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IOIO for Android Beginners Guide
by a1ronzo | March 21, 2011 | 29 comments Skill Level: Beginner

Introduction

This is the beginners guide for the IOIO for Android board and is intended for users that have never written an Android app. The goal of this tutorial is to show how to write a simple app that communicates with the IOIO board.

IOIO for Android

The programming language used to write an Android app is Java. If you are not familiar with Java, this tutorial will only go over writing a simple Java app using the IOIO library. This tutorial will not cover how to use the features within your Android device, like GPS, accelerometer, touch screen, etc. Once you get to the point where you want to use the vast array of features on your Android device, we suggest first looking at the technical resource section on developer.android.com. If you still can't find the examples you are looking for, simply browsing the web will result in a ton of information and examples that show you how to communicate with all of the great pieces of hardware within your Andriod device.

In general, the holy grail for developing Android apps is developer.android.com. There, you will find most of the information on Android development. For documentation/downloads specific to the IOIO and for more advanced discussions about the IOIO, see these links:

• IOIO Wiki
• All of the Downloads you need
• IOIO discussion group

Here are the pieces of hardware you will need to complete this tutorial:

• Android enabled device using OS 1.5 or greater.
• IOIO for Android board
• USB cable that is compatible with your Android device
• 5-15V power supply with at least 1A of current. You will need to power the IOIO through the VIN and GND pins or there is an optional JST connector on the back of the board. It will need to be soldered into place and can be used with this adapter and wall wart power supply. More information at the end of the tutorial found here.

Installing the Android Development Environment

The first step is to install the Android SDK (software development kit). It is highly recommended to install the Eclipse IDE + ADT plugin. developer.android.com has written a great tutorial on how to do this. It can be found here:

• Android SDK

If you have any problems, see the Troubleshooting section from developer.android.com.

When you reach Step 4 in the Android SDK tutorial, you will at least need to install the SDK components relevant to the Android device you will be working with. For example, if you have an Android phone, goto Settings > About Phone and scroll down to Android Version. You must install the SDK platform corresponding to the Android version of your device.

If you are not sure which packages to install and have the necessary resources on your computer, you can go ahead and install all of the available packages.

Import the HelloIOIO Example

Instead of creating a new project from scratch, we can import an existing IOIO project that has all of the files ready to go. If you need instruction on creating a new project, see the Hello World example on developer.android.com.

To import an existing project...

1) Download the latest 'Android Software Image' zip file (App-IOIOxxxx, where xxxx is the software/library version number).

Note: If you are using an older IOIO board, make sure the version number of your IOIO library is less than or equal to the version number of your firmware. In other words, if you can't get the sample app to work with an older IOIO, use one of the older library versions or upgrade the firmware on your IOIO using the IOIO Manager and then use the latest download.

2) Unzip the downloaded package and you should see a handful of files. This is where you will find the main IOIO library and some examples.

Now, find the HelloIOIO folder (located in /applications), and copy or drag the HelloIOIO folder into a location where you will keep your Android projects.

3) Next, open Eclipse, then goto File > Import, and select 'Existing Projects Into Workspace'. Then hit Next.

4) Another window will pop up (as shown below). Select 'Select Root Directory' and navigate to the HelloIOIO file you just unzipped. Be sure the check box is selected for your project. Now hit Finish.

5) You should now have HelloIOIO in your project explorer in Eclipse. Notice that there is a small red x next to the project name. This means there are build errors, so whenever you see this, you know something needs to be fixed. In this situation, we need to link the IOIO library to our project, as outlined in the next step.

6) Now we need to link the IOIO library to your project which will give you full access to the IOIO API. The IOIOLib file contains the libraries that allow you to communicate to the IOIO board. It is found in the IOIOLib directory:

Follow the exact same steps in 3 and 4 above, except use the IOIOLib file instead of the HelloIOIO file.

After you added the IOIOLib file into the workspace, select the HelloIOIO project, then on the top toolbar goto: Project > Properties. Then, select 'Android' in the list to the left. In the 'Library' section, click add, then add the IOIOLib library. You should see the IOIOLib with a green check mark as shown below.

Also, make sure the 'Project Build Target' is properly selected according to the specific Android OS you are using.

Note: If you ever need to change your build target (say you are using a device with a different Android OS), you can change it here.

7) The next thing you need to do is make sure your app has internet permissions. To do this, open the AndroidManifest.xml file located in the main project tree. Make sure you are in the permissions tab, then click Add > Usage Permissions, then make sure the 'Name' field is android.permission.INTERNET. See the picture below for reference:

After you have done this and saved your project, the projects explorer window should look something like this:

Notice the red x error flags are gone.

The project tree has many files. You really don't need to mess with the IOIOLib project tree so you can minimize that one. The file that contains the java code for the IOIO is in HelloIOIO > scr > ioio.examples.hello > MainActivity.java. Double click on the MainActivity.java file and you should see this:

Here you can start writing code and changing the HelloIOIO sketch. At this point you can keep reading or jump immediately to setting up your IOIO board and testing the app.

The MainActivity.java file contains the code that talks to the IOIO board. If you want to change the UI (user interface or graphics) of your app, the res > layout  > main.xml file is where you make the changes. The main.xml file in the HelloIOIO example uses an interface that looks like this:

For more information on XML layouts, see the hello world example on developer.android.com, then scroll down to the 'Upgrade the UI to XML Layout' section.

The Example IOIO Sketch

After you have imported the HelloIOIO file and linked the IOIOLib file, you are ready to start writing code. The example sketch displays a toggle button on the screen, which enables control of the on-board LED. This example shows a very simple usage of the IOIO and will give you an idea of what to expect when programming.

