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Trip Zone test with Comparator input for Sine-wave generation

Other Parts Discussed in Thread: CONTROLSUITE, TMS320F28035

Hi,

In the example "epwm_dcevent_trip_comp" under TMS320F28035 from ControlSUITE, it shows how to generate and  trip the epwm signal based on the result of the on-chip comparator.

I am just wondering how to use this technique to generate and trip a sinusoidal-wave (by epwm) instead of a regular square-wave (by epwm) which is the one used in the example.

I know how to generate a sine-wave by using a look-up table from IQmath library. Basically, I just use the table to calculate and update the counter-compare value(CMPA) during each ePWM interrupt.

I tried to use the same method to modify the example which uses an ePWM Trip Zone interrupt. It didn't work. It didn't give a time-varying-duty-cycle epwm signal.  It seems like it was not able to update the CMPA value.

Maybe I have some incorrect understandings of the trip-zone interrupt ? or this example?

Really need your hlep.

Thank you,

Frank