9-0 down counter using JK Flipflop

Discussion in 'Digital Circuit Design' started by Mondemundi, Sep 20, 2016.

  1. Mondemundi

    Thread Starter New Member

    Sep 20, 2016
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    Hi ! I am currently making a 9-0 counter using a jk flipflop and a 7 segment.

    It starts to countdown but the problem is it starts at 15 not in 9 how can i make it start at 9 and reset again. Thank you very much !
     
  2. AlbertHall

    Well-Known Member

    Jun 4, 2014
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    connect the appropriate set/reset pins of the flip-flops to the active state (might be high or low depending on which JK you are using) to set the '1001' state.
     
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  3. dl324

    Distinguished Member

    Mar 30, 2015
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    Welcome to AAC!
    Is the counter synchronous or asynchronous?

    Is this homework?

    Post a schematic. Anytime you ask a circuit question and don't post a schematic, expect to be asked to do so.
     
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  4. Mondemundi

    Thread Starter New Member

    Sep 20, 2016
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  5. Mondemundi

    Thread Starter New Member

    Sep 20, 2016
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    Yes sir this is an Asynchronous Counter..
    I am currently working on this and getting really frustrated.. i have attached the schematic i made.. the other preset and clear are on the HIGH state
    pls check if its right Thank you very much
     
  6. AlbertHall

    Well-Known Member

    Jun 4, 2014
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    so the count goes (in the order drawn):
    1001 9
    0001 8
    1110 7 <= NAND gate inputs both 1
    1000 1
    ...
    I think you may need a wider NAND.
     
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  7. Mondemundi

    Thread Starter New Member

    Sep 20, 2016
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    Thanks sir .. Ill try it nooww
     
  8. dl324

    Distinguished Member

    Mar 30, 2015
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    Is this homework?

    Why are you decoding 10? This is a count down counter that starts at 15. You need to get the counter out of the illegal states when the count is 15.
     
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