Using push buttons to activate keyboard buttons

Discussion in 'The Projects Forum' started by CRMISH, Feb 12, 2010.

  1. CRMISH

    Thread Starter New Member

    Feb 12, 2010
    1
    0
    Hi
    I sure this is really simple, but I dont know where to start.:confused:

    I have a program on my computer that is controlled by specific buttons on my keyboard. There are only 14 buttons required.

    I want to use different switches to send a signal to the keyboard to activate these keystrokes.

    I was going to just keep the keyboard intact, have solenoids hovering over the desired keyboard buttons and just have the solenoid depress the keyboard button like a normal finger would.

    However I think that there must be an easier way. Im thinking that arcade game buttons must be triggering commands to a computer of some description.

    Any help or even just a direction of what to google would be greatly appreciated.

    Thank You
     
  2. JDT

    Well-Known Member

    Feb 12, 2009
    658
    85
    The keyboard sends a scan code to the computer to the computer when each key is pressed. The computer itself determines what actual character this corresponds to. These codes are sent serially to the computer using a USB or PS2 serial connection. For more about these codes see:-

    http://en.wikipedia.org/wiki/Scancode

    You could use a small microprocessor, like a PIC, and some buttons or digital inputs, that will send the required code when the button is pressed or the input is active.

    Not too difficult to do if your computer has the older PS2 keyboard input. For a USB connection could be harder!

    Another option would be to find an old computer keyboard, take it to bits, and use the electronics. The keys on a keyboard are multiplexed in a grid. You will have to find out which wires are connected together for the keys you want.
     
  3. t06afre

    AAC Fanatic!

    May 11, 2009
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  4. hobbyist

    Distinguished Member

    Aug 10, 2008
    764
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    Hi

    I made something similar,
    a girl at work asked me if I could make a keyboard that would automatically type out all the characters, for those smiley faces and pictures for messenger service, using just the touch of one button.

    She was just kidding, but I took it as a fun design challenge.

    Here is what I came up with.

    Was Not, yet finished, just at the final working stages, it has 10 buttons for 10 pictures.

    keyboard 1.JPG

    I bought 2 cheap K-mart keyboards, one for taking apart and doing reverse engineering on it, and a second to do the actual prototype build.

    Through testing I found that electrical signals was not the function, but rather mechanical connections, was how this worked.

    So using reed relays, was the way to go with this.

    Here is the circuit board in the keyboard, with wires that I soldered on to go to my circuitry.

    wires soldered to ketboard circuit board.JPG

    wires soldered back away from fingers, by scraping away ~981.JPG

    Then the holes drilled thru keyboard and wires routed.

    holes through keyboard.JPG

    wiring to pins ontop of keyboard.JPG

    That was a lot of fun that I decided to design another one for myself this time, that would be portable, can be slid in and out of a connector to the keyboard, as a seperate module.

    Here it is, in module form.

    100_1516.JPG

    So it can be done, you just have to find out how your particular keyboard functions.
     
    Last edited: Feb 12, 2010
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