USB devices for Android

One of the most interesting new products presented at Google I / O 2011 can be considered the announcement of the full-fledged work of Android devices with USB.
The new Android supports two USB modes - the host (Host mode) and the device (Accessory mode) .

With the host mode, everything is simple and clear - this is the connection to the Android device of the keyboard, mouse, digital camera, external drives, etc.
But with the USB mode, the device is much more interesting. In this mode, external USB equipment acts as a host for an Android device and such external equipment can be docking stations, robotic controllers, diagnostic and musical equipment, sports equipment, card readers and much more. USB hardware for Android must support the protocol ( Android accessory communication protocol )

You can clearly understand the difference between the two modes by the scheme:

When an Android device acts as a USB host, it feeds the bus. When the Android device is in USB device mode, the bus is powered by the equipment connected to it.
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Host USB modes and USB devices are supported starting with Android 3.1 (API level 12). USB device mode is also ported to Android 2.3.4 (API level 10) as a library that supports a large set of devices. The equipment manufacturers themselves decide to add this library to their system image or not.

Android Open Accessory

For the development of USB hardware for Android, the Android Open Accessory Development Kit (ADK) is proposed, which is the implementation of USB hardware for Android and includes an Arduino- based layout, Accessory mode firmware code and an Android hardware interaction application.

In the role of hardware for development is a set of RT-ADK & RT-ADS , which we are trying to sell for ~ $ 390

Although this is just an Arduino Mega2560 , Circuits @ Home USB Host Shield integrated into the board, and a set of sensors and controls. This set will cost up to $ 100.

In addition to various sensors and indicators for Arduino, there are a large number of expansion cards (Arduino shield) that can turn a USB device, for example, into a robot.

Presentation of the Android Open Accessory API and Development Kit (ADK) on Google I / O 2011

Android Open Accessory should facilitate the emergence of a large number of different accessories for Android devices.

In the future, it is planned that Android Open Accessory will also support Bluetooth, in addition to the USB interface.