Is there a list anywhere of which Android devices (phones, tablets) support the ADK / accessory mode? From what I have read, I known that the Nexus One, Nexus S and Xoom do
When I was digging around in the CyanogenMod 7.1 kernel sources for my Galaxy S2 I found that the USB accessory driver missing from kernel 2.6.35.7 (I think the kernel .config flag is CONFIG_USB_ANDROID_ACCESSORY).
From what I've found by a lot of searching and forum digging was that the accessory driver was implemented in Honeycomb (3.x) but backported to Gingerbread (2.3), and should be available from kernel 2.6.35.15. I made a few unsuccessful attempts to compile my own kernel, with the plan to cherry pick the driver but for some reason I was not able to make the phone boot with my custom kernel.
I am now running an early experimental CyanogenMod 9 ICS (4.0.3) build on my SGS2 and it is possible to have the phone talk with my Arduino board. I made the phone able to toggle an LED on the board so I guess it is time to start working on my plans for world domination.