Digital I/O Expansion

[David Andrews]

I have to expand i/o on a system that now has only 4 inputs and 4 outputs.
I need 12 inputs and 13 outputs.

Anybody got any ideas, i thought this would be easier.
Im familiar with the '249 output latches '151 and input multiplexors
but cant seem to get what i need... ?????

 

[Dan Hollands]

Hard to offer any advice when you give no clue as to the type of system you
are talking about
Computer
Data Logger
Controller of some type
etc

--
Dan Hollands
1120 S Creek Dr
Webster NY 14580
585-872-2606
QuickScore@USSailing.net
www.QuickScoreRace.com
"David Andrews" <dsandrews@verizon.net> wrote in message
news:tpS7f.9607$%A1.9383@trndny01...

I have to expand i/o on a system that now has only 4 inputs and 4 outputs.
I need 12 inputs and 13 outputs.

Anybody got any ideas, i thought this would be easier.
Im familiar with the '249 output latches '151 and input multiplexors
but cant seem to get what i need... ?????

 

[David Andrews]

Dan,

It is a small embedded controller. I have to design an interface board
anyway.
Problem is mainly with the outputs now. I cant figure out how to expand the
4 into a greater number.
Im am not worried about the software end of it..



"Dan Hollands" <dhollan3@rochester.rr.com> wrote in message
news:g268f.108488$7b6.26987@twister.nyroc.rr.com...

Hard to offer any advice when you give no clue as to the type of system
you
are talking about
Computer
Data Logger
Controller of some type
etc

--
Dan Hollands
1120 S Creek Dr
Webster NY 14580
585-872-2606
QuickScore@USSailing.net
www.QuickScoreRace.com
"David Andrews" <dsandrews@verizon.net> wrote in message
news:tpS7f.9607$%A1.9383@trndny01...
I have to expand i/o on a system that now has only 4 inputs and 4
outputs.
I need 12 inputs and 13 outputs.

Anybody got any ideas, i thought this would be easier.
Im familiar with the '249 output latches '151 and input multiplexors
but cant seem to get what i need... ?????

 

[Bart]

"David Andrews" <dsandrews@verizon.net> wrote in message
news:7yc8f.14224$%A1.10257@trndny01...

Dan,

It is a small embedded controller. I have to design an interface board
anyway.
Problem is mainly with the outputs now. I cant figure out how to expand
the
4 into a greater number.
Im am not worried about the software end of it..



"Dan Hollands" <dhollan3@rochester.rr.com> wrote in message
news:g268f.108488$7b6.26987@twister.nyroc.rr.com...
Hard to offer any advice when you give no clue as to the type of system
you
are talking about
Computer
Data Logger
Controller of some type
etc

--
Dan Hollands
1120 S Creek Dr
Webster NY 14580
585-872-2606
QuickScore@USSailing.net
www.QuickScoreRace.com
"David Andrews" <dsandrews@verizon.net> wrote in message
news:tpS7f.9607$%A1.9383@trndny01...
I have to expand i/o on a system that now has only 4 inputs and 4
outputs.
I need 12 inputs and 13 outputs.

Anybody got any ideas, i thought this would be easier.
Im familiar with the '249 output latches '151 and input multiplexors
but cant seem to get what i need... ?????





Would a binary to decimal decoder work? Program the four outputs to

be 4bit binary numbers and end up with 16 outputs?
Look at truth table for Fairchild's DM74LS154 chip.
Bart

 

[Jasen Betts]

On 2005-10-26, David Andrews <dsandrews@verizon.net> wrote:

I have to expand i/o on a system that now has only 4 inputs and 4 outputs.
I need 12 inputs and 13 outputs.

Anybody got any ideas, i thought this would be easier.
Im familiar with the '249 output latches '151 and input multiplexors
but cant seem to get what i need... ?????

use two of your pins one to clock and one to sense state zero on a counter
that gives you a sequential address scanner...

your 6 remaining lines are inputs and outputs to those addresses.

--

Bye.
Jasen