Custom bluetooth keyboard

Bluetooth conversion of a Kinesis contour keyboard to a bluetooth keyboard.

Brainstorming

Available approaches

Options	Pros	Cons
USB HID to bluetooth adapter	No modification of the keyboard necessary (for USB versions of the keyboard) Usable on any USB keyboard	USB HID host chips are uncommon and expensive Programming USB HID host may be complicated PS/2 version of keyboard may or may not have USB output (though there are USB related markings on the PCB) If capable, would likely require modifications to the original controller board
PS/2 to bluetooth adapter	Simpler to decode than USB HID Any microcontroller can be used No modification of the keyboard necessary (for PS/2 versions of the keyboard) Usable on any PS/2 keyboard	USB version of keyboard may or may not have PS/2 output If capable, would likely require modifications to the original controller board
Custom replacement keyboard controller with integrated bluetooth	Getting data directly from button matrix is likely simpler than decoding some other protocol Opportunity to add extra features Likely better battery life Any microcontroller (with enough IO) can be used	Kinesis keyboards have some advanced programmability - reimplementing that on a custom controller could take some time Requires interfacing with the key matrix directly which either requires special connectors or soldering to the key matrix

Features

• Bluetooth module might have audio capabilities in addition to the required HID function
  • Use keyboard as audio extender - include a headphone port in keyboard
  • Kinesis has a key recognition click speaker built in which can be hard to hear when listening to music, but might still annoy others
    • Overlay key click sound over bluetooth audio signal
• USB interface for charging
  • disable bluetooth while charging and instead use the USB connection
• Saving, editing, and uploading custom keyboard layouts to the keyboard from the computer
  • Cross platform application
  • Keyboard layers could be saved, exported, and uploaded individually
    • Example:
      • Standard keyboards have "qwerty" on the base layer and the shift key brings them to the next layer containing "QWERTY" (assuming qwerty keyboard)
      • The Kinesis firmware has a keypad layer, so when you press the keypad button, the keys under the right hand become a numpad and the shift key moves between the layers of the numpad (numbers or arrows)
    • Separate keys and their shifted values for more finely tuned layouts (can be done in xmodmap in Linux, but this isn't portable/cross platform)
      • May not act as expected in some programs as normally it is the computer that determines the shift's effect on the key, not the keyboard
      • Probably need to take special consideration into key sequences (eg pressing shift then x as opposed to x then shift)

Reference

• Development example using Bluegiga WT12
• WT12 breakout boards - supposedly open hardware, but I haven't seen the layout files yet
• WT12 module
• Custom bluetooth IBM Model M using a salvaged bluetooth module from a mini keyboard - salvaged PCB
• Custom bluetooth IBM Model M using a salvaged bluetooth module from a mini keyboard - custom PCB
• Custom bluetooth HHKB using the WT12