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UCD3138PSFBEVM-027: EADC measurement

maria
Prodigy 55 points
Part Number: UCD3138PSFBEVM-027
Other Parts Discussed in Thread: UCD3138

Hello everyone hope you re good !

I want to know how can i get measurement of the EADC input (EAP0) using the UCD3138 ,

I tried to connect it with a potentiometer but i always get random results and none of them is correct . 

I m doing something wrong apparently.

Thank you for your help

  • 0
    TI__Expert 7020 points

    Hello,

    Are you testing EADC with UCD3138PSFBEVM-27, or with UCD3138 control card?

    Did you connect a DC voltage signal to EADC pin?

    How did you read EADC result? How do you know the result is not correct?

    Regards,

    Bosheng

  • 0
    TI__Genius 17090 points

    Getting the EADC running is a bit complicated.  You have to start a DPWM, enable it to provide a sample trigger, use the fault mux to route the sample trigger to the proper front end, and then get the proper front end.  Then you can use the memory debugger to read the EADCVALUE register to see what you are getting.  There are 4 lab training programs for the UCD here:  https://www.ti.com/tool/UCD-TRAINING-LABS.

    LAB 4 gets the EADC going and controlling a feedback loop with the DPWM, but that doesn't matter - you can just read the EADC value with the memory debugger.

    This E2E post has a list of the videos which go with the labs.  I recommend them as well to learn about the UCD and especially how to program it.  

  • 0 in reply to Ian Bower
    TI__Expert 7020 points

    Hi Maria, can you answer my questions in my previous post? Also, have you tried the training labs?

  • 0
    TI__Genius 17090 points

    Maria, I don't know what happened to this thread.  There were some more questions and replies between us that seem to have gotten lost.  To try again with my latest responses, I suggest using just the control card so that you don't have issues with the PSFB EVM.  Some other notes:

    The EADC and the EADCDAC only have range up to 1.6 volts.  The EADC itself only has a limited dynamic range, adjusted by the EADCDAC.  If you set the EADC Gain to 8, you only have a range of +-32 mV around the setting of the EADCDAC.  If you run the gain down to 1, it goes to +-256 mv.  I'd suggest setting the gain to 1, set the input voltage to 0.8 V, and run the EADCDAC up until you see a response.  Or you could just set it near 0 and set the EADC DAC to 0 as well.  You can use either the EADC value or the absolute value, but you have to have your voltage in the range of the EADC.  I suggest reading through the UCD3138 Technical Reference Manual to see what's there, at least.  The UCD power peripherals are unique and very good at doing power supply topologies cost effectively, but this uniqueness means they're not the easiest to understand.  

  • 0 in reply to Ian Bower
    TI__Genius 17090 points

    Maria, I'm going to close this thread, since you opened a new one.  Please switch to that one.