how to design a 30 second counter?

Discussion in 'Homework Help' started by toyota8, Oct 26, 2008.

  1. toyota8

    Thread Starter New Member

    Oct 26, 2008
    8
    0
    how to design a 30 seconds counter using jk flip flops? i can only do a 31 seconds counter.
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    You add external gates like AND gates to sense the count of 30 (1Eh). Take a look at a decade counter to see how they roll over at 9 instead of F.
     
  3. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    You might be able to preload the 5 F/Fs with the value 1 on overflow instead of resetting them to zero. That way your count would start from 1 instead of 0. That would give you a 30 count.

    hgmjr
     
  4. toyota8

    Thread Starter New Member

    Oct 26, 2008
    8
    0
    Thanks for the advice, but the problem is I am doing a 30 seconds synchronous countdown. I did simulation in Digital Works but it didn't turn out well. How can i make Q0=1, Q1=Q2=Q3=Q4=1, means it will start from 00001 instead so the NOT will b 30, cuz wat i did was attaching Q bar to the decoder.. If anyone can provide me a simple .dwm file or a picture of the circuit diagram, I would be thankful. Any links with info similar ti these questions are also helpful. Thanks a lot :D I have tried, and tried and u people r my only hope.. Bless.
     
    Last edited: Oct 27, 2008
  5. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Perhaps you could post up your logic diagram so we can see what you have got working.
     
  6. toyota8

    Thread Starter New Member

    Oct 26, 2008
    8
    0
    [​IMG]

    Here's the diagram. Not sure what went wrong. Thanks :D
     
  7. toyota8

    Thread Starter New Member

    Oct 26, 2008
    8
    0
    another thing that i would like to know is that how can we display a two digit number using two seven segments. Like when it goes from 9 to 10, both the seven segments should light up as 1 and 0, etc. Using a single seven segment connected to the BCD decoder i could only display numbers up to 9. Can anyone teach me what is the way to utilise two seven segment displays? Thanks...
     
  8. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Think of two counters, two display drivers, and two displays.
     
Loading...