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Can CLA be used to generate additional software PWM's on 2806x

Blake Carpenter
Expert 6825 points
Other Parts Discussed in Thread: TMS320F28044

Hi,

I have a customer who is out of PWM's on a 2806x.  Could the CLA be used to generate additional PWM's using essentially software?

Additionally, do you have any recommendations of the easiest part with greater PWM's that would be the easiest port with the lowest cost?

Thanks!

Blake

  • 0
    TI__Guru* 95315 points
    Blake,
    I don't know what else the customer needs, but have they taken a look at TMS320F28044? It has 16 PWM modules.
  • 0 in reply to Hareesh Janakiraman
    TI__Guru 57255 points

    Hi Blake,

    Please note that eCAPs can also be used to generate PWM waveforms.  The F2806x has 3 eCAP modules.  Note that they don't have all the bells & whistles of the ePWM module.

    So:
    (8 ePWM * 2) + 3 eCAP = 19 PWMs.  These can be done without much grief.  Numbers assume the 100pin LQFP package.

    After that, yes, the CLA could be utilized to bit-bang PWM waveforms.  As you can likely imagine, such an implementation may be quite cycle-intensive.  And it will depend on the exact PWM need.

    How many PWMs do you need to output?


    Thank you,
    Brett

  • 0 in reply to Brett Larimore
    TI__Guru 57255 points

    I hit send and now I'm rethinking it... 

    The CLA on this F2806x device doesn't have access to the GPIOs directly.  It can touch a number of peripherals though.
    (because of the architecture, the main way to toggle an IO via the CLA in this device is to force a PWM, which it can access, high or low [via ACQSFRC])

    As a result, I don't think the CLA will be able to increase the amount of PWMs you can output (it would only be able to steal one so that it can create one - which doesn't help you).  Sorry for my previous response.


    Thank you,
    Brett

  • 0 in reply to Brett Larimore
    TI__Expert 6825 points
    Thanks Brett! Great answers! Nice thought about the eCap and I really appreciate the follow-up post on the CLA to keep us from going down a rathole...

    Best Regards, Blake