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TMS320F280039C: CMPSS to DC to TripZone connections not working

Shrikant Khade
Prodigy 30 points
Part Number: TMS320F280039C


Tool/software:

Hi,

We want to use CMPSS + ePWM.DC + ePWM.TZ in order to latch the PWMs to high impedance when an analog signal reaches a threshold

We have configured following:

- CMPSS: CMP3_HP = A14, CMP3_HN = threshold (2048), DAC ref  = VDAC, CTRIPH (ePWM-XBAR) is used for output, mux selection = in signal 4

- ePWM- XBAR : Mux = MUX4, Signal = trip4

- ePWM.DC : Digital compare B-High = All trip inputs, Combinational = Trip4, condition for event 1B and 2B =  Event when DCxH high

- ePWM.TZ : Default config (i.e.  set all to high impedance).

With this configuration, we are observing that only ePWM3B is getting disabled, that too not completely (see glitched below). And ePWM3A is not disabled at all.

Can you propose a solution please.

  • 0
    TI__Mastermind 28220 points

    Hi Shrikant,

    I don't see any mention of tripping PWM3A according to your description. What registers are you modifying to attempt to trip PWM3A?

    Are you using a CBC or OSHT trip? If using a .force trip, the PWM output can change from tripped to untripped sporadically depending on the input signal, whereas CBC and OSHT trips get latched by the PWM module.

    Thank you,

    Luke

  • 0 in reply to Luke Jones
    Prodigy 30 points

    Hello Luke, 

    Thanks for the hint. 

    We went through "epwm_developers_guide.pdf" and identified following.

    So, we enabled the CBC trip for DCBEVT2 and it works fine.

    Thanks.