Building an input device to send a specific keystroke (or set of keystrokes) to a computer
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Posted by on May 21, 2008, 12:08 pm
Please log in for more thread options to an extent. I don't want it to have all the keys however. There is a particular application that requires only a single key: scroll lock. I want to set it up as a sort of hand-held clicker. Long story short, this is designed to interface with a time keeping program. When someone crosses the finish line, the timekeeper currently holds Function-Scroll Lock which gets kind of annoying. I had envisioned something a little better for the poor guy, basically a push button that connects to the computer and sends the scroll lock code to the computer via USB. I'm not a newb to electronics, it's just been many years since I've taken on any project and I've never done anything with keyboards or computer interfaces before. Does anyone know of some references I can use to get this off the ground, or if there are details of a similar project out there somewhere? I did an initial google search that didn't return much. | |||||||||||||||||||
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Posted by Rich Grise on May 21, 2008, 1:56 pm
Please log in for more thread options Hack the keyboard itself, and put a spst switch in parallel with the "scroll lock" contacts. Or alternatively, you could completely hack a keyboard into an input device, a la; http://www.neodruid.net/KeyZilla and put a smart Y connector to arbitrate. Good Luck! Rich | |||||||||||||||||||
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Posted by Stephen J. Rush on May 21, 2008, 6:48 pm
Please log in for more thread options On Wed, 21 May 2008 09:08:13 -0700, fny1182 wrote:
> I want to build a device (ideally USB) that functions as a keyboard, to
> an extent. I don't want it to have all the keys however. There is a > particular application that requires only a single key: scroll lock. I > want to set it up as a sort of hand-held clicker. > > Long story short, this is designed to interface with a time keeping > program. When someone crosses the finish line, the timekeeper currently > holds Function-Scroll Lock which gets kind of annoying. I had envisioned > something a little better for the poor guy, basically a push button that > connects to the computer and sends the scroll lock code to the computer > via USB. Hacking the keyboard is the simplest approach, just a SPST switch and some cable. If you don't want to hack into the computer, Micro Chip and Atmel make microcontrollers that include USB interfaces. This may look like massive overkill for one key, but some of these chips are absurdly inexpensive. | |||||||||||||||||||
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Posted by Michael Black on May 21, 2008, 8:11 pm
Please log in for more thread options On Wed, 21 May 2008, Stephen J. Rush wrote:
> On Wed, 21 May 2008 09:08:13 -0700, fny1182 wrote:
> >> I want to build a device (ideally USB) that functions as a keyboard, to
>> an extent. I don't want it to have all the keys however. There is a >> particular application that requires only a single key: scroll lock. I >> want to set it up as a sort of hand-held clicker. >> >> Long story short, this is designed to interface with a time keeping >> program. When someone crosses the finish line, the timekeeper currently >> holds Function-Scroll Lock which gets kind of annoying. I had envisioned >> something a little better for the poor guy, basically a push button that >> connects to the computer and sends the scroll lock code to the computer >> via USB. >
I don't know what it's like with USB keyboards (I've never had one, so I
> Hacking the keyboard is the simplest approach, just a SPST switch and > some cable. If you don't want to hack into the computer, Micro Chip and > Atmel make microcontrollers that include USB interfaces. This may look > like massive overkill for one key, but some of these chips are absurdly > inexpensive. > can't look inside) but at least some PS/2 keyboards I've opened have a nice small circuit board, separate from the matrix board for the actual keys. Those then make it really easy to make a custom keyboard or whatever, since it's really easy to extract the small board. Of course, in the old days, this sort of thing would most easily be done with the use of a parallel input board, or even one of the control lines on a serial board. It does require adapting software to look for the keypress on the serial or parallel board, and these days it seems like serial interfaces are not standard in computers, maybe not even parallel printer ports these days. If the software can be modified, the most easily accesible thing nowadays may be the mouse, in effect a USB interface that can take a number of on/off inputs. Michael | |||||||||||||||||||
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Posted by jameshanley39@yahoo.co.uk on May 21, 2008, 10:42 pm
Please log in for more thread options On 21 May, 17:08, fny1...@rofl-online.com wrote:
> I want to build a device (ideally USB) that functions as a keyboard,
> to an extent. I don't want it to have all the keys however. There is a > particular application that requires only a single key: scroll lock. I > want to set it up as a sort of hand-held clicker. > > Long story short, this is designed to interface with a time keeping > program. When someone crosses the finish line, the timekeeper > currently holds Function-Scroll Lock which gets kind of annoying. I > had envisioned something a little better for the poor guy, basically a > push button that connects to the computer and sends the scroll lock > code to the computer via USB. > > I'm not a newb to electronics, it's just been many years since I've > taken on any project and I've never done anything with keyboards or > computer interfaces before. Does anyone know of some references I can > use to get this off the ground, or if there are details of a similar > project out there somewhere? I did an initial google search that > didn't return much. My suggestion is not along the lines you are thinking about at all.. Since it's purely a computer DIY solution rather than an electronics one. Attach an external keyboard to the computer*laptop?) he is using. So you have a separate scroll lock key . No need for an Fn key Now rip off all the keys leaving just the scroll lock key. The only disadvantage is it is a small button, but that's no big deal. So there you have it, your device with a single button. It would be a relatively big keyboard he would carry around.. just for a tiny little button!!! But maybe with your electronic skills, you could hack it into something smaller! Or with some delicate DIY, maybe hack the button into something bigger! Another solution may be the ext keyboard, and also to use software to remap every key to scroll lock.. or all Function Keys as in F1-12 To scroll lock. If that's possible to map many keys to one key. But I think the above solution of just a keyboard with scroll lock key, is pretty good. | |||||||||||||||||||
> to an extent. I don't want it to have all the keys however. There is a
> particular application that requires only a single key: scroll lock. I
> want to set it up as a sort of hand-held clicker.
>
> Long story short, this is designed to interface with a time keeping
> program. When someone crosses the finish line, the timekeeper
> currently holds Function-Scroll Lock which gets kind of annoying. I
> had envisioned something a little better for the poor guy, basically a
> push button that connects to the computer and sends the scroll lock
> code to the computer via USB.
>
> I'm not a newb to electronics, it's just been many years since I've
> taken on any project and I've never done anything with keyboards or
> computer interfaces before. Does anyone know of some references I can
> use to get this off the ground, or if there are details of a similar
> project out there somewhere? I did an initial google search that
> didn't return much.