up-down counter 74191 using push button

Discussion in 'The Projects Forum' started by nasimimtiaz, Sep 21, 2011.

  1. nasimimtiaz

    Thread Starter New Member

    Sep 19, 2011
    1
    0
    hi,
    i need to use two push button with up-down counter 74191. PRESSING one push button will count one digit UP and PRESSING the other one will count one digit DOWN.

    I read the datasheet. But i am not understanding it. i am attaching a figure can anyone give me a clue how to connect it. i know i need to use push-up or pull down resistors to prevent floating point....but the idea is not clear to me.....pls help
     
  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    It doesn't work like that.

    The 74191 has an up/down select input, and a clock input. Every time you get a clock input, it counts in the direction of the up/down select input.

    Here, the pulser is a clock source:
    [​IMG]

    Is this a homework assignment?
     
  3. elec_mech

    Senior Member

    Nov 12, 2008
    1,513
    193
    As SgtWookie asked, is this a homework assignment?

    Do you have to use this particular IC or can you use another?

    In addition to having a single clock input and a select up/down input, note this IC is a binary counter. This means it will count from 0-15, not 0-9. Therefore, you're going to see some interesting things on the display from 10 to 15 - see the datasheet for the 74LS47, it will show you.

    If you only want to count from 0 to 9 and not 0 - 15, then you need a decade counter, not a binary counter. Take another look at the 74LS191 datasheet, it should also list another IC - one with a decade counter.
     
Loading...