ds1820 and pull up resistor

[deniah]

Hi

I have question about pulll up resistors and ds1820 sensor.
If cable length between microrontroller and ds1820 is 1-2 meter,
where pull up resistor must be placed,
near microcontroller or near ds1820?

Thanks

 

[zeyad.kassaby]

Hi

I have question about pulll up resistors and ds1820 sensor.
If cable length between microrontroller and ds1820 is 1-2 meter,
where pull up resistor must be placed,
near microcontroller or near ds1820?

Thanks

Pull up resistor will by put near the microcontroller
for practical world try 120 ohm or matching the ip of any digital CMOS circuit
Best REgards
ziad :wink:

 

[betwixt]

At the micro end but I would use ~1K. If you use a lower value the dissipation in the sensor increases and it starts to heat itself up. Obviously this makes it read higher temperatures than it should.

If you are using normal power and ground connections, also place a 100nF capacitor across them at the sensor end if you can, especially over 2m or longer.

Brian.