• State TI Thinks Resolved
  • Locked Locked
  • Replies 8 replies
  • Answers 1 answer
  • Subscribers 83 subscribers
  • Views 1281 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

CCS/TMDSCNCD28335: C2000 eCAP and ePWM interference/issues

Jack Haynes
Prodigy 30 points
Part Number: TMDSCNCD28335

Tool/software: Code Composer Studio

I am attempting to build a transceiver on the F28335 DSP using Simulink and CCS. The basis for the transmitter is a PWM modulator circuit using the ePWM block from the C2000 support package. The receiver demodulation circuit relies on the eCAP block in rising edge capture format. When using two F28335 DSPs with one setup as a transmitter and the other as a receiver the circuits function successfully and the output is what is required. However as soon as the ePWM and eCAP blocks are used on the same model in attempt to make a transceiver the outputs give erroneous data readings. Have attached Simulink models for the transmitter and receiver. What could be the issue with having the eCAP and ePWM blocks used in the same model ?

  • 0
    TI__Mastermind 42195 points

    Jack,

           I have forwarded this to Simulink expert.

    From a C2000 perspective, there could be many causes.

    1. What do the erroneous readings look like?
      1. Are some readings correct and some incorrect?
      2. Could you be typing the variable wrong? ie. Calling a Uint32 a Uint16, losing some data
      3. Possibly you are using the wrong interrupt to read out the capture values?

    Regards,

    Cody 

  • 0 in reply to Cody Watkins
    Mastermind 6460 points

    Hi,

    What is the step time of the model? Could it be that when both model are combined the step time is not enough to handle the execution overhead resulting in overrun condition? Please let us know if you can attach the model for quick reference.

  • 0 in reply to venkatesh chilapur
    Prodigy 30 points

    ReceiverF - Copy.zipHi Venkatesh,

    The solver is in FixedStepDiscrete mode with step size auto(2.5 e-05). Have attached the model for reference. I did run a code profiler that says there shouldn't be an overrun issue but perhaps you can find something.  

    Thank you.

  • 0 in reply to Cody Watkins
    Prodigy 30 points

    Hi Cody,

    Sometimes the data reads correctly depending on what 3x 8bit numbers are being sent from transmitter to receiver.  For example when sending 6,20,33 the data outputs correctly as seen in the first attached image.

    However certain numbers/data cause the outputs to read wrong for example 7,20,33 where the output reads 7,148,33 (seen in second image). Interestingly this wrong output is the expected 20 plus 128 , so perhaps the MSB is being misread ?

    Thanks

  • 0 in reply to Jack Haynes
    TI__Mastermind 42195 points
    Jack,
    that seems like a reasonable conclusion to me... maybe it's because 7 is an odd number, and the LSB of the first number wasn't cleared from the data stream which leads to the MSB of the second number to read as a 1? Does the bad data only occur after odd numbers? I'm just taking guesses based on wild assumptions.

    None the less Venkatesh is intimately involved in the development of these blocks and should be able to get to the route cause soon!

    Regards,
    Cody
  • 0 in reply to Cody Watkins
    Mastermind 6460 points

    Hi Jack,

    Thank you for updating us with the model. Please bear with me while we continue to investigate the problem.

    We will keep you posted very soon.

  • 0 in reply to venkatesh chilapur
    Mastermind 6460 points

    Hi Jack,

    We need to understand your implementation in detail to debug further.

    Please let us know if you can reach us via our tech support channel so that we can arrange a WebEx for further discussion.

    www.mathworks.com/.../contact_us.html

  • 0 in reply to venkatesh chilapur
    TI__Mastermind 42195 points
    Jack,
    was this ever resolved?

    Regards,
    Cody