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MetaWear Guide Series Part 4

Using Board Modules
Created: 06 February 2016

This is part 4 of a multipart series showing you how to get started with the MetaWear platform. View the contents of the series to easily skip forwards or backwards

About Modules

Now that we have established a connection to the board, we can begin interacting with modules.

Modules are on-board sensors or features supported by the firmware.

We do this by calling MetaWearBoard.getModule.

Let’s start with a simple example, allowing us to turn on the LED lights on the board.

First, we’ll add two buttons underneath our connect button: LED on and LED off. Add the following to activity_my.xml:

<Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="LED on"
        android:id="@+id/led_on"
        android:layout_below="@+id/connect"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="58dp" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="LED off"
        android:id="@+id/led_off"
        android:layout_centerVertical="true"
        android:layout_centerHorizontal="true" />


Then in our MyActivity.java file let’s import the LED module and declare the object. We’ll also import UnsupportedModuleException for our error handling:

//other imports

import com.mbientlab.metawear.UnsupportedModuleException;
import com.mbientlab.metawear.module.Led;

public class MyActivity extends AppCompatActivity implements ServiceConnection {

    //CONSTANTS
    private final String MW_MAC_ADDRESS= "D5:9C:DC:37:BA:AE"; //update with your board's MAC address
    private static final String TAG = "MetaWear";
    private Button connect;
    private Button led_on;
    private Button led_off;

    //METAWEAR OBJECTS
    private MetaWearBleService.LocalBinder serviceBinder;
    private Led ledModule; //Declare the ledModule
    private MetaWearBoard mwBoard;

    //rest of code


Then inside the connected section of our ConnectionStateHandler we define the module using getModule. Note that this is wrapped in a try/catch statement. If we tried defining the ledModule somewhere else, such as in onCreate, it would cause an error as at that point board connection handling may not be complete:

private final ConnectionStateHandler stateHandler= new ConnectionStateHandler() {
        @Override
        public void connected() {
            Log.i(TAG, "Connected");
            try {
                ledModule = mwBoard.getModule(Led.class);
            } catch (UnsupportedModuleException e) {
                e.printStackTrace();
            }
        }


The last thing we need to do is add the onClick handlers, also within the connected() code block. To quote the docs:

LED patterns function as a pulse with four main parameters to modify: rise time, high time, fall time, and duration. These parameters are modified using the ColorChannelEditor and each color channel (rgb) is configured independent of the other colors allowing you to program different patterns for each color.

So we use ColorChannelEditor inside our onClick and then commit the result first, then we play them:

led_on=(Button)findViewById(R.id.led_on);
            led_on.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    Log.i(TAG, "Turn on LED");
                    ledModule.configureColorChannel(Led.ColorChannel.BLUE)
                            .setRiseTime((short) 0).setPulseDuration((short) 1000)
                            .setRepeatCount((byte) -1).setHighTime((short) 500)
                            .setHighIntensity((byte) 16).setLowIntensity((byte) 16)
                            .commit();
                    ledModule.play(true);
                }
            });

To turn the LED off, it’s just one line of code within our second onClick:

led_off=(Button)findViewById(R.id.led_off);
            led_off.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    Log.i(TAG, "Turn off LED");
                    ledModule.stop(true);
                }
            });

Go ahead and run the app - you should see the LED turn on and off when you press the LED on and LED off buttons. Make sure you connect to the board first! You always need to connect to the board before you can do anything with it. Now we’re really making progress. Spend some time playing with different settings for the LED duration, intensity and color.

In the next section we will look at streaming data.

Note You can view all these changes in the github repository on the branch version-0.3

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