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A simple(?) question about a funky waveform on a data sheet — Parallax Forums

A simple(?) question about a funky waveform on a data sheet

ElectricAyeElectricAye Posts: 4,561
edited 2008-09-26 12:50 in Propeller 1
Hi all,

I'm not a EE so I'm sure this question will seem moronic to most of you. I keep seeing this kind of waveform/clocking diagram on data sheets but I don't understand what it's telling me. I understand signals and waveforms, but what's this double up-and-down figure supposed to represent???

thanks a heap,
Mark
CuriousWaveform.jpg
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Comments

  • parskoparsko Posts: 501
    edited 2008-09-25 15:42
    Mark,

    I think it's simply to denote that the wave could be either a 1 or a 0. I had the same question a few years ago:

    http://forums.parallax.com/forums/default.aspx?f=25&m=136802

    -Parsko
  • ElectricAyeElectricAye Posts: 4,561
    edited 2008-09-25 15:49
    Hey, parsko, thanks for the quick answer. It's a question that's pestered me for weeks and weeks.

    cheers,
    Mark
  • LeonLeon Posts: 7,620
    edited 2008-09-25 15:57
    It's a "don't care" condition.

    Leon

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Amateur radio callsign: G1HSM
    Suzuki SV1000S motorcycle
  • Paul BakerPaul Baker Posts: 6,351
    edited 2008-09-25 23:01
    Actually it's not a don't care, don't care is illustrated by a either cross hatch or slanted shading. The "high and low" waveform indicates a run-time defined data level as defined by the protocol. While it's value isn't pre-defined, it's value is important at run time, hence it can't be a don't care.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Paul Baker
    Propeller Applications Engineer

    Parallax, Inc.
  • ElectricAyeElectricAye Posts: 4,561
    edited 2008-09-26 12:50
    Leon and Paul,
    thanks for filling me in on this.

    cheers,
    Mark
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