#include <reg52.h>
#define uchar unsigned char
#define uint unsigned int
sbit DS=P2^7;           //define interface 定義接口
uint temp;             // variable of temperature  定義一個變量用來表示溫度
uchar flag1;            // sign of the result positive or negative 定義一個標志，標志溫度是否還是正
sbit P2_0=P2^0;          //數碼管位選
sbit P2_1=P2^1;
sbit P2_2=P2^2;
unsigned char code table[]={0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,  //數字編碼
                        0xf8,0x80,0x90};
unsigned char code table1[]={0x40,0x79,0x24,0x30,0x19,0x12,0x02, //帶小數點的編碼
                        0x78,0x00,0x10};

void delay(uint count)      //delay   延時子程序
{
  uint i;
  while(count)
  {
    i=200;
    while(i>0)
    i--;
    count--;
  }
}

void dsreset(void)       //send reset and initialization command  發送初始化命令子程序
{
  uint i;
  DS=0;
  i=103;
  while(i>0)i--;
  DS=1;
  i=4;
  while(i>0)i--;
}

bit tmpreadbit(void)       //read a bit    讀一位
{
   uint i;
   bit dat;
   DS=0;i++;          //i++ for delay
   DS=1;i++;i++;
   dat=DS;
   i=8;while(i>0)i--;
   return (dat);
}

uchar tmpread(void)   //read a byte date     讀一個字節
{
  uchar i,j,dat;
  dat=0;
  for(i=1;i<=8;i++)
  {
    j=tmpreadbit();
    dat=(j<<7)|(dat>>1);   //讀出的數據最低位在最前面，這樣剛好一個字節在DAT里
  }
  return(dat);
}

void tmpwritebyte(uchar dat)   //write a byte to ds18b20 給溫度傳感器寫一個字節
{
  uint i;
  uchar j;
  bit testb;
  for(j=1;j<=8;j++)
  {
    testb=dat&0x01;
    dat=dat>>1;
    if(testb)     //write 1
    {
      DS=0;
      i++;i++;
      DS=1;
      i=8;while(i>0)i--;
    }
    else
    {
      DS=0;       //write 0
      i=8;while(i>0)i--;
      DS=1;
      i++;i++;
    }

  }
}

void tmpchange(void)  //DS18B20 begin change   發送溫度轉換命令
{
  dsreset();
  delay(1);
  tmpwritebyte(0xcc);  // address all drivers on bus
  tmpwritebyte(0x44);  //  initiates a single temperature conversion
}

uint tmp()               //get the temperature         得到溫度值
{
  float tt;
  uchar a,b;
  dsreset();
  delay(1);
  tmpwritebyte(0xcc);
  tmpwritebyte(0xbe);
  a=tmpread();
  b=tmpread();
  temp=b;
  temp<<=8;             //two byte  compose a int variable
  temp=temp|a;
  tt=temp*0.0625;
  temp=tt*10+0.5;
  return temp;
}

void readrom()          //read the serial    讀取溫度傳感器的序列號子函數
{
  uchar sn1,sn2;
  dsreset();
  delay(1);
  tmpwritebyte(0x33);
  sn1=tmpread();
  sn2=tmpread();
}


void delay10ms()            //delay           延時10MS子函數
  {
    uchar a,b;
    for(a=10;a>0;a--)
      for(b=60;b>0;b--);
   }
void display(uint tem)           //display       顯示子函數
  {
     uchar j,A1,A2,A2t,A3;
     A1=table[tem/100];
     A2t=tem%100;
     A2=table1[A2t/10];
     A3=table[A2t%10];
   //  for(j=50;j>0;j--)
   //  {
       P0=A1;
       P2_0=0;
       P2_1=1;
       P2_2=1;
       delay10ms();
       P0=A2;
       P2_1=0;
       P2_0=1;
       P2_2=1;
       delay10ms();
       P0=A3;
       P2_2=0;
       P2_0=1;
       P2_1=1;

 //     }
   }


void main()                                 //主函數
{
  do
  {
    tmpchange();                           //溫度轉換，
   // delay(200);
    display(tmp());                        //顯示溫度值
  }                while(1);
}