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ADS131E08: Cannot get samples faster than 16-kSPS

Evan Ryker
Prodigy 20 points

Part Number: ADS131E08

I have a project which requires fast sampling for a time-sensitive application. I have a custom board with the ADS131E08. I am sampling analog sensors on all 8 channels. However, I cannot get samples faster than 16KHz. I have checked all the required voltages setup parameters for the chip and that I'm setting registers correctly (as far as I can tell). At 32- and 64-kSPS, would the DRDY signal have a period of 32 and 64KHz, respectively? (Ignoring any data transfers). Right now it has a period of 16KHz. What might I be doing wrong?

  • 0
    TI__Guru** 101305 points
    Evan,


    Yes, you should see the /DRDY signals at the 32kSPS and 64kSPS data rates every 31us and 15.6us respectively. Setting the data rate should be as simple as setting the DR[2:0] bits in the CONFIG1 register. It would be 001 for 32kSPS and 000 for 64kSPS.

    At this point I would check two things. First, check that this is correctly written in your code and then written into the device. I would also read the register back to verify that the write of the register setting the data rate is correct. Second, if you're using a scope to check the /DRDY, I would make sure that the scope resolution is enough to capture the /DRDY signal. If the /DRDY pulse is narrow, then the scope resolution may miss all of the output pulses.

    At this point I'm not sure why the data rate doesn't appear to go above 16kSPS. Just check the two things I mentioned and post back.


    Joseph Wu
  • 0 in reply to Joseph Wu
    Prodigy 20 points

    Thank you so much for your help. I had evidently modified my register write function incorrectly and I was reading back different values. I fixed the issue and set the sensor to convert at 64kSPS. Success! Thanks again.