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ADC128S102EVM: Differences between the two ADC128S102EVM versions when interfacing to an Arduino Due

William Marchant
Prodigy 30 points
Part Number: ADC128S102EVM

I have two versions of the ADC128S102EVM board: a small one we bought a year ago and a much larger one where all the inputs are broken out to SMA connectors. 

I can plug the old style ADC128S102EVM directly to an Arduino Due and it works fine. 

But connecting the newer style board directly to the Arduino returns a zero value all the time.  But the setup starts to magically work if the control lines go to a protoboard before going to the Arduino. 

I'll double check the jumpers I'm using but I don't think that's the problem.  We have a second "new style" board in a test configuration at another facility and it doesn't work when directly connected to the Arduino either. 

Any other suggestions?

Thanks!

  • 0
    TI__Mastermind 24940 points

    Hello, 

    Yes, we discontinued the smaller board version you have, since the communications card for that board was no longer supported. The bigger board is an updated version to use the new communications card, which was included in the EVM package, the PHI, which is a TI internal board. 

    I am not understanding your set up, would you please provide a flow/block diagram or a picture of how/what you are trying to to connect. 

    If I am understanding correctly, it sounds like this protoboard you are using provides something that the Arduino needs to communicate to the EVM that is missing when connecting the EVM and Arduino directly together. I would suggest taking a good look at what the prototype board is offering that the Arduino needs. 

    Regards

    Cynthia

  • 0 in reply to Cynthia
    Prodigy 30 points

    Hi Cynthia:

    When I use single jumper wires to connect the following signals together:

    Arduino pin 10 to TI EVM J26 CS

    Arduino SPI 1 to TI EVM J26 DOUT

    Arduino SPI 3 to TI EVM J26 SCLK

    Arduino SPI 4 to TI EVM J26 DIN

    and the TI EVM board VA and VD are 3.3V

    The results I get from the eval board are zero.

    If those single wires get replaced by two wires going to a protoboard, then it works and we get reasonable numbers from the analog input channel 4.  Single lengths of jumpers worked with the old evaluation board. 

    So it seems like a "trivial" change of adding extra wire length, or that a connector is now in the way, make the new board happy.

    Thanks for taking a look at this.

  • 0 in reply to William Marchant
    TI__Mastermind 24940 points

    This is very odd; it is the opposite case that is desired, short connections.

    Would you connect an oscilloscope and provide a screen shoot of the digital bus, including all four signals, CS, DIN, DOUT, SCLK

    Even if there is a reflections issue here, the DOUT should not be consistently low. 

    Regards

    Cynthia