how to make digital thermometer using 1820 sensor

[harishwww]

hi
i want to make digital thermometer using ds1820 sensor and 8051 micro i just need circuit diagram pls help me

 

[betwixt]

Circuit diagram ???? It only has three pins!

One to ground, one to +5 and one to any digital I/O pin on the 8051.

Brian.

 

[Tahmid]

Hi,
Brian, you forgot to mention that the output of the DS18B20 that connects to the 8051 IO pin has to be pulled up. You could use a 4.7k resistor for pull-up. This isn't exactly with 8051, but you can easily get the idea from this circuit:
**broken link removed**

Hope this helps.
Tahmid.

 

[mishra12]

i hope this will work

yes sensor out put needs pull up cheers

 

[ckshivaram]

10K pull up is always fine.

 

[harishwww]

Init_DS18B20(void)
{
unsigned char x=0;
DQ = 1;
delay (8);
DQ = 0;
delay (80);
DQ = 1;
delay(14);
x=DQ;

delay(20);
}

ReadTemperature(void)
{
unsigned char a=0;
unsigned char b=0;
unsigned char tt=0;
Init_DS18B20();
WriteOneChar(0xCC);
WriteOneChar(0x44);
Init_DS18B20();
WriteOneChar(0xCC);
WriteOneChar(0xBE);
a=ReadOneChar();
b=ReadOneChar();
a=a>>4;
tt=b<<4;
tt=tt|a;
return(tt);
}

void display_tempmain(unsigned char i)
{
……
}
void main(void)
{unsigned char temp;
led_run=0;
while(1)
{ temp=ReadTemperature();
display_tempmain(temp);

}
}

help me on writing this code is this correct

 

[mishra12]

where is the include ......?
sbit ....?

 

[betwixt]

More importantly....where is WriteOneChar() ?
What does 'x' do? (I know, but does the original poster?)

Sorry about forgetting the pull-up resistor!

Brian.