[TowerTalk] Radio Button IC?

[Charles Gallo]

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 at 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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