> -----Original Message-----
> From: Ian McLean [SMTP:ianmclean@OPTUSHOME.COM.AU]
> Sent: Wednesday, March 12, 2003 10:27 AM
> To:   PICLIST@MITVMA.MIT.EDU
> Subject:      Re: [a bit OT]: suggestions for a huge I/O capabilities
> microcontroller?
>
> Why on earth do you want a micro with over 70 I/O pins ?  You are much
> better off using multiplexer chips (many different ones to choose from)
> that
> can encode 1 to 16 lines (or more) into BCD or even serial/I2C over just
> two
> wires to the micro,  reducing the port count requirement on your micro
> very
> dramatically.  This is nearly always how I/O expansion is done on any
> micro.
> These devices can be cascaded to provide many more than 70 I/O ports if
> required.
>
> Building imbedded design solutions of any real significance usually
> involves
> using more chips than just the micro ;)
>
> Rgs
> Ian.
>
When you say multiplexer are you talking about a priority encoder? are
pretty useless for port expansion IMHO,


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