单片机memoirs 15 DS18B20 On May 6,2013

温度采集：
c:DS18B20.zip
#include
#include
#define uchar unsigned char
#define uint unsigned
sbit rs=P2^4;
sbit rw=P2^5;
sbit e=P2^6;
sbit dq=P2^3;
uchar zm1[]="  temperature:   ";
uchar zm2[]="      00.0 c     ";
uchar zm3[]="   NO DS18B20    ";
uchar i,lsb,msb,result,flag,sign,point,x;  //p小数 s正负号,flag器件存在标志，i循环变量
void delay(int t)
    { while(t--);}
void DS18_delay(int useconds)//延时函数
 {
 int s;
 for (s=0; s }
void write_com(unsigned char com)
{  e=0;
  rs=0;
  rw=0;
  P0=com;  
  delay(50);    
  e=1;
  delay(50);
  e=0;
  delay(50);        }
void write_data(unsigned char dat)
{  e=0;
  rs=1;
  rw=0;
  P0=dat;
  delay(50);
  e=1;
  delay(50);
  e=0;   
  delay(50);       }
void start()
{  delay(200);
  write_com(0x38);
  delay(200);
  write_com(0x38);
  delay(200);
  write_com(0x38);
  write_com(0x38);
  write_com(0x08);
  write_com(0x01);
  write_com(0x06);
  write_com(0x0c); }
void lcd(char *p)
{  int j;
  write_com(0x80);
  for(j=0;j<18;j++)
  { write_data(zm1[j]); }
  write_com(0x80+0x40);
  for(j=0;j<18;j++)
  { write_data(p[j]);   }  }
uint reset()  
{      dq=0;  //复位程序
   DS18_delay(29); 
        dq=1;
   DS18_delay(3); 
flag=dq;
DS18_delay(25); 
return(flag);
} 
uchar read() //读操作低位在前
{  uchar dat=0;
   for(i=0;i<8;i++)
       { dq=1;  
DS18_delay(1);    
     dq=0;
dat>>=1;
dq=1;
   if(dq)
dat|=0x80;
DS18_delay(4);
}
  return(dat);
}  
void write(uchar dat)  //写低位在前
{ for(i=0;i<8;i++) 
{  dq=0;
  dq=dat&0x01; // 充当1us_nop_();
  DS18_delay(5);
  dq=1;
  dat>>=1;   
}
DS18_delay(4);
}
void disp(uchar lsb,uchar msb)
{   sign=(msb>>3)&0x01;  //取符号
lsb>>=4;
    msb<<=4;
result=lsb|msb;
point=(int)((float)(((~(lsb-=1))&0x0f)*0.625));
    if(sign==1)
{ result-=1;
 result=~result;
 result=result&0x7f; }
if(result>=0x64)
{zm2[5]=result/100+0x30;}  else zm2[5]=' ';
if(result>=0x0a)
{zm2[6]=(result/10)%10+0x30;} else zm2[6]=' ';
zm2[7]=result%10+0x30;
zm2[9]=point%10+0x30;
if(sign) zm2[4]='-';  else zm2[4]=' ';
lcd(zm2);  
} 
void main()
{   start();
lcd(zm2);
while(1)
 { flag=reset();
   if(!flag)
 { write(0xcc);    
write(0x44);
DS18_delay(125);
reset();
write(0xcc);
write(0xbe);
disp(lsb=read(),msb=read());
/* DS18_delay(29); //525.18
DS18_delay(3); //72.70
DS18_delay(25);    //454.64
DS18_delay(1); //37.98
DS18_delay(4); //90.06
DS18_delay(5);   //116.8 */
 }
else lcd(zm3);  
    }  
}