Help needed with Frequency Counter

Discussion in 'Homework Help' started by Malsch, May 13, 2011.

  1. Malsch

    Thread Starter New Member

    Mar 19, 2011
    23
    0
    Hi, I need to design a simple frequency counter to measure the frequency of a square wave input (hence signal conditioning is not needed for now). I have understood the concept that the counter needs to count the input pulses for 1 second and display them on a 7-segment. My problem is how am i going to use the latch function (LE) to keep showing the frequency that was counted.

    This is what I came up with so far:
    [​IMG]

    The input signal (in this case 50Hz) triggers the 1Hz monostable, hence counts for 1 second. The problem is that after that 1 second, the counter resets to zero and recounts to 49 in this case. I need to find a way to keep the counter on 49 rather than going back to zero. Later I will add a 10Hz and 100Hz monostable for decimal points but for now I need to understand this concept.

    Thank you.
     
  2. wmodavis

    Well-Known Member

    Oct 23, 2010
    737
    150
    You need to use the LE (latch enable) to read and store the data from the counters. You have them grounded. Then read and update the latch every new reading.
     
  3. Malsch

    Thread Starter New Member

    Mar 19, 2011
    23
    0
    yes i know. the problem is that when i connect them, the counter marks 50, but then goes back to 0, then back to 50, then 0 etc...
     
  4. BillB3857

    Senior Member

    Feb 28, 2009
    2,400
    348
    Have you made a flow chart of the required sequence? After you figure out the sequence of what needs to happen you will be able to figure out how to make it happen.
     
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