PWM turn off

Sandhya Jetti

Other Parts Discussed in Thread: CONTROLSUITE

Hello all,

I ran into a problem and couldnt find a solution so far, wondering if you can help out.

When my external interrupt signal triggers on falling edge (yellow signal), i wan the PWM to turn OFF immediately. Looks like it waits half period more and this is very intermittent, a lot of times, it instantly turns off the PWM. i have attached a picture.

__interrupt void xint2_isr(void)
{
               EALLOW;
                EPwm2Regs.AQCTLA.bit.PRD = AQ_CLEAR;               //Stop +X pwm
            EPwm2Regs.AQCTLA.bit.CAU = AQ_CLEAR;

EDIS;}

Is there any register I can use to make sure to turn it off instantly at all times? Thanks in advance

over 10 years ago

0 Maria Todorova over 10 years ago

Guru 13185 points

Hello,
I have never checked it using osc, but how about if you use Trip Zone (TZ) modul?

Best regards,
Maria

0 Gautam Iyer over 10 years ago

Guru 192875 points

As Maria suggested... C2000 devices have a special functional division in ePWM module called "Trip Zones". These are meant for above kind of operations and are instant at turning the PWMs Off. You can find more details about the same in ePWM user guide itself and sample codes are available in controlSuite.

Regards,
Gautam

0 Sandhya Jetti over 10 years ago in reply to Gautam Iyer

Intellectual 535 points

Maria, thanks for your reply.

I explored the TZ option but chose to take the input signal as external interrupt and i have some extra code in that ISR.

Can anyone explain what is happening with that one extra PWM pulse?

0 quark over 10 years ago in reply to Sandhya Jetti

Expert 2220 points

Consider TZFRC. You can force a trip event from software (e.g., from ISR).
Also, consider TZEINT. You can cause an interrupt when a trip-zone is triggered.

So you have two ways to do this.
(1) Either keep your ISR the way it is but instead of changing PRD and CAU, just write to TZFRC.
(2) Or, use hardware trip-zone triggering and make that call a new ISR for all the other stuff you want done.

0 Sandhya Jetti over 10 years ago in reply to quark

Intellectual 535 points

Thank you quark, will give a shot with TZFRC registers .

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PWM turn off