I would love to see more about your project.  I am looking at using an old
floppy controller for a stepper which would only use 2 pins.  I am actually
feeding show lambs.  I already have four chutes with gates and a motor to
open them.  My current plan is to use a rotary feeder type arrangement
activated with a relay and positioned with a microswitch.  The stepper will
be used to deliver the feed to the proper chute.

I probably have enough IO, there is just all those bells and whistles that I
start wanting as this thing evolves.
Another PIC like the F628 might be used for version 2.  But I am getting in
a bind to finish.

Are your LED digits, single LED's or 8element?  I need to be able to set the
clock and quantities, I may resort setting the clock by making it where it
has to be powered up at a certain time.

How did you multiplex the LeD's

Thanks

-----Original Message-----
From: pic microcontroller discussion list
[mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Pic Dude
Sent: Wednesday, May 15, 2002 12:16 PM
To: PICLIST@MITVMA.MIT.EDU
Subject: Re: [PIC]: Multiplexing - multipurpose IO


That's weird -- I'm doing the same.  Using a 16F872 for
the greater number of I/O pins, and cause I have some of
them  laying around.  Why not use one bigger chip instead
of two?  The other reason I'm using the F872 is cause
it was a fairly simple and straightforward wiring change
to get my 16F84 programmer to program the F872's.

BTW, there are a lot of responses coming your way re: why
you should use the F628 instead of the F84A.  :-)

My circuit consists of 4 LED digits for a clock and info
display, and 3 buttons -- mode, up and down.  The friend
with whom I'm working on this has many animals (turtles,
cats, fish, etc) and so may have different types of
feeders.  For now, one of them will have a stepper motor
with its own controller, so I just need to provide a
pulse for each "unit" of feed quantity.  This I'll do
through a relay.  However, I have some extra pins that
I may need to put into use as a stepper motor controller
if we decide to do that later.

The LED's are multiplexed, there is no need to mux the
switches, and I would avoid multiplexing anything like
a relay.  You can get away with multiplexing LED's due
to persistence of vision, but you'd need to understand
the effects of what a pulsing relay output for example
would do to your feeder.  There are too many PICs with
more IO out there to bother with this option, unless
you have another good reason.

Cheers,
-Neil.




-----Original Message-----
From: pic microcontroller discussion list
[mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Rex Byrns
Sent: Wednesday, May 15, 2002 11:40 AM
To: PICLIST@MITVMA.MIT.EDU
Subject: [PIC]: Multiplexing - multipurpose IO


From a Newbie.

I am building an animal feeder that will dispense certain amounts of feed
several times a day.
I am using a 16f84a.  I am looking for a way to use outputs as momentary
switch inputs.
For example, I would like to use an output that turns on a relay, to also
read switch closures/openings to increment the number of rotations of the
feeder to give more food and use a button hold (i.e. 3 seconds) to reset
count to zero.

Is this a case for maybe 2 pics or can it be done fairly simply?

Thanks
        Rex

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