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Up/Down synchronous counter

  1. Jun 23, 2012 #1
    Hi guys.

    I'm wondering if someone could explain why when trying to make a 3 bit up/down counter using T flip flops, there are two and gates connected to the final multiplexer ?

    Can someone explain how you approach this?

    And same with the JK Flip flop but with an xor gate.

    I'm really confused on how you come up with this.

  2. jcsd
  3. Jun 23, 2012 #2


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    Gold Member

    When doing a Google search on "3 bit up/down counter using T flip flops" it appears to be a homework problem. May I suggest you Google search those many sites and find your answers there?
  4. Jun 27, 2012 #3
    When we are doing the excitation table for counters...why is the W=0 for the next state not included?
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