TMS320F28075: 3 ch of EXT SYNC IN

Hello,

Is this in regards to the EPWM external sync source lines? Can you explain the context of why you are needing 3 channels of external sync ins? Can you 'OR' the signals to route them all into the existing 2 external sync paths- if not, what is the desired sync scheme?

Best Regards,

Allison

Hello,

We need three separate sink inputs to achieve a specific goal of the team.

What we want to implement is,
We want to use the individual zero crossing points of the three inverter currents as sink inputs for the three PWMs. (We want to receive the zero crossing points of each current as sink inputs for the PWMs and control the PWMs according to the phases of each current.
Looking at the "Figure 15-8. Time-Base Counter Synchronization Scheme" of 28075, there are only two EXTSYNCINs, so I don't think we can simply implement the behavior we want.

We want to "control three PWMs individually by receiving three separate external sink inputs", but is it possible to implement it by combining various functions of the DSP?

Best Regards,

Hi,

Thanks for the follow up. Please allow another day for me to form my response. Appreciate your patience!

Best Regards,

Allison

Hello,

Thank you for the follow up. Ah I see, so you want each of the three EPWMs to have separate (and external) sync sources.

One option is you could leverage the digital compare submodule of the EPWMs. To do so, you could have three separate GPIO inputs (your three separate sync sources) routed in through the XBARs to the digital compare and use these as DCxEVENTs which can be used as sync sources for the EPWM. Below reflects the path (diagram from EPWM Digital Compare submodule TRM chapter). Please let me know if this seems feasible for your application.

Best Regards,

Allison

Thank you for your kind reply.

I will review the implementation of the function as you have informed me.

Best Regards,

Sounds good. I will await your update.

Best Regards,

Allison