe0,0xfe,0xf6,0xff,0x02};
//Common anode LED segment code table "0" "1" "2" "3" "4" "5" "6" "7" "8" "9" "off" "-"              
uchar code scan_con[4]={0xf7,0xfB,0xfD,0xff}; //Column scan control word
uchar data temp_data[2]={0x00,0x00}; //Read temperature temporarily
uchar data display[5]={0x00,0x00,0x00,0x00,0x00}; //Display unit data, a total of 4 data and one operation temporarily

//
//
//
/*********************11us delay function****************************/
//
void delay(uint t)
{
  for (;t>0;t--);
}
//

/****************Display scan function****************************/
scan()
{
  char k;
     for(k=0;k<4;k++) //4-bit LED scan control
{
  Disdata=dis_7[display[k]]; //Data displayif
  (k==1){DIN=1;} //Decimal point displaydiscan
  =scan_con[k]; //Bit selectiondelay
  (300);
}
}
//
//
/****************DS18B20 reset function****************************/
ow_reset(void)
{
char presence=1;
while(presence)
{
  while(presence)
   {
    DQ=1;_nop_();_nop_();//Pull from high to low
DQ=0;                                       
delay(50); //550 us
DQ=1;                                        
delay(6); //66 us
presence=DQ; //presence=0 Reset successful, continue to the next step
   } 
   delay(45); //Delay 500 us
   presence=~DQ;         
}
DQ=1; //Pull high
}
//
//
/****************DS18B20 write command function****************************/
//Write 1 byte to the 1-WIRE bus
void write_byte(uchar val)
{ 
  uchar i;
  for(i=8;i>0;i--)
  {
   DQ=1;_nop_();_nop_(); //Pull from high to low
   DQ=0;_nop_();_nop_();_nop_();_nop_(); //5 us
   DQ=val&0x01; //The lowest bit is moved out
   delay(6); //66 us
   val=val/2; //Shift right 1 bit
   }
   DQ=1;
   delay(1);
}
//
/****************DS18B20 read 1 byte function****************************/
//Get 1 byte from the bus
uchar read_byte(void)
{
uchar i;
uchar value=0;
for(i=8;i>0;i--)
{
  ow_reset(); delay(200); write_byte(0xcc); //send command write_byte(0x44); //send conversion command ow_reset(); delay(1); write_byte
  (
  0xcc
  )   ;
  // send   command write_byte(   0xbe)   ;   temp_data   [ 0]= read_byte ( ) ; // read the byte of temperature value   temp_data   [1   ] =   read_byte (   )  ; //Read the high byte of temperature value   temp=temp_data[1];





















  temp<<=8;                                               
  temp=temp|temp_data[0]; // Two bytes are combined into an integer variable.
  return temp; //Return temperature value
}
//
/****************Temperature data processing function****************************/

//The lower half byte of the binary high byte and the higher half byte of the low byte form a byte.
After the binary of this //byte is converted to decimal, it is the hundreds, tens, and units of the temperature value, and
the lower half byte of the remaining //low byte is converted to decimal to be the decimal part of the temperature value.

/************************************************************/
work_temp(uint tem)
{
uchar n=0;
if(tem>6348) // Temperature value positive or negative judgment
     {tem=65536-tem;n=1;} // Negative temperature two's complement, flag position 1
      display[4]=tem&0x0f; // Get the value of the decimal part
  display[0]=ditab[display[4]]; // Store the decimal part display
      [4]=tem>>4; // Get the middle eight digits, that is, the value of the integer part
  display[3]=display[4]/100; // Get the hundreds digit data and store it
  display[1]=display[4]%100; // Get the last two digits and store it
  display[2]=display[1]/10; // Get the tens digit data and store
  it display[1]=display[1]%10;  
/******************Sign bit display judgment*****************************/
  if(!display[3]) 
  {
    display[3]=0xF5; //No display when the highest bit is 0if
    (!display[2])
{
   display[2]=0xF5; //No display when the second highest bit is 0
}
  }
  if(n){display[3]=0xF4;} //The highest bit displays "-" when the temperature is negative
}
//
//
/********************Main function****************************/
main()
{
  Disdata=0x00; //Initialize portdiscan
  =0x00;
  for(h=0;h<4;h++) //Display "8888" when powered on
      {display[h]=8;} 
  ow_reset(); //Convert once before powering
  onwrite_byte(0xcc); //Skip ROM
  write_byte(0x44); //Send conversion commandfor
  (h=0;h<100;h++) //Display "8888" when powered on
      {scan();}
  while(1)
  {
work_temp(read_temp()); //Process temperature data
scan(); //Display temperature value
  }
}