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TMS320F28027: QEP pulse count with external logic.

Taeyeong Kim
Prodigy 70 points
Part Number: TMS320F28027


Hi

I'm using 320F28027 for motor control, And hope to get QEP encoder pulse.
Is it possible some glue flip-flop separate CW/CCW pulse and 28027 count?

Regard

Kim taeyeong

  • 0
    TI__Mastermind 19321 points

    Hi Kim,

    Thanks for your question. Can you provide more details and clarification on what you are asking? I am having trouble understanding your question

    Regards,

    Peter

  • 0 in reply to Peter Luong1
    Prodigy 70 points

    I want to get position inform from quadratue encoder pulse A and B.
    D flip-flop with D connected to A and CLK to B can result direction inform.
    NOR logic combined from A and RC delayed /A will make A down-edge pulse.
    We can get separated CW / CCW pulse from direction and pulse signal combination.
    If two counter on DSP can count CW and CCW pulse, we can subtract.

  • 0 in reply to Taeyeong Kim
    TI__Mastermind 19321 points

    Hi Kim,

    I'm still having trouble understanding what your question is exactly. Would you be able to explain more clearly or provide a diagram about what you are asking about? The "position information" within the eQEP module can be examined by looking at the QPOSCNT register. Are you using an encoder and can separately examine the signals coming out of the device into the QEP module? 

    Regards,

    Peter

  • 0 in reply to Peter Luong1
    Prodigy 70 points

    F28027 don't have QEP module. So I'm asking if the counter/timer module can handle encoder pulse.

  • 0 in reply to Taeyeong Kim
    TI__Mastermind 19321 points

    Hi Kim,

    Thanks for the clarification. I believe this is possible to do since reading the encoder pulses just requires a simple FSM implementation and timers are what are used on other MCU device families which don't have dedicated QEP modules. I will allow the Timer expert to comment on the feasibility of this

    Regards,

    Peter

  • 0 in reply to Peter Luong1
    TI__Mastermind 25790 points

    Hi Kim,

    I also believe this should be possible, but may require some software overhead. You can setup the timer and an interrupt for the timer. Within the Interrupt service routine you can check the value of the encoder pulses. If the frequency of these pulses changes then you'll need to re-adjust your timer period. 

    This is not an implementation we have created so unfortunately the implementation would have to be up to you to develop. If it is still possible for you to transition devices I would suggest moving to a C2000 device that does contain an eQEP module as it would remove a lot of the software overhead. 

    Best Regards,

    Marlyn