user6804: I want to connect an Android Galaxy S2 phone to my UNO Arduino using USB OTG functionality.
I can upgrade/root the android to any version I want. My goal is to be able to communicate between the devices (send/receive data).
I've tried to search for whether that's possible but found conflicting answers whether Galaxy S2 and the Arduino UNO would be able to be connected this way.
Anyone knows whether this is possible? If yes - Do I need to do anything special - such as rooting the device, flashing it to a certain rom or something like that?
Thanks in advance!

user6740: If you use a bluetooth serial module - e.g. google hc 06 - you can do it wirelessly. I have a had good results with this - you can hook it up to pins 0 & 1, then use the stock arduino serial code. Probably not a good idea to hook up to both the bluetooth module and the USB (e.g. for programming) at the same time, they may interfere with each other.

user3866: Method 1. Basically you do not need root permission to communicate over USB. I am making app for Android for my project and using this FTDriver
Method 2. If you are not programming in JAVA then you can try third party apps like: 

Arduino Uno Communicator

Uno doesn't have FT232 chip so I found it a bit harder. So instead I have FT232 chip and use SoftwareSerial. 
Method 3. To communicate with Arduino you can use Bluetooth with HC-06 module. There are lots of third party apps to connect and send/receive data. Bluetooth Terminal

6804: <p>I want to connect an Android Galaxy S2 phone to my UNO Arduino using USB OTG functionality.
I can upgrade/root the android to any version I want. My goal is to be able to communicate between the devices (send/receive data).</p>

<p>I've tried to search for whether that's possible but found conflicting answers whether Galaxy S2 and the Arduino UNO would be able to be connected this way.</p>

<p>Anyone knows whether this is possible? If yes - Do I need to do anything special - such as rooting the device, flashing it to a certain rom or something like that?</p>

<p>Thanks in advance!</p>
 6740: <p>If you use a bluetooth serial module - e.g. google hc 06 - you can do it wirelessly. I have a had good results with this - you can hook it up to pins 0 &amp; 1, then use the stock arduino serial code. Probably not a good idea to hook up to both the bluetooth module and the USB (e.g. for programming) at the same time, they may interfere with each other.</p>
 3866: <p><strong>Method 1.</strong> Basically you do not need root permission to communicate over USB. I am making app for Android for my project and using this <a href="https://github.com/ksksue/FTDriver" rel="nofollow noreferrer">FTDriver</a></p>

<p><strong>Method 2.</strong> If you are not programming in JAVA then you can try third party apps like: </p>

<ul>
<li><a href="https://play.google.com/store/apps/details?id=com.primavera.arduino.listener&amp;hl=en" rel="nofollow noreferrer">Arduino Uno Communicator</a></li>
</ul>

<p>Uno doesn't have FT232 chip so I found it a bit harder. So instead I have FT232 chip and use <code>SoftwareSerial</code>. </p>

<p><strong>Method 3.</strong> To communicate with Arduino you can use Bluetooth with HC-06 module. There are lots of third party apps to connect and send/receive data. <a href="https://play.google.com/store/apps/details?id=Qwerty.BluetoothTerminal&amp;hl=en" rel="nofollow noreferrer">Bluetooth Terminal</a></p>
