#include

sbit DQ = P3^3;     //定义DS18B20端口DQ 

sbit BEEP=P3^7 ;

unsigned char presence ;

unsigned char code  LEDData[ ]   = {0xC0,0xF9,0xA4,0xB0,0x99,0x92,0x82,0xF8,

                                                          0x80,0x90,0xff};

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();

sbit DIN = P0^7;   //小数点

bit  flash=0;          //显示开关标记

/**********************************************************/

void Delay(unsigned int num)//延时函数

{

  while( --num );

}

/**********************************************************/

 Init_DS18B20(void)//初始化ds1820

{

     DQ = 1;      //DQ复位

     Delay(8);    //稍做延时

     DQ = 0;      //单片机将DQ拉低

     Delay(90);   //精确延时 大于 480us

     DQ = 1;       //拉高总线

     Delay(8);

     presence = DQ;    //如果=0则初始化成功 =1则初始化失败

     Delay(100);

     DQ = 1;

     return(presence); //返回信号，0=presence,1= no presence

}

/**********************************************************/

ReadOneChar(void)//读一个字节

{

unsigned char i = 0;

unsigned char dat = 0;

for (i = 8; i > 0; i--)

  {

    DQ = 0;                // 给脉冲信号

    dat >>= 1;

    DQ = 1;                // 给脉冲信号

    if(DQ)

     dat |= 0x80;

    Delay(4);

  }

    return (dat);

}

/**********************************************************/

WriteOneChar(unsigned char dat)//写一个字节

{

  unsigned char i = 0;

  for (i = 8; i > 0; i--)

  {

    DQ = 0;

    DQ = dat&0x01;

    Delay(5);

    DQ = 1;

    dat>>=1;

  }

}

/*********************************************************/

Read_Temperature(void)//读取温度

{

  Init_DS18B20();

  if(presence==1)       

   { beep();flash=1;}      //DS18B20不正常，蜂鸣器报警

   else

   {

     flash=0;

     WriteOneChar(0xCC);  // 跳过读序号列号的操作

     WriteOneChar(0x44);  // 启动温度转换

     Init_DS18B20();

     WriteOneChar(0xCC);  //跳过读序号列号的操作

     WriteOneChar(0xBE);  //读取温度寄存器

     temp_data[0] = ReadOneChar();   //温度低8位

     temp_data[1] = ReadOneChar();   //温度高8位

   }

}

/*********************************************************/

Disp_Temperature()//显示温度

{

  unsigned char  n=0;

  display[4]=temp_data[0]&0x0f;

  display[0]=ditab[display[4]];     //查表得小数位的值

  display[4]=((temp_data[0]&0xf0)>>4)|((temp_data[1]&0x0f)<<4);

  display[3]=display[4]/100;

  display[1]=display[4]%100;

  display[2]=display[1]/10;

  display[1]=display[1]%10;

  if(!display[3])                       //高位为0，不显示

  {

    display[3]=0x0a;           

    if(!display[2])                    //次高位为0，不显示

     display[2]=0x0a;

  }

P0 = 0xc6;    //显示 C

P2 = 0x7f;

Delay(300);

P0 = 0x9c;    //显示 ° 

P2 = 0xbf;

Delay(300);

P0 =LEDData[display[0]] ;  //显示小数位

P2 = 0xdf;

Delay(300);

P0 =LEDData[display[1]];  //显示个位

DIN = 0;

P2 = 0xef;

Delay(300);

P0 =LEDData[display[2]];  //显示十位

P2 = 0xf7;

Delay(300);

P0 =LEDData[display[3]];  //显示十位

P2 = 0xfb;

Delay(300);

P2 = 0xff;                          //关闭显示

}

/*********************************************************/

void beep()

  {

    unsigned char i;

    for (i=0;i<100;i++)

    {

      Delay(60);

      BEEP=!BEEP;                 //BEEP取反

    }

    BEEP=1;                          //关闭蜂鸣器

  }

/*********************************************************/

void main(void)

{

  while(1)

  {

    Read_Temperature();

 if(flash==0)             

 {Disp_Temperature();}

 else P2 = 0xff ;           //DS18B20不正常，关闭显示

  }

}