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ADS9811: Interfacing TI Sitara with ADS9811

Claus Hohensinn
Prodigy 20 points
Part Number: ADS9811
Other Parts Discussed in Thread: ADS8568, ADS9813EVM, ADC-PHI-PRU-EVM, ADS9813, TSWDC155EVM, ADS9817EVM, TMDS243EVM, TMDS64EVM, TMDSHSECDOCK, TMDSCNCD263

Tool/software:

Dear TI Team,

we are reworking an older design that uses FPGAs and ADCs and stumbled across ADS9811 and ADS8568. For the ADS8568 we were assured that the combination of a Sitara microcontroller and the ADC could work. As we are forced to increase the ADCs sampling rate, we also would like to have the possibility to use switch to a faster ADC as the ADS9811. Is there any possibility to connect and properly use ADS9813EVM in combination with ADC-PHI-PRU-EVM and TMDS243GPEVM?

best Regards,

  Claus

  • 0
    TI__Expert 6741 points

    Hi Claus,

    Thanks for your question! To better understand your use-case, may I ask what kind of application this is for?

    While we do not have any example code for ADS9811 + Sitara, I believe you could use the PRU interface on the Sitara to communicate with ADS9811. If your previous design was using FPGA, would it be possible to use an FPGA with ADS9811? We have ADS98xx FPGA example code available. For evaluation, you may choose to use the ADS9813/11EVM with the FPGA TSWDC155EVM and the GUI software that is available online.

    Please let me know if I can help answer any additional questions.

    Best regards,

    Samiha

  • 0 in reply to Samiha Sharif
    Prodigy 20 points

    Hi Samiha,

    Thanks for the quick reply! The application targets custom made sensor cells that have to be sampled simultaneously. We are planning to update the existing system with a more powerful ADC so that we could possibly improve on resolution and speed.

    Using an FPGA is unfortunately not an option as our expertise in embedded systems is heavily on the microcontroller side...

    We have seen the possibility to combine ADS9813/11EVM with the FPGA TSWDC155EVM and this would be feasible for evaluation purposes. BUT we would need to somehow constantly acquire data in a scripted way. If there was a possibility to use (for example poython or any other) scripting language for evaluation and testing, this would be a big improvement. So question is, is there any chance to communicate and/or receive data in an automated (scripted) way with this combination?

    Best Regards,

      Claus

  • 0 in reply to Claus Hohensinn
    TI__Expert 6741 points

    Hi Claus,

    Thanks for the information! The ADS9817EVM (multiplexed variant of ADS9813) does have Python API available. If you take a look at this and it is what you are looking for, I can discuss with our software team about providing you with a Python API for ADS9813EVM. Alternatively, the ADS9813EVM does have a scripting window of sorts that can be used to access the various features of the GUI (such as the capture button, etc), which you could loop over for multiple captures and store the ADC output data into an array, for example. However, in both the case of Python API and the GUI, ADC data captures are not being streamed to the PC. They are being captured into DDR memory and then transferred to the PC afterwards. The delay during transfer makes it so our evaluation software is not able to do true continuous capture. Keeping this in mind, if either of these evaluation approaches work for you, please let me know.

    While we do not have example code for the Sitara solution, if you choose to use the Sitara TMDS243EVM/TMDS64EVM, those EVMs have an HSE connector through which you can access the PRU. You would not be able to use the ADC-PHI-PRU-EVM adapter board as the ADS9813EVM has an FMC connector, not PHI. The TMDSHSECDOCK + TMDSCNCD263 boards may also be used to access the PRU signals.

    Best regards,

    Samiha

     

  • 0 in reply to Samiha Sharif
    Prodigy 20 points

    Hi Samiha,

    thanks for the quick response, we are internally discussion which way to go. For Evaluation purposes, we think we could use a python API (if TI could provide it).

    For the next steps, any information regarding the combination of sitara processor and the ADS9813 would be helpful. We plan to read out the ADC with sitara and do some FFT calculation. As we are still in the design process, we would be really interested if there are any obstacles using such a combination (readout speed, FFT calculation, etc...). I am well aware, that we will have to try this out, but if there are already concerns regarding this combination, we would greatly appreciate any additional information!

    best regards,

      Claus

  • 0 in reply to Claus Hohensinn
    TI__Expert 6741 points

    Hi Claus,

    Understood! Let me get back to you about the Python APIs in a couple of days once I discuss with the team.

    As I am not too familiar with the Sitara solution, I would recommend speaking with the Sitara team about this use-case. I believe the PRU interface may be used, but I will move this ticket to the Sitara team so they may share their input. The ADS9811 interface may use 2 data lanes or 4 data lanes, and may be DDR or SDR depending on the use-case. Here is a datasheet diagram of 2-lane DDR mode for the Sitara team's reference:

    Best regards,

    Samiha

  • 0 in reply to Samiha Sharif
    TI__Expert 6000 points

    Hi Claus,

    As Samiha mentioned above, the Sitara solution uses the PRU core to generate the required interface protocol with which it can interface with ADCs.

    You can know more about the implementation details of the existing ADS85x8 PRU ADC interfacing examples here - https://software-dl.ti.com/mcu-plus-sdk/esd/AM243X/latest/exports/docs/api_guide_am243x/EXAMPLES_PRU_ADC_ADS85X8_DETAILS.html

    Couple of questions before we look into extending the above implementation to ADS9813:

    What precision and readout speed do you need for sampling the ADC data?

    Which core is the one that will be eventually consume the ADC data? What OS is running on that core?

    Regards,

    Nitika

  • 0 in reply to Samiha Sharif
    TI__Expert 6741 points

    Hi Claus,

    Wanted to send you an update on the Python API - our software team is working on it and we should have it ready by early next week. 

    Best regards,

    Samiha

  • 0 in reply to Nitika Verma
    Prodigy 20 points

    Hi Nitika,

    To answer your questions: 

    the precision has to be >=14bit with a sample rate of around 1MSps. 

    As we are in a very ealy stage of evaluating this solution, I cannot definitely say which OS we will be using - probably TI RTOS! Regarding the core, there are also evaluations starting as we now have purchased TMDS243EVM and are evaluating it as well!

    BR,

      Claus

  • 0 in reply to Samiha Sharif
    Prodigy 20 points

    Thanks for the update! I just wanted to mention that we are very happy with all the support we are getting - Thanks for that!

    BR,

      Claus

  • 0 in reply to Claus Hohensinn
    TI__Expert 6000 points

    Hi Claus,

    Thanks for the information.

    With AM243x EVM, the FFT calculation can be performed by the R5F core using the data transferred to it from PRU (similar to the ADS8568 implementation).

    I will discuss the feasibility of your sampling requirements with the team as well and get back to you.

    Regards,

    Nitika