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Counter with increment acknowledge

Discussion in 'Electronic Basics' started by Baroje, Dec 11, 2003.

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  1. Baroje

    Baroje Guest


    I need a digital counter which has the ability of sending the
    acknowledgement signal on one of its outputs! I need to be 100 percent sure
    that counter is incremented when button is pressed or some other event ocur!
    When counter is incremented electrical signal must be send to one of the
    counter outputs so that some other device can know for sure that the counter
    was inrcemented.

    Where can I buy counter with this ability or if not how can I modify one of
    the existing counters to act like I want and need???

  2. Depending on your frequency requirements a microcontroller will do it

    As an alternative you can use a standalone counter with a communication port
    (BCD output or even RS232 or GPIB output), and just read the displayed value
    with one of these ports to check if a change as happened...

    What is the application about ? May be could we help more...

    Robert Lacoste
  3. CWatters

    CWatters Guest

    Sounds like an application for a small micro like the PIC or smaller.
  4. But what don't you trust about the counters that you need this flag?
    Unless you have a really odd design (ie there is an input to the counters
    from somewhere else so you can't guarantee that each button press does
    count), once you've got a good design the counter will increment each time
    the button is pressed.

    If you don't trust the button press, ie the button is flakey, then
    you add circuitry so each time the button is pressed, there is a short
    audio beep.

    If it's really that you need a strobe for something else when there
    is a button press, then you use the button press signal as the strobe.

  5. Baroje

    Baroje Guest

    Like I said on the other group, it is about distance control. When the
    button is pressed and the counter increments someone else who is not in the
    same place must know that the increment did ocur. He do not know the state
    of the counter, he only need to know that increment was performed correctly!

    I don't know how this will work since I don't have a computer present
    Do you think it could be done by connecting a reley on that output you are
    talking about, and when the increment ocur the reley can for example turn on
    the light bulb!
  6. Baroje

    Baroje Guest


    What I need is a singal from the counter and not from the button. THe
    button is pressed OK, I trust that, the counter increments and here I need
    confirmation so that for example on same distance, where I cannot see the
    counter I know that counter realy did increment. Important thing is that I
    do not need to know the state of counter on the distance but only did it or
    did it not increment!
  7. Baroje

    Baroje Guest

    I had similar idea but I do not know so much about that problem. Can you
    tell me a little more.??

  8. Steve Wake

    Steve Wake Guest

    It sounds like you are trying to communicate information instantaneously.
    Maybe possible on a useful basis in a couple of hundred years time, but in
    the meantime you need to control the expectations of the people who want you
    to build a star trek style teleporter.
  9. Rich Grise

    Rich Grise Guest

    Then monitor the state of the button signal at the point where it
    enters the counter. If you can not trust that your counter increments
    when it receives that button-press signal, then you have a defective

    It's just that simple.

    And what specifically is the application about? Can you describe
    what is being counted? Where are these people standing or sitting?
    What do they see? That sort of thing. We're all insatiably curious,
    you know. :)

  10. You haven 't explained why YOU think this is important.
    Seems like the obvious answer to most of us.
    In that case the same button-press signal that increments
    the counter *IS* your remote signal.
    If you trust the button-press signal, and you trust the counter
    to reliably increment, then the button-press signal itself can
    be reliably used as your remote indicator.
    Perhaps you should explain why you think this is ever an
    issue. Otherwise we will be going round and round forever.
  11. Baroje

    Baroje Guest

    This application is about railway safety. My customers want to have double
    security and there is nothing I can do. It needs to be done no mather what.

    It is something like this. The trains are passing through the station or the
    switch and we are counting them. That's where I need a counter. The counter
    is either automaticaly increment or by the railway staff on the station. For
    some reason the bastards on the railways want to have a electrical signal
    from the counter to confirm its incrementing, they do not want to confirm
    the incrementig using the input signal in the counter. They say somethin
    like this: " Ok, there is input signal and after that the counter is
    incremented, BUT what if there is somekind of error (due to weather or any
    other reason) and you have an input signal but the counter does not
    increments itself. We want to have independent (independent from input
    signal) confirmation of the incrementing"!

    It is very important from the safety stand to be absolutely sure about the
    number of trains in one rail section!

    Thank you for your time.

  12. Mjolinor

    Mjolinor Guest

    It's a belt and braces job. You need to install 100% redundancy and
    duplicate everything to satify a requirement like that.
  13. Seems fairly straight forward. I think the answer has been given
    before though. You'll need some sort of clock to register the LSB of
    the counter. Then compare this register's input and output with an XOR
    gate. You'll get a '1' out of the XOR gate for one clock period after
    the counter increments. If you really want to look for the entire
    counter incrementing you can register the entire counter, add 1 and
    compare to the current value of the counter.
  14. And what condition allows it to not increment? SOmething in the circuit,
    or because the counter has reached the maximum count? If the latter,
    then you just watch for that.

  15. CWatters

    CWatters Guest


    What would happen if the counter made a spurious extra count? For example
    train systems are noisy environments (lots of high currents and voltages
    flying about). If you have long wires it wouldn't be hard for noise or
    perhaps a local lightening strikes to cause "extra" phantom button presses.

    I suggested using a small microprocessor in an earlier reply and now I'm
    going to suggest you use TWO!

    Let's call them the "Button micro" and the "Counter Micro" - put one at each
    end of the wire.

    Arrange it so that both microprocessors maintain the same count. When the
    button is pressed the "button micro" increments it's count and sends a
    packet of information down the wire. The packet could contain the new count
    and perhaps a message telling the counter to increment or decrement it's owb
    copy. The counter micro should increment it's counter and compare the result
    with what the button micro said. If they agree then the Counter micro can
    send an acknowledgement message back to the Button micro to say "I got that
    one thanks". Add some extra code and it's easy to ensure that both micros
    check each other is working ok. They can even send each other test messages
    when no button presses occur just to check the wire isn't broken or the
    power failed at one end (eg "you still awake messages?) .

    If there is a power cut at one end it can even ask the other end what the
    last count was when power is restored.

    Many micro like the PIC series have UARTs or serial interfaces of other
    sorts in them to make this easy.

    The system could also be made expandable. For example what happens next
    month when they change their minds and want TWO buttons and two counters but
    you have already installed only one wire? It's simple you just make the
    counters addressable and they share the wire. Many micros have addressable
    serial interfaces for this sort of thing.
  16. Colubris

    Colubris Guest

    What about a mechanical counter? Less prone to misfires from
    electrical "noise", cheap, durable.
    Maybe put a microswitch inside the counter that gets hit by the
    mechanism inside the counter. If the microwsitch gets a closure at
    each count, you know the counter actually incremented. Could maybe use
    two counters for redundancy.

  17. There are new problems with completely redundant systems.
    What happens if the counter circuig fails, but the redundant
    "confidence indicator" circuit works?
  18. Exactly what I was going to suggest.
    It pays to read the entire thread before responding! :)
  19. Rich Grise

    Rich Grise Guest

    How much money do these people have? What kind of display? Point
    an array of photodiodes, or a CCD camera at the displays, and
    analyze its output. When one of the digits changes, you've
    counted. Actually, you only need to watch the LSB. Maybe
    a tiny photodiode very close to each LED segment. If it's
    an LCD, then you'll probably have to look at the input
    signals, unless you have a photosensor that can read an
    LCD. Otherwise, tear into the circuit and monitor the
    outputs of whatever's driving the display.

    I'd be cheaper to hire bonded employees.

    Good Luck!
  20. Rich Grise

    Rich Grise Guest

    Or a spycam in their office. ;-)
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