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How to obatin more data points from the ADS1258 EVM into the ADCPro

Andres Botello
Prodigy 40 points
Other Parts Discussed in Thread: ADS1258, ADCPRO, ADS1278

Hello,

I am using the ADS1258 EVM (acquisition board) to record 4 channels simultaneously, and i am using the the ADCpro software to record the data. 

My switch delay time is 0 micro seconds.

According to the ADCpro manual: "the number of samples taken depends on the block size set in the test plug-in and/or the number of points set to record in the data recorder." in addition to that it tells us that "the max block size for any test is 1 048 578 samples per channel." but for some reason i am not being able to obtain more than 60 000 samples per channel. My data rate is 5.8342kHz

we are using the data recorder in ADCpro and saving it to a file

My main goal is to at least obtain 2 minutes of data using 4 channels, each recording (a minimum of 1 000 000 samples per channel) simultaneously.

Thank you,

Andres

 

  • 0
    TI__Mastermind 44550 points

    Hi Andres,

    Welcome to the TI E2E Forums!

    It is possible that the ADS1258EVM Plugin for ADCPro places an additional limitation on the number of data points you can collect. Let me look into this and get back to you tomorrow.


    Best Regards,
    Chris

  • 0 in reply to Christopher Hall
    TI__Mastermind 44550 points

    Hi Andres,

    I verified that ADCPro is working. The problem seems to be in the DSP firmware. I'll look into whether or not we can provide a fix.

    In the meantime, you can use the data recorder to capture data over a long period of time. Choose a large sample set of 60,000 or less and check the "Auto" box.

    You will get several text files worth of data. You could then concatenate all of the files (removing all headers except the first one) and read the data back into ADCPro using the File Reader in the "EVM" menu.

    Then set your sample size higher (to 1,000,000) and click acquire to plot the data file.

    The data will not be perfectly contiguous (as there may be some missing samples between data files), but it should be sufficient to see long term affects.

    Here is an example of two data files I combined to get 100,000 samples:

    (the noise is from leaving the inputs floating)

    Best Regards,
    Chris

  • 0 in reply to Christopher Hall
    Prodigy 40 points

    Hi Chris,

    thank you so much for your help.

    I am going to use this procedure for the time being, but i will still need to be able to record continuous data up to  1 000 000 samples.

    Please let me know as soon as you have  the fix to the DSP firmware available.

    Thank you so much once again.

    Andres Botello

  • 0 in reply to Andres Botello
    TI__Mastermind 44550 points

    Hi Andres,

    The firmware fix would be nontrivial. We are not able to support a fix to the ADS1258EVM firmware at the moment.

    To capture more that 60,000 contiguous samples, you would need to look into writing a program to to do this on whichever platform you like that would support an SPI interface; and have sufficient memory to store the data or a fast enough interface to stream the data to a computer.

    Regards,
    Chris

  • 0 in reply to Christopher Hall
    Prodigy 40 points

    Thank you so much, 

    One more question: Can I use MATLAB to control and acquire data from the ADS1258EVM ?

    Andres Botello

  • 0 in reply to Andres Botello
    TI__Mastermind 44550 points

    Hi Andres,

    Unfortunately, there is not a way to control the ADS1258EVM using MATLAB and the MMB0. You would need some software "hooks" that you could call in MATLAB to control the MMB0 firmware.

    If you use another hardware platform with a serial peripheral interface and with some existing MATLAB drivers, then nothing would stop you from connecting it to the ADS1258EVM and controlling it that way.

    With just a quick search I found this device which looks like it might do what your asking for: http://www.mathworks.com/hardware-support/spi-interface.html

    Best Regards,
    Chris

  • 0 in reply to Christopher Hall
    Prodigy 40 points

    Hi Chris,

    Thank you for your answer,

    Do you think LabView would be a better option to control the ADS1258EVM?

    Thank you,

    Andres Botello

  • 0 in reply to Andres Botello
    TI__Mastermind 44550 points

    Hi Andres,

    LabVIEW is a good option, but the best software option will probably depend on what you're most proficient at using. I recommend looking online for software examples and making a decision based on the trade-off between effort and cost you want to put into your project...

    For both MATLAB and LabVIEW you will need an intermediate hardware platform to go between the PC and the ADS1258EVM. National Instruments offers various tools to do this (example here).

    You might also want to look into using an Aardvark from Total Phase (I think this can interface with both MATLAB and LabVIEW).

    Your cheapest option may be to use a TI MSP430F5520 LaunchPAD, but this would require additional work to write the MSP430 software for interfacing between the PC and ADS1258 SPI.

    In the end, what is your application and goal? I may be able to help you narrow down hardware options further based on what your looking to accomplish.


    Best Regards,
    Chris

  • 0 in reply to Christopher Hall
    Prodigy 20 points

    Hi Chris,

    I work with Andres and we are still trying to get around the issue of recording more that 60,000 contiguous samples on at least 8 channels, preferably without having to write our own control software.  I was just looking at the ADS1278 which would actually be a better option for our project.  Do you know if the ADS1278EVM has the same firmware issue, or can we record over 60k samples (up to the ADCPro ~1,000k limit) with this converter.


    Thanks

    Thomas

  • 0 in reply to Thomas Ketterl
    TI__Mastermind 44550 points

    Hi Thomas,

    I tested it out...

    I was able to capture 507,000 points contiguously on all 8 channels:

    I found that the ADS1278EVM Plugin does have an enforced blocksize limit of 507,904 points:

    So, it is better than the ADS1258EVM, but still not the full 1,000,000 samples you were after.

    Best Regards,
    Chris

  • 0 in reply to Christopher Hall
    Prodigy 20 points

    Thanks for looking into this! 

    508kS is definitely much better.  Just in case, you don't happen to be aware of a ADC EVM with similar performance (>16bit, 6 channels or more, >1kSps per channel) that can save a higher amount of samples?


    Also, do you know if the ADS1278EVM can be purchased separately from the MMB0 motherboard, since we already have the MMB0 when we purchased the ADS1258EVM?

    Thanks again!

    Thomas

  • 0 in reply to Thomas Ketterl
    TI__Mastermind 44550 points

    Hi Thomas,

    I've sent an email to you with your E2E registered email address.

    Best Regards,
    Chris

  • 0 in reply to Christopher Hall
    Prodigy 10 points
    Sorry members. But I'm always confused about Data Rate, Samples and Block Size. I've been trying so many different configurations on ADC pro Software and reading the files after that to see the difference but I couldn't understande.

    Can someone clarify those concepts?
  • 0 in reply to Euller lima
    TI__Mastermind 44550 points

    Hi Euller,

    The data rate generally refers to how often you can retrieve data from the ADC. However, due to filter latencies when starting a new conversion or when switching channels, this may not always be the case.

    "Samples" refers to the total number of samples or data points collected. Generally, if these samples are contiguous and collected without interruption, then the time to collect these samples will be: Collection time = (Samples / Data rate).

    In ADCPro the block size is the number of contiguous samples that the software collects.

    • When using the "Acquire" button to collect data, the block size and the number of samples are the same.

    • When using the "Continuous" button to collect data, ADCPro will collect a number of samples equal to the "block size", display this data, and then repeat this process over and over until you stop the continuous collection mode. The data displayed any in one graph will be contiguous, but from one time-domain plot to the next the data between "blocks" may not be contiguous (meaning if you were measuring a sine wave and you concatenated all off the "blocks" of data into a larger data set, you might see some missing samples between the data "blocks").

     

    I hope that helps,
    Chris