Thread: Laptop keyboard ribbon cable protocol?

  1. #1
    Registered User Alpo's Avatar
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    Apr 2014

    Laptop keyboard ribbon cable protocol?

    Hello all,

    I've been looking for information on how keyboard data is transmitted from a laptop keyboard, through the ribbon cable they use. I haven't been able to find any information however, so I was wondering if anyone here had any information on them? If there is no set standard for how they must communicate, does anyone have any likely guesses?

    There seems to be 26 pins on both of the ones I've looked at, so it seems like the information would be digital? Even so 26 pins is a lot isn't it (that would be 67 million unique values possible correct?)?

    Anyway, it was just a thing I got curious about the other day, thanks to anyone for information!
    WndProc = (2[b] || !(2[b])) ? SufferNobly : TakeArms;

  2. #2
    and the hat of int overfl Salem's Avatar
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    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
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  3. #3
    Registered User Alpo's Avatar
    Join Date
    Apr 2014
    Quote Originally Posted by Salem View Post
    I think the PI matrix board must be similar in concept to how the ribbon cable communicates. I managed to find some tutorials on key detection from a matrix such as this (using an Arduino).

    The idea seems to be there is voltage between the column and row of the key that is pressed, and to determine the exact key you sort of loop through the columns on that row using digitalWrite to turn them off one by one, and when the row output goes to 0 volts you've found the key that was pressed. I'm not sure of the mapping of this laptop keyboard, but it might be possible to figure out with a multi-meter.

    Thanks for the info, that was an interesting thread!
    WndProc = (2[b] || !(2[b])) ? SufferNobly : TakeArms;

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