TMS320F28375S: Effect of AQCSFRC on PWM interrupt serving time

Shreni P

Part Number: TMS320F28375S

Hi team,

Does continuous software forcing in Action Qualifier(AQCSFRC) for a certain period of time effect the same PWM interrupt serving time?

I have been continuously software forcing Action qualifier output for half a power cycle, and I have copied TBCTR value at every start of the same PWM interrupt.

I observed TBCTR value sometimes starting from a value in between 200-400.

But when I have software forced only for the first time of zero crossing, this issue has not been observed. So, Please clarify me if it is this continuous software forcing that is causing delay in interrupt serving?

Thanks,

Shreni. P

11 months ago

0 Ryan Ma 11 months ago

TI__Genius 11106 points

Hi Shreni,

What do you mean by continuous software forcing? Have you instead looked at using the trip zone submodule? How are you generating your interrupt, are you using event trigger?

Best,

Ryan Ma

0 Shreni P 11 months ago in reply to Ryan Ma

Prodigy 90 points

Hi Ryan,

1) Continuous software forcing in the sense I have been setting EPwmxRegs.AQCSFRC.bit.CSFA = 1 in every 125us for 10msec. I am doing this to avoid any contention that can be caused with shadow to active loading of CMP=0 at TBCTR = 0(As mentioned in TRM). While using this, I sometimes observed delay in the interrupt serving time.

Instead of above, when I set the same only at the first instant of zero crossing, I didn't observe the delay mentioned above.

2) I didn't use Tripzone submodule. I only want to forcefully turn off a switch at zero crossing to avoid the above mentioned contention.

3) Yes, I have used Event trigger. Interrrupt shall be served at every second event of TBCTR= 0

Thanks,

Shreni. P

+1 Ryan Ma 11 months ago in reply to Shreni P

TI__Genius 11106 points

Hi Shreni,
Here are some threads that may answer your question that you are describing. Please let me know if you have further questions.

https://e2e.ti.com/support/microcontrollers/c2000-microcontrollers-group/c2000/f/c2000-microcontrollers-forum/762744/ccs-tms320f28379d-action-qualifier-continuous-s-w-force-aqcsfrc-register-and-pwm-first-pulse

https://e2e.ti.com/support/microcontrollers/c2000-microcontrollers-group/c2000/f/c2000-microcontrollers-forum/739046/tms320f28035-about-aqcsfrc-activate-latency

Shreni P said:
Does continuous software forcing in Action Qualifier(AQCSFRC) for a certain period of time effect the same PWM interrupt serving time?

The PWM interrupt serving time should be independent of the AQCSFRC, if you are seeing this could you provide a scope shot and provide any basic configuration of said output?

Best,

Ryan Ma

0 Shreni P 10 months ago in reply to Ryan Ma

Prodigy 90 points

Hi Ryan,

I found the issue is not because of AQCSFRC but it is another peripheral's interrupt that is effecting PWM interrupt serving time. Thanks for your time.

Thanks,

Shreni. P

C2000™︎ microcontrollers

C2000 microcontrollers forum

TMS320F28375S: Effect of AQCSFRC on PWM interrupt serving time