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ADS131M04EVM: About ADS131M04EVM test issue

Jimmy WANG
Genius 4065 points
Part Number: ADS131M04EVM
Other Parts Discussed in Thread: ADS1278

Hi team,

My customer tests the EVM board. found some problem.

The customer uses a HIOKI SS7012 to simulate a thermocouple signal. then signal to connect to  ADS131M04EVM.

RD setting K type temp setting as 325.4C

RD sees from the GUI that the ADC reading value fluctuates greatly. pic and setting as below. (OSR=1024)

2. Customer set OSR is 16384 then the result as below. (OSR setting 16384)

But the customer is still not satisfied with the results of this test. Due to they compare with  ADS1278. Same condition but ADS1278 reading value almost stable .

Customer spec is 0.1C. so they hope to scroll value count< 20.

RD print reading value is shown on the screen. you can see the reading rang is 326.3°C～326.6°C 

they hope the reading value very stable even after the decimal point. so can some solution can improve it?
  • 0
    TI__Mastermind 18900 points

    Hello Jimmy,

    There's nothing obviously wrong as far as I can tell, so we'll have to dig deeper. In addition, I don't have the conversion from codes (to voltage) to temperature so I do not have an accurate voltage or code specification we are trying to attain. This does not prevent me from fixing the problem but it does help me understand the issues and if the performance is unattainable.

    Assuming the clock source was switched using JP6 when switching from high power mode to low power mode, then I will assume the data is good. Especially in the first data set, the signal is periodic. Can they please provide the FFT and Histogram page for this input where the SS7012 provides 325.4C and OSR = 1024 with high resolution mode? I would like to see if we see a tone somewhere out higher in frequency. I'm not sure how the SS7012 provides the thermoelectric power, but I expect the signal to be a DC signal which would indicate some extrinsic noise might be in the system.

    Other than that, can they also go to the register map page and click the save icon to save the configuration? By providing it I can take a look at the settings. For example, if the data is around 326.4C when it should be 325.4C could indicate a DC offset that has not been calibrated out (but not might help with the spread of the signal).

    Best,

    -Cole

  • 0 in reply to Cole Macias
    Genius 4065 points

    HI team,

    SS7012 provides a DC signal around 15mV. 

    Register mapping is shown below. If need more info please let me know. thx 

  • 0 in reply to Jimmy WANG
    TI__Mastermind 18900 points

    Hello Jimmy,

    Thanks for the register map. Looks like all the default settings so that's most likely a dead end.

    I'll need a screencap of the spectral analysis page (the entire page, not just the graph) or if they could provide an excel capturing the data, I can do the analysis on my side. That captured waveform does not look like a 10mV DC signal.

    Best,

    -Cole

  • 0 in reply to Jimmy WANG
    TI__Mastermind 18900 points

    Hello Jimmy,

    Any update on this?

    Best,

    -Cole

  • 0 in reply to Cole Macias
    Genius 4065 points

    Hi team,

    The issue has been solved. thx