1-WIRE Temp sensor unstable reading

  • Hi All,

    I'm wondering why I have erratic changes in temperature readings. The readings can jump anywhere from 0.3 to 0.8 of a degree at a time within a second, then back again. I would assume a 1-wire sensor with a metal casing would be a stable thermal mass.

    What could cause them to be so unstable? I have the driver set to 200ms execution. Another thing to note is the unstable sensors are around 0-3°C, the stable ones are around 18-20°C



  • Hi Mike,
    never heard of such a problem. Please provide more information, namely:

    • What hardware are you using as the 1-Wire master? Monarco HAT?
    • How many sensors in total are you using?
    • How long is the wiring?
    • Can you try swapping the temperature probes?
    • Does the problem persist if you use fewer sensors? E.g. removing the stable ones temporarily.
    • How often does this happen?
    • Do you have a time plot showing the reported problem?
    • Any errors in the System log?

    Kind regards,

  • Hi Jaroslav,

    I only had 4 sensors, and I am using the Monarco hat. The sensor cables are all 1.5m long is a star formation.

    I have ordered more as I think I had a bad batch. I have issues with the same sensors not working after a power loss.

    I will let you know more once I have tried the new sensors.



  • An update to the above. I'm now very sure I had a bad batch of sensors, it turns out I'm not alone. Over people have seen the same thing having bought sensors from certain websites.

    Be careful when buying 1-Wire sensors as it seems there are cheaper, not so reliable ones flooding the market.



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