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Original question:

Count external clock pulses with hardware counter on C2000

TMS320F28075: Counting pulse trains from six inputs.

Hideaki Nambu
Mastermind 9165 points

Part Number: TMS320F28075

Hello,

My customer would like to count the numbers of pulses from six input channels. The pulses represent rotations of six fans.

Could you please advise how to count them ?

I read the original thread and thought once that the eQEP (Direction-count Mode) were useful, but there are only three instances.

Could you please advise any other peripherals which provide three more counters like the eQEP to observe six inputs?

 

 

  • 0
    TI__Genius 15385 points

    HI Hideaki,

    I assume the 6 inputs are coming on 6 different GPIOs simultaneously, correct?

    What will be the maximum frequency of the Pulse train?

    You can use CLB as counter to count input pulses.

    Regards,

    Nirav

  • 0 in reply to Nirav Ginwala
    Mastermind 9165 points

    Nirav,

    Thank you for your reseponse.

     

    >> I assume the 6 inputs are coming on 6 different GPIOs simultaneously, correct?

    Yes.

     

    >> What will be the maximum frequency of the Pulse train?

    333Hz = 3msec.

     

    >> You can use CLB as counter to count input pulses.

    Maybe. If we move to F28076.

     

     

    We found the eCAP would be a good choice also. Do you have any concerns ?

    We are looking into the TRM p.2004:

    15.7.3 Example 3 - Time Difference (Delta) Operation Rising Edge Trigger

  • 0 in reply to Hideaki Nambu
    TI__Genius 15385 points

    Hi Hideaki,

    I had thought about eCAP but that will not continuously count the pulses in HW, CPU bandwidth will be used. 

    15.7.3 Example 3 - Time Difference (Delta) Operation Rising Edge Trigger - This can be used, you will have to enable interrupt for CEVT4. Meaning every 4 rising edge interrupt will be generated, and you can add that to the count within ISR.

    Regards,

    Nirav

  • 0 in reply to Nirav Ginwala
    Mastermind 9165 points

    Nirav,

    Thank you for your comment.

    We understood.

     

    Still, the eCAP sounds good for us.

    Our customer can stay on the F28075. And they would like to use a timer-ISR function and sample a single pulse cycle, and measure its cycle time.

     

    I would like to open a new thread and ask about the CAPx register. Thank you again.

    https://e2e.ti.com/support/microcontrollers/c2000/f/171/t/894083