• State
  • Locked Locked
  • Replies 3 replies
  • Subscribers 81 subscribers
  • Views 1258 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

LAUNCHXL-F28377S: LAUNCHXL-F28377S: number of ePWM Pins

Christian Simon
Prodigy 50 points

Part Number: LAUNCHXL-F28377S

Hi,

I need a launchpad with 24 PWM outputs. According to the Quickstart Guide of the LAUNCHXL-F28377S there are 14 PWM outputs. I found out that if I configure GPIO4 as EPWM3A I get a total of 15. Are there any pins left i can use to get the pwm out of the launchpad? If not so, would it be a better solution to:

a) lead out some GPIOs (160-168) with PWM support via wiring pencil

b) use 9 GIPOs with Timers to make for the left PWMs for a total of 24

I would like to use the launchpad and not to come up with a solution from scratch to speed up development. Is there another launchpad i could use?

Thanks in advance

Simon

  • 0
    TI__Guru 57255 points

    Hi Simon,

    If you look, the limitation on the amount of PWMs is limited by the F28377S in the 100LQFP package, not necessarily by the LaunchPad connectors.

    There is a F28379D launchPad, however it does not give you access to many more PWMs through its connectors.  It also utilizes a BGA footprint, and so it will be challenging to bring any of the pins that aren't already routed.

    Note that the eCAP peripherals can be utilized directly to create PWM signals.  The eCAP won't have as much functionality as the ePWM, but it is possible. The eCAP can generate PWMs and save the CPU from need to do PWM generation, at least.  With ePWMs and eCAPs, I still don't believe you will reach 24 - but you may get close.

    It really depends on what you are trying to use the C2000 device for, but it likely will not be desirable to utilize the C2000 CPU to bit-bang PWMs. 

    The ePWM peripheral on the C2000 is a great assistant in making a power system work.  If you need 24 PWMs and want to utilize the powerful ePWM, I would recommend taking a look at the TMDSDOCK28379D.  This platform brings out more of the device's pins.


    Thank you,
    Brett

  • 0 in reply to Brett Larimore
    Prodigy 50 points
    Hi Brett,

    first of all thank you for your recommendations. After looking at the F28379D launchPad i found out that i can manage to get out 23 PWM ( 6 of it by using the eCAP APWM function via xbar). I also looked over the scematics. There are 4 DAC outputs on the launchpad witch come from the GPIOs 157- 160. These GPIOs are lowpass filtered (RC) and then lead to the connectors. Can i desolder the resistors (and replace them with 0R) and the capacitors to use the PWM functionality on those pins?

    thank you in advance

    simon
  • 0 in reply to Christian Simon
    TI__Guru 57255 points

    Hi Simon,

    I haven't specifically researched if you'll be able to get 24 or greater out of this LaunchPad, but it looks like you're thinking about things correctly.  Just make sure you aren't double-counting any specific peripheral (ie remember that you can only use PWM1A once, etc :) ).

    Converting the PWM DAC outputs to PWMs does make sense to me.


    Thank you,
    Brett