Other Parts Discussed in Thread: TMDSCNCD28379D
Tool/software:
Hello,
I am using the TMDSCNCD28379D control card for my application. I am also facing this issue where DBCTL registers seem to be getting updated in immediate mode (instead of the configured global shadow-to-active mode) which also leads to faulty circuit operation. I am updating the shadow registers only when certain if-else conditions are met and the EPwm signals generated are otherwise okay when DBCTL need not be updated.
Following is the EPwm Module Configuration:
For EPwm1-8, PHSEN is ENABLED, SYNCOSEL = SYNC_IN
The SYNCO is generated by EXTSYNCIN1 through INPUTXBAR5.
GLDMODE = 3 (shadow-to-active load when SYNC occurs),
GLD = 1 and GLDCFG[REGx] = 1 for REGx = CMPA, CMPB, DBCTL, DBRED, DBFED
Additionally, I have also enabled local shadow modes of these registers (DBCTL2, DBCTL, CMPCTL) just as a precaution.
SYNCO Generation:
I am using EPwm10 counter as a reference (its PHSEN and SYNC are disabled as it is a reference counter). When EPwn10[CMPB] reaches a certain value, an interrupt is triggered. In the ISR, the GPIO linked with INPUTXBAR5 is toggled to generate SYNCO.
DBCTL Shadow registers:
The shadow register values are updated in a different, lower priority ISR than the one above. My expectation was that the loading would occur upon subsequent SYNCO generation. However, the attached image seems to indicate otherwise. The magenta waveform is a toggled GPIO pin indicating when the shadow registers are updated in the code. The blue-green waveform is a DBCTL bit fed to the DAC and monitored on oscilloscope. We can see that soon after the GPIO is toggled, the DBCTL bit changes value, suggesting an immediate loading. The subsequent SYNCEVT occurs much later (the dotted cursor), evidenced by the changed duties of the PWM signals.
Kindly let me know if it is possible to configure DBCTL for proper global shadow-to-active loading with this micro-controller. I’m available for any further information you may need.
Thanks in advance for your time,
Tharun
