7410 and 7400 nand gate question

Thread Starter

bdogpot

Joined Nov 29, 2013
10
this is what my finished project looks like. it binary counter, when all of the inputs are zero and the 5th in put k = 0. It will add one to the count so instead of getting 0000 you get 0001. and when k = 1, it adds two to the count so instead of 0000 you get 0010.
 

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WBahn

Joined Mar 31, 2012
29,976
What you have is not a counter. A counter is a state machine, which requires a means of maintaining state (i.e., memory), which requires sequential circuits, which require feedback. You have a purely combinatorial circuit so the output is purely a function of the five inputs. Give the same five inputs and you will get the same four outputs.
 

Thread Starter

bdogpot

Joined Nov 29, 2013
10
Your right to a T that is not the exact definition of a counter. I misplaced my words. But it is adding a 1 or 2 logically depending on k being on or off.
 

Thread Starter

bdogpot

Joined Nov 29, 2013
10
If you have N3, N2, N1, N0 as 0000 it would display M3, M2, M1, M0 as 0000. But when k is introduced as a 0 it will add a 1 so instead of M being 0000 its 0001. When k = 1 it adds 2 to M so instead of 0000 its 0010. Any thing above 1111 for M is don't cares.
 

WBahn

Joined Mar 31, 2012
29,976
If you have N3, N2, N1, N0 as 0000 it would display M3, M2, M1, M0 as 0000. But when k is introduced as a 0 it will add a 1 so instead of M being 0000 its 0001. When k = 1 it adds 2 to M so instead of 0000 its 0010. Any thing above 1111 for M is don't cares.
This makes NO sense!

The input k has to be either a 0 or a 1. It can't be anything else. So when you say, "If you have N3, N2, N1, N0 as 0000 it would display M3, M2, M1, M0 as 0000" is that with k=0 or k=1? It has to be one or the other. But, whichever it is, that will be in conflict with what you say it will display when k=0 and when k=1.

And it tells me nothing about what the circuit is supposed to do when N3,N2,N1,N0 are anything other than 0000.

The first step in solving a problem is clearly stating the problem you are trying to solve. I don't know what this circuit is supposed to do, but you need a statement such as, "Given a 4-bit input N[3:0], produce a 4-bit output M[3:0] such that M=N+1 if k=0 and M=N+2 if k=1." That pretty much rules out having M=N ever. Is that what you are trying to implement?
 

ScottWang

Joined Aug 23, 2012
7,397
It looks like some kind of the multiplexer, if it want to be a counter, it needs a flip flop as this to memory the status of high and low, and then the high or low signal can be shifted by the clock, but I can't find it on your circuit, do I miss something?
 

Thread Starter

bdogpot

Joined Nov 29, 2013
10
This makes NO sense!

The input k has to be either a 0 or a 1. It can't be anything else. So when you say, "If you have N3, N2, N1, N0 as 0000 it would display M3, M2, M1, M0 as 0000" is that with k=0 or k=1? It has to be one or the other. But, whichever it is, that will be in conflict with what you say it will display when k=0 and when k=1.

And it tells me nothing about what the circuit is supposed to do when N3,N2,N1,N0 are anything other than 0000.

The first step in solving a problem is clearly stating the problem you are trying to solve. I don't know what this circuit is supposed to do, but you need a statement such as, "Given a 4-bit input N[3:0], produce a 4-bit output M[3:0] such that M=N+1 if k=0 and M=N+2 if k=1." That pretty much rules out having M=N ever. Is that what you are trying to implement?
the last few sentences were dead on with what I was trying to say the whole time. I have learned a lot from this project in the fact that I am still a noob to everything. I will continue to get better with how I relay and ask for help and exactly what the problem is. and to the post after there are know flip flops involved with the circuit.
 

WBahn

Joined Mar 31, 2012
29,976
the last few sentences were dead on with what I was trying to say the whole time. I have learned a lot from this project in the fact that I am still a noob to everything. I will continue to get better with how I relay and ask for help and exactly what the problem is. and to the post after there are know flip flops involved with the circuit.
I'm glad you are learning a lot. For sure, learning how to communicate information is something that can be pretty difficult and can take a long time to get good at -- and few ever truly master it. I certainly haven't.

When asking someone to verify your design, it is usually better to walk them through the design instead of expecting them to analyze the final result.

Let's take a short aside and consider a simple example.

I come to you and say that I have developed a way to generate numbers that are the difference of two square numbers. I ask to you verify my design by checking to see if 589*335 is, indeed, the difference of two square numbers.

How up are you for doing that?

Now let's say that I come up to you and say that I have developed a way to generate numbers that are the difference of two square numbers. I ask to you verify my design by checking the following design steps.

C = a number that is the difference of two square numbers.
C = A² - B²
C = (A+B)(A-B)

Example:
A=462; B=127
(A+B) = 589
(A-B) = 335

At this point, without doing any math beyond checking that my computation for (A+B) and (A-B) were correct, you are probably confident in saying that the produce of 589 and 335 is, in fact, the difference of two square numbers.

The point here is that, instead of giving us your final circuit, walk us through the design process that led to that circuit, or at least an abbreviated version of it. Otherwise, it is just too much work for people to analyze your work to provide complete feedback or verification.

As a bonus, doing so helps you really learn how to document and present your work.
 

adamclark

Joined Oct 4, 2013
472
This makes NO sense!

The input k has to be either a 0 or a 1. It can't be anything else. So when you say, "If you have N3, N2, N1, N0 as 0000 it would display M3, M2, M1, M0 as 0000" is that with k=0 or k=1? It has to be one or the other. But, whichever it is, that will be in conflict with what you say it will display when k=0 and when k=1.

And it tells me nothing about what the circuit is supposed to do when N3,N2,N1,N0 are anything other than 0000.

The first step in solving a problem is clearly stating the problem you are trying to solve. I don't know what this circuit is supposed to do, but you need a statement such as, "Given a 4-bit input N[3:0], produce a 4-bit output M[3:0] such that M=N+1 if k=0 and M=N+2 if k=1." That pretty much rules out having M=N ever. Is that what you are trying to implement?
mmmmmk...lol..sorry.. needed a laugh
 
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