> -----Original Message-----
> From: Trevor Page [SMTP:trevor.page@PACE.CO.UK]
> Sent: Thursday, August 01, 2002 3:55 PM
> To:   PICLIST@MITVMA.MIT.EDU
> Subject:      [PIC]: Expanding PIC I/O
>
> Hi list.
>
> I have an application where I need to generate a relatively large number
> of
> (slow) PWM signals. I'm not sure how many at the moment, but we could
> assume
> this number would far exceed the number of available IO on a PIC.
> Actually,
> the fact that it is PWM is probably not relevant. Let's just say that I
> need
> to expand the IO of my PIC. I don't need bi-directional IO. All I want to
> do
> is generate a large number of PWM signals, which will be low-pass filtered
> to get some crude analogue control voltages.
>
> The most obvious solution to me at the moment is through the use of a
> number
> of octal / hex latch ICs, such as the 40174. On the other end of the
> scale,
> I could use a Xilinx CPLD if I wanted to go mad (and needed the speed,
> which
> I don't).
>
> Can anyone suggest their own favourite solution for expanding IO on a PIC,
> to get a large number of digital outputs? Any particular device I should
> consider looking at?
>
> Thanks in advance,
>
> Trevor.
>
You could consider another PIC that is dedicated to the PWM and has a
two/three wire interface to your main controller.

Regards

Mike

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