DS18B20温度传感器数据数码管显示程序

//接上18B20温度传感器（另购）数码管显示出当前温度
#include <reg52.h>
#define uchar unsigned char
#define uint unsigned int
sbit DS=P2^2;           //define interface 定义接口
uint temp;             // variable of temperature   温度变量
uchar flag1;            // sign of the result positive or negative  结果的正负号
sbit dula=P2^6; //声明一个特殊duan段变量，该位变量等价于P2寄存器的bit 6，即P2.6
sbit wela=P2^7; //               位
unsigned char code table[]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,
                        0x07,0x7f,0x6f,0x77,0x7c,0x39,0x5e,0x79,0x71};
unsigned char code table1[]={0xbf,0x86,0xdb,0xcf,0xe6,0xed,0xfd,
                        0x87,0xff,0xef};

void delay(uint count)      //delay 延迟任意时间 可定义
{
  uint i;
  while(count)
  {
    i=200;
    while(i>0)
    i--;
    count--;
  }
}

 /*------------------------------------------------------------------------------------------------------------------------------------------------
             复位和初始化
------------------------------------------------------------------------------------------------------------------------------------------------*/

void dsreset(void)       //send reset and initialization command 发送复位和初始化命令
{
  uint i;
  DS=0;               
  i=103;    //将总线拉低480us~960us  主机发出480-960us的低电平脉冲
  while(i>0)i--;
  DS=1;    //然后拉高总线（释放后变为高电平），若DS18B20做出反应会将在15us~60us后将总线拉低
  i=4;    //15us~60us等待   如果有低电平则说明总线上有器件做出了应答（复位成功），若一直为高电平则无应答 。
  while(i>0)i--;
  //while(DS);
}

/*------------------------------------------------------------------------------------------------------------------------------------------------
             读操作   主机把主线拉低1us后，若送出0则为低（0），若送出1则为高（1）
------------------------------------------------------------------------------------------------------------------------------------------------*/
bit tmpreadbit(void)       //read a bit
{
   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 1byte=8bit
{
  uchar i,j,dat;
  dat=0;