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TMS320F28335: Delay in PWM signals

Mohammed Chaker
Prodigy 50 points

Part Number: TMS320F28335

Hello everyone, 

I want to program the card TMS320F28335 so that it can give as output two signals ePWM1X and ePWM2X. The isssue that I'm having is that these two signals are delayed with a value of 3.84us even if my program doesn't include this delay (I'm assuming it's a hardware issue). I used the deadband option in the ePWM bloc, which erased the delay from the "left" side of the pulse, while the one on the right remained. What are the solutions that I can implement in my program to fully get rid of this delay between the two signals ? 

You can see below the two signals. 

  • 0
    TI__Mastermind 42195 points

    Mohammad,

    you are off by approximately 576 clock cycles, we have a sync chain to enable the user to maintain a phase relationship between two PWMs.

    Some good questions to ask yourself:

    1. Have you used the sync chain?
    2. Do you have PHSEN set?
    3. Is there a non-zero value in TBPHS?

    All of these details and more can be found in the ePWM Reference Guide for the device.

    Regards,
    Cody 

  • 0 in reply to Cody Watkins
    Guru 14640 points
    Reference: processors.wiki.ti.com/.../C2000_Archived_Workshops

    "I was able to use the EPwm code from the multi-day workshop to create 5 PWMs at 8 KHz, with a delay of 30 usec for each one, then have associated ADC interrupts displayed using a spare GPIO. I found it very easy to make the changes from the original code to add PWMs, and synchronize them with a delay."

    If you use the EPwm code from the F28335 workshop (chapter 7) as a starting point, you would be able to synchronize PWM1 and PWM2 with No delay. I recommend the code from the workshop because it was pretty easy to follow and make the changes necessary.