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Android Open Accessories gains third party support

May 16, 2011 — by Eric Brown — from the LinuxDevices Archive — 7 views

Google's Android 3.1 Open Accessories initiative for connecting Arduino-based gadgets via USB has attracted third-party support. In addition to the RT-manufactured Google reference platform, Future Technology Devices International (FTDI) is preparing a compatible product using a “Vinco” development board that incorporates the Vinculum II USB controller, and Microchip is shipping a compatible PIC24F Accessory Development Starter Kit that uses its own PIC microcontroller.

The Android 3.1 update released by Google last week at Google I/O (starting with the Motorola Xoom tablet) was largely concerned with fixing the problems in Android 3.0. However, at least one major structural enhancement was provided by the release's improved USB support and by a related Arduino-based Android Open Accessories initiative.

Google has published an Android Accessory gadget control platform API and application development kit (ADK). The ADK, which has been backported to the new Android 2.3.4 for smartphones, enables any USB-connected accessory designed with the API to interact with Android devices.

As detailed on Google's Android Open Accessory site, the ADK builds upon the newly enhanced USB skills of Android 3.1 and Android 2.34 to help developers create Android hardware peripherals that connect to Android devices via USB, enabling the peripherals to act as a USB host. Initially, at least all the external devices must use a device compatible with the popular Arduino microcontroller platform.

Now, third parties are announcing support for the platform, including FTDI and Microchip (see farther below).

RT's RIC Android 2011 robot prototype, controlled by an Android Accessory ADK
(Click to enlarge)

A reference hardware reference platform design kit for the API is offered by Google and manufactured by RT Corp. However, it is currently listed by RT as being sold out, with "next production in the end of May." The Japanese robotics equipment manufacturer sells the kit for 31,500 Yen ($389).

RT-ADK hardware reference platform, with Arduino-based RT-ADK (left) and RT-ADS Android interface board on right 

The baseboard, called the RT-ADK (above), incorporates the Arduino Mega open source electronics prototyping platform. The Mega module is based on the Atmel Atmega1280, an 8-bit AVR microcontroller with 64K, 128K, or 256KB of programmable flash memory.

A second RT-ADS board offers the Android interface, plus sensors and input devices. These include a joystick, three buttons, and three LEDs, plus light, temperature, and touch sensors. There are also two software-operable relays, and three connectors for servo motors, says RT.

Google's bowling ball labyrinth, controlled by a Motorola Xoom running Android 3.1 and the Open Accessory ADK

At Google I/O, RT demonstrated the kit driving a robot prototype it calls RIC Android 2011 (see the image earlier in this story). Also at Google I/O, Google showed off a giant bowling ball labyrinth game controlled by the Open Accessory ADK (see image directly above). In other Open Accessories initiative demos, LifeFitness demonstrated an exercise bike (below), said to be enabled with the ADK to permit integration with Android devices.

LifeFitness exercise bike with Open Accessory integration

Our sister publication eWEEK has posted a slide show of the Google I/O segment covering the Open Accessories initiative. In addition, Neil McAllister provides a solid overview of the technology on InfoWorld's Developer-World site

FTDI's Vinco board

Future Technology Devices International (FTDI), known for its USB technology, has announced its intention to support the Android Open Accessories initiative with its Vinculum II dual USB host/device controller IC, as well as its "Arduino-inspired" Vinco development board. The Vinco board, which integrates the Vinculum II chip (pictured at right) is said to be a superset of the Arduino Duemilanove/Uno, adding two extra rows of headers comprising 10 new pins.

The Vinco board offers an advantage over working directly with an Arduino module because the host controller capability is already integrated into the board, says FTDI. This means engineers do not need to integrate an extra USB host controller card or IC to implement Android Open Accessories, thereby "dramatically shortening the development process and reducing the bill of materials," says the company.

FTDI's Vinco board
(Click to enlarge)

FTDI did not say when the products would be available with Open Accessories support, but the company is demonstrating the technology at the Maker Faire at the San Mateo Events Center in San Mateo, Calif. on May 21-22.

Microchips ships starter kit

Microchip announced two Accessory Development Starter Kits for Android, which consist of a development board and a freely downloadable software library to "enable the fast and easy development of Android smartphone and tablet accessories," according to the company. The kit is compatible with the Android Open Accessory API and supports Android 2.3.4 and 3.1, says the company.

PIC24F Accessory Development Starter Kit

(Click to enlarge)

Available now, the PIC24F Accessory Development Starter Kit is based on an Atmel Atmega-like Microchip 16-bit PIC24F microcontroller, which offers 16 MIPS performance @ 3.3V, according to Microchip. The chip is said to support up to 96KB RAM and offers integrated USB OTG.

In the third quarter, the company plans to ship a PIC32 version of the kit, available for the same $80 price as the 16-bit version. The PIC32 would appear to be based on the 32-bit PIC microcontroller, which features an 80MHz MIPS M4K core, up to 128KB SRAM and 512KB flash memory, and support for Ethernet, CAN, and I2C, among other interfaces.

PIC24F starter kit board (left) with Android display unit

(Click to enlarge)

The initial PIC24F Accessory Development Starter Kit features a type A USB OTG connector and an on-board debugger, says Microchip. Also included are a button-based programming user interface, LEDs, a potentiometer, and device charger circuitry supporting up to 500mA power.

In addition, the board supplies "standard Arduino connectors," says Microchip. The latter are said to support connections to a variety of third-party "Shield" expansion daughter cards available for the growing number of open platform Arduino modules.

The kit ships with schematics and gerber files, as well as a free software library that includes a sample application protocol and an abstraction layer, says Microchip. Sample accessory applications are said to include:

  • automotive (car kits, audio, GPS)
  • home devices (audio docks, remote controls, data backup),
  • fitness/health (glucose meters, fitness equipment)
  • business (credit-card terminals, projectors)

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