Hi, can you please recommend the cheapest and most simple Arduino setup that would be able to communicate with the Novation Launchpad via USB?
I'm deciding whether to go with Arduino or Raspberry PI.
Unless that device emulates something standard such as a keyboard you won't be able to connect to it at all unless you find/write USB drivers for your platform.
It looks as if it is designed to interface directly to the 'Live' application (whatever that is) and not be used as a general purpose input device.
When you plug it in to a PC, does it appear as a standard keyboard?
I think it's not standard at all, I was prepared to debug it and write my own driver, however I'm not sure if the hardware is even able to communicate with any USB device since the "USB host" capability is listed only for the Arduino Due. I was wondering if it is possible to code a USB host simulator on the Leonardo or Arduino Mini without HW modifications (maybe except a resistor or two)
For example ? http://shokai.github.com/ArduinoFirmata-Android
There are USB host shields that can be used for UNO and compatible Arduinos that don't already have a host port. However, writing a USB driver is far from simple especially when it is for an unknown device. Unless you know what you're getting in to, I suggest you look at the existing keyboard/mouse HID examples and see whether you think you would be capable of creating something that complex and getting it to work.
a little bit of follow up:
I used a Pro Mini and I am communicating with the LEDs and buttons directly through the shift registers on the Launchpad. I completely bypassed the Launchpad onboard microcontroller (72f63bk2m1) and USB
Hi!
Hey I have a sudden need to use my Launchpad (version 1) as a standard MIDI controller to 'perform' MIDI notes into an audio/midi sequencer - Afterward I will play the audio track to my speakers, and the MIDI track back into a computer (from external interface - Tascam US-1641) to trigger light scenes (using American DJ MYDmx program).
The MYDmx program can accept note/on note/off MIDI data to control the scenes I set up.
However, it will not accept the USB hosted input from the Launchpad.
So.... I need to convert the Launchpad to a 5-pin DIN (MIDI note/on note/off) controller.
~I don't care about lights in the Launchpad~
I could do this with any MIDI keyboard I have laying around.
However, the Launchpad provides a nicer layout for assigning light scene changes! 
It looks like you were able to accomplish this functionality?
I'd be interested in chatting with you to see if this is something I could build and program
easily to use my Launchpad for the whole reason I bought it LOL.....
THANKS!
Jeff