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Is it possible for an Android 4 phone with only a standard micro-USB port (not OTG), to be provided with a USB host port through an adapter using the Android accessory protocol? Do such adapters exist?

The adapter would need power and 2 USB ports. One USB port would act as a host and plug any USB device (for example a keyboard), the other would act as an 'Android accessory' and plug into the phone. Android should be able to use the device as if it were plugged in directly to a host port (on a tablet).

It would be really great if the adapter was also powered by micro-USB, and that it could pass-through data to a computer host (Storage, tether, ADB, etc.).

Diagram:

Android USB host adapter

Is all/any of this possible? Do such adapters exist? If not, how would I make one?

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  • My first question, can't post images yet. :-( I'll edit it in when I can... – James Haigh May 8 '12 at 4:12
  • animuson: Yay, thanks! :-) – James Haigh May 10 '12 at 21:56
  • I've read the question thrice and looked at the diagram, and I'm still not sure what you're asking... – Logos May 11 '12 at 3:42
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    Logos: Which bit are you struggling with? Since 3.1, Android has supported USB host-mode. This is great for tablets but not much use for phones. Android 3.1 also introduced the 'Android accessory protocol' - an extension to attempt to address some of the shortcomings of USB. The adapter should provide a USB host port, and tunnel whatever is plugged into it to the phone over the Android accessory protocol. The phone should be able to use the plugged in device as if it had a /native/ USB host port. The phone should still be able to communicate with the laptop as if it were plugged in directly. – James Haigh May 11 '12 at 10:48
  • Ahhh. I've never used Honeycomb, so I know zippo about USB host mode on Android - that's why I'm not understanding. Time to update my knowledge! – Logos May 11 '12 at 12:48

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