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ADC3444: Interface to AM572x GP EVM

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Replies: 5

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Part Number: ADC3444

Hi,

I have the Sitara evaluation module TMDSEVM572x that contains the AM5728 and my question has to do with interfacing a high speed analog to digital converter (ADC), like the ADC3444, to this kit.  Specifically, I am trying to identify a high speed ADC evaluation module that I could use for prototyping purposes and that would "hook up" to the Sitara EVM without breadboarding anything.  While performing my search, I found the thread "ADC3444: ADC3444 and AM5728 interfacing through LVDS serial interface", which was asking very similar questions.  My requirements at this time are that the ADC sample rate be at a minimum 10MSPS, preferably on the order of 100MSPS, 16 bit, 4-Vpp minimum (5 would be better) and I only need 2 channels.  The general application is for industrial measurement solutions, not camera or video, and I'd like to get the ADC output into one of the AM5728 DSP cores.  I read elsewhere that serialized LVDS is the preferred output data interface for high speed ADCs, so I am guessing that LVDS will need to be considered.  However, I am very new to the Sitara EVM so I don't know if LVDS will work or at least I am not sure if there are any other options, or more importantly, what is the *best* option.  In the referenced thread, it was stated that "The best ADC choice will depend on the needed sample rate and number of channels, and what interface works best with the Sitara device."  Unfortunately, no follow up to that statement other than more questions appears in that thread.  Since I am not yet locked into a specific ADC (that is what I am trying to determine), have I provided enough information to answer the question: What ADC EVM works best with the Sitara TMDSEVM572x EVM, subject to the ADC requirements stated above?  What about an EVM-based ADS5263?

Thank you,

Nick

  • Hi Nick
    I'm not familiar enough with the Sitara evaluation module to know what high speed ADC EVMs might be compatible.
    I am going to re-direct this question to the TMDSEVM572x experts to see if they can provide any additional information regarding which interfaces on that platform might be flexible enough to interface to a general purpose high speed ADC EVM.
    Best regards,
    Jim B

  • In reply to Jim Brinkhurst84999:

    Hi Nick
    The current generation Sitara devices do not have native support for LVDS.
    We look at the ADC you listed here to see if there is anything we can propose - we can work with Jim and team to see if there are any potential solutions feasible now or in future.

    For some of the lower sampling rate ADCs, really popular in grid / protection relay space we recently have done a TI design that uses the Sitara PRU-ICSS to interface to ADCs

    www.ti.com/.../TIDA-01555

    For LVDS displays we recently did a TI design with a rgb to lvds/oldi bridge
    www.ti.com/.../tida-010013

    For most high speed ADC , I see that we usually have to end up having an FPGA in between.

    We will look more closely if there is any other alternatives to this.

    Any additional clarification on what kind of ADCs and what kind of performance , cost targets you may have (for system BOM) , will be helpful.
    When you said you are not locked to a specific ADC, it would be good to understand the end application and requirements etc.

    Regards
    Mukul
  • In reply to Mukul Bhatnagar:

    Thanks for your responses Mukul/Jim.

    To clarify, my main objective is to explore the capabilities/limits of the AM5728 for signal processing applications. For example, I'd like to experiment with FFT speeds and sizes that can be implemented on the dual core C66 and to generate a set of results similar to what is shown in the white paper "Very large FFT for TMS320C6678 processors". I am particularly interested in the highest sustained rate achievable for different size FFTs. I don't have any cost targets, just a sample rate requirement, which as I mentioned needs to be 10MSPS minimum (plus other requirements previously stated). To open up my options at this point, I can reduce this to 2MSPS.  By industrial measurement, I simply mean that I am acquiring voltage waveforms within which information is encoded (e.g., various modulation techniques). An EVM-based ADC that interfaces directly with the TMDSEVM572x would be ideal for me at this point since I am focused more on the capabilities of the AM5728 than I am on the actual application.  If necessary, an FPGA in between is also ok, as long as I can get hold of some guidelines on how interface that to both ADC and the TMDSEVM572x.

    Nick

  • In reply to Nick Ossur:

    Hi Nick
    Thanks for the additional background.
    I do not think that the AM57x EVM was intentionally designed to be friendly to attach to an FPGA board or ADC EVM for that matter.
    So I do think you may need to evaluate blue wiring or creating a custom board that helps connect the EVMs or ADC directly.

    For FPGA the popular options are GPMC or PCIe.
    For ADC direct attach, I think you should seriously look at a PRU based approached for a parallel interface. I mentioned TIDA-01555 previously.
    Here is another TI Design
    www.ti.com/.../TIDA-00942
    This may be with sampling rates more closer to your requirements?
    This TI Design works with AM335x BBB, which is a very popular device and board. The PRU interface it leverages is similar to the PRU you will see on AM57x, so this could serve as a potential building block or evaluation on how to get the data in.

    Hope this provides some more areas you can dig deeper.

    Regards
    Mukul
  • In reply to Mukul Bhatnagar:

    Thank you Mukul. 

    I'll need to familiarize myself with GPMC and PCIe, and consider the PRU approach that you referenced in order to know which is the best path for me to move forward.  The choice may boil down to which one is most appropriate given the 16-bit ADC, 2MSPS (or better) sample rate requirement.  I believe you have provided enough information for me to proceed, I'll just need to invest a little more time than I was hoping would be necessary.  Thank you very much for your feedback.

    Nick

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