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From: "red rover"
Subject: Re: Help Please!
X-Newsreader: Microsoft Outlook Express 6.00.2800.1106
Date: Wed, 25 Sep 2002 20:10:37 -0400
NNTP-Posting-Date: Wed, 25 Sep 2002 20:05:37 EDT
Organization: Bell Sympatico
I would say that it is an impressive 4th year assignment. When I was
in school it took until the end of 3rd year to start "thinking"
and even then many things that seem so obvious now were difficult to
grasp. I would agree with the 3 weeks estimate.
To get you going in the right direction I would suggest you look at prior
and learn some of the jargon. The user-loadable value may be termed "preset"
or "jammable" inputs. In the old days (pre-fpga and asic) such devices were
widely used building blocks so take a look at a datasheet like the 4029
This has a schematic for an up/down counter with both decade and binary
I'm not familiar with CircuitMaker but my guess is that it will take you at
least 3 hours
to stare at this circuit, try and think how it works and enter it into
making any errors. But you'll learn alot just thinking about how this
I recall this is an synchronous design so you'll have to alter that.
I assume you made a mistake in your modulo 12 comments. If the counter can
from 0-12 then it really is a modulo 13 counter. Modulo 12 would be 0-11.
I assume that the display is in decimal format and the first digit is 0 or 1
as you state
but the second digit would be 0-9 (not 0-12). Is that correct?
Now you would need to decode the maximum desired count and use that to clear
the counter (ie: if you are counting 0-11 then decode 11 and do a
synchronous clear). Tricky with an updown counter but since the cd4029 can
be both a decade or BCD counter that will give you clues as to how to solve
this. This is tricky because if your
counting down you don't want to keep going from 0-11-0-11-0-11.
Now to do the 7 segement display check out a BCD-to-7 segment display chip.
Say the CD4511...
It shows how that chip solved the problem.
You may have to modify this for your application but you get the idea.
Truth table, karnaugh map reduction, combinational logic...
As the slogan goes on that old TV show "Math-net", an educational spoof of
"Cogitate and Solve".
"j.b. miller" wrote in message
> That's quite an impressive 1st year assignment. Are you talking High
> university or college ? Obviously the teacher has great faith in your
> ability to do such a task.
> I suggest you spend some honest time figuring out how Circuit maker really
> works and start with small parts of the 'puzzle'.
> From past experience, something that should take 3 hours , probably will
> take 3 days or 3 weeks. Case in point ,tossing in a 40Gig drive. No matter
> what settings I use 2 different computers refuse to see it.And I've got 30
> years of 'pc' knowledge.
> There may be a user's group for the software you're using, that may be a
> place to start, or the manufacturer !
> Asking someone else to do your homework is not polite or proper. Besides
> once you know how it works, you'll be in a better position than the rest
> the class !
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