> First you must have a method to put the PWM output
> on/off. The AP note uses the TRIS bit of RB4 for this.
> Probably OK.

You think the tristate should be flipped eh?  Why not just use the duty
cycle as a switch? You have a preference I take it?

>
>
>>If that's the case,  then how would you go about doing that?
>>Would this require a second timer that runs at some "baud rate"
>>that pulls data from a  register and sends it out the pwm?
>
>
> You don't have to tie up a hole counter for this, just
> another software counter.

A counter is a counter though.

>
> Note that each "bit" wil be a specific number of periods of the
> PWM signal. So you can just as well count the number of PWM
> periods output and, when the correct number is reached, just
> shut of the PWM output.
>
> This can be done easily by using the "overflow interrupt" of the
> timer controling the PWM module. In the ISR you then just
> decrement a counter and, when it reach zero, shut the PWM output
> off.

I like that idea.  I'll look in to it some more.

Thanks.

-Shawn


> Using this method it's also easy to get clean on/off so you
> always gets whole and clean PWM pulses. You could either also
> control the "on" of the PWM in the ISR, or just monitor the
> "timer interrupt flag" somewhare else in your code.
>
> I used this concept in an IR sender using the PWM module to
> produce the 38Khz carrier, and using sequences of PWM
> pulses of different length to idicate "start", "1" and "0" bits.
> Looks very much the same as this application...
>
> Jan-Erik.
>
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