Hacking a keyboard

Looking for an easy way to get a lot of input possibilities attached to the computer, you could think of hacking a keyboard. That is taking it apart, finding the key matrix (a matrix is like a chessboard), and making the switches you need. It is all very well described here:

http://www.extremetech.com/article2/0,2845,2301149,00.asp

but also the writer warns that: there is no standard key matrix, so all types of keyboards have to be checked individually and that you have to be careful not to damage your computer, third you have the problem of ghosting, that is three buttons might awaken an extra ghost button.

Alternatives are available: prepared boards. A bit more expensiv, but first of all, you know it will work, second, you cannot damage you computer.

These hacks are listed here: http://wiki.arcadecontrols.com/wiki/Keyboard_Encoders

So I-PAC (USB): (31 euro’s + 4 TAX, feb 2009)

http://www.ultimarc.com/ipacve.html

it comes with WinIPAC:

http://ultimarc.com/download.html

KeyWiz40-Eco (26 dollar, TAX ? )

http://groovygamegear.com/webstore/index.php?main_page=product_info&cPath=76_80&products_id=200

(no experience yet with these hack-boards! But they seem to be good…although noting is better then DIY, ok maybe sometimes it does not function then….:-)

Since the keyboard strokes are recorded and taken care of in FLASH (for instance) no need to reprogram the strokes anywhere else.

As an alternative to keyboard or the above mentioned keyboard chip, one could simple use the ARDUINO like the key matrix. Making ports input, and reading out the combinations, using the FLASH connection (or other) described elsewhere in this DIY blog.

first possibility: simple using the ports, setting all ports to input, use a 100 - 200 Ohm resistor and a switch.

second possibility:(using less ports, making combinations)

For instance: using 3 ports:0 = low, 1 = high, ports are connected to a single switch.

000 = a, (sending an a through the serial connections)

001 = b

010 = c

011 = d, etcetera

since the ARDUINO has 14 input ports (not counting the analog ports) we have a bewildering number of possibilities. (2 to the power of 14)

Third possibility, like the keyboard matrix:

use two rows of ports, look at the keyboard, 4 rows of keys, from bottom to top, use 4 porst for these rows, then take for instance 5 keys in each row, and connect these to five other ports, so each key is connected (with a switch) to 2 ports, the first determining which row to pick and the second which character in the row.

Then you see suddenly how many keys there are on a keyboard! Covering the whole keyboard with an ARDUINO, you have to divide the keyboard into regions, adding the number of rows, or take an extra switch to connect to each key…This will be a lot of work!

Maybe the above mentioned keyboard alternative is not so bad after all?

(Using the ARDUINO with FLASH, you need serproxy, and setting the serproxy config to the port used by the ARDUINO software - see other blog.)

So i started buying a flexible keyboard on the market. The purple one i didn’t sacrified, but a white one. Seeing through the layer reveals the wiring. On the side we have the chip. There are a lot of shortcut revealed! Trying out connections from the two side, sometimes the computer falls asleep, sometiems all is saved :-). So indeed be careful! I used male connectors to slip inside the matrix board. Here some pictures: (try connecting wires from the strip left under to the strip right under…

we bought this for CrossLab:

http://groovygamegear.com/webstore/index.php?main_page=product_info&cPath=76_81&products_id=235