Using the TruConnect Android Library

The TruConnect Android Library is a Java library for developing Android apps that interact with TruConnect running on an AMS00x module. Using the TruConnect Android Library you can connect to the TruConnect module, switch it to remote COMMAND mode and issue TruConnect commands to it. See Serial Interface for a description of remote COMMAND mode.

This application note describes the TruConnect Android Library and the demonstration app. To illustrate how the library works, it describes some simple modifications to the demonstration app.


The demonstration app requires a BLE-capable Android test device, such as a smart phone or tablet, and a Wahoo evaluation board, containing an AMS00x Bobcat module running TruConnect.

This application note assumes some familiarity and experience with:

  • Java
  • mobile development
  • event driven application development
  • the Android SDK
  • an IDE such as Android Studio.

See for detailed documentation of Android development.

Set Up

Obtain a copy of the TruConnectAndroid Library from

Obtain the Android SDK and Android Studio from

Open Android Studio and import the TruConnect Android project, at the top level of the TruConnect Android Library working copy.

Switch on USB debugging mode for your Android test device and connect it to the computer running Android Studio.

With the factory settings, the TruConnect module begins to advertise immediately on applying power. Advertising stops after a few minutes. Press the Reset button to start advertising again.

Alternatively, to make the TruConnect module advertise forever, open a TruConnect terminal to the module and set bl v h d : advertising high duration to 0:

set bl v h d 0

Structure of the TruConnect Android Library

The TruConnectAndroid Project contains the truconnectandroid package, and the demonstration app package.

The truconnectandroid package contains the following packages:

  • BLE - enums and classes for handling BLE commands and connections
  • test
  • truconnect - enums and classes for handling TruConnect commands and responses.

The central class of the truconnect package is the TruConnectManager class. This contains methods corresponding to all TruConnect commands and variables. It also contains methods for handling scanning and connection from the Android device, and for sending commands and receiving command results, via the TruConnectHandler class.

Building and Running the Demo App

In Android Studio:

  • Select the app package.
  • Click the Run App button.
  • Android Studio builds the demo app, uploads it to your test device and runs it.

With the Wahoo board:

  • Power up, or press reset to start advertising.

The demo app has two activities, corresponding to two display windows:

MainActivity DeviceInfoActivity
Command Mode
Stream Mode
Data Received

On startup, the MainActivity display shows.

On your test device:

  • Tap the Scan button. The demo app scans, detects the TruConnect module and displays its ID.
  • Tap the TruConnect module ID in the scan list. The demo app switches to the DeviceInfoActivity display and displays some information from the sensors and buttons on the Wahoo board, connected to TruConnect module GPIOs.
    • The ADC field displays the GPIO 9 value, corresponding to the Wahoo thermistor.
    • The GPIO field displays the value of GPIO 12, corresponding to Wahoo Button 2.
    • The LED ON/OFF button controls GPIO 14, the red LED in the Wahoo tricolor LED. The button indicator is lit when the LED is on.
  • Tap the Read Values button. This sends commands to the Wahoo board, obtains the command results and refreshes the data displayed in the fields.
    • The ADC value may change. If you place a finger on the Wahoo thermistor (circled) the value may decrease as the thermistor heats.
    • If you update while pressing Button 2 on the Wahoo board, the GPIO field value changes to 1. Release Button 2, update and the value returns to 0.
  • Tap the LED ON/OFF button on your test device. The Wahoo board red LED lights in the tricolor LED.
  • Tap the Command mode button to switch to Stream mode. In Stream mode, you can send data to the Bobcat module and receive data from the module. Type in the app text field and tap Send to send data. In the TruConnect terminal on the module, type data to see the data appear immediately in the app data received panel.

Structure of the Demo App

The demonstration app contains two activities, and a service that maintains the BLE connection when switching between activities.

The demonstration app, in the app package, contains:

  • Activity classes:
    • MainActivity - view of Scan button and the list of devices scanned
    • DeviceInfoActivity - view of connected TruConnect module information
  • Service class:
    • TruConnectService - the shared service that maintains the BLE connection to the TruConnect module
  • Device - represents a BLE device found by the scan
  • DeviceList - provides the array of devices listed in the scan list

The activities receive intents from the TruConnectService as BLE events take place.

Modifying the Demo App

This section describes some simple modifications to the TruConnect Android demo app. These are intended to provide an indication of how the code is structured.

We perform some minor re-styling, to match the theme, and add another GPIO to the device info display.

In the file paths below, /TruConnectAndroid refers to the directory containing the working copy of the TruConnectAndroid repository.

The ACKme logo icon used in the demo app can be replaced with a logo of your choice. The icon files are .png files located in the resource directories. The pixel resolutions are as shown below:

  • /TruConnectAndroid/app/src/main/res/drawable-hdpi/ackme_icon.png (72×72)
  • /TruConnectAndroid/app/src/main/res/drawable-mdpi/ackme_icon.png (48×48)
  • /TruConnectAndroid/app/src/main/res/drawable-xhdpi/ackme_icon.png (96×96)
  • /TruConnectAndroid/app/src/main/res/drawable-xxhdpi/ackme_icon.png (144×144)

Create copies of your icon at the required resolutions in the resource directories. In our example we created icon files named sdc_icon.png.

The logo icon is specified in two places in the application manifest, /TruConnectAndroid/app/src/main/AndroidManifest.xml.

