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From: email@example.com (Alan Fowler)
Subject: Re: I need an 8 to 256 decoder or equivalent
Date: Tue, 19 Nov 2002 11:21:23 GMT
Organization: Whitethorn Software
References: <7UjB9.9017$N02.firstname.lastname@example.org> <email@example.com> <firstname.lastname@example.org> <8R-cnRA7Wa8lI0ugXTWcqw@comcast.com>
NNTP-Posting-Date: Tue, 19 Nov 2002 10:19:53 +0000 (UTC)
X-Newsreader: Forte Agent 1.5/16.451
"David Jones" wrote:
>well, I don't know what the device your talking about is but price really
>doesn't matter for this project unless the parts are like hundreds of
>dollars. size is essential so I will consider. right now actually I need to
>go back and take a couple days to learn about digital electronics in general
>because I've been trying to take short cuts and am not getting very far. I
>think it would be more effective to learn the theory and theory of
>components before I try to build much.
>thanks for the help
Try using two four bit to 16 output decoders. can't
remember the part number, it's 20 years or so since I did
this sort of thing.
Connect the first to the top four bits, the second
to the bottom four bits, and you now have two lots of 16
outputs. Use these as an X-Y matrix, with a LED at each
>"Keith R. Williams" wrote in message
>> In article <email@example.com>,
>> firstname.lastname@example.org says...
>> > "Bertrand" schreef in bericht
>> > news:email@example.com...
>> > > Hi,
>> > >
>> > > > You would need seventeen 74xx154's. First, wire the bottom 4
>> > bits
>> > > > (let's call them ADDR3 thru ADDR0) to the '154's address inputs
>> > >
>> > > :\
>> > > It would use a lot of board-space; why not using a small
>> > > EPLD/FPGA/things-that-can-be-programmed ?
>> > Which small EPLD/FPGA/thing-that-can-be-programmed
>> > with 256 outputs do you recommend ?
>> A "little" overkill but the Virtex-Pro 2VP4 (FF672 package)or perhaps
>> two 2VP2s (FG256 package). There's all sorts of other toys in there
>> for blinkin' lights too.
>> Well they *are* smaller than 17 74XX154s and you didn't say you were on
>> a budget. ;-)
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