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Quadrature Encoder to up/down pulses with discrete logic - paging logic gate gurus

Discussion in 'Embedded' started by Spehro Pefhany, Apr 21, 2004.

  1. Spehro Pefhany

    Rich Grise Guest

    Well, when you're at the detent, B is indeterminate. But A is high.
    So, when A is high, ignore B.

    When A is low, a low-to-high on B means "one click clockwise", and
    a high-to-low on B means "one click counter-clockwise". What's so
    hard about that?

    Cheers!
    Rich
     
    Rich Grise, Apr 23, 2004
    #21
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  2. Debouncing and optimizing the logic into a minimum number of easily
    available packages. It's also a bite-sized amusing problem that a few
    people here can solve with their eyes closed.

    Best regards,
    Spehro Pefhany
     
    Spehro Pefhany, Apr 23, 2004
    #22
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  3. http://www.speff.com


    Spehro,

    Can't find my first reply and I may have missed some others as well thanks
    to the quality of the newsserver of my provider. :-(

    Nevertheless, after a good nights sleep, some thinking and reading the
    available replies I came to the circuit below. The XORs are providing short
    clockpulses on each edge that clocks the value of the other signal in a
    D-flipflop. You can make the delay somewhat longer by an RC-combination if
    required. Bounce does not matter, it only clocks the same data once more.
    Some more thinking makes me believe I saw a circuit like this in an Elector
    issue. Must be many years ago.

    View with fixed font

    +---------------+
    | | .----. Bo
    Ai | __ | +-|D Q|---
    ---+-+----------| | | | | |
    | __ |=1|-|---|-|> |
    +---| | +--|__| + + | |
    |=1|--+ \ / | |o--
    +-|__| X '----'
    | / \
    | +----------+ + .----. Ao
    Bi === | __ +-|D Q|---
    --+-------+-----| | | |
    | __ |=1|-------|> |
    +----| | +-|__| | |
    |=1|---+ | |o--
    +-|__| '----'
    |
    |
    ===
    GND
    created by Andy┬┤s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de


    petrus
     
    petrus bitbyter, Apr 23, 2004
    #23
  4. Spehro Pefhany

    GPG Guest

    The board does not care. It can be set so that a positive or a negative
    or both edges result in a keypush
     
    GPG, Apr 27, 2004
    #24
  5. Spehro Pefhany

    Fred Bloggs Guest

    Your idea is flawed in the context of the subject encoder-
     
    Fred Bloggs, Apr 27, 2004
    #25
  6. Spehro Pefhany

    GPG Guest

    Does not supply directional info.
     
    GPG, Apr 27, 2004
    #26
  7. Spehro Pefhany

    GPG Guest

    Clever- the same can be done with an HC neg edge triggered FF, but
    If you are using it with a conventional pc keyboard, turn off repeat,
    the reset will occur when the input changes F or Rev.
     
    GPG, Apr 28, 2004
    #27
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