Unlocking an Android phone

Android is an open source operative system released by Google. Carriers and manufacturers create their own version based on the Android code but they block some funtionalities and add commercial applications. Though it is an open source OS, they design a specifically Android OS version for the device and they don’t allow you to install other operative systems. Unlocking your phone allows to install a custom operating system (also known as custom ROMs) with innovatives features and root the phone to have complete access to the system.

Why root the phone ?

Rooting the device allows to modify the device’s software on the very deepest level. The greatest advantage that rooting provides is the ability to install powerful applications  that requires more than usual privileges on your device. When your phone is rooted you can
Android_unlock install apps to access and edit the system memory, speed up or slow the chip for more performance and battery life,  connect to WiFi networks that have proxy settings, block advertisements on websites and apps… Moreover, if your phone is rooted it is pretty easy to manage the operating system, backup and restore your data and manage custom ROMs.

Why install a custom ROM?

A custom ROM is simply a version of Android to replace the version of Android that the manufacturer provided on your device. Custom ROMs are created by developers and in most of cases they take away all the bloatware that is usually impossible to remove, increase performance and/or improve battery life.

There are hundreds of custom ROMs but CyanogenMod is probably the most popular and
cyanogenmod one of the most reputable. CyanogenMod is supported for a huge variety of phones and it includes some cool features such as gestures in locked-screen mode, music player and other apps, phone goggles, set up a VPN to tunnel all your IP and network data, install apps to the SD card (this safe a lot of space!) and much more. 

How to root the phone and install a custom ROM

The bootloader is the code that loads the system software on the devices and determines which applications must run in the startup (boot up) process. Manufactures block the bootloader for security reasons but also to prevent you to install custom ROMs. Unlock the bootloader is the first step to install a custom firmware on your Android phone.

HTC_BootloaderNot all the Android-phones can be unlocked although it is possible in the most advanced onces. Some manufactures such as HTC, Samsung or Google launched the official tools to unlock the bootloaders. In this post I will show the steps for HTC phones altough it is really easy to find the steps for other phones on the xdna developers forum.

 Be aware that unlock your bootloader may void your warranty.

1. Backup

Before start unlocking your phone it is highly recommended to backup all your data. You can use your Google account to backup your apps and automatically sync back when the process was complete. HTC Sync, available from the HTC website allows to backup your contacts, messages, notes, call logs….The application Go Backup Pro has the same purpose.

2. Unlocking the bootloader (HTC phones)

HTC_unlockBootloaderThe official webpage of HTCDev provides all the resources to unlock the bootloader of your HTC. If you follow all the steps of the HTCDev guide you will get your unlock code to root your phone. You need to download the Android SDK and once downloaded it basically consist on start the device into Bootloader mode and run the adb (which is on the SDK) to get the token, which is an unique code that identifies your phone. Then they will provide you with a unlock token to copy on the phone and unlock the bootloader from the Bootloader screen. All the steps are detailed in the website.

3. Rooting the phone

The bootloader is now unlocked but still not rooted. There are different ways to root your phone, for example installing the application ClockworkMod from Google Play and use the feature Reboot into Recovery. You can also create and run your temp_root script (be sure your phone is plugged in) with the following code:

adb shell mv /data/local/tmp /data/local/tmp.backup
adb shell ln -s /data /data/local/tmp
adb reboot
adb shell echo "ro.kernel.qemu=1 > /data/local.prop"
adb reboot

If you want to remove the temp root you can create and run the remove_temp_root script with the following code:

adb shell rm /data/local.prop
adb shell rm /data/local/tmp
adb shell mv /data/local/tmp.backup /data/local/tmp
adb reboot

4. Installing a custom ROM

There are lots of custom ROMs you can download and install on your phone. One of the most populars is CyanogenMod which offers features not found in the official Android based firmware. You could choose another one though, and the process will be basically identical.

clockwormodBe sure the custom ROM you chose is supported on you phone and download it. Then copy the downloaded zip file to the phone SD card. If you didn’t download Clockworkmod, you will need to do at that point. This applications allows to root your phone and install custom ROMs among other possibilities. Installing the downloaded custom ROM is as easy as tap into the Install ROM from SD Card and wait until process finish.  I highly recommend to do a backup of the current ROM before start the installation.

At this point your phone is rooted and running a customized operating system. You have super-user privileges, you can control everything from your phone,  you can do wathever you want!

