C51 DS18B20 read ROM CRC

[sherryliu]

#include <reg51.h>
#include "intrins.h"


unsigned char code tab[]={0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90};

sbit DQ=P3^3;
unsigned char tempL=0;
unsigned char tempH=0;
unsigned char temp2=0;
unsigned char temp3=0;
unsigned char temp4=0;
unsigned char temp5=0;
unsigned char temp6=0;
unsigned char temp7=0;
unsigned char temp8=0;

float temperature;



void delay(unsigned int k)
{
unsigned int n=0;
while(n< k)
{
n++;
}
return;
}


void delay1(void)
{
int k;
for(k=0;k<400;k++);
}



void display(int k)
{
P2=0xfe;
P0=tab[k/1000];
delay1();

P2=0xfd;
P0=tab[k%1000/100];
delay1();

P2=0xfb;
P0=tab[k%100/10];
delay1();

P2=0xf7;
P0=tab[k%10];
delay1();

P2=0xff;
}



Init_DS18B20(void)
{
unsigned char x=0;
DQ=1;
delay(15);

DQ=0;
delay(70);


DQ=1;
delay(15);


}


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);
}



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);
}



ReadTemperature(void)
{

Init_DS18B20();
WriteOneChar(0xcc);
WriteOneChar(0x33);

// Init_DS18B20();
// WriteOneChar(0xcc);
// WriteOneChar(0x44);
// delay(125);
// Init_DS18B20();
// WriteOneChar(0xcc);
// WriteOneChar(0xbe);
tempL=ReadOneChar();
tempH=ReadOneChar();
temp2=ReadOneChar();
temp3=ReadOneChar();
temp4=ReadOneChar();
temp5=ReadOneChar(); )
temp6=ReadOneChar();
temp7=ReadOneChar();
temp8=ReadOneChar();
// temperature=((tempH*256)+tempL)*0.0625;
// delay(200);
// return(temperature);
}



void main()
{
float i;
while(1)
{
i=ReadTemperature();
display(i);
}
}





Hi Everyone
Could you tell me how to set read ROM CRC&set Hi and Li limited? I simulated Read "temp8" value is "FF" in Keilc. Suppose I want add 8 and more DS18B20 in program,what will to change,