Custom bluetooth keyboard

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

Brainstorming

Available approaches

• USB HID to bluetooth adapter
  • Pros:
    • No modification of the keyboard necessary
  • Cons:
    • USB HID host chips are uncommon and expensive
    • Programming USB HID host may be complicated
• PS/2 to bluetooth adapter
  • Pros:
    • Simpler to decode than USB HID
    • Any microcontroller can do it
  • Cons:
    • USB version of keyboard may or may not have PS/2 output
• Custom replacement keyboard controller with integrated bluetooth
  • Pros:
    • Getting data directly from button matrix is likely simpler than decoding some other protocol
    • Opportunity to add extra features
    • Likely better battery life
  • Cons:
    • 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 HID and audio capabilities
  • 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

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