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HDC1010: Any condition for humidity returning 0?

Lukasz Przenioslo
Expert 2630 points
Part Number: HDC1010
Other Parts Discussed in Thread: HDC2010

Hello there,

I have the following problem. I have some devices placed "in the field". This is only a prototype and I have no way of physically debugging them for a while. Each device has a HDC1010 to measure temperature and humidity. In the end those 2 variables are sent to the online server. The problem is I can see only the last measurements for now, which makes the debugging even harder.

The issue: one of the devices keeps returning humidity equal to 0 for a while now. Its temperature is changing normally. It was raining not so long time a go I believe, since the other sensors all show humidity 100 %. My question is:

Is there any faulty condition for the HDC1010 device, when it will return humidity register equal to 0, or will not return anything through I2C at all?

I believe the device is not broken, since it keeps returning proper temperature values. I would appreciate all help in this matter.

  • 0
    TI__Genius 11750 points
    Howdy Lukasz,

    The HDC1010 humidity and temperature sensor has an exposed sensor on the bottom on the device. In the case that this sensor is exposed to contaminants in the form or particles or vapors, this will affect sensor performance and may create the issue you are noticing.

    There are a few documents that display correct storage and handling and design guidelines, which I've included below:

    Humidity Sensor: Storage and Handling Guidelines: www.ti.com/.../snia025
    Optimizing Placement and Routing for Humidity Sensors (Rev. A): www.ti.com/.../snaa297

    As an experiment, can you turn on the internal heater to the device for a few minutes and verify the results?

    If you are currently in the prototype phase I would encourage you to visit the HDC2010 product page, as it is a lower power sensor, with smaller form factor.

    Best Regards,
    Matt
  • 0 in reply to Matthew Sauceda
    Expert 2630 points

    Hello, thank you for answer.

    I am familiar with placement and routing.

    I would also like to turn on HEAT, but unfortunately this system is not accessible by me. Its remote and the data received are through the server. I have noticed the following scenario: the humidity was 0 %, then it shifted to around 90% and started to lower to the level of other sensors. It seems like for some reason the humidity was 0% instead of 100%, can this happen? I have noticed the integrated humidity offset comparing to other sensors. After the time since posting my question, the problematic sensor is still shifter a bit. Its humidity its 56%, while others are around 40-45%.

    Would using HEAT here solve the problem? But that would also cause false temperature readings, am I correct?

    About the HDC2010: The HDC1010 is already to small for us. I would love it to be larger and easier to solder. Space is not a constraint in this application.

  • 0 in reply to Lukasz Przenioslo
    TI__Genius 11750 points
    Hi Lukasz,

    When the HDC devices are exposed to condensation the value of the RH output drops to zero (0), this alerts the user to turn on the heater to remove the condensation that affects the reading. The purpose of the heater is to prevent and remove condensation from the device. The newer grade of devices have a heater with larger current draw that allows for brief rapid heating to drive off any condensation on the devices. The HDC2010 device has a typical heater current of 90mA, which helps address this condensation alert.

    This mechanism will be thoroughly explained in future documentation.

    Please let me know if this answers your question.

    Best Regards,
    Matt
  • 0 in reply to Matthew Sauceda
    Expert 2630 points

    At the moment we will try to use the HDC1010 heating functionality before moving further to HDC2010. But are you suggesting that the ~7 mA heating capability of HDC1010 is not enough anyways?

    Thanks you for the information about 0 humidity. This helped me understanding whats going on. So would you say that this algorithm is correct?

    1. Humidity becomes 0
    2. Turn on heater
    3. Increase temp/ humidity reading frequency to once per second in order to heat more often.
    4. Turn off the heater after the humidity drops to bellow 90 %?
  • 0 in reply to Lukasz Przenioslo
    TI__Genius 11750 points

    Howdy Lukasz,

    The HDC sensors work best in non-condensing environments, but in the case of condensation the procedure you've mentioned above should work.  Additionally, you will need to wait for a small duration to ensure that the temperature equalizes to ambient conditions, before an accurate read is to be triggered. 

    Best Regards,

    Matt

  • 0 in reply to Matthew Sauceda
    Expert 2630 points

    Hello Matt,
    I have an additional question regarding this topic. Our HDC1010 sensor that is in the field for about 3 weeks now, is returning 0 humidity for couple days (temperature is ok). Does that mean that there is so much integrated moisture that cannot evaporate? Or should we consider this sensor is broken?

    Note that we did not use HEAT there yet.

  • 0 in reply to Lukasz Przenioslo
    TI__Genius 11750 points

    Hi Lukasz,

    This may be the case, are you able to visually verify this, or turn on the heater to verify changes in RH output?

    Best Regards,

    Matt

  • 0 in reply to Matthew Sauceda
    Expert 2630 points

    Thanks for answer,

    unfortunately no and no. But the humidity is back to normal now. The thing is it kept with 0 for couple days, while some other sensors (pretty much next to it) went on normally. How is this possible? Did the offset integrate so much?