A Counter Which Counts to 5 and Then Turns on a Led

Thread Starter

kucar17

Joined Apr 26, 2020
7
Hello there, hope you are all well and healthy during those times. I have a question which I cannot solve. Question is like this:

Design a counter which counts from 0 to 5 and then stops and turns on a led. The process is initiated by pressing start push button. (Please use J-K Flip Flop with preset and reset asynchronous inputs).

I have some knowledge about flip flops and partially know counting until a desired value. But I can only manage the counter to reach 5 and then starting over again. I do not know how can I stop it and I have no idea about implementing a LED on the circuit. Can someone help me? I have looked up so many sources and I am very confused right now.

Thanks so much for all of your helps in advance.
 

MrChips

Joined Oct 2, 2009
21,044
Your counter is being clocked by a CLOCK signal. Is that correct?
How would you prevent the CLOCK signal from propagating to the counter?
 

Thread Starter

kucar17

Joined Apr 26, 2020
7
0-to-5.png
This is what I tried so far, I believe this counter counts from 0 to 5. I do not know where to implement the Led.
 

WBahn

Joined Mar 31, 2012
25,732
View attachment 205496
This is what I tried so far, I believe this counter counts from 0 to 5. I do not know where to implement the Led.
Don't design asynchronous counters unless you are prepared to do it properly and show that there is no possibility of a critical race condition or of a glitch on any of the asynchronous inputs.

Simply design a synchronous counter that has the appropriate state transition to the same state.
 

RBR1317

Joined Nov 13, 2010
547
This is what I tried so far, I believe this counter counts from 0 to 5.
It appears that you have not been taught the technique of JK Transition Mapping, so let's quickly run through the procedure. First, construct the Next-State Table. Since the counter stops at the value "5" some entries will be "Don't Care" conditions. Then make the Transition Table for each bit (i.e., state variable) from its CURRENT to its NEXT state, according to the following rules: [0→0=0], [0→1=α], [1→0=β], [1→1=1]. Transfer the Transition Table to a Karnaugh Map for each state variable (i.e., JK flip-flop); the J & K input for each flip-flop will start with the same Transition Map. Now the magic happens.

J: α{1β} - For the J inputs, the "α" transitions are required for minimization so they are changed to a value of "1"; the "1" & "β" transitions are optional for minimization so they are changed to a value of "X", i.e. treated the same as "Don't Care" conditions. "0" transitions are excluded from minimization so they remain as a "0" value in the "J" Karnaugh map.

K: β{0α} - For the K inputs, the "β" transitions are required for minimization so they are changed to a value of "1"; the "0" & "α" transitions are optional for minimization so they are changed to a value of "X", i.e. treated the same as "Don't Care" conditions. "1" transitions are excluded from minimization so they are changed to a "0" value in the "K" Karnaugh map.

Final step is to minimize the Karnaugh map for each "J" & "K" input to obtain the logic necessary so each JK flip-flop will behave as specified in the NEXT-State Table.
 

Attachments

dl324

Joined Mar 30, 2015
10,702
At this point, we don't know if s/he is supposed to use an asynchronous counter. The circuit posted would imply that. AFAIK, there's no widely used method for the formal design of asynchronous counters.

The OP seems to be waiting for someone to post a solution.
 

orhunkan

Joined Apr 29, 2020
6
At this point, we don't know if s/he is supposed to use an asynchronous counter. The circuit posted would imply that. AFAIK, there's no widely used method for the formal design of asynchronous counters.

The OP seems to be waiting for someone to post a solution.
Actually he is not waiting for someone to post a solution.I guess we're from the same college and we are not getting a good education.Probably he is trying to understand the parts that we didn't solve any examples or not given even a detailed information about it during the lesson.
 

WBahn

Joined Mar 31, 2012
25,732
Actually he is not waiting for someone to post a solution.I guess we're from the same college and we are not getting a good education.Probably he is trying to understand the parts that we didn't solve any examples or not given even a detailed information about it during the lesson.
If that't the case, then you might start looking for a different college. Employers want to hire people that got a good education and aren't going to cut you slack because of where you went to school. They are much more likely to not even look at your application because of where you went to school.
 

orhunkan

Joined Apr 29, 2020
6
If that't the case, then you might start looking for a different college. Employers want to hire people that got a good education and aren't going to cut you slack because of where you went to school. They are much more likely to not even look at your application because of where you went to school.
In my country, our college is one of the top colleges actually. It's very bad for us. Some of people doesn't even try to solve the questions. They're just writing the answers they can found on the internet and textbooks.
 

WBahn

Joined Mar 31, 2012
25,732
Then the sad reality is that you will have to take responsibility for your own education and find a way to get a good one despite the college. You are taking steps in that direction, which is good. You approach needs to be very much one of "I will put in the blood, sweat, and tears before I ask for help and then I will only accept just enough help to get me past the specific point I am stuck on and then it's back to blood, sweat, and tears."
 

dl324

Joined Mar 30, 2015
10,702
Some of people doesn't even try to solve the questions. They're just writing the answers they can found on the internet and textbooks.
That was a sad reality even in the days before the internet. My high school had a coach who had to teach geometry. He only knew one way to solve problems - whatever was in the teaching guide.
 
Top