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TIDM-02000: CMPPSS RampGenerator, Resetting Ramp

Gokhan G.
Intellectual 590 points
Part Number: TIDM-02000

Hi,

I'm working on F280048. I'm investigating software of each PCMC phase shifted full bridge topologies. I'm implementing RAMP generator. Below is configuration for usage of internal CMPSS with Ramp generator.

I generate ePWM4 signals and it drives complementary at %50 duty cycle

I obtained below waveform when there is no signal applied to positive of high comparator;

I obtained below waveform when there signal is applied to positive of high comparator;

YELLOW: ePWM4A is HIGH at zero and LOW at PERIOD. I get LOW the ePWM4A using tripzone. It works as above.

GREEN: Comparator output HIGH signal

RED: External signal to comparator high Input

Everything works correct except that RAMPGenerator doesn't restart when TBCTR=PERIOD.

I got specific question as below.

As I drawed below, .

I set comparator as below;

 CMPSS_configRamp(CMPSS5_BASE,65535,263U,0U,4U,true);

I set SYNCPER signal as below;

 HRPWM_setSyncPulseSource(EPWM4_BASE,HRPWM_PWMSYNC_SOURCE_ZERO);

However, I need to ALSO restart count down operation of Ramp Generator from max level when TBCTR=PERIOD. However, I don't know how to do and also I didn't see any code at then TIDM-02000.

I got specific question as below.

1) Could you please copy and paste related lines to here at TIDM-02000? I don't know how this issue is managed at TIDM-02000.

2) Could you please explain how I can ALSO reset ramp when TBCTR=PERIOD in my code? Reset at TBCTR=Zero should remain in order to monitor rectified current sensor output in PSFB topology.

That means if current is lower than Ramp signal, Ramp signal continues to drop down to 0V and waits next TBCTR=Zero. But I need that ramp signal should restart even if it doesn't reach zero, it should restart when TBCTR=PERIOD.

3) CMPSS section of reference manual is really confusing. It say that HRPCTL isn't related to HRPWM registers. However, I configured the SYNCPER signal from HRPCTL, High Resolution Period Control Register.

You can review reference manual. If I didn't use EPWM4 with HRPWM feature, can't I use CMPSS to sync for ePWM4?

Thanks in advance.