PC Keyboard rewiring

[[email protected]]

I am having the following problem shown in this diagram, and have a
solution that I think might work - but I am not sure.
Here is the diagram:

http://img207.imageshack.us/img207/1161/kbproblem4bb.png

My problem is that I am trying to build a music controller -
essentially a bunch of sample triggers - and this is most cheaply done
via keymappings, which the software (Ableton Live 5) supports. But, to
get the keys I need, I will use almost every key and its shifted
complement.

This has led to two issues:

One, I can make EITHER the shifted keys work OR the non-shifted keys,
simply by activating the keyboard matrix's shift key and then wiring
spst switches to the other mappings. Alternately, I can of course leave
the shift key off, and wire stuff that way.

Two: The other issue is if I attach the shift leads to two switches,
each switch will turn on ALL keys hooked to the switch - enabled wires
- I guess the current flows through the whole circuit, so I was
thinking diodes might be the answer.

I even though about using TWO usb keyboards, and wiring one for the
shifted and one for the non-shifted keys. Either way, though, I cannot
permanently wire the shift key in the ON position, and so I still must
solve problem #2 in any case.

I'm very new to electronics, though so this might be off base. I know
there HAS to be a solution - because obviously, the keyboard has the
ability to do this prior to dissassembly!

If anyone can suggest another solution - like a way to send the keys
from a custom-built controller that sends the ASCII codes, or the scan
codes - I'd be interested in other options as well. One other
potentioal snag with my plan is that if I press a button to a shifted
character and another to a non-shifted char, BOTH chars will be
shifted, unless I can somehow figure a way to send the signals
alternately.

If you want to see the controller concept I am building, you can see it
here:
http://www.midibox.org/forum/index.php?topic=6402.0

 

[Tim Wescott]

I am having the following problem shown in this diagram, and have a
solution that I think might work - but I am not sure.
Here is the diagram:

http://img207.imageshack.us/img207/1161/kbproblem4bb.png

My problem is that I am trying to build a music controller -
essentially a bunch of sample triggers - and this is most cheaply done
via keymappings, which the software (Ableton Live 5) supports. But, to
get the keys I need, I will use almost every key and its shifted
complement.

This has led to two issues:

One, I can make EITHER the shifted keys work OR the non-shifted keys,
simply by activating the keyboard matrix's shift key and then wiring
spst switches to the other mappings. Alternately, I can of course leave
the shift key off, and wire stuff that way.

Two: The other issue is if I attach the shift leads to two switches,
each switch will turn on ALL keys hooked to the switch - enabled wires
- I guess the current flows through the whole circuit, so I was
thinking diodes might be the answer.

I even though about using TWO usb keyboards, and wiring one for the
shifted and one for the non-shifted keys. Either way, though, I cannot
permanently wire the shift key in the ON position, and so I still must
solve problem #2 in any case.

I'm very new to electronics, though so this might be off base. I know
there HAS to be a solution - because obviously, the keyboard has the
ability to do this prior to dissassembly!

If anyone can suggest another solution - like a way to send the keys
from a custom-built controller that sends the ASCII codes, or the scan
codes - I'd be interested in other options as well. One other
potentioal snag with my plan is that if I press a button to a shifted
character and another to a non-shifted char, BOTH chars will be
shifted, unless I can somehow figure a way to send the signals
alternately.

If you want to see the controller concept I am building, you can see it
here:
http://www.midibox.org/forum/index.php?topic=6402.0

There are a number of projects that use PC keyboards, and the protocol
to the computer is well documented. Do some web searches, see what you
come up with.

If it were me, even though I'm pretty good with this kind of stuff, I'd
be tempted to find a project that replaces a keyboard and start with that.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Posting from Google? See http://cfaj.freeshell.org/google/

 

[Jonathan Kirwan]

There are a number of projects that use PC keyboards, and the protocol
to the computer is well documented. Do some web searches, see what you
come up with.
<snip>

I wouldn't say "well documented." Just prolifically. I haven't seen
anything on the web either as accurate or as detailed as my copy of
IBM's Technical Reference series on the subject of the traditional
keyboard. Even taking multiple sites together. Which is too bad
because that information is important for robust use and not easily
inferred through examination.

Jon

 

[[email protected]]

The problem is that I am new enough to electronics that I might not
understand what's been written! This is totally new territory for me,
and what I have learned so far has been through experimentation only.

I've certainly been searching for the info, but either I don't know
what to search for or the info isn't documented. The closest I have
found were people referring to "key ghosting", which gave me the diode
idea.

 

[Rich Grise]

I am having the following problem shown in this diagram, and have a
solution that I think might work - but I am not sure. Here is the diagram:

http://img207.imageshack.us/img207/1161/kbproblem4bb.png

My problem is that I am trying to build a music controller - essentially a
bunch of sample triggers - and this is most cheaply done via keymappings,
which the software (Ableton Live 5) supports. But, to get the keys I need,
I will use almost every key and its shifted complement.

People have been doing this for decades - in fact, there are boxes on
the market that accept a whole bunch of contact closures and send
keycodes to the PS-2 keyboard port. I don't konw if they have them
in USB yet. Here's a place to start:

http://www.google.com/search?q=keyboard+hack

Have Fun!
Rich

 

[Rich Grise]

People have been doing this for decades - in fact, there are boxes on the
market that accept a whole bunch of contact closures and send keycodes to
the PS-2 keyboard port. I don't konw if they have them in USB yet. Here's
a place to start:

http://www.google.com/search?q=keyboard+hack

Here's another:
http://www.neodruid.com/KeyZilla

Cheers!
Rich