How a matrix keypad works?

Discussion in 'The Projects Forum' started by hwde, Dec 4, 2007.

  1. hwde

    Thread Starter New Member

    Dec 4, 2007
    6
    0
    Hi, is there anyone know how a matrix keypad works? i need it for my project. But , i don't how it's works. any website i can refer to?
    btw, i need to study on PCB routing for a 8 layers board. Is there any useful resources i can refer to when do routing? any recommended e-books about pcb routing method?

    thanks for your help. :p
     
  2. BlackBox

    Member

    Apr 22, 2007
    20
    0
    A keypad Matrix (that is i suppose a HEX matrix, with 16 pushbuttons) works a little like a transistor memory exept for it uses fisical switches istead of transistors:
    It has 4 input lines, imagine four wires running vertically, and four output lines running across the first. If some of the crossings is pressed, it's wires are shortcut. e.g.:
    Call the horizontal wires A0 to A3 and the vertical wires B0 to B3
    the matrix of connections is like this:

    A0B0 A0B1 A0B2 A0B3
    A1B0 A1B1 A1B2 A1B3
    A2B0 A2B1 A2B2 A2B3
    A3B0 A3B1 A3B2 A3B3

    then you cycle the input lines high (use a counter for example) and for each input line you read the output lines. The point where high lines cross indicates a pushed button. If you pull B1 High (and the others low) if some key is pressed the voltage is transferred to the corresponding row wire, so if you get A1 and A3 high as output you know that the buttons (A1B1) and (A3B1) are pressed.

    As for the routing, i haven't got the slightest idea, i hate routing with all my heart!
     
  3. hwde

    Thread Starter New Member

    Dec 4, 2007
    6
    0
    Halo, thanks for your info. It helps me to understand well. :D
     
  4. Voltboy

    Active Member

    Jan 10, 2007
    197
    0
  5. hwde

    Thread Starter New Member

    Dec 4, 2007
    6
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    Thanks Yoda..;)
     
  6. jamaljony

    New Member

    Mar 13, 2009
    1
    0
    i m new come, thank u very much i m happy.
     
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