Android With Arduino

There must be a lot of people out there who love trying out things with Android, and who spend a lot of time experimenting with it. Here is something for those who love creating things with FOSS and electronic prototyping boards.

Arduino is an Open Source, single-microcontroller elec­tronics prototyping board with easy-to-use hardware and software. It was developed in 2005 by Massimo Banzi and David Cuartielles. Arduino is capable of interacting with the en­vironment by receiving inputs from a broad range of sensors and responding by sending outputs to various actua­tors.

Android with Arduino

The Arduino board consists of 8-bit Atmel AVR microcontrollers. In ad­dition, the board has a standard way of connecting the CPU with various other complementary components to increase its functionality through a number of add-ons called shields. You can either assemble an Arduino board yourself or purchase it (pre-assembled) from http://arduino.cc/en/Main de­pending on your needs.

Installing and working with Arduino

The microcontroller on the Arduino board is programmed via Arduino Pro­gramming Language (based on Wiring) and Arduino Development Environ­ment (based on Processing). The Open Source Arduino environment can be downloaded for Windows, Linux or Mac OS X from http://arduino.cc/en/Main/Software and extracted. This makes writing the code and uploading it to the board very easy. As the envi­ronment is written in Java, make sure you have Java installed.

When you are finished with instal­lation, start off with Arduino program­ming. When working with electronic prototyping boards, all programmers must be familiar with 'Hello World' sample of physical computing - for microcontrollers that don't have a display device, an LED is added. So just start the Arduino software, select your board model and enter the fol­lowing code:

int ledPin = 13; // LED connected to digital pin 13

void setup() {pinMode(ledPin, OUTPUT);// sets the digital pin as output}

void loop() {digitalWrite(ledPin, HIGH); // sets the LED on delay(1000); // waits for a second digitalWrite(ledPin, LOW); // sets the LED off delay(1000); // waits for a second

Once you've typed in the code, connect your board via USB, and up­load the program to it. As the LED has polarity, you need to fix it onto the board carefully. The long leg, typically positive, should be connected to pin 13, and the short leg to GND (i.e., ground). The LED starts turning 'on' and 'off' at intervals of one second, as shown in Fig. 1.

The Arduino LED shown blinking

Connecting Arduino to Android

To connect your Arduino board to an Android device, you need an Amarino toolkit. Amarino is a project devel­oped at MIT to connect Arduino and Android via Bluetooth. It has been released under GNU GPL v3.

The Amarino toolkit consists of three main components:

1. Android application called Amarino
2. Arduino library called MeetAndroid
3. Amarino plug-in bundle (op­tional)

You can download these toolkit components from http://code.google. com/p/amarino/downloads/list. Moving on, if you want to work with Amarino, you need an Android- powered device running version 2.x, though it supports version 1.6 too. Moving on to the Arduino board, you can have a Lilypad or Duemilanove, with a Bluetooth shield such as BlueSMiRF Gold and Bluetooth Mate, or an Arduino BT, which comes with Bluetooth attached to it already.

Installing Amarino is simple. After you've downloaded 'MeetAndroid' library, extract and copy it to 'Arduino Libraries' directory. Install 'Amarino.apk' package to your Android device by downloading directly to it or by calling 'adb install Amarino.apk.' Make sure your device is connected to the computer via USB, and the PATH is set correctly for 'Android SDK Tools' directory.

Now follow these steps to get the Arduino board connected to Android:

Authentication

Open the in­stalled Amarino application and click 'Add BT Device' to search for your Arduino BT device. Make sure that it is turned on. But before the two can talk to each other, they must be authenti­cated. Select the device and confirm pairing with it from the notification bar. Typically, the pin number is 1234, 12345 or 0000. Once your Arduino BT device is authenticated, it's ready to go. See Fig. 2.

Amarino app homescreen

Creating events

Next, install the plug-in bundle (AmarinoPluginBundle.apk) from http://code.google.com/p/amarino/ downloads/list. Thereafter you can head to event creation. Start the Amarino application and launch 'Event Manager' of your Arduino BT device. Click 'Add Event → Test Event.' This is a test event - a demo that sends a random number (0-255) every three seconds. Now your Android device is ready to communicate with the Arduino board, so set up the latter.

Setting up Arduino

Open your Arduino software and select 'File^ Examples → MeetAndroid → Test.' When the project opens, change the baud rate of your Bluetooth module from 57600 to 9600, as highlighted in Fig. 3. Upload the sketch to the board. If there is no LED on the board, you can attach one to pin 13.

Arduino 'test' program code

Running the test program

Now your Android device and Arduino board are ready to talk to each other. In the Amarino application on your Android device, click 'Connect' to com­municate with the Arduino board. As soon as Android connects to Arduino, it starts sending a random number every three seconds, and that lights the LED for one second. You can monitor the process by pressing 'Monitoring' on the main screen of the application.

Applications

This concept of connecting Android to Arduino can be very handy in mak­ing electronics projects more useful by increasing their flexibility. It can easily be used in home automation controls, power consumption meters, Bluetooth-controlled robots, managing devices from the computer and much more. There is little doubt that Amarino brings us more power by helping us connect Arduino with Android.