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[crimsonheadGCN]

So I derived the following truth table for a 2 - bit synchronous down counter:

Flip Flop inputs
J1K1 J2K2
0 x 0 x
1 x x 0
x 0 0 x
x 1 x 0


x = do not care conditions.

Is it possible to have all Xs in the J2 and K2 part equal to 0? (like the following:
J1K1 J2K2
0 x = 0
x = 0 0
0 x = 0
x = 0 0

If so, how would the logic equation look like if it was all x = 0?

 

[crimsonheadGCN]

Anyone?

 

[rastex]

If it's a don't care then why wouldn't it work if you set the X's to 0's, and why not figure out the logic equation yourself?

 

[firebricks3]

I don't see why J2 and K2 couldn't be all zeroes, assuming this down counter doesn't have any orphan states.

 

[firebricks3]

Also, if both J2 and K2's equations were both zero, i'd imagine you would only have to hook both up to ground.