[SOLVED] DS18B20 convert confuse

[sherryliu]

#include<reg52.h>
#include <intrins.h>
#define uchar unsigned char
#define uint unsigned int
sbit DATA = P1^1;
uchar code table[]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f,0x77,0x7c,0x39,0x5e,0x79,0x71};
int temp;
int ss;
int dd;
int j;
uchar data b;
uchar data buf[4];
int alarmH=320;
int alarmL=100;

sbit k1=P2^5;
sbit k2=P2^6;
sbit k3=P2^7;
sbit k4=P2^4;
sbit bell=P1^0;
sbit HLight=P1^2;
sbit LLight=P1^3;
sbit warn=P1^4;
sbit Red=P1^6;
sbit Green=P1^7;
bit set=0;
bit Flag=0;
int n;

void key_to1();
void key_to2();
void delay(uint);
void key();
void Show();

void delay(uint num)
{
while(num--) ;
}


Init_DS18B20(void)
{
uchar x=0;
DATA = 1;
delay(10);
DATA = 0;
delay(80);
DATA = 1;
delay(20);
x=DATA;
delay(30);
}
ReadOneChar(void)
{
uchar i=0;
uchar dat = 0;
for (i=8;i>0;i--)
{
DATA = 0;
dat>>=1;
DATA = 1;
if(DATA)
dat|=0x80;
delay(8);
}
return(dat);
}
WriteOneChar(unsigned char dat)
{
uchar i=0;
for (i=8; i>0; i--)
{
DATA = 0;
DATA = dat&0x01;
delay(10);
DATA = 1;
dat>>=1;
}
delay(8);
}
int ReadTemperature(void)
{
uchar a=0;
uchar b=0;
int t=0;
float tt=0;
Init_DS18B20();
WriteOneChar(0xCC);
WriteOneChar(0x44);
Init_DS18B20();
WriteOneChar(0xCC);
WriteOneChar(0xBE);
a=ReadOneChar();
b=ReadOneChar();
t=b;
t<<=8;
t=t|a;
tt=t*0.0625;
t= tt*10+0.5;
return(t);
}
void display00()
{
dd=-(temp-1);
buf[1]=dd/100;
buf[2]=dd/100;
buf[3]=dd%100/10;
buf[0]=dd%10;

for(j=0;j<5;j++)
{
P2=0xff;
P0=0x00;
P2=0xfd;
P0=0x80;
delay(100);
P2=0xff;
P0=0x00;
P2=0xf7;
P0=0x40;
delay(100);
P2=0xff;
P0=0x00;
P2=0xfb;
P0=table[buf[2]];
delay(100);
P2=0xff;
P0=0x00;
P2=0Xfd;
P0=table[buf[3]];
delay(100);
P2=0xff;
P0=0x00;
P2=0Xfe;
P0=table[buf[0]];
delay(100);
P2=0xff;
}
}

void display()
{
buf[1]=temp/1000;
buf[2]=temp/100%10;
buf[3]=temp%100/10;
buf[0]=temp%10;
for(j=0;j<3;j++)
{
P2=0xff;
P0=0x00;
P2=0xfd;
P0=0x80;
delay(300);
P2=0xff;
P0=0x00;
P2=0xf7;
P0=table[buf[1]];
delay(300);
P2=0xff;
P0=0x00;
P2=0xfb;
P0=table[buf[2]];
delay(300);
P2=0xff;
P0=0x00;
P2=0Xfd;
P0=table[buf[3]];
delay(300);
P2=0xff;
P0=0x00;
P2=0Xfe;
P0=table[buf[0]];
delay(300);
P2=0xff;
}
}
void key()
{ if(k1!=1)
{
delay(20);
if(k1!=1)
{
while(k1!=1)
{ key_to1();
for(n=0;n<8;n++)
Show();
}
}
}
if(k2!=1)
{
delay(20);
if(k2!=1)
{
while(k2!=1)
{ key_to2();
for(n=0;n<8;n++)
Show();
}

}
}
if(k3!=1)
{ TR0=1;
temp=ReadTemperature();
}
if(k4!=1)
{ delay(20);
if(k4!=1)
{
while(k4!=1);
set=!set;
if(set==0)
{
Red=0;Green=1;
}
else
{
Green=0;Red=1;
}
}
}
}
void key_to1()
{
TR0=0;
temp+=10;
if(temp>=1100)
{temp=-550;}
if(set==0)
{alarmH=temp;}
else {alarmL=temp;}
}
void key_to2()
{
TR0=0;

temp-=10;
if(temp<=-550)
{temp=1100;}
if(set==0)
{ alarmH=temp;}
else { alarmL=temp;}
}

void alarm(void)
{
if(temp>alarmH||temp<alarmL)
{ //bell=1;
//delay(50);
//bell=0;
Flag=1;
}else {Flag=0;}
}

logo()
{ P0=0x40;

P2=0xf7;
delay(50);
P2=0xfb;
delay(50);
P2=0Xfd;
delay(50);
P2=0Xfe;
delay(50);
P1 = 0xff;
}

void Show()
{ if(temp>=0)
{HLight=1;LLight=0;display();}
if(temp<0)
{HLight=0;LLight=1;display00();}
}
void main()
{
TCON=0x01;
TMOD=0X01;
TH0=0XD8;
TL0=0XF0;
EA=1;
ET0=1;
TR0=1;
EX0=1;

for(n=0;n<500;n++)
{bell=1;warn=1;logo();}
Red=0;
while(1)
{
key();
ss=ReadTemperature();
Show();
alarm();
if(Flag==1)
{bell=!bell;
warn=!warn;}
else {bell=1;
warn=1;}
}
}
void time0(void) interrupt 1 using 1
{ TH0=0X56;
TL0=0XDC;
temp=ss;
}




Hi guys,could you help me explain this mean?Suppose ,measuring 85.C,first a=50,b=05,t=0550,then tt=550*0.0625=34.375 or tt=550H*0.0625=1360*0.0625=85,finally t=tt*10+0.5=34.375*10+0.5=344.25 or t=tt*10+0.5=85*10+0.5=850.5,Thanks!!!

 

[jayanth.devarayanadurga]

The output od DS18B20 is 2 bytes

a = 0x50, b = 0x05, t = 0x0550

t = b << 8 puts the b in high byte of t

t = t | a adds a to low byte.

a and b contains the low and high bytes

If a = 0x02 and b = 0x03 then

t = 0x0302

tt = 0x0302 * 0.0625 = 48.125

t = tt * 10 + 0.5 = 481.25 + 0.5 = 481.75

 

[sherryliu]

Hi jayanth,i know what you are said,because t is int,from -32768to 32767,tt is float that tt=0x0550*0.0625=85.0000,finally t=tt*10+0.5=85*10+0.5=850.5.how to convert from float to int? Thanks for your reply.

 

[jayanth.devarayanadurga]

If you assign float value to int it will be saved as int. Eg: if you assign float 320.46 to int then it becomes 320.