# Digital input and find output questions

#### Benengineer

Joined Feb 6, 2016
133

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#### Benengineer

Joined Feb 6, 2016
133
The Four D flip flops, the front three D flip flops are positive triggle edge and last one is negative triggle edge.

Joined Mar 10, 2018
4,057
What is the state of all the flops prior to the first clock ?

Regards, Dana.

#### dl324

Joined Mar 30, 2015
13,082
Show all of your work.

#### Benengineer

Joined Feb 6, 2016
133
Show all of your work.
I just get this question and I don't know the previous condition. I guess we can assume a certain condition. My answer is the red graph in above.

#### Benengineer

Joined Feb 6, 2016
133
What is the state of all the flops prior to the first clock ?

Regards, Dana.
I don't know what it is exact state. I guess we can assume certain state. The red graph is my answer. I am not sure if I am right.

#### Benengineer

Joined Feb 6, 2016
133
Show all of your work.
The red graph is my answer and Y is output shown there.

#### dl324

Joined Mar 30, 2015
13,082
The red graph is my answer and Y is output shown there.
Your answer is wrong. If you show all of your work, we can see where you got off track.

#### Benengineer

Joined Feb 6, 2016
133
Your answer is wrong. If you show all of your work, we can see where you got off track.
Can you show what it is your answer?

#### dl324

Joined Mar 30, 2015
13,082
Can you show what it is your answer?
That's not the way homework help works. If we just give you answers, you can't learn from your mistakes.

The fact that I took the time to do the problem and told you that your answer is wrong should have been enough incentive for you to go back and check your work.

#### WBahn

Joined Mar 31, 2012
26,398
I don't know what it is exact state. I guess we can assume certain state. The red graph is my answer. I am not sure if I am right.
The only assumption you need to make, and it's a reasonable one, is that before the first clock edge in your diagram there was a reset event and each of the four flip-flops reset to the state indicated in the diagram.

From that point, track the output of ALL of the flip flops and determine what happens at each succeeding clock edge.

As already pointed out, you must show YOUR work. We will help YOU find any problems so that YOU can finish what is, after all, YOUR homework.

#### Benengineer

Joined Feb 6, 2016
133
That's not the way homework help works. If we just give you answers, you can't learn from your mistakes.

The fact that I took the time to do the problem and told you that your answer is wrong should have been enough incentive for you to go back and check your work.
Sorry. Here is my answer.

#### bertus

Joined Apr 5, 2008
21,524
Hello,

Could you add the traces for points A and B to your drawings?

Bertus

#### WBahn

Joined Mar 31, 2012
26,398
Sorry. Here is my answer.
View attachment 152553
That is not your WORK, that is your claimed ANSWER. How did you get it? Magic? Intuition? Reasoning? It's already been pointed out that it is wrong (though I haven't verified that personally). That's all the more we can tell you because that's all you've given us to work with.

You need to show your WORK -- which means the steps that you took to go from the diagram to the answer. That's the only way we can help you identify where you went wrong.

#### Benengineer

Joined Feb 6, 2016
133
That is not your WORK, that is your claimed ANSWER. How did you get it? Magic? Intuition? Reasoning? It's already been pointed out that it is wrong (though I haven't verified that personally). That's all the more we can tell you because that's all you've given us to work with.

You need to show your WORK -- which means the steps that you took to go from the diagram to the answer. That's the only way we can help you identify where you went wrong.

#### dl324

Joined Mar 30, 2015
13,082
A picture is worth a thousand words.

Look at the clock edges that your solution transitions on.

How can the two Y pulses transition on different edges of clk?

Last edited:

#### Benengineer

Joined Feb 6, 2016
133
A picture is worth a thousand words.

Look at the clock edges that your solution transitions on.
I don't know what you mean by Look at the clock edges that your solution transitions on. When it hits positive edge, it will change. Please point to specific edge.

#### dl324

Joined Mar 30, 2015
13,082
I don't know what you mean by Look at the clock edges that your solution transitions on. When it hits positive edge, it will change. Please point to specific edge.
The first pulse transitions on rising edges. The second transitions on falling edges.

#### Benengineer

Joined Feb 6, 2016
133
A picture is worth a thousand words.

Look at the clock edges that your solution transitions on.
View attachment 152562
How can the two Y pulses transition on different edges of clk?
Please see this pictures I did. It may be clear.

#### dl324

Joined Mar 30, 2015
13,082
Please see this pictures I did. It may be clear.
View attachment 152564
Your description is too difficult to follow. We use timing diagrams to convey that type of information.

Show the waveforms for all flip flops to show how you came up with Y.