If ASCII codes are only 7 bit, why my laptop keyboard has too many wires in its bus connection ?

Discussion in 'General Electronics Chat' started by Abhinav Himanshu, Aug 30, 2016.

  1. Abhinav Himanshu

    Thread Starter New Member

    Feb 18, 2016
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    Can anyone please explain what around 25 wire bus for laptop keyboard does , it will be helpful if you can explain role of each wire?
     
  2. Robin Mitchell

    Well-Known Member

    Oct 25, 2009
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  3. crutschow

    Expert

    Mar 14, 2008
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    3,226
    It varies with the keyboard design.
    You'd have to find the schematic for the specific keyboard you have.
    There are additional wires for power and ground, as well as special functions that aren't in the ASCII code.
     
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  4. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    The keys are arranged as a matrix (rows and columns), which is scanned to identify which key is pressed.
    Keyboards vary, but mine has 6 rows of 18 keys. Those could be scanned using 6+18 wires plus a ground connection, = 25 wires. Yours may be similar.
     
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  5. AlbertHall

    Well-Known Member

    Jun 4, 2014
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    The keyboard also includes touch pad and buttons on some models.
     
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