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ADS8688EVM - How to make real time measurement

Michele Ghul
Prodigy 250 points
Other Parts Discussed in Thread: ADS8688EVM-PDK

I am working on an ADC, it is the ADS8688EVM-PDK. I configured that with my pc, I installed the TI software, but I noticed that the software does not allow you to read more than 13k samples.  So I am wondering if it possible to go above this limit and keep reading data in real time until you want.

Thank you in advance.

  • 0
    TI__Expert 3675 points

    Hi Michele,

    You could read 8 million samples from the GUI if you are operating at speeds greater than 100kSPS.
    This is explained on page 22 of the EVM user guide. I have attached a snap shot for quick reference.

    Regards,
    Rahul

  • 0 in reply to RahulVK
    Prodigy 250 points

    Thank you for fast and clearly response. I didn' t think i could do that because, when i run the software and chose at a sampling rate of 500Ksps, I set the number from 131,072 to 131,073 samples, but, the software reset the value to 131,072.

    However i would like to ask for something else. There would be the possibility to make measurement in real time? Or even the possibility to store and process data in real time in some way?

    I tried to interface the ADC with Labview trough the serial but Labview didn' t recognise it. I don' t exactly know how much is wrong what i am saying, but i would like to connect it to a microcontroller like a MyRIO, where run a VI program. don' t how much complex would it be, and if it is possible for example by using some .dll s.

  • 0 in reply to Michele Ghul
    TI__Expert 3675 points
    Hi Michele,

    The number of samples is adjusted to the closest power of 2. If you entered 131073, it will be adjusted to 131072.

    I am assuming you want to monitor data on a computer real time. The challenge with real time data monitoring on a computer is getting a continuous data stream over the interface port of the computer. At 16-bit 500kSPS rate, we are talking 8 mbits/sec transfer rate over USB/serial port. It is not impossible, but needs some tweaking.

    The interface with the ADC remains consistent, irrespective of which host platform you use. Hence, if you have a platform which can give greater than 8 mbits/sec transfer rates, you could implement real time monitoring.

    Regards,
    Rahul
  • 0 in reply to RahulVK
    Prodigy 250 points

    Thank you Rahul, sorry for the delay.

    I tried to use a serial communication using Labview, in particular I used the VISA resource name, but when i tried to select the Port from the VISA list box               I didn' t manage to select the PORT; when I went to Device Manager of Windows i noticed that the computer didn' t recognised the ADC as a flash drive.

    I will send you a screen of Device Manager as soon as possibile

    This is the diagram block. It works. I used it with an arduino.

  • 0 in reply to Michele Ghul
    Prodigy 250 points

    Here the screen:

    As you could see the computer doesn' t recognise the ADS8688EVM as a Universal Serial Bus Controller but as a Portable Device(like e.g. a smartphone). For this reason I can' t use a serial communication with Labview. So have you any suggestion of program or things what i can do to make real time measurement?

  • 0 in reply to Michele Ghul
    TI__Expert 3675 points
    Hi Michele,

    The SDCC will not be detected as a communications port on the computer. This is because of the way SDCC works and the associated drivers.

    SDCC would not be a platform, at this point, to develop a real time monitoring system.

    You would need a host which you can interface with the system and have a software around it. Just like the Arduino you mentioned. Key care about would be the data transfer rate between the host and the computer.
  • 0 in reply to RahulVK
    Prodigy 250 points
    Thank you Rahul i performed a SPI communication with it, even if i had some troubles. But I am going to open a new topic for that.
    However i would like to ask you a last question.

    Should I need a microcontroller with a frequency at least of 17Mhz or is not it necessary?

    Best regards,
    Michele
  • 0 in reply to Michele Ghul
    TI__Expert 3675 points

    Hi Michele,

    The host controller needs to generate a timing pattern as shown in the figure below.

    The clock frequency in this pattern is maximum 17-MHz. Hence a controller capable of generating this SCLK rate will work for this application.