USB to USB keyboard protocol converter ====================================== Hardware requirement -------------------- Arduino Leonardo http://arduino.cc/en/Main/ArduinoBoardLeonardo Circuit@Home USB Host Shield 2.0 https://www.circuitsathome.com/products-page/arduino-shields/usb-host-shield-2-0-for-arduino-assembled/ Buying Arduino Leonardo and USB Host Shield 2.0(from Circuit@home) will be the easiest way, you won't need even soldering iron. Arduino's Shield will also work well but I think Sparkfun's needs to be modified. http://arduino.cc/en/Main/ArduinoUSBHostShield https://www.sparkfun.com/products/9947 Also Pro Micro 3.3V(not Mini) or Teensy with mini host shield will work with some fixes on signal/power routing. https://www.circuitsathome.com/products-page/arduino-shields/usb-host-shield-for-arduino-pro-mini https://www.sparkfun.com/products/12587 https://www.pjrc.com/teensy/td_libs_USBHostShield.html Build firmware -------------- $ git clone git://github.com/tmk/tmk_keyboard.git $ cd tmk_keyboard $ git submodule init $ git submodule update $ cd converter/usb_usb $ make Program converter. Push reset button on Leonardo before run this command. Serial port name(COM17) depends your system. On Linux I got /dev/ttyACM0. $ DEV=COM17 make program or $ avrdude -patmega32u4 -cavr109 -b57600 -Uflash:w:usb_usb.hex -PCOM17 Limitation ---------- Only supports 'HID Boot protocol'. Not support keyboard LED yet. Note that the converter can host only USB "boot protocol" keyboard(6KRO) and not NKRO, it is possible to support NKRO keyboard but you will need to write HID report parser for that. Every NKRO keyboard can have different HID report and it is difficult to support all kind of NKRO keyboards in the market. Update ------ 2014/12/11 Added Hub support(confirmed with HHKB pro2) Resource -------- USB Host Sheild 2.0 https://www.circuitsathome.com/products-page/arduino-shields/usb-host-shield-2-0-for-arduino https://www.circuitsathome.com/products-page/arduino-shields/usb-host-shield-for-arduino-pro-mini USB Host Sheild 2.0 source https://github.com/felis/USB_Host_Shield_2.0 Arduino USB Host Shield(with bootst converter) http://arduino.cc/en/Main/ArduinoUSBHostShield Arduino source https://github.com/arduino/Arduino/hardware/arduino/{cores,variants} Initial release of TMK USB-USB converter https://geekhack.org/index.php?topic=33057.msg653549#msg653549 http://deskthority.net/workshop-f7/is-remapping-a-usb-keyboard-using-teensy-possible-t2841-30.html#p74854 Arduino-based hardware keyboard remapper - Colemak forum http://forum.colemak.com/viewtopic.php?id=1561 Teensy + Host Shield http://www.pjrc.com/teensy/td_libs_USBHostShield.html