Arduino code to use a PS/2 based "Creative Labs Prodikeys DM" MIDI keyboard on USB
I have seen a video about the Creative Labs Prodikeys range of products - these are computer keyboards with a row of piano keys attached to them. I instantly wanted to have one. (More info on these weird things)
Unfortunately, when searching eBay I could only find a "Prodikeys DM" which is the PS/2 version - no USB, no DIN jacks... There is also some proprietary "driver magic" going on: The included Windows XP software sends some "magic" commands to the keyboard in order to activate its MIDI capabilities. After that, it sends MIDI data to the Windows MIDI subsystem. This, unfortunately, does NOT work with PS/2-to-USB dongles or any non-XP operating system :-(
So: We need a specialized PS/2-to-USB adaptor. That's what this is.
Since PS/2 is a very simple protocol, it is easy to use an Arduino to "speak PS/2" without using any additional parts. This part is quite easy. What's left is the whole USB MIDI/HID keyboard stuff... LUFA for the rescue!
The trick is to split the problem up into two parts: a PS/2 part (talking to the Prodikeys) and an USB part (talking to the computer). This can both be done on one regular Arduino UNO R3.
- Get an Arduino UNO R3 which has an ATMEGA32u2 USB controller. Others using a FTDI or CH340 do not work.
- Upload the Arduino sketch ProdikeysDM onto the Arduino (using the Arduino IDE or an ISP programmer)
- Now update the USB firmware on the secondary processor: Unplug the USB cable from your Arduino and connect an ISP programmer to the secondary ISP port near the USB jack. (You can use the "Arduino ISP" example to turn an Arduino into an ISP programmer if you don't already own such a device). Flash the .hex file from KeyboardMIDI firmware onto it. I have included a "flash_write.sh" script for that. After the USB processor has been flashed, you will not be able to upload sketches via USB any more unless you flash the original firmware back to the USB controller. You can always do so using an ISP programmer and the Arduino IDE.
- Now physically connect the ProdikeysDM keyboard to the Arduino: PS2-VCC to +5V, PS2-GND to GND, PS2-CLK to D3, PS2-DATA to D4. (Refer to "PS2Keyboard" examples on the web)
- You are now ready to plug the Arduino into a computer and it should show up as "Prodikeys DM multifunction keyboard", having a HID-Keyboard, and a MIDI-capable audio device.
- Have fun jamming along!
- Hint: Use Shift+Octave for semitone tuning, Ctrl+Octave to change patches
- Not all standard typing keys have been correctly implemented. Shift+Cursor does not work, for example.
- Status LEDs and NumLock can't be toggled at the moment