dc flip flop probs..

[cyborg0 at GlobalEyes.net]

Ok.. I have been working on this encoder circuit.. it *seems* to work
pretty well, but I have one problem: sometimes while it goes into the
detent position it triggers the opposite direction and it stays on...

I *think* it may be related to something I read in the ttl cookbook
chapter on flip flops..

There is a section that says that you should NOT have a status change on
D when C (clk) is high.. Of course, the way the encoder knobs works is
that when turning CW, D = 1 ..
Then, C transitions to 1 which reads D=1 into the flop. Next, C=1 when D
transitions to zero. Could this be causing the intermittent
mis-triggering? I personally have never heard of this nor have any of my
colleagues at work, but...Anyone else heard of this or had a problem
with this?

I guess I could use a seperate edge trigger using another gate, but I
would like to avoid doing this.


Rob