We are using a Comparator to generate a sync event and force the PWM counter to start at zero on an F28035.
The PWM is forced high at zero and forced low at compareA upcounting (pwm counter is upcounting).
To avoid additional sync events after the first one, we added the Digital Compare Event Filter / Blanking Window.
The filter starts at counter=zero, without offset.
The problem is that "sometimes", the filter does not seem to work. In that case, the sync event is generated permanently as long as the comparator is active, so the PWM counter is kept at zero and the pwm pulse is longer by the length of the comparator.
To verify this, we generated a PWM interrupt at zero which toggles a GPIO.
red: current
green: comparator output
blue: PWM zero interrupt GPIO
It seems as if the DCEVT filter has no effect - we get pwm zero interrupts as long as the comparator is active.
The filter blanking window DCFWINDOW is set to 100 (= 1.666 usec @ 60MHz), so the "Blanking Windows can NOT overlap" problem
( https://e2e.ti.com/support/microcontrollers/c2000/f/171/t/450130 ) should not occur here.
In a second image, you see that the PWM on time is suddenly longer by the amount of the comparator on time (compare value identical), obviously caused be the sync event(s) during comparator high:
green: comparator
yellow: PWM
Any help on how to get the Digital Compare Event Filter / Blanking Window to work correctly is appreciated.
Stephan