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ADS1262EVM-PDK: ADS1262EVM, LabView Auto Calibration Based on Temperature

joeqsmith
Prodigy 30 points

Part Number: ADS1262EVM-PDK

Hello,

I am in the process of evaluating the ADS1262EVM-PDK.   I changed the supplied LabView code to allow streaming the data for longer data collections.   The LabView functions make calls to some lower level code which TI does not appear to provide the source for.   I started running a controlled temperature stability test, holding the temperature constant while monitoring the evaluation board.   What I am seeing is steps in values that are reported.  

If I had to guess, it appears that the underlying code that I don't seem to have the source for, may monitor the IC's temperature and run some sort of calibration if the temperature changes by some amount. 

Is it possible that this question could be passed onto the group that developed the lower level code and see if they could confirm what I am seeing.   It's not a problem if this is what is happening.  I just want to understand why it is behaving this way.    

Thanks.

  • 0
    TI__Mastermind 44640 points

    Hi joeqsmith,

    Welcome to the TI E2E Forums!

    Unfortunately, the ADS1262EVM-PDK low-level firmware was written by a third-party so I don't know exactly what is happening under the hood. I don't believe the firmware is calibrating or intentionally modifying the data in any way. If it was, then the EVM would not be able to provide a reliable means of evaluating the true device performance.

    What temperatures are you using to test the EVM and motherboard? I know that some of the components on the motherboard in particular do have limited operating temperature ranges, so if you are operating at hot or cold temperature extremes you may run into issues.Within 0-60 C is probably okay. Do you see the data jumps happen at room temperature as well? Any data that you can share would be helpful.

    Another thing that could be happening, if you modified some of the lower level LabVIEW code that affects how data is transferred, you may start to get corrupted data due to data misalignment. To see if this is the case, you could try replacing the modified code that performs the data collection with the original collect VI to see if the jumps go away.

  • 0 in reply to Christopher Hall
    Prodigy 30 points

    Thank you for the response. 

    Normally, I suspect users would collect data using ADCPro for short runs.  The shifts are not instant and I suspect this is because it takes some time for the ADC's temperature to change.   I'm talking hours. 

    The first time I noticed the shift is when I had covered the board with a towel.   While controlling the temperature,  I saw the shift going from room temp to 30C and then when I brought it back down to 22C.  

    The shifts are in the order of 10 to 20uV, out of a 1V signal.   Once it settles, the temperature needs to change a fair amount before I will see it step again. 

    I am continuing to run the board at 22C to see if it ever shifts with a constant temperature.   If it remains stable for 24 hours,  the my next step will be to read all the registers on every collection and check to see if they have changed.    I will let you know what I find out.   It's really odd and I don't see anything in the datasheet that would lead me to believe it's the ADC.  

  • 0 in reply to joeqsmith
    Prodigy 30 points

    I am very happy to say this was completely a problem with how I structured my software and nothing to do with the lower level code supplied by TI.   Thank you for your support.

  • 0 in reply to joeqsmith
    TI__Mastermind 44640 points

    Hi joeqsmith,

    I'm glad to hear that you resolved the issue! Thanks for letting us know.