Post project 39: Output Signals from a Keyboard Controller
August 08, 2014
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There must be many PC users out there with an old USB keyboard kicking
around in a junkbox somewhere. Maybe it’s got a mechanical fault you haven’t
got round to fixing yet. No matter, this hack will turn it into something
much more useful!
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Take an old USB keyboard apart and you will find a small PCB containing a minimum of three status indicator LEDs for Number Lock, Caps Lock and Scroll Lock. With a little hardware modification and the help of software library functions we can use these to switch signals to the outside world. The computer operating system allows more than one keyboard to be attached at any one time so there is no reason why we can’t plug a second keyboard into a spare USB port. In normal operation the Scroll Lock indicator is practically never used.
Don't miss any project, take out a free membership to Elektor.POST now!
Take an old USB keyboard apart and you will find a small PCB containing a minimum of three status indicator LEDs for Number Lock, Caps Lock and Scroll Lock. With a little hardware modification and the help of software library functions we can use these to switch signals to the outside world. The computer operating system allows more than one keyboard to be attached at any one time so there is no reason why we can’t plug a second keyboard into a spare USB port. In normal operation the Scroll Lock indicator is practically never used.
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