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DDC264EVM: Application Inquiry

Renan Santos Adriano
Mastermind 25315 points

Part Number: DDC264EVM

Hello Team,

Posting on behalf of my customer:

We are working with the DDC264EVM evaluation board. The goal for our project is to achieve a 6ks/s sampling rate with a 160us integration time but when these parameters are set, the time it takes to read data from memory is 2s. 

Is it possible to read the data faster than 2s from memory?

Also, I wanted to understand how the program averages the data, how often can it do this for.

Our goal is to average 600 samples every 100ms and to read it from memory each time.

Regards,

Renan

  • 0
    TI__Mastermind 19815 points

    Hi,

    We will need additional 24 hrs to get back to you.

    Thanks

  • 0 in reply to ChienChun Yang
    TI__Mastermind 25315 points

    Hello ChienChun,

    Any update on this?

    Regards,

    Renan

  • 0 in reply to Renan Santos Adriano
    TI__Mastermind 19815 points

    Hi,

    Sorry, I will need additional time to get back to you.

    Thanks

  • 0 in reply to ChienChun Yang
    TI__Mastermind 19815 points

    Hi,

    Sorry for the delay.

    Could you please clarify and explain more what you mean by "the time it takes to read data from memory is 2s."?

    Which time duration did you measure? e.g. Start from when and Stop at when?

    And, which average value are you referring to? Are you referring the average value as example shown in the user guide page 18 5.3.4, Average column?

    Thanks

  • 0 in reply to ChienChun Yang
    TI__Mastermind 25315 points

    Hello ChienChun,

    Please see customer response below:

    Question: Is it possible to read data faster than 0.9s from memory?  (Maybe if possible to read every 100ms)  P.S I adjusted some parameters to obtain 0.9s instead of 2s but can’t get it faster than this.

     Answer: By this I mean when pressing refreshing all for all registers and then pressing the Fast data button, the program begins to collect data. I used a stopwatch on my phone to record the time it takes to acquire this data by starting the time when I press the Fast data button and then stop the time when it says done taking the data at the bottom of the screen on the program.

     Question: Also, I wanted to understand how the program averages the data, how often can it do this for. Our goal is to average 600 samples every 100ms and to read it from memory each time. By average in the Data Summary tab it shows Channel, Average, RMS noise, P2P noise. The one found in the columns.

     Answer: By average in the Data Summary tab it shows Channel, Average, RMS noise, P2P noise. The one found in the columns.

     Question: I also would like to know how to access the ISSI SRAM 16MB IC chip memory from the EVM board whether through programming so we don’t have to record the data manually x number of times. We would like to see the data for each channel being recorded every lets say 160us, how would we acquire this data?

     Please let me know, Thank you

    Regards,

    Renan

  • 0 in reply to Renan Santos Adriano
    TI__Mastermind 19815 points

    Hi,

    I will need more time to get back to you.

    Thanks

  • 0 in reply to ChienChun Yang
    TI__Mastermind 25315 points

    Hello ChienChun,

    Good day.

    Any update on this request?

    Regards,

    Renan

  • 0 in reply to Renan Santos Adriano
    TI__Mastermind 19815 points

    Hi,

    We need more time to look into this.

    Thanks

  • 0 in reply to ChienChun Yang
    TI__Mastermind 25315 points

    Hello ChienChun,

    Any update on this?

    Regards,

    Renan

  • 0 in reply to Renan Santos Adriano
    TI__Mastermind 19815 points

    Hi,

    1. that is the latency and processing time the OS and GUI need to experience.

    2. we are still discussing whether we disclose this.

    3. Could customer explain more detain what he is thinking to do with the SRAM? access or bypass? and how?

    The EVM and GUI are meant to be sold and used as is. The GUI and the host on EVM do the intermediate works to communicate with the devices and retrieve and display the day. we don't support the special usage like that , e.g. hacking or only interface one particular component on the EVM.

    Any special usage that is not mentioned in the user guide may disrupt the normal functionality of the EVM and GUI, which is not recommended.

    Thanks

  • 0 in reply to ChienChun Yang
    TI__Mastermind 25315 points

    Hello ChienChun,

    Please see update from customer below:

    Thank you for your response. We need to measure a small drift of the laser beam with a 64-pixel photodiode array and we would like to have 20 bit accuracy. The photocurrent can be as high as 1 uA so that we have to use a 6kS/s rate. With this rate we believe we are losing several bits with a short integration time (~160 us) and noise due to input capacitance.

    With the GUI it takes a 0.8 s to save each sample. It seems the 6 kS/s data are not averaged as there is no options in the menu. Therefore, we save each sample into a file and later average the data for approximately 200 samples to recover 20 bits. It takes minutes to save files and the laser beam drifts over this time so the averaging does not help. We would like to get data with up to 20 bits at a 6kS/S rate and average them over a period of time of 100 ms or so.

    Would you help with the following questions:

    1) The processing time of the GUI ( 0.8 s) is much longer compared to the integration time of 160 us. Does it mean that multiple samples are taken for a selected 6kS/S (=160 us integration time)? Does the board store them in the RAM and average them over some period of time? It seems there is no control on averaging time of multiple samples in GIU. We think that the samples from ADC are stored in the RAM and one can get them later for averaging.

    2) In the past TI forum I saw that .cpp and .h files were posted named USB_IO_for_VB6.dll", "USB_IO_for_VB6.cpp", and "USB_IO_for_VB6.dl.h", and "CyAPI.h". However no CyAPI.cpp file compatible to CyAPI.h file is provided. Can you provide us with CyAPI.cpp file? We believe this can help us to get many samples fast enough so that we can average them for recoverings bits lost due to a short integration time and get the laser beam position data with a 100 ms rate.

    Thanks in advance.
    Regards,
    Renan
  • 0 in reply to Renan Santos Adriano
    TI__Mastermind 19815 points

    Hi,

    I will need to discuss internally to see what is allowed to disclosed.

    Try to get back to you 2/24.

    Thanks

  • 0 in reply to ChienChun Yang
    TI__Mastermind 19815 points

    Hi,

    After internal discussion, We cannot disclose/share/support the source code.

    Thanks