On Thu, 9 Aug 2001, Alan B. Pearce wrote:

> >Based on this, I simply don't understand the F84 fixation.
>
> because from an earlier reply to one I suggested the 16F627/8 he already has
> a number of them.
>
> The way to do it without having the CCP is to use the INTR input to start
> the timer on the rising edge of the waveform, change the edge sensitivity to
> falling edge, on the next interrupt save the timer count and set the edge
> sensitivity back to rising edge. Initialise the timer ready to start
> counting again on the next interrupt. The value you have saved is the pulse
> width.

If you want a software PWM routine that has single instruction cycle
resolution then check out:

http://www.dattalo.com/technical/software/pic/pwm256.txt

It can be configured for pulses 256 or 4096 cycles wide. It works.
I've used and others have used it too.

I suppose one could convert it into a servo controller. But special
care must be taken to ensure the code is isochronous.

Scott

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