Replace the instances of the line android:icon=”@drawable/ackme_icon” with a specification for your new logo. For example:

        ... >
            ... >

Rebuild the app and run it on your test device to see the changes.

Adding a Control for Button 1

This section demonstrates how to add a control for Wahoo Button 1 to the Device Info activity.

Wahoo Button 1 corresponds to GPIO 6.

The layout of the DeviceInfoActivity is specified in /TruConnectAndroid/app/src/main/res/layout/activity_device_info.xml.

The (Button 2) GPIO field is specified with a TextView tag containing the attribute android:text="GPIO".

Copy the specification for the (Button 2) GPIO TextView to create another TextView for Button 1 directly above it in the XML. Note that as well as creating the new TextView, with modified attributes, we also modified the original (Button 2) GPIO TextView attributes. This layout aligns the Button 1 and Button 2 displays horizontally:

<RelativeLayout xmlns:android=""

        android:layout_alignParentEnd="true" />

In the file /TruConnectAndroid/app/src/main/res/values/strings.xml, add the button title string gpio_b1_value_title, with content GPO B1:, above the gpio_value_title string, and modify the gpio_value_title string content to GPO B2::

    <string name="update_button_text">Read Values</string>
    <string name="gpio_b1_value_title">GPIO B1:</string>
    <string name="gpio_value_title">GPIO B2:</string>
    <string name="adc_value_title">ADC:</string>

The remaining changes are in the file /TruConnectAndroid/app/src/main/java/ack/me/truconnectandroiddemo/

At the beginning of the DeviceInfoActivity class definition, we declare variables for Button 1:

  • the declarations for TEST_B1_GPIO GPIO number
  • the TextView instance mGPIOB1TextView
  • A flag to track updating: mGPIOB1UpdateInProgress
public class DeviceInfoActivity extends Activity
    public static final String TAG = "DeviceInfo";
    private static final int ADC_GPIO = 12;//thermistor on wahoo
    private static final int TEST_GPIO = 9;//button2 on wahoo
    private static final int TEST_B1_GPIO = 6; // Button 1
    private TextView mADCTextView;
    private TextView mGPIOTextView;
    private TextView mGPIOB1TextView;  // Button 1 
    private boolean mADCUpdateInProgress = false;
    private boolean mGPIOUpdateInProgress = false;
    private boolean mGPIOB1UpdateInProgress = false; // Button 1

In the onCreate method, add a line for the Button 1 TextView, as shown:

protected void onCreate(Bundle savedInstanceState)

    mADCTextView = (TextView)findViewById(;
    mGPIOTextView = (TextView)findViewById(;
    mGPIOB1TextView = (TextView)findViewById(; // Button 1 

Add the TEST_B1_GPIO initialization to the DeviceInfoActivity.initGPIOs method:

private void initGPIOs()
        mTruconnectManager.GPIOFunctionSet(TEST_GPIO, TruconnectGPIOFunction.NONE);
        mTruconnectManager.GPIOFunctionSet(TEST_B1_GPIO, TruconnectGPIOFunction.NONE); // Button 1 
        mTruconnectManager.GPIOFunctionSet(TEST_GPIO, TruconnectGPIOFunction.STDIO);
        mTruconnectManager.GPIOFunctionSet(TEST_B1_GPIO, TruconnectGPIOFunction.STDIO); // Button 1 
        mTruconnectManager.GPIODirectionSet(TEST_GPIO, TruconnectGPIODirection.INPUT);
        mTruconnectManager.GPIODirectionSet(TEST_B1_GPIO, TruconnectGPIODirection.INPUT); // Button 1 

Add a line to update the Button 1 GPIO to the DeviceInfoActivity.updateValues method, and a flag to track processing of the command:

private void updateValues()
    mADCUpdateInProgress = true;
    mGPIOUpdateInProgress = true;
    mGPIOB1UpdateInProgress = true; // Button 1

    Log.d(TAG, "Updating values");
    mTruconnectManager.GPIOGet(TEST_B1_GPIO); // Button 1 

This has the effect of sending the TruConnect command to get the value of the Button GPIO. The response to the command is delivered by the TruConnectService as an intent with the action ACTION_COMMAND_RESULT. The BroadcastReceiver accordingly calls the handleCommandResponse method, which extracts the TruConnect command response as variable result from the Intent extra bundle.

Finally, in the DeviceInfoActivity.handleCommandResponse method, add a case to handle the Button 1 GPIO update. Note that the commands are queued and processed in the order called. In the updateValues() method, the GPIO get command for Button2, TEST_GPIO, is called first, so the corresponding flag mGPIOUpdateInProgress is processed first when handling the command response.

private void handleCommandResponse(Intent intent)
        switch (command)
            case GPIO_GET:
                if (mGPIOUpdateInProgress)
                    message = String.format("GPIO B2: %s", result);
                    mGPIOUpdateInProgress = false;
                    Log.d(TAG, "Updating "+message);
                else if(mGPIOB1UpdateInProgress) { // Button 1
                    message = String.format("GPIO B1: %s", result);
                    mGPIOB1UpdateInProgress = false;
                    Log.d(TAG, "Updating "+message);

Build and run the app to see the result of these changes.

Press Button 1 on the Wahoo and click the Update button on the app.

These minor modifications indicate how functionality can be changed with small edits to the existing layout files and DeviceInfoActivity methods. For more complex changes and new features, a detailed knowledge of Android development is required.

ModifiedChangesTruConnect Version
2015-Apr-16Updated for new library version1.5+