(from our introduction)

The Twiddler is a one-handed chording keyboard that is quite popular with wearable and mobile computing groups and accessibility advocates. The current generation of Twiddler uses a corded PS/2 keyboard interface. It uses “chording” or pressing several control buttons at once in order to create a keypress, thus permitting typing with one hand, and keeps the wrist in a natural alignment while it is being used. The first Twiddler had only a serial interface, while the current version, the Twiddler 2, uses a standard keyboard and mouse PS/2 interface. While the Twiddler improves mobility by freeing one hand while not losing any of the functionality of a standard keyboard, it is still attached by cables to its host computer, which limits the user's freedom and range of motion, and preventing the quick changeover of the Twiddler to another computer. To make it more useful for mobile computing, developed a variation of the Twiddler that connects to the host computer wirelessly via the IEEE 802.15.1 Protocol, commonly known as Bluetooth®.

The Bluetooth HID Twiddler is also extremely useful because it requires no drivers to be installed on host machines that support HID profiles and Bluetooth, allowing a user to move from host computer to host computer without any interruption in functionality.

How to Build a Bluetooth Twiddler - Hardware (PDF)

How to Build a Bluetooth Twiddler - Software (DOC) (add'l formats available)

• How to Build a Bluetooth Twiddler - Source Code Flowchart

How to Build a Bluetooth Twiddler - Documented Source Code (ZIP)

BT Twiddler Presentation (PPT)

April 12, 2007 Just discovered - flashing a Bluecore chipset does not require the Casira Bluecore Development Kit. Flashing the device requires a home-made cable, using a DB25 connector (25 Way D-type - the computer end of a parallel printer cable) with a particular pinout. This effectively reduces the development costs of this project by $3025 to around $325 and makes this project even more accessible to the public. Instead of connecting the wires to the Casira dongle, attach them to a connector that can be mounted on the twiddler. The other end of the connector can be attached to the DB25 cable, providing a way to reprogram your BTT without having to open it up every time.

Note: You will still need to use Casira's IDE and utilities to flash the chipset, this just simplifies the necessary hardware to do so.

Pinout Mapping:

Please note that the Bluecore2 chipset uses 3.3v signals, while computers may use 5v (some laptops use 3.3v), so it's probably a good idea to add a voltage reducer to your homebrew cable. Have fun!