用DS18B20构成测温系统

#include AT89X52.H>

#include INTRINS.h>

unsigned char code displaybit[]={0xfe,0xfd,0xfb,0xf7,

0xef,0xdf,0xbf,0x7f};

unsigned char code displaycode[]={0x3f,0x06,0x5b,0x4f,

0x66,0x6d,0x7d,0x07,

0x7f,0x6f,0x77,0x7c,

0x39,0x5e,0x79,0x71,0x00,0x40};

unsigned char code dotcode[32]={0,3,6,9,12,16,19,22,

25,28,31,34,38,41,44,48,

50,53,56,59,63,66,69,72,

75,78,81,84,88,91,94,97};

unsigned char displaycount;

unsigned char displaybuf[8]={16,16,16,16,16,16,16,16};

unsigned char timecount;

unsigned char readdata[8];

sbit DQ=P3^7;

bit sflag;

bit resetpulse(void)

{

unsigned char i;

DQ=0;

for(i=255;i>0;i--);

DQ=1;

for(i=60;i>0;i--);

return(DQ);

for(i=200;i>0;i--);

}

void writecommandtods18b20(unsigned char command)

{

unsigned char i;

unsigned char j;

for(i=0;i8;i++)

{

if((command 0x01)==0)

{

DQ=0;

for(j=35;j>0;j--);

DQ=1;

}

else

{

DQ=0;

for(j=2;j>0;j--);

DQ=1;

for(j=33;j>0;j--);

}

command=_cror_(command,1);

}

}

unsigned char readdatafromds18b20(void)

{

unsigned char i;

unsigned char j;

unsigned char temp;

temp=0;

for(i=0;i8;i++)

{

temp=_cror_(temp,1);

DQ=0;

_nop_();

_nop_();

DQ=1;

for(j=10;j>0;j--);

if(DQ==1)

{

temp=temp | 0x80;

}

else

{

temp=temp | 0x00;

}

for(j=200;j>0;j--);

}

return(temp);

}