DS18b20 attached and device result requently vary regularly

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riker1
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DS18b20 attached and device result requently vary regularly

#1 Post by riker1 » 13 Jul 2018, 09:34

Hi
haveing DS18b20 attached and device result requently vary

I experienced that once or twice a day the results vary

temp shows increased values but temp is not changing.

messure the fridge so temp is quite constanct.

Thanks for hints.

using firmware mega-20180507
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TD-er
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Re: DS18b20 attached and device result requently vary regularly

#2 Post by TD-er » 14 Jul 2018, 08:13

Looks like a single measurement error on a regular interval.
Is it possible some disturbance is picked up on the wire connected to the sensor?
For example an electro motor switching on or off?
You may want to look at terminating the cable using resistors.

riker1
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Re: DS18b20 attached and device result requently vary regularly

#3 Post by riker1 » 14 Jul 2018, 14:17

thanks
ok, could be the motor of the fridge, but this starts more often.

I have a resistors attached.

Maybe I need a stronger one?

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grovkillen
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Re: DS18b20 attached and device result requently vary regularly

#4 Post by grovkillen » 14 Jul 2018, 14:28

The temp is maybe a defrost function once a day or something?
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Shardan
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Re: DS18b20 attached and device result requently vary regularly

#5 Post by Shardan » 16 Jul 2018, 20:34

Try to add a capacitor of about 22...47µf to +3.3V and Gnd as near to the DS18B20 as possible.
Regards
Shardan

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