我用51
单片机读18B20的温度，读不出来，程序是这样的
#include
#include
#define unchar unsigned char
#define unint unsigned int
***it tda=P1^4;
unchar i,t;
unint tt;
void delay(unchar z)
{
uncharx,y;
for(x=0;x
for(y=0;y<110;y++);
}
void reset()
{
tda=1;
i++;
tda=0;
i=103;
while(i>0)
i--;
tda=1;
i=4;
while(i>0)
i--;
}
void write(unchar date)
{
unchartemp;
for(t=0;t<8;t++)
{
temp=date&0x01;
date=date>>1;
if(temp==1)
{
tda=0;
i++;
i++;
tda=1;
i=8;
while(i>0)
i--;
}
else
{
tda=0;
i=8;
while(i>0)
i--;
tda=1;
i++;
i++;
}
tda=1;
}
}
bit read_bit()
{
bitdat;
tda=0;
i++;
tda=1;
i++;
i++;
dat=tda;
i=8;
while(i>0)
i--;
return(dat);
}
unchar read()
{
unchardat,j,z;
dat=0;
for(z=1;z<=8;z++)
{
j=read_bit();
dat=(j<<7)|(dat>>1);
}
return(dat);
}
void start()
{
reset();
delay(1);
write(0xcc);
write(0x44);
}
unint get()
{
unchara,b;
uninttemp;
temp=0x00;
reset();
delay(1);
write(0xcc);
write(0xbe);
a=read();
b=read();
temp=b;
temp=temp<<8;
temp=temp|a;
temp=temp*0.0625+0.5;
return(temp);
}
main()
{
while(1)
{
start();
delay(5);
tt=get();
if(tt>0&&tt<=25)
P2=0x01;
if(tt>25&&tt<=30)
P2=0x02;
if(tt>30&&tt<=35)
P2=0x04;
if(tt>35)
P2=0x0f;
if(tt==0)
P2=0x00;
}
}
