Would a 74147 work for the encode side? 1 of 10 in, gives you bcd out, then
feed to a 7442 to go back to the 10. Of course, the other families of chips
should work too
On May 1, 2013, at 10:27 AM, Jim Lux <jimlux@earthlink.net> wrote:
> On 5/1/13 6:54 AM, Mike wrote:
>> Hello,
>>
>> Is there a single IC that will provide the same functions as the old car
>> radio buttons?
>>
>> Building a direction selector for an eight direction receiving antenna
>> system and would like to use push buttons to select the direction. Desire
>> is to have the first button pushed to lock out the other buttons should two
>> or more buttons be push at nearly the same time. Something similar to the
>> way the station selector buttons worked on old car radios.
>>
>> An arrangement using several discrete ICs has been worked out, but would be
>> nice to have a single IC do the same thing. I've looked through several
>> parts supplier catalogs, but haven't found an IC that seems to do the
>> functions as the old car radio buttons.
> If you don't want to use the mechanical approach (which IS still available,
> by the way)..
>
> I don't know how much design and construction you want to do.. (e.g. there
> are off the shelf industrial PLCs that might do this).
>
> Assuming you're thinking in terms of Normally Open Pushbuttons and LED
> indicators..
>
> You'll need a programmable part, since there's no off the shelf "1 of N"
> latching selector. The basic selector logic could easily be programmed in
> the smallest CPLDs, but the tools aren't necessarily easy to get started with
> or cheap. And, as you've noted, It's not trivial to do with 1 or 2 MSI parts
> like a '148 8:3 priority encoder, a 3:8 '138 decoder and some sort of latch.
>
> So that pushes you to something like a microcontroller (AVR, PIC, etc.). If
> you have a software dev background, you have a wealth of options to choose
> from.
>
> If I didn't have anything, and was starting from scratch, this is the ideal
> application for an Arduino or Teensy (or other microcontroller).
>
> You don't need any special prom/PLD programmer, just a USB port on your
> computer (any OS). The Arduino Uno is available at Radio Shack (and a
> gazillion other places). The Teensy3 is available from pjrc.com or
> adafruit.com etc.
>
> The code to do it would be easy to write. The Arduino environment is easy to
> learn if you don't come from a software development background (umpty
> gazillion middle and high school students doing science projects can't be
> wrong). The code may not be the finest or most efficient or make a CS major
> happy, but usually it works, and if it doesn't it's easy to change.
>
> There are off the shelf boards that plug into Arduinos for the interfaces..
> push buttons, LEDs to light up, relay boards, etc. take a look at
> sparkfun.com or adafruit.com for a starting point. Once you know the keywords
> to search for, google is your friend.
>
> 8-10 buttons and LEDs is easy.
>
>
> If you want to go the CPLD route.. you might talk to the faculty at a local
> community or 4 year college. Your project is quite typical of a class
> assignment in "introduction to digital logic using FPGAs" so you might find
> someone willing to do it, and make the parts, etc. as a "senior project" kind
> of thing.
>
>
>
>
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