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Discussion Groups | TMS320C28x | Fuzzy in PWM waves

Technical discussions about the TI C28x DSPs (including the C2810, C2811, C2812, F2801, F2806, F2808, F2810,, F2811, F2812, R2811 and R2812).

  

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Fuzzy in PWM waves - Balasubramanian - May 9 6:54:32 2008



Dear all,

First of all, Let me thank this discussion group for being active and
accepted me as a member. I am new to DSP . Having following doubts in PWM
generation.

*1)*  If I generate PWM for the same frequency and duty ratio using Event
Manager A and Event    Manager B and observe the PWMS in scope, I saw that
the PWMs using EV B is phase shifted by 284ns from  PWMs using EV A. why
there is a differene of 284ns when I use the same frequency and duty ratio
for EV A as well as EV B?  I kept zero dead band. I didn't get any error
during compilation and building my program. Something fuzzy……….

Can any of you provide answer to me? Have you faced this kind in your
experience?

*2)      *To generate PWM with specific delay, how do I know having
particular number in for loop provide this much delay? For example if I use
for (i=0; i=25; i++) {},

How much delay will be introduced by this loop if I execute it in Event
manager subroutines?

I am eagerly waiting to know the answer for the above two queries from any
of you(experts).

Thank you all

Regards

Bala



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Re: Fuzzy in PWM waves - dotm...@gmail.com - Aug 30 14:39:42 2008


Dear all,
>
>First of all, Let me thank this discussion group for being active and
>accepted me as a member. I am new to DSP . Having following doubts in PWM
>generation.
>
>*1)*  If I generate PWM for the same frequency and duty ratio using Event
>Manager A and Event    Manager B and observe the PWMS in scope, I saw that
>the PWMs using EV B is phase shifted by 284ns from  PWMs using EV A. why
>there is a differene of 284ns when I use the same frequency and duty ratio
>for EV A as well as EV B?  I kept zero dead band. I didn't get any error
>during compilation and building my program. Something fuzzy���.
>
>Can any of you provide answer to me? Have you faced this kind in your
>experience?
>

this is normal, coz the two timers didn't start simultaneously. 284ns is the delay due to
instruction execution.

u may search for "how to synchronize timers" from old posts.
>*2)      *To generate PWM with specific delay, how do I know having
>particular number in for loop provide this much delay? For example if I use
>for (i=0; i=25; i++) {},
>
>How much delay will be introduced by this loop if I execute it in Event
>manager subroutines?
>
>I am eagerly waiting to know the answer for the above two queries from any
>of you(experts).
>
>Thank you all
>
>Regards
>
>Bala
>

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