Converting MIDI over USB data to Keyboard HID ?

Here is what I am wanting to do... Convert MIDI information into Keystrokes and have the Arduino function as a USB Keyboard HID.

I know this should be relatively simple if I used a standard 5 pin MIDI DIN cable into the arduino... However, the difference with my project is the music keyboard I am wanting to use with it only outputs MIDI over USB - It is the Akai Synthstation 25 - http://www.akaipro.com/synthstation25. The Akai has a USB mini-B connector which is used to send out the MIDI information.

Is there a way to receive this information with the arduino and still be able to use the arduino's main USB port to connect to a PC to be recognized as a Keyboard HID?

Some background on the project: I have a handheld PC (NEC Mobilepro 900) which runs Windows CE and has a USB-host port, however there are no MIDI drivers for Windows CE. But USB Keyboards do work with the USB-host port. So I want to convert the MIDI data from the Akai to typing keyboard data to use on the Mobilepro.

Would this even be possible?

Thanks for any help or advice.

Sorry, also forgot to mention my Arduino is the Arduino Uno.

Edit: Also I have not gotten the Akai Synthstation yet, so if it may be simpler to get another keyboard with an actual MIDI 5 pin DIN connection, then I may go that route.

You should be able to get that working with a USB host shield. Here's an example for MIDI: http://www.circuitsathome.com/mcu/interfacing-midi-devices-with-arduino-using-usb-host-shield. The shield is about US$25 from sparkfun. A cheaper option would be to investigate V-USB http://code.rancidbacon.com/ProjectLogArduinoUSB.

You can find details on adding HID keyboard support to the Uno here: http://arduino.cc/playground/Main/InterfacingWithHardware#USB

dhunt: You should be able to get that working with a USB host shield. Here's an example for MIDI: http://www.circuitsathome.com/mcu/interfacing-midi-devices-with-arduino-using-usb-host-shield. The shield is about US$25 from sparkfun. A cheaper option would be to investigate V-USB http://code.rancidbacon.com/ProjectLogArduinoUSB.

You can find details on adding HID keyboard support to the Uno here: http://arduino.cc/playground/Main/InterfacingWithHardware#USB

Great, thanks for the useful info!

Also, I've ordered an M-audio O2, which has not only MIDI-USB, but also a regular old style MIDI port. So I will probably just use that to simplify things. Now to get everything together and see if I can figure out how to code it. You may see me on the "Programming questions" forum soon :)