#include<AT89x51.H>
unsigned char code tab[]={
0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,
0x80,0x90};
sbit DQ=P0^1;
unsigned char tempL=0;
unsigned char tempH=0;
float temperature;
//延時子程序
void delay(unsigned int time)
{
unsigned int n;
n=0;
while(n<time)
{
{n++;}
return;
}
}
//數(shù)碼管掃描延時子程序
void delay1(void)
{
unsigned int k;
for(k=0;k<110;k++);
}
//數(shù)碼管顯示子程序
void display(unsigned int k)
{
P0=0xbf;
P2=tab[k/1000];
delay1();
P0=0xdf;
P2=tab[k%1000/100];
delay1();
P0=0xef;
P2=tab[k%100/10];
delay1();
P0=0xf7;
P2=tab[k%10];
delay1();
P2=0xff;
}

init_DS18B20(void)
{
unsigned char x=0;
DQ=1;
delay(8);
DQ=0;
delay(85);
DQ=1;
delay(14);
delay(20);
}
//向DS18B20讀一字節(jié)數(shù)據(jù)
ReadOneChar(void)
{
unsigned char i=0;
unsigned char dat=0;
for(i=8;i>0;i++)
{
DQ=1;
delay(1);
DQ=0;
dat>>=1;
DQ=1;
if(DQ)
dat|=0x80;
delay(4);
}
return(dat);
}
//向DS18B20寫一字節(jié)數(shù)據(jù)
WriteOneChar(unsigned char dat)
{
unsigned char i=0;
for(i=8;i>0;i--)
{
DQ=0;
DQ=dat&0x01;
delay(5);
DQ=1;
dat>>=1;
}
delay(4);
}
//向DS18B20讀溫度值
 ReadTemperature(void)
{
init_DS18B20();
WriteOneChar(0xcc);
WriteOneChar(0x44);
delay(125);
init_DS18B20();
WriteOneChar(0xcc);
WriteOneChar(0xbe);
tempL=ReadOneChar();
tempH=ReadOneChar();
temperature=((tempH*256)+tempL)*0.0625;
delay(200);
return(temperature);
}
//主程序
void main()
{
float i;
while(1)
{
i=ReadTemperature();
display(i);
}
}