All About Circuits Forum [Urgent] Design a counter with using D Flip-Flop
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#1
03-18-2009, 01:05 PM
 Astrokit New Member Join Date: Mar 2009 Posts: 1
[Urgent] Design a counter with using D Flip-Flop

The question is :
Design a counter that counts pulses on line w and displays the count in the sequence 0,2,1,3,0,2, ... Use D Flip-Flops in your circuit.

i wanna ask how to design this circuit?
What are the steps to design this circuit?
and What is the answer of this question?

the ans. of the expressions are D(input) of A = A XOR B and D(input) of B = not A??

thank a lot~ =]
#2
03-18-2009, 11:44 PM
 Papabravo Senior Member Join Date: Feb 2006 Location: Michigan, USA (GMT-5) Posts: 5,850

Write a Truth Table
Code:
``` A  B  |  P  Q
---------------
0  0  |  1  0
0  1  |  1  1
1  0  |  0  1
1  1  |  0  0```
Select All
Columns A and B represent the current Q-output state of each of the D-Flip-Flops
Columns P and Q represent the next Q-output state of D-Flip-Flops A and B respectively.
When you present the next Q-output state on the D-inputs, the sequence of states is:
Code:
`0 -> 2 -> 1 -> 3 -> 0 ...`
Select All
By inspection:
Code:
```P = .NOT. A
Q = A .XOR. B = (A .AND. .NOT. B) .OR. (.NOT. A .AND. B)```
Select All
P and Q could, of course, be any functions of two boolean variables, and the sequences would change accordingly.
[Question] What sequence do you get if you swap the functions for P and Q?

It's not rocket science after all, just boolean algebra.
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#3
03-18-2009, 11:51 PM
 wr8y Senior Member Join Date: Sep 2008 Location: Griffin, GA USA Posts: 232

Quote:
 Originally Posted by Papabravo It's not rocket science after all, just boolean algebra.
That Boolean guy was WAY ahead of his time.

But I still think Boolean Algebra is weird stuff.
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#4
03-19-2009, 02:07 AM
 Papabravo Senior Member Join Date: Feb 2006 Location: Michigan, USA (GMT-5) Posts: 5,850

Quote:
 Originally Posted by wr8y That Boolean guy was WAY ahead of his time. But I still think Boolean Algebra is weird stuff.
That's George Boole,

http://en.wikipedia.org/wiki/George_Boole

and I think Tensor Algebra, Riemanian Manifolds, Fractal Geometry, and Stochastic Calculus are way more wierd and complicated. Just my opinion -- I could be wrong.

http://en.wikipedia.org/wiki/Tensor_algebra
http://en.wikipedia.org/wiki/Riemannian_manifold
http://en.wikipedia.org/wiki/Fractal
http://en.wikipedia.org/wiki/Stochastic_calculus
__________________
We never have time to do it right,
But we always have time to do it over.

Last edited by Papabravo; 03-19-2009 at 02:12 AM.

 Tags counter, design, flipflop, urgent

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