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PS/2 Keyboard

Discussion in 'General Electronics Discussion' started by JHarmon, Jul 26, 2012.

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  1. JHarmon


    Jun 30, 2012
    I'm trying to build a circuit that can read keyboard signals through a stripped PS/2 connector.

    So after researching how these things work, I stripped off the connector and found a red, white, green, and yellow wire (along with some wire with no insulation that I assume is just for shielding).

    These wires need to correspond to Voltage, Ground, Clock, and Signal.

    I originally assumed red was voltage, white was ground, yellow was clock, and green was signal... Frankly, if I can just figure out which is voltage and which is ground, I think I'm good...

    Right now I'm just trying to connect the clock to a binary counter (74LS161) so that when I press a key, it counts to 8. My power supply is 5V with a max current of 700mA (more than enough for the keyboard). Red to 5V, white to ground, and my entire circuit is shorted out (can't power the binary counter).

    So that can't be right. I've tried a few combinations but now I'm just confusing myself. Does anyone have experience with these things and can give me some tips? I can't find much technical documentation on the keyboards, either...

    The model of the keyboard is DP/n 09C487, but that really shouldn't matter. All PS/2 keyboards should be the same...
  2. CocaCola


    Apr 7, 2012
    Open the keyboard up and trace the wires on the internal circuit board, you should easily be able to identify ground and voltage on the circuit board, then you have a 50/50 shot of getting clock and signal right with just a guess ;)

    They will have all the same pin out and connection, but the wire colors will be random and vary between manufacture...
  3. JHarmon


    Jun 30, 2012
    Ok, I figured out the wires. I wired voltage and ground to +5V and 0V. Still not working (I press a key and my counter doesn't change)... Does anyone have any ideas?
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