On Sun, Sep 29, 2002 at 08:10:13AM -0400, Olin Lathrop wrote:
> > Olin, you do bring up an interesting point. If the duty cycle is set to 0
> > then does the output stay a flat low? Or does it glitch every cycle?
>
> I think the output will stay flat low.

That's good.

>
> > For this purpose it probably doesn't matter. I was still interested in the
> > TRIS register because it only required manipulating a single bit and not
> have
> > to track the value in the ducy cycle register.
>
> You only have to write two values to the duty cycle register, 0 for off and
> whatever you want the duty cycle to be for on.  Duty cycle changes won't
> take effect until the start of the next PWM cycle, but keeping track of
> whole carrier pulses is probably a good idea anyway.  I would assume you
> describe the various on and off times in numbers of carrier pulses anyway.

I hadn't planned to. 26.3 uS, the period of a 38 Khz carrier, isn't exactly
conducive to clean manipulation. I think that's probably the one advantage to
controlling the output buffer directly, precise turnon/turnoff without having
to wait until the end of the cycle.

BAJ

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