Modulo 10 up/down counter

Discussion in 'Homework Help' started by Earl Vickery, Sep 11, 2019 at 3:31 AM.

  1. Earl Vickery

    Thread Starter New Member

    Sep 1, 2019
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    I am not sure how i should wire up the counting down part of the circuit. Currently when it is counting down it starts at 5 because of the AND gate that resets the illegal states. I've tried to figure it out myself. I know some more logic gates are needed so it starts at 9 but im stuck.


    Thanks for any help in advance.
    I am new to circuits
     
    Last edited: Sep 11, 2019 at 3:38 AM
  2. MrAl

    AAC Fanatic!

    Jun 17, 2014
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    Why only reset 2 of the flip flops when the illegal count is reached?
    Do the other two stay reset?
     
  3. Earl Vickery

    Thread Starter New Member

    Sep 1, 2019
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    I didn't reset the others because it doesn't seem to count down at all then. I know there is something wrong with my reset logic but just cant think of it.
     
  4. Earl Vickery

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    Sep 1, 2019
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    I've been stuck on this for the past couple of days. I know its something simple, but i cant think of it. I will take a break and come back to it.
     
  5. MrAl

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    Jun 17, 2014
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    Hi again,

    Normally what you do is make up a logic state diagram and work from that.
    To get into an implementation you study each flip flop section until you know how each individual stage works and translates into the state diagram.
    Look up "logical state diagram" and see if that helps.
     
  6. dl324

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    Mar 30, 2015
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    Show your work and post the entire text of the problem.
     
  7. MrAl

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    Jun 17, 2014
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    You seem to be on the right track, but what is happening with the set 's' inputs? Take a look at that first.
     
  8. Earl Vickery

    Thread Starter New Member

    Sep 1, 2019
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    I have been playing around with set and reset inputs of the FFs. I think i have made some progress with it though it does seem a bit messy. Will post what i changed soon.
    Thanks for the help
     
  9. Picbuster

    Well-Known Member

    Dec 2, 2013
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    First off all identify what you want
    1:up/down counter
    2:controlled by push buttons.
    3:Startup value 0 5 9

    What do we need a counter:
    are there decimal counters available?
    if not we have to use a binary counter.
    can we use a 0-15 counter with a set and reset?
    and so on
    never start thinking in components start with what functions you want and even more important what you don't want to happen.
    The produce a simple flow chart
    next step is to identify components based on previous finding and definitions.

    But it's your brain to solve this. We only can help you to discover the technical parts of your own brains.

    Picbuster
     
  10. MrChips

    Moderator

    Oct 2, 2009
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    I am not sure that you are taking the correct approach.
    You are attempting to create a finite state machine
    Do you know anything about Karnaugh maps?
    Read up about Moore machine and Mealy machine.
     
  11. MrAl

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    Jun 17, 2014
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    Hi,

    Well it looked like you were either at or near the solution so it must be something silly wrong that's why i pointed out that the set inputs were not grounded.
     
  12. dl324

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    Mar 30, 2015
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    It seems that you've taken a binary up/down counter and you're trying to make it a decade counter by adding reset logic. Is that what the problem requires?

    I've designed a decade up/down counter with JK flip flops and it required about a dozen gates.
     
  13. RBR1317

    Senior Member

    Nov 13, 2010
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  14. Earl Vickery

    Thread Starter New Member

    Sep 1, 2019
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    The current course i am doing has not taught us anything advanced or even of something of an intermediate level. All i have been given for this task is the very basic fundamentals of flip flops like a JK or a D and how they are used in shift registers or ripple counters. From what i have seen so far from everyone's input is that i am lacking in so many skills that could help me.

    For anyone that wants to know the whole story i am basically making a decade counter because that is what will help me make a counter that goes from 0-99 on a hex display. I was given this task only 3 weeks in. See attached image as well/
     
  15. RBR1317

    Senior Member

    Nov 13, 2010
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    However the attachment provided gives the following requirement: "... showing the track number(between 1 and 99)."

    Apparently you will need to use the set & reset inputs to the flip-flops to set the initial state to "1". Also, the clock signal and the UP/DOWN state will be generated by the same push-buttons; that will be an interesting problem to solve in Logisim.
     
  16. Earl Vickery

    Thread Starter New Member

    Sep 1, 2019
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    At this point in time i am more interested in getting a 0-9 up/down counter working than anything else. Also a 0-99 counter is being accepted for the task since everyone is finding it so difficult to get a 1-99 counter working. I haven't done much work on my current circuit but will continue during the weekday.
    Thank you everyone for your help and input. Not entirely sure what the end result will be but i will be happy as long as i can get a 0-9 counter working
     
  17. ag-123

    Member

    Apr 28, 2017
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  18. dl324

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    Mar 30, 2015
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    7 variable Kmaps would be a bit much to solve. I do 6 without much thought, but I'd prefer not to do 7.

    It still isn't clear from stage3.PNG how you're supposed to design the counter. The usual way is to make a truth table and generate the boolean equations for the gating logic from that.
     
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