Asynchronous UP/DOWN Counter(T) - simple question.

[darthachill]

I try design simple, asynchronous UP/DOWN Counter Flip-Flop T. But I have problem with analysis

Counter counts : 0,1,2,3,4,5,6(SWITCH direction) 2,1,0...?
Why this is Happend, Why after switch direction ther is no 5 ,4,3 ?? All day i looking what is wrong, but I can't find any solution.
I appreciate any Help

 

[ronsimpson]

If this was a simple question you would have had an answer before now. lol

I don't like asynchronous counters. I like synchronous counters. It looks to me that when you rise SWITCH flip-flip 3 advances. Probably under some conditions other FFs will clock with SWITCH.

With a synchronous counter SWITCH can change state many times and nothing happens until there is a clock edge.