On Wed, 12 Dec 2001, Bala Chandar wrote:

> Roman Black wrote:
>
> > Hi Bala, I didn't claim to do anything magic,
> > just that it worked without needing another
> > chip. :o)
> >
> > What you require above is an interesting
> > challenge. You have 27 separate signals that
> > you want to connect to 16 pins? Wow.

    I don't want to be crude, BUT you may connect almost all directly to
the chip with a good hw design. Not 27 but probably 20...25.
Think a little, you don't have too many LEDs? One bicolour led ( two pic
pins ) could signalise a lot of states with different colours/blinking
modes.Why you need 7 seg AND leds ? Can't you do it only on 7seg display ?
9 buttons AND 8 relays coud be connected on 6+1 pic pins using a
simple 3 to 8 decoder and a 3 x 3 matrix for buttons. That +1 pin is
available also for other jobs. I don't remember exactly your input
requested parameters but often when you need serial/parallel extra devices
is definitely the sign you must change to another microcontroller.
( excep designs dealing with dosens of relays and thousents of leds )
regards,
Vasile

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