Hi Paul,

>  Does this all make sense?  Or did you know it already?  I should be
> interested to know.

I understand most of what you are saying.  No, I think this is a very
good method.  I am in the midst of trying to gather up information
to pick the best structure for this particular project.  So far my
options seem to be:
        a) Pick another PIC - one with more I/O pins
        b) Mux the I/O pins
        c) Use I2C
        d) Serial transfer using shift registers (quasi I2C?)

Still undecided.  I really like the I2C method but the only thing
holding me back is that none of my devices have the I2C feature
(including the micro......I want to use the PIC16F84 because of
re-programmability).  I like it because future addons don't require
a complete re-think of the structure, but they can be plugged in
as a daughter board or external upgrade module (same thing really,
just different marketing terms)


>>                         2) The timer for PIC to PIC serial
>>                            communication
>
>  Not so easy.  You will see many threads recommending you stick to
> a "state machine" using the main program loop as the timing element!

Can you elaborate on the "state machine" ??????  I want to communicate
PIC to PIC via a serial two wire scheme (data & ground).  The
communication link may change to RF data modules in the future.


>>                         3) The timer for frequency measurement (20KHz
>>                            to 80KHz)
>
>  Not so easy at the same time as 2) above.  Depends on whether you want
> to measure frequency as such (count clicks over a second = easy) or
> period and do a division (both tedious!).

I want count the number clicks for a set time period.

Regards,

-Randie

/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/
*/ Randie Ohtsji                                                     /*
/* Glenayre R&D, Vancouver, BC  CANADA   Phone: (604) 293-1611 x4555 */
*/ Email: rohtsji@glenayre.com           Fax:   (604) 293-4317       /*
*/                ________                                           /*
/*               / ____/ /__  ____  ____ ___  _________              */
*/              / /___/ / _ \/ __ \/ __ `/ / / / __/ _ \             /*
/*             / /_\ / /  __/ / / / /_/ / /_/ / / /  __/             */
*/             \____/_/\___/_/ /_/\__,_/\__  /_/  \___/              /*
/*                ________________________/ /                        */
*/               /_________________________/                         /*
/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/