TMS320F280039C-Q1: Any difference between two ways to update the phase shift in PWM

Shuqing Zhou

Intellectual 1745 points

Part Number: TMS320F280039C-Q1

Tool/software:

Hi experts,

I ask this for my customer.

My customer has two ways to update the phase shift of two PWM.

1. Fix the time of updating the TBPHS, if they want to modify the phase-shift value, they will modify the value of TBPHS

2. Fix the value of TBPHS, but modify the updating time. They use TBCTR=COMPC to generate the sync pulse, and in the sync time, they will change the COMPC to change the sync time.

Now they want to check:

1. Is any difference between two ways to change the phase-shift value? Which way is recommended?

2. Is it have possibility to miss the pulse in these two ways?

BRs

Shuqing

3 months ago

0 Allison Nguyen 3 months ago

TI__Mastermind 23230 points

Hi Shuqing,

Both ways can be used. In my experience, developers have run into issues when updating their TBPHS at various locations when consistently updating their TBPHS and/or action qualifier events (CMP values). Consider if their action qualifier events (CMP values, etc) constant, or being updated. If being updated, when? I would recommend changing the value of TBPHS rather than changing where TBPHS This way, the TBPHS is always updated at the same time and you will be able to know what TBPHS is in regard to CMP values.

In either case, the developer should be aware of what the TBPHS value is, when it is going to be loaded/applied to the PWM, and where this timing is in reference to their action qualifiers. Issues of a missed actions/edges can occur if their TBPHS is loaded and skips over the action qualifying event. I've described this in past threads as well, and included a workaround that generally covers simple cases. Please refer to these:

Best Regards,

Allison

C2000™︎ microcontrollers

C2000 microcontrollers forum

TMS320F280039C-Q1: Any difference between two ways to update the phase shift in PWM