#include<reg51.h>
#define Disdata  P0
#define  weima  P1
sbit dq=P3^4;
unsigned flag;
unsigned char code table[]={0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90,0xff,0xbf};
void delay(unsigned int useconds)
{unsigned int s;
for(s=0;s<useconds;s++);
}
/********復位函數*********/
unsigned char ow_reset(void)
{unsigned char presence;
dq=0;
delay(73);
dq=1;
delay(12);
presence=dq;
delay(70);
return(presence);
}
/********寫1位值*********/
void write_bit(unsigned char bitval)
{dq=0;
if(bitval==1)
dq=1;
delay(15);
dq=1;
}
/********寫入字節函數*********/
void write_byte(unsigned char val)
{unsigned char i;
unsigned char temp;
for(i=0;i<8;i++)
{temp=val>>i;
temp&=0x01;
write_bit(temp);
}
delay(25);
}
/********位讀取函數*********/
unsigned char read_bit(void)
{unsigned char i;
dq=0;
dq=1;
for(i=0;i<10;i++);
return(dq);
}
/********字節讀取函數*********/
unsigned char read_byte(void)
{unsigned char i;
unsigned char value=0;
for(i=0;i<8;i++)
{if (read_bit())
value|=0x01<<i;
delay(120);
}
return(value);

}
/********讀暫存器*********/
void read_scratchpad(void)
{unsigned char j=0,pad[10];
write_byte(0xBE);
for(j=0;j<9;j++)
pad[j]=read_byte();
}

/********讀取溫度函數*********/
float read_temperature(void)
{unsigned char get[10];
unsigned char temp_lsb,temp_msb;
unsigned char k;
float t;
ow_reset();
write_byte(0xCC);
write_byte(0x44);
delay(60);
ow_reset();
write_byte(0xCC);
write_byte(0xBE);
for(k=0;k<9;k++)
get[k]=read_byte();
temp_msb=get[1];
temp_lsb=get[0];
if(temp_msb>=0x08)
{temp_lsb=(~temp_lsb)+1;
temp_msb&=0x07;
temp_msb=(~temp_msb)+1;
t=(-1)*(temp_msb*16+temp_lsb*0.0625);
}
else
{t=temp_msb*16+temp_lsb*0.0625;
}
return t;
}