The code in the MainActivity.java file is shown below.

		package ioio.examples.hello;

import ioio.examples.hello.R;
import ioio.lib.api.DigitalOutput;
import ioio.lib.api.exception.ConnectionLostException;
import ioio.lib.util.AbstractIOIOActivity;
import android.os.Bundle;
import android.widget.ToggleButton;

/**
 * This is the main activity of the HelloIOIO example application.
 * 
 * It displays a toggle button on the screen, which enables control of the
 * on-board LED. This example shows a very simple usage of the IOIO, by using
 * the {@link AbstractIOIOActivity} class. For a more advanced use case, see the
 * HelloIOIOPower example.
 */
public class MainActivity extends AbstractIOIOActivity {
	private ToggleButton button_;

	/**
	 * Called when the activity is first created. Here we normally initialize
	 * our GUI.
	 */
	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		button_ = (ToggleButton) findViewById(R.id.button);
	}

	/**
	 * This is the thread on which all the IOIO activity happens. It will be run
	 * every time the application is resumed and aborted when it is paused. The
	 * method setup() will be called right after a connection with the IOIO has
	 * been established (which might happen several times!). Then, loop() will
	 * be called repetitively until the IOIO gets disconnected.
	 */
	class IOIOThread extends AbstractIOIOActivity.IOIOThread {
		/** The on-board LED. */
		private DigitalOutput led_;

		/**
		 * Called every time a connection with IOIO has been established.
		 * Typically used to open pins.
		 * 
		 * @throws ConnectionLostException
		 *             When IOIO connection is lost.
		 * 
		 * @see ioio.lib.util.AbstractIOIOActivity.IOIOThread#setup()
		 */
		@Override
		protected void setup() throws ConnectionLostException {
			led_ = ioio_.openDigitalOutput(0, true);
		}

		/**
		 * Called repetitively while the IOIO is connected.
		 * 
		 * @throws ConnectionLostException
		 *             When IOIO connection is lost.
		 * 
		 * @see ioio.lib.util.AbstractIOIOActivity.IOIOThread#loop()
		 */
		@Override
		protected void loop() throws ConnectionLostException {
			led_.write(!button_.isChecked());
			try {
				sleep(10);
			} catch (InterruptedException e) {
			}
		}
	}

	/**
	 * A method to create our IOIO thread.
	 * 
	 * @see ioio.lib.util.AbstractIOIOActivity#createIOIOThread()
	 */
	@Override
	protected AbstractIOIOActivity.IOIOThread createIOIOThread() {
		return new IOIOThread();
	}
}

In the code above, there are plenty of comments that explain what each line does. This app is a great starting point for making sure your development environment and the IOIO board is working correctly.

Eclipse is a very powerful tool and gives debugging information in real time. For instance, if you write code that doesn't make sense, Eclipse will show a red x next to the line in question and even give you suggestions as to how to change the line of code. Simply hover your mouse cursor over the line and you will see something like this:

Keep in mind, if you have errors, you will not be able to compile and run your code, you will need to fix any errors.

Also, the IOIOLib has thorough JavaDocs that can be generated and browsed via Eclipse. Goto Project > Generate Javadocs.

Here are some more resources to help you out with writing code:

• For all Android types, see the Android package index.
• For IOIO types and examples, see the IOIO Wiki.

Compiling, Loading, and Running the App on Your Android Device

If you change any part of the code, simply saving the project compiles the program and creates a new HelloIOIO.apk file. An apk file is a compressed Android Package file, similar to zip and jar. files, that is used to create an app on your Android device. This file can be found in the HelloIOIO project tree within the bin directory.

Here are the steps to get the example app working on an N1 Android phone running the 2.3.3 platform.

1. Enable USB debugging. Settings > Applications > Development > Enable USB Debugging

2. Install the apk file. The easiest way to get the apk file on your device is to plug the device into your computer. When prompted to install drivers, point to the driver located in Android (should be in Program Files for Windows users) > android-sdk > extras > google > usb_driver. Next, right click on the HelloIOIO project in the project explorer within Eclipse goto Run As > Android Application (or hitting the green play button on the top tool bar runs your application as well). Your apk file should now be installed on your android device. Unplug your android device from your computer, then move to the next step. More information on the Google USB driver is found here.

3. Prepare the IOIO board. The only thing you need to do for the HelloIOIO example is power the IOIO board. Keep in mind, the IOIO board will always need an external power supply between 5-15V. Single cell LiPos batteries will NOT work with this connector, you need a 5-15V input. You can connect the power supply to the VIN and GND pins (headers will need to be soldered in place), as shown here OR...

...you can use the optional JST connector on the back of the board for a more secure power connection as shown below. The suggested parts are PRT-08612, TOL-08734, and power supply TOL-08269.

4. With the IOIO powered, you can plug the USB cable into the IOIO and into your Android device. The Android device should show that USB debugging is connected in the notification bar, in addition, the Android should indicate it is charging. If you don't see either of these two notifications, try adjusting the 'chg' potentiometer next to the USB connector on the IOIO board. The potentiometer changes how much current is being used by the power supply to charge the phone. If there isn't enough, then the phone might not be detected by the IOIO.

5. Open the Hello IOIO app and toggle the button, you should see the yellow stat LED come on and off. Congratulations! You are now on your way to creating your very own IOIO apps!

Note: The best way to develop IOIO apps is to have your phone plugged into your computer while writing and editing the code. Then running the application (as shown in step 2) will erase the old app and load the newly edited app onto your phone. You can now unplug your phone from your computer, then plug it into the IOIO to test what you have done. 

Here are some videos using the IOIO:

Updating the IOIO Firmware

The IOIO firmware is code that sits on the PIC microncontroller located on the IOIO board. Sometimes new changes will be pushed out and you might have an board with older firmware. There is a very simple way to update the IOIO firmware. 

• IOIO Manager Wiki