• State
  • Locked Locked
  • Replies 1 reply
  • Subscribers 81 subscribers
  • Views 194 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

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.

TMS320F28377D: SWFSYNC while using XINT2

Ugnius Subacius
Expert 1180 points
Part Number: TMS320F28377D

Hi,

I am having issues getting SWFSYNC to work correctly for PWM module while XINT2 (INPUT5) has a pin assigned.

From the datasheet my understanding is that the PWM sync can be triggered from the INPUT5 pulse. However having INPUT 5 pulled high or low (no transition after set-up) should have no effect.

Also it looks like the INPUT5 is always connected to EXTSYNCIN1 and EPWM1 sync source and cannot be disconnected:

The issue I am having is PWM counters not syncing correctly when INPUT 5 has a pin assigned.

If the assigned pin is always pulled high, the sync works fine.

If the assigned pin is always pulled low, the sync does not work (the counters are slightly out of sync).

My questions are:

1. Is it possible to disconnect INPUT 5 from EXTSYNCIN1? If it is to be used as XINT2.

2. Is it possible to disconnect EXTSYNCIN1 altogether from all PWMs? If external sync is not to be used.

3. Is there any reason why software triggered PWM sync would not work properly when INPUT 5 pin is pulled low?

  • 0
    TI__Mastermind 24095 points

    Hi,


    Ugnius Subacius said:
    1. Is it possible to disconnect INPUT 5 from EXTSYNCIN1? If it is to be used as XINT2.

    Same input goes to both places, there is no additional switch disable one function vs another. In this case, since you are using XINT2 function it propagates to EXTSYNCIN1 as well. Only way to disable this is by not using synchronization function (disable PHSEN).

    Ugnius Subacius said:
    2. Is it possible to disconnect EXTSYNCIN1 altogether from all PWMs? If external sync is not to be used.

    From the diagram you had above, EPWM4 onwards you can chose a different option using the corresponding SYNCINSEL mux - but for EPWM1 this is connected by default.

    Ugnius Subacius said:
    3. Is there any reason why software triggered PWM sync would not work properly when INPUT 5 pin is pulled low?

    from "Figure 15-5. Time-Base Submodule Signals and Registers" of the TRM, the EXTSYNCI and Software triggered force signals are ORed and used for synchronization. Hence, I believe SW forced SYNC will be blocked if the INPUT5 is high, not when it's low. Can you check this again?