Connecting an Android phone and the Kinect sensor

The Microsoft’s Kinect sensor revolutionized the touch-free gaming experience two years ago. The open source drivers and frameworks opened a new world of possibilities for researchers and developers. The official SDK made easier to develop new speech, posture and gesture applications.

The possibilities for smarthone applications are nearly endless in number and design. The Android SDK and all the resources available on Internet combined with the latest smartphone models make easy to imagine and develop new applications and new features.



But, what if we go one step further to combine an Android-based smartphone and the Microsoft’s Kinect sensor? although the SDKs, the IDEs, the libraries, the programming language…everything is different, it is possible to integrate them. The first step consists on communicating them in order to share messages and data through the TCP protocol. In this post I will show how to program the TCP server running on the Kinect application and programmed in C# language. The client will run on the Android device and coded in Java language. 

KinectServer (C#)

KinectServerThe TCP server uses the official Microsoft Kinect SDK, the TCP protocol and C# language to run as a server. In this first implementation it accepts client connections and is able to send and receive data. The server accepts, in theory, an unlimited number of connections and it spawns a thread for each client connected.

The server class creates a new TcpListener to accept socket communications at port 3200. It creates a new Thread for client connections.

  class Server
    private TcpListener tcpListener;
    private Thread listenThread;

    public Server()
      this.tcpListener = new TcpListener(IPAddress.Any, 3200);
      this.listenThread = new Thread(new ThreadStart(ListenForClients));

The server blocks until a client has connected and when a client connects, it creates a new thread to handle communication with the client. 

private void ListenForClients()

  while (true)
    //blocks until a client has connected to the server
    TcpClient client = this.tcpListener.AcceptTcpClient();
    System.Console.WriteLine("Client connected");

    //create a thread to handle communications with connected client
    Thread clientThread = new Thread(new ParameterizedThreadStart(HandleClientComm));

The next function allows to communicate the client and the server. The server waits until the client has sent a message and then it sends a new message to the client. After that, it closes the communication.

private void HandleClientComm(object client)
  TcpClient tcpClient = (TcpClient)client;
  NetworkStream clientStream = tcpClient.GetStream();

  byte[] message = new byte[4096];
  int bytesRead;

  while (true)
    bytesRead = 0;

      //blocks until a client sends a message
      bytesRead = clientStream.Read(message, 0, 4096);

    if (bytesRead == 0)
      //the client has disconnected from the server

    //message has successfully been received
    ASCIIEncoding encoder = new ASCIIEncoding();
    String mes = encoder.GetString(message, 0, bytesRead);

    //Server reply to the client
    byte[] buffer = encoder.GetBytes("Hello Android!");
    clientStream.Write(buffer, 0, buffer.Length);

The server must run in background while the Kinect application is running and collecting data such as the video stream or the depth stream. To run it for testing I recommend to create a new instance from the MainWindow.

   public partial class MainWindow:Window {
          Server TCPServer = new Server();

Finally, to test if the server is listening for new connections, open a new command window and run the netstat. It will list the tcp connections on the port 3200.

netstat -anp tcp | find “:3200”

Telnet also allows to connect to the server and test the communication. The following command will show ‘Hello Android’ on your command window, which is the message that the server is sending to the client. 

telnet localhost 3200 //(telnet @ipserver #port)

AndroidClient (Java)

AndroidClientAny Android device running the TCP client should be able to connect and share information to the Kinect Server. The client is programmed in Java language and using the Android SDK. In this first implementation it sends a message to the server, although t is not difficult to implement the functionalities to share data from the phone such as a file or raw data collected from the sensors. 

The client will run on the background, which means we have to create a new AsyncTask to handle the communications with the server. The class has the socket and the input and output streams.

public class InternetTask extends AsyncTask<string, void,="" string=""> {
DataOutputStream dataOutputStream = null;
DataInputStream dataInputStream = null;
Socket socket;
String message;

The function doInBackground creates a new socket and exchange the messages. The socket connects to the server using its ip and port where is listening. Then it sends a message and wait for the reply which will be showed on the screen.

protected Void doInBackground(String... params) {
    try {
        socket = new Socket("",3200); //connect to the server
        //Send message to the server
        dataOutputStream = new DataOutputStream(socket.getOutputStream());
        dataOutputStream.writeUTF("Hello Kinect!");

