# Counter Flip Flop Help Please!

[PLAIN]http://img713.imageshack.us/img713/853/98302269.jpg [Broken]

So I included the waveform I drew in the picture. The first one is the clock pulse, the second is the output from the T-flip flop on the left, and the third is the output from the T-flip flop on the right. I'm really not sure if this is right. What I did was treated the flip flop on the right like a normal T-flip flop, toggling on a high clock pulse, and then since that output is connected to a xor whose output is connected to the other T-flip flop (I didn't know what the X meant, so I assumed it was a high) so whenever the output from the right was low the left output would toggle, and whenever the output on the right was high the left output would remain unchanged.

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Gold Member
Seems like Q will change when T = 1. This means output #2 will change ever clock pulse. Output #1 will only change if x is different to Q of JK #2.

Ok so does that mean by wave for the second output is right? I think that's what I did.

Gold Member
From what you have drawn if the top one is Q2, second one is x and third one is Q1 then I don't think the third wave form is correct.

No the first is the clock pulse, second is Q1, third is Q2. I'm not sure what X is, I took it as always high, is it suppose to vary?

Gold Member
If x is always high then Q2 would change every clock pulse (since T2 is held high), and Q1 would change every time x and Q2 are different on a clock pulse.

[PLAIN]http://img204.imageshack.us/img204/4349/booh.jpg [Broken]

Edit: Hm I think I figured it out, when x is low it counts up, when x is high it counts down. If that's right the rest can be ignored.

Ok so for example this is when X is high. The first wave (on top) is the clock pulse, the second is Q2, and the third is Q1. Q2 toggles on every positive edge, and since X is high Q1 toggles when Q2 is low. I wasn't sure if Q2 being low means it was just low, or it turns low, but I took it to mean if Q2 were just low, then Q1 would toggle, is that what is meant?

Anyway, is this wave ok?

Or does Q2 rise on the first rise of the clock pulse because Q2 is low, so T on the left flip flop is high, and then it would lower on the 3rd rise of the clock pulse because Q2 was just low? Is that it?

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