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santumevce1412



Joined: 08 Jan 2008
Posts: 24
Post02 Oct 2008 6:53   updown counter
Design a 2bit up/down counter with clear using only with gates

Pls dont write verilog or vhdl code...
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wudanyu



Joined: 02 Oct 2008
Posts: 4
Post02 Oct 2008 14:17   updown counter
try google image search engine
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vtmc



Joined: 05 Sep 2008
Posts: 6
Helped: 1
Post02 Oct 2008 20:21   Re: updown counter
My idea is:

First, a DFF with its reverse output feeding back into its data input forms a frequency divider by two.

Put two such divider in serial gives you a two bit counter, counting in one direction (the data output of 1st DFF should be connected the the 2nd DFF, and both DFF's data output will be the 2 bits output of the counter).

Reset should be connected to both DFF's reset.

To make it counter backward, my suggestion is to invert the output (so that 00 01 10 11 will be 11 10 01 00).
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svicent



Joined: 11 Jul 2001
Posts: 405
Helped: 20
Post02 Oct 2008 22:22   Re: updown counter
Equations:

Q0 = CLEAR' Q0'

Q1 = (CLEAR' UP' Q1' Q0') + (CLEAR' UP' Q1 Q0) + ( CLEAR' UP Q1' Q0) + (CLEAR' UP Q1 Q0')

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Prototyp_V1.0



Joined: 03 Apr 2007
Posts: 62
Helped: 9
Location: Norway
Post15 Oct 2008 1:42   Re: updown counter
Here is a 4 bit counter. No problem to remove the two lower flipflops to get a 2 bit counter.

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