        //Receive message from the server
        dataInputStream = new DataInputStream(socket.getInputStream()); 
       message = inputStreamToString(dataInputStream);

        //Write the message on the screen
        TextView tv = (TextView) findViewById(R.id.status); //TextView element to show the received message

    } catch (UnknownHostException e) {
    } catch (IOException e) {
    } finally {
        if (socket != null) {
            try {
                socket.close(); //close the connection
            } catch (IOException e) {
        if (dataOutputStream != null) {
            try {
                dataOutputStream.close(); //close the output stream
            } catch (IOException e) {
        if (dataInputStream != null) {
            try {
                dataInputStream.close(); //close the input stream
            } catch (IOException e) {

Depending on your application you will need to run the client when the app starts, when a button is clicked or when another application is running. In this example I created a button that starts the client to connect to the Kinect server.

public void btnConnectToServer(View view) {  
        InternetTask task = new InternetTask();

Tilt the Kinect from the Android phone

At this point the Kinect and the Android can exchange messages. However, it is not difficult to implement an application to send some data from the phone, such as a file, a song or raw data collected with the sensors. For example, you can tilt the Kinect to point to your phone using the raw values collected with the orientation sensor. This requires some work so I will explain how to do in the following post, although you can tilt the Kinect using Up and Down buttons.

Tilt Kinect

Any ideas for future applications integrating the Kinect and the Android phone?

Google I/O at the Brightcove

Google I/O is an annual developer-focused conference held by Google. The event takes place in San Francisco (CA) but they have extended events in many cities around theIMGP6679.jpg world. The Brightcove, in Boston, showed off the Zencoder cloud transcoding service at the conference. I had the opportunity to join developers, engineers and passionate students to watch and discuss some of the conferences.

Google Play

Google Play is the Google’s distribution platform which allows to download music, books, movies, videos, games and applications. Google redesigned the platform both mobile and web versions. They also introduced new services such as Google Play Games and new features such as the personalize suggestions based on the user preferences and search history.

Google Play Games is the new game service with real-time multiplayer action and multi-platform synchronization. The gaming experience becomes more social, allowing for example to invite and play with your friends and share your scores. It can be synchronized with other platforms such as tablets, computers, smartphones running both Android and iOS, which is an interesting feature for the developers.

Google Play StoreA monthly music subscription service has been introduced for the Google Play Music. It allows to play all songs available in the market and also to upload your songs.  Google Play Books now allows to upload your files to the cloud and it includes a Read Now section that features books you have recently uploaded, purchased or read.

Google also announced a new education program that will help teachers manage and push out apps, books and other educational content to student tablets and computers: Google Play for Educational Program.

Google +

The social network of Google has been redesigned  with responsive design in the feeds, a tags feature to dig into more content and a new photo manager and editor.

google-plus-featuresWhen you upload hundreds of pictures, Google+ Photos will choose the best ones based on the bright and contrast, number of people in the picture, famous landmarks and attractions and it will use face-recognition algorithms to select the one where you and your friends appear in the picture.

Google Hangouts is a new application that substitutes Google Talk. The new multi-platform app allows to chat, share videos and pictures with your friends. It is available on Android, iOS and Chrome.

Google Maps and localization

Google released new APIs to improve localization and battery life on Android devices. An interactive map will recommend location, compare travel modes and integrate Street View and Google Earth on Google Maps. The new APIs includes better outdoor localization, indoor localization and navigation and human activity recognition.


The most common IDE to develop Android apps is Eclipse which runs on Windows, Linux and Mac. But Google developed their own IDE, Android Studio that runs on all operative systems.

The new features that Android Studio includes are the navigation drawer, a better integration with Google Analytics and the possibility to launch beta and alpha versions of the applications.

Samsung Galaxy S4

The new Samsung Galaxy S4 from Google is a completely unlocked device. It comes with an unlocked bootloader that gives to the developers a root access to the operating system. The phone will be release on June and it costs $649.


Other features

Google Voice Search is already available for Android devices but Google wants to expand its voice search capabilities and other features on Google Search for desktop devices, a fundamentally change the way the people look things up on its search engine.

Google Wallet, the online payment method from Google, enables now to send money as a Gmail attachment over other interesting functionalities. It will be integrated on the Chrome browser wich gets faster, more secure and includes faster video-streaming.

