# Analyze sequential circuit

#### mo2015mo

Joined May 9, 2013
157
Hi guys ,

I have been having problem with the attached question (fig 1), I have tried to solve it as attached figure 2,

Is this solution correct? IF Not ..why and what the correct solution..

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#### LDC3

Joined Apr 27, 2013
924
Since B0 is always 1, then you can remove every other row in your state table. Why have it in there if it is not needed. You should state that B0 is always 1 before the table so the professor will know why it is not included in the table.

Since Q = B1, whenever Q is different from B1 as in the 7th, 8th, 15th, and 16th state, what will happen? What should you say on the table?

#### mo2015mo

Joined May 9, 2013
157
Since B0 is always 1, then you can remove every other row in your state table. Why have it in there if it is not needed. You should state that B0 is always 1 before the table so the professor will know why it is not included in the table.

Ok, i remove it.(see attached fig 3)

Since Q = B1, whenever Q is different from B1 as in the 7th, 8th, 15th, and 16th state, what will happen? What should you say on the table?
How different ?? Q = B1

I filled next state Q(t+1) by characteristic table for JK-flipflop

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#### LDC3

Joined Apr 27, 2013
924
What I am saying is that since Q (an output) sets B1 (an input) to the same level, how can you have B1 as 0 when Q is forced to 1 since J is 1 ? What happens then ?

#### mo2015mo

Joined May 9, 2013
157
What I am saying is that since Q (an output) sets B1 (an input) to the same level, how can you have B1 as 0 when Q is forced to 1 since J is 1 ? What happens then ?
it is toggling command

#### mo2015mo

Joined May 9, 2013
157
Really did not understand.. Please explain more

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Last edited:

#### LDC3

Joined Apr 27, 2013
924
OK, now that we established that the output Q toggles, that is then written in the state table. Does the toggling effect any other outputs (A>B, A=B) ?

#### mo2015mo

Joined May 9, 2013
157
OK, now that we established that the output Q toggles, that is then written in the state table. Does the toggling effect any other outputs (A>B, A=B) ?
yes , because B1 = Q and B0=1

#### LDC3

Joined Apr 27, 2013
924
Do the outputs toggle continuously, or does a steady state develop ? If it toggles for more than 10 cycles (depending on the number of states), I would probably say it was continuously.

#### mo2015mo

Joined May 9, 2013
157
yes, the outputs toggle continuously
i have written all the probabilities of the output in the state table

Use Don't care ?

#### mo2015mo

Joined May 9, 2013
157
Where the wrong in the state table ?? J-k Column or Q(t+1) Column or external output??

#### LDC3

Joined Apr 27, 2013
924

#### mo2015mo

Joined May 9, 2013
157
Just saying that the output toggles would be good enough.
ok ,i.e. my solution (fig3) is correct

#### LDC3

Joined Apr 27, 2013
924
yes, it's correct