Arduino Hellschreiber Keyboard

I am looking at keyboard options to use with the Arduino Hellschreiber communicator. I would like something small and portable. There are mini QWERTY keyboards out there, however the Arduino will not support a USB keyboard directly. If the keyboard is downward comparable with the PS2 standard there is library to support that method. The PS2 library is large and will take up most of the Arduino memory though. This made me look at alternate keyboard designs. The alternate designs I have reviewed have significantly fewer keys than the familiar QWERTY keyboard. These methods are mostly based on a Chorded Keyboard. You have fewer keys but you need to press multiple keys at once to produce the different characters. I have now reviewed several of these methods using a very nice application called Autohotkey which is open source and free. Using this application and user submitted scripts I have tried out the following methods:

• T9 - Text on a numeric pad like the old cellphone method
• Frogpad (like) - A reduced size one handed method
• Thumbscript - Another numeric pad method
• ASETIOP - A two handed 10 key method
• Braille - A two handed 8 key method
• 7KAT - A 7 Key Alternate Typing method

Some of the above could not be fully tested due to limitations of my keyboard. Not all keyboards can support pressing 4 or more keys at the same time.

The last method evaluated was GKOS. I could not find a Autohotkey script for it but one could be adapted from the Braille script, however it does require up to 6 keys to be presses at the same time so it would be limited with my keyboard. There is also a program EXE available from the GKOS site that fully implements the method using either keys on your keyboard or the numeric pad that I did experiment with to better understand GKOS. In addition the site also has links to building your own keyboard using 6 switches and an Arduino library!

Since there is an Arduino library, I plan to wire up a 6 key pad and fully test it. This 6 key method seems neat, however it will depend on how quickly it can be learned and if I can obtain a decent typing speed.

I like the idea of this minimal 6 key pad to use on a portable system but it still may not be practical and I will fall back to either a PS2 keyboard or a QWERTY keyboard built from discrete buttons and shift resisters using the Arduino function ShiftIn.