Edge-triggered latches: Flip-Flops

Discussion in 'Feedback and Suggestions' started by tony ennis, Aug 25, 2012.

  1. tony ennis

    Thread Starter New Member

    Aug 25, 2012
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    This page: http://www.allaboutcircuits.com/vol_4/chpt_10/5.html

    The following comes out of the blue:

    I assume the invalid state is that Q and Q' are both 0. Only when writing this did I realize that this isn't the entire problem. When the clock pulse goes low, we can't say for sure what the next state of the flip-flop will be and thus the flip-flop goes insane.

    This would manifest as a real effect if the set/reset were being controlled by a push-button. The push button might be held down for large amounts of time, causing the flip-flop to settle on some unexpected value for long enough for something unexpected to happen.

    My feedback would be to introduce and explain the invalid state with more words. Of course, this is from a novice...

     
    Last edited: Aug 25, 2012
  2. Wendy

    Moderator

    Mar 24, 2008
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    Just an opinion, but I think it is OK. Have you studied race conditions?
     
  3. tony ennis

    Thread Starter New Member

    Aug 25, 2012
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    Nope. I was looking up up/down counters are realized I wasn't going to understand them until I really understood flip-flops. So I started at the beginning... I just thought it was a bit abrupt.

    Who is the target audience for the page I linked?
     
  4. MrChips

    Moderator

    Oct 2, 2009
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    Sorry, politics not allowed on this forum.
     
    shortbus and tony ennis like this.
  5. Georacer

    Moderator

    Nov 25, 2009
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    @OP,

    You aren't entirely wrong about what you are trying to explain. Indeed, race conditions are a pain and cannot be explained easily.

    It even doesn't have to do with the fastest transistor, but sometimes by the more potent. I wouldn't try to explain the ins and outs of a race condition.

    You describe the repercussions of the race condition nicely, though.
     
  6. Wendy

    Moderator

    Mar 24, 2008
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    My interpretation is it is a college level course. It is weak in some ways, deep in others.
     
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