Other Parts Discussed in Thread: C2000WARE
Tool/software:
Hi experts
My customer is currently using the F280039C DSP for the R&D of the DAB project. There is a phase-shifting requirement for the control of the ePWM waveform. Initially, when using the phase-shifting register TBPHS for phase shifting, it was found that there would occasionally be abrupt changes in the ePWM waveform. After debugging, we learned that the main reason is that TBPHS does not have a shadow register, so its loading timing cannot be synchronized with those like tbprd and cmp. Subsequently, the up-down counting mode is adopted, and periodic interrupts are generated. Each time a periodic interrupt is entered, the values of CMPA/B are adjusted according to the phase value. The operations are as follows:
The test result is as follows:
After doing this, the phase-shifted waveform has changed. As shown in the blue waveform below, the yellow one above is the normal reference PWM waveform. The target waveform after phase shifting should be shifted by 90 degrees, with both frequency and duty cycle at 50%. However, in reality, changes have occurred as shown by the blue waveform, and we are not sure what is causing this. Could you please help provide guidance? Thank you!
