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ADS1271-EVM software does not recognize MMB0

Chris Roed
Intellectual 960 points

Other Parts Discussed in Thread: ADS1271

Hello,

I'm using an ADS1271-EVM on an MMB0 and Win7 64bit os.  My OS recognizes the MMB0 and it shows up in the device manager, but when I run the ADS1271 softare it cannot find the MMB0.

I've tried using the Win7 compatibility wizard and running the program as a winxp sp2 program, but it still can't find the MMB0.

Any suggestions? 

  • 0
    TI__Mastermind 23235 points

    The current version of the software only support Windows XP.  It has not been ported to support Windows 7.

  • 0 in reply to Greg Hupp
    Prodigy 140 points

    So since Windows XP is obsolete, does this mean that now the ADS1271 is also obsolete?  If not how can I evaluate it?

  • 0 in reply to Jim Avant
    TI__Mastermind 23235 points

    The ADS1271 device in still active; the status of the devices are shown at the top of the product page.

    Currently, the software only supports WinXP; we are evaluating current software for future requirements.

  • 0 in reply to Greg Hupp
    Prodigy 140 points

    So I found an old XP machine and got the software working.  I was seeing crazy harmonics on the waveform in the software and tracked this back to an inherent DC offset on the ADS1271 eval. board at about -1.5V.  When I bypassed the input amplifiers I saw the same offset but now positive instead of negative.  I can't couple directly to the board because I have an even larger DC offset on my board so I was connecting through a .1 uF capacitor.  Is there any way to remove this inherent offset on the eval. board?  Can you explain why it is present?  By the way I tried directly tying the grounds on the two boards together and that made no difference.

    Any help will be sincerely appreciated.

  • 0 in reply to Jim Avant
    TI__Mastermind 23235 points

    Are you using S3-S6 to bypass the input buffers or just solder/direct connection somehow?  You might try using the switch if you're not using it to make sure something weird isn't happening.  There is no reason that you should get that large of an offset on the EVM, so we need to investigate a little.

    If you carefully short the inputs to the ADC (make sure that you aren't shorting you signal source, does the DC offset go away?

  • 0 in reply to Greg Hupp
    Prodigy 140 points

    I'm using the switch. No soldering.  I notice that when I disconnect my inputs the offset goes to zero.  So it must be in the way I'm trying to connect a single-ended signal into a differential circuit.  My 5Vp-p AC signal actually swings around 10VDC, but that high DC voltage swamps out the inputs of the eval. board.  That's why I coupled with a capacitor.


    Is there an easy way to convert the eval. board's differential buffer into a single-ended to differential buffer?

  • 0 in reply to Jim Avant
    TI__Mastermind 23235 points

    Connect the positive terminal to the input signal.  Tie the negative terminal to the mid-point of the input signal (ie DC value if you have a sine wave).  This should get the best signals without an offset into the ADC

  • 0 in reply to Greg Hupp
    Prodigy 140 points

    Yes, that's where I originally started.  With this connection I see two problems:

    1) I still see a DC offset of about 350 mV.  This limits my input range to about 4.6Vp-p.  This DC is being dropped across my final resistor in my filter chain on my board (100 ohms).  I can short across this resistor and see the DC offset go away, however I'm still left with problem 2.

    2) I still see some harmonics.  3rd Harmonic is about 75 dB down.  Should be closer to 100 or more.

    See attached screen capture.