Hi team,
My customer is using F28035 in their current platform. Here is a problem they encountered in their system. And we would like to find out whether we have a good solution with new Type 4 PWM on F28004x.
Assumming PWM1 and PWM2 (corresponding to PWMA & B in the figure) are 2 PWM channels with same PRD and 180 degree(PHS=1/2 PRD) phase shifting. And two channels synchronize at PWM1 CNT=0.
1. When it works normaly at fixed frequency(assuming PRD=100), PWM2 CNT=PHS=50 when synchronization happens at PWM1 CNT=0. If PWM toggles at CPMA=60, obviously, we can get the PWM waveform we want since both channel CNT will reach 60.
2. However, if the frequency changes to PRD=150. At PWM1 CNT=0, PWM CNT will jump from 50 to 75 since synchronization happens. If the CPMA happens to be in the range 51-74, then the CNT will not reach CMPA in this period, thus the PWM action will not happen. In other word, the PWM wave on PWM 2 will lost.
The ideal way to solve this problem is to be able to config the PWM to toggle when CNT>CMPA rather than CNT=CMPA. Since I know we do not support such configuration on C2000, I am writting to ask your opinion on this problem. I believe this is a common problem in changing frequency scenario, and our team did some important optimization on F28004x type 4 PWM for this application. Please kindly share your comments.