Using Android’s sensors

Most of the smartphones have a wide array of sensors to measure motion, position and envirommental conditions. The Android platform supports several sensors, both hardware-based and virtual, such as accelerometer, gyroscope, proximity, temperature, illuminance or humidity.

Managing sensors in Android is not difficult and there are good references and documentation on the developers website.  The basic steps to get the sensor values, such as the accelerometer’s data or the temperature, are summarized in this post.

1.List the sensors

Before using the senors it’s important to know which are available in the device. To check it on the app:

List sensors

2. Enable the sensors

To enable the sensors and get the data we have to obtain instances of SensorManager and sensors we want to access. Then enable them and register the listeners to start collecting the data. In the example we enable accelerometer, orientation and temperature sensors.
Enable sensors

It is important not to forget to unregister the listeners when the app is not working or when sensor values are not needed. At least it is needed to register them on the onCreate() and onResume() methods and unregister them on the onPause() method. Unregister sensors

3. Get the sensor values

The OnSensorChanged() method is used to get the sensor values, the timestamp, the type of sensor or the accuracity. The contents of the values array depend on which sensor type is being monitored. For the accelerometer values, values] correspond to i=x,y,z but for other sensors check Android documentationGet values

4. Use the sensors data

Usually sensor values are used in the app but it also can be stored in a file to analyze, for example, on the computer. Following there are two examples, the first one shows the data on the device screen and the second one correspond to a plot of the collected accelerometer data while walking.



Getting started with Android SDK

Android is an operating system designed for mobile phones and tablets. It is developed for a consortium of hardware, software and telecommunications companies leaded by Google. Nowadays it is the most-used smartphone platform worldwide with more apps developed, whereas iOS from Apple is the platform with more app downloads.

The programming language used to develop Android applications is Java and the most used IDE is Eclipse. The Android SDK provides all the tools and API libraries to build, test and debug the Android apps. In this post I will try to show you how to build your first Android app.

1. Installing the Android SDK

The first step consists on download and install the Android SDK. Once installed, you can download the packages from the Android SDK Manager.

2. Adding Platforms and Packages

The Android SDK Manager allows to download the platforms and tools, which are needed to develop an Android app. Available packages on the SDK Manager are: tools for debugging and testing apps, documentation for the Android platform APIs, the SDK platform and system images for each version of Android, a collection of samples, the Google APIs and the support libraries.

To download the platforms, tools and components, launch the SDK Manager and when it opens click Install to install the recommended packages into your Android SDK Environment.

3. Installing the ADT Plugin for Eclipse

The Eclipse IDE for Java Developers contains what you need to build Java applications but you can also use any other IDE for Java. However, if you use Eclipse you have to install the ADT Plugin. It extends the capabilities of Eclipse to build Android apps with UI interfaces and using Android Framework packages.

To install the ADT Plugin on Eclipse: Help > Install New Software, click on Add buttonand add the repository from the following URL location


Once the installation completes, restore Eclipse.

4. Creating an Android Project

Open Eclipse and click on New > Project > Android Project.  Firstly you have to set the Application Name (name that appears to users), Project Name (name of your project visible in Eclipse), Package Name (package namespace for your app), the SDK version against which you will compile your app and the minimum SDK required. The following screens provides tools to create a launcher icon for the app and templates from which begin building the app.


5. The Android Project

The Android project created includes a default set of “Hello World” source files:

  • src/ Directory for the app’s main source files coded in Java.
  • res/ Directory which contains app resources:
    • drawable/ Drawable objects such as bitmaps.
    • layout/ Files that define the user interface.
    • values/ XML files that contains a collection of resources (strings, color definitions…)
  • Androidmanifest.xml Define all components of the app and describes the fundamental characteristics.

5. Running the app

You can install and run the app on an Android device or on the emulator.

5.1 Run on a real device

Plug in your Android device on the computer with the USB cable to run the app on the device. You might need to install the USB driver. Once installed enable USB debugging on the device on Settings > Developer Options.

To run the app from Eclipse, click the Run button from the toolbar. The app will be automatically installed and it will start running on the device.

5.2 Run On the emulator

To run the app on the emulator an Android Virtual Device (AVD) has to be created. Launch the Android Virtual Device Manager click New, get it a name, a platform target, a SD card size and create the AVD. 

To run the app from Eclipse, click the Run button from the toolbar. The app will be automatically installed and it will start running on the AVD.