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SpiffChorder FAQ

- What exactly is the SpiffChorder?

The SpiffChorder is an implementation of chording keyboard Chorded keyboard. It is an input device where characters are typed by pressing multiple keys at the same time. It was designed to entirely replace a computer keyboard. Specifically, the SpiffChorder consists of the hardware and software needed to emulate a conventional usb keyboard in an object or objects with only a small number of keys or switches on it. For the purposes of building one, you can think of it as functionally consisting of four main components, two hardware, and two software:

  1. the circut board: the actual electronics not including the keyswitches, you will likely not modify this part, you just build it.
  2. the input device: the thing with the keyswitches on it. Just about anything you can get an open/closed signal from can be used a a keyswitch. Typically this consists of keyswitches on some sort of object that fits in or straps to your hand, sits on a desk or is part of an article of clothing, or a dashboard but it can also be a separate electronic device that turns finger or other motion into on/off signals. You can model this after one of the existing patterns or put your switches on anything you think will work.
  3. the keymap files: the part of the software that maps chords to keyboard events. This is easy to modify without any knowledge of programming languages.
  4. the program: the rest of the software. Written in C, you will likely not modify any of these files.

- Multiple Keys? How many?

The circuit design of the SpiffChorder allows for up to 8 keys for chording and up to 3 additional keys that can be used as modifiers (ctrl, alt, shift). The implementation that sees the most use consists of a total of 7 keys all used for chording in this case the modifiers are also entered as chords.

- Are all possible variations "stable"

No, since you can change the code and you can modify the keybindings you could render it unstable. You could create a keymap where you have no way to get out of a special mode or state unless you unplug it (for example, no way to undo caps lock). However, if you exercise a little planning and care in designing your keymaps, this should not be an issue. The SpiffChorder device and the modified_nasa have been in daily use for over two years so we feel safe saying that this combination is “stable”.

- How much does it cost to build?

The software is open and free. You only pay for the parts of your chorder. The circuit can be built for under $25 US. The input device cost depends on what you want to use for switches and such, if you want a 7 key desktop or handheld chorder you can do that with good keys for under $10 US, if you want to embed a sensor system for chording in the latest haute couture, then you may spend a little more. In addition you will need access to a programmer for the amtel microprocessor to load the code the first time. If you don't have that Greg will program your chip for you at no cost. Just send him a chip and a self addressed stamped envelope. Contact him first to confirm address and schedule.

- Do I need a programmer every time I want to change the chords?

No, you only need the programmer once. Part of what is loaded on to the chip is a usb bootloader. Once the chip has this bootloader it can be put into program mode by holding down a particular chord while you connect it to the usb port. In this way you can download changes as often as you like without the need for any additional hardware.

spiffchorder/faq.1269829130.txt.gz · Last modified: 2010/03/28 22:18 by priestdo
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