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TMS320F28379D: When is the counter restarted in the eQEP unit?

Teruhiko Ozuchi
Prodigy 30 points

Part Number: TMS320F28379D
Other Parts Discussed in Thread: LAUNCHXL-F28379D

Tool/software:

Hello,

I'm looking for a solution to my problem.

I am developing embedded software using CCS12.6 with LAUNCHXL-F28379D hardware.

The eQEP unit is used to obtain the motor speed. When the obtained counter value is output to DAC to check the continuity of the angle, a phenomenon is observed in which the count value momentarily deviates after detecting a Z-Pulse (Index-Pulse).

The eQEP setting values are shown in the figure below.

eQEP Settings:
The eQEP is designed to reset the counter when the rising edge of the Z-Pulse is detected.

My question is, when does the counter restart?　Is it after the Z-Pulse drops to a LOW level?　Or is it when the first A-Pulse or B-Pulse edge is detected after reset?

  • 0
    TI__Mastermind 27736 points

    Taken from our TRM under the section: Position Counter and Control Unit (PCCU)

    Depending on what mode you're using it'll be based on the rising edge or falling edge. Example if you're using the index event.

    Best,

    Ryan Ma

  • 0 in reply to Ryan Ma
    Prodigy 30 points

    Hi, Mr.Ryan

    Thank you for your quick response.

    I guess my explanation was not clear enough.

    It count at the rising and falling edges, so I set the resolution to quadruplicate. And I have the counter set to clear on the rising edge of the Index signal.　

    I would then like to know when the update of the counter value will start after the counter is cleared.

    An example is shown in the figure below.

    For example, if the Z-Pulse is output as shown in this figure, at which timing is the counter restart performed, A), B), or C)?

    Best regards.

    Teruhiko Ozuchi

  • 0 in reply to Teruhiko Ozuchi
    TI__Mastermind 27736 points

    Hi Teruhiko,

    I am confirming with design on this when the POSCNT starts to count up again.

    Please allow me another day to get a response, apologize for any delay.

    Best,

    Ryan Ma

  • 0 in reply to Ryan Ma
    TI__Mastermind 27736 points

    Hi Teruhiko,

    I have confirmed with design team that the POSCNT will start counting again on your A) case.

    A) - First Polarity change of A-Pulse or B-pulse after counter reset

    Best,

    Ryan Ma

  • 0 in reply to Ryan Ma
    Prodigy 30 points

    Hi Mr.Ryan,

    Sorry for my late reply.

    Thanks to your help, I resolved my software problem.

    Thank you so much.

    Best regards.

    Teruhiko Ozuchi