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TIDC-CC2650STK-SENSORTAG: Sensortag temperatures and humidities wildly inaccurate - do the sensors degrade?

JEREMY JOHNSON
Prodigy 20 points
Part Number: TIDC-CC2650STK-SENSORTAG
Other Parts Discussed in Thread: CC2650, CC2650STK, TMP007, HDC1000

Hi!  Apologies if this is a repeat,, but I couldn;t find the same problem in any other thread...

I have a stack of sensortag-2 devices I bought back in 2015, and an urgent requirement to monitor temperature and humidity on an experiment that needs to be run next week.  The sensortag devices would be ideal for this.  I dug them out and replaced the batteries, and made sure the TI sensortag app was on my phone, and was delighted to find on searching for them with the app that they connected!


I was somewhat less delighted to find that the ambient temperature and humidity reported by all of the devices was wildly inaccurate - from -36 deg. C to +123 deg C, and RH from 0 to 90% (in the same 21 deg. RH 40% environment).   For reference, the values reported by light-meter, motion-sensor etc appear more-or-less reasonable, and behave the way one might expect (ie lux goes to zero if you hide the device under an upended mug etc)

I also tried one completely un-used device I found still in its box.  Exact same problem.

Has anyone any idea why the temperature and humidity sensors are behaving the way they are?  Or what I can do to fix it by next Monday?  Do the sensors degrade with time?  Do they require some kind of reset or recalibration?  If so, how is that achieved?

Thanks for any and all suggestions!

Jeremy Johnson

  • 0
    Prodigy 20 points

    Part number CC2650 SDK

    Hi!  Apologies if this is a repeat,, but I couldn;t find the same problem in any other thread...

    I have a stack of sensortag-2 devices I bought back in 2015, and an urgent requirement to monitor temperature and humidity on an experiment that needs to be run next week.  The sensortag devices would be ideal for this.  I dug them out and replaced the batteries, and made sure the TI sensortag app was on my phone, and was delighted to find on searching for them with the app that they connected!


    I was somewhat less delighted to find that the ambient temperature and humidity reported by all of the devices was wildly inaccurate - from -36 deg. C to +123 deg C, and RH from 0 to 90% (in the same 21 deg. RH 40% environment).   For reference, the values reported by light-meter, motion-sensor etc appear more-or-less reasonable, and behave the way one might expect (ie lux goes to zero if you hide the device under an upended mug etc)

    I also tried one completely un-used device I found still in its box.  Exact same problem.

    Has anyone any idea why the temperature and humidity sensors are behaving the way they are?  Or what I can do to fix it by next Monday?  Do the sensors degrade with time?  Do they require some kind of reset or recalibration?  If so, how is that achieved?

    Thanks for any and all suggestions!

    Jeremy Johnson

    (ps - apologies for the lack of part number, but if I put the right part number in I can ONLY post to the bluetooth forum, which isn;t the right place I feel)

  • 0 in reply to JEREMY JOHNSON
    TI__Genius 10580 points

    Jeremy,

    Keep in mind that the CC2650STK is a reference design and evaluation platform, so it's very possible that sensors "lost" calibration sitting on a shelf for several years. Also, the SensorTag reference platform supplies raw, uncalibrated sensor outputs to the IoT enabled BLE Client. This means that it is up to the system designer to implement the necessary calibration. You can refer to the datasheets for the individual sensors for more information. (HDC1000 is the humidity sensor, TMP007 is the Infrared thermopile sensor)

    Are you running the latest firmware on the SensorTag? This can be updated via the mobile app and may help fix issues.

    Regards,

    Daniel