Support additional sensors

Fitness devices that implement a standard Bluetooth Low Energy GATT profile are automatically supported by Google Fit. If your device doesn't implement one of these profiles, you can create an Android app that manages the communication with the fitness device and exposes it to Google Fit as a software sensor. You can also expose custom software sensors in your app.

To create a software sensor in your app, you extend the FitnessSensorService class and declare it as a service in the manifest file. When users install your app, Google Fit makes your software sensors available to other apps. When an app registers to receive data from a software sensor in your app, Google Fit binds to your service.

Note: For best practices when you manage user data, see Google Fit Developer and User Data Policy.

Declare a sensor service

To define a software sensor, declare a FitnessSensorService in your app's manifest file:

<service android:name="com.example.MySensorService"
         android:process=":sensor">
  <intent-filter>
    <action android:name="com.google.android.gms.fitness.service.FitnessSensorService" />
    <!-- include at least one mimeType filter for the supported data types -->
    <data android:mimeType="vnd.google.fitness.data_type/com.google.heart_rate.bpm" />
  </intent-filter>
</service>

The service in this example runs in a separate process, as specified by the android:process attribute. For more information, see Processes.

Implement a sensor service

To implement a software sensor, extend the FitnessSensorService class and implement its abstract methods. The details of the implementation depend on your particular use case, but the following example provides general guidelines:

Kotlin

class MySensorService : FitnessSensorService() {
    override fun onCreate() {
        super.onCreate()
        // 1. Initialize your software sensor(s).
        // 2. Create DataSource representations of your software sensor(s).
        // 3. Initialize some data structure to keep track of a registration
        // for each sensor.
    }

    override fun onFindDataSources(dataTypes: List<DataType>): List<DataSource> {
        // 1. Find which of your software sensors provide the data types requested.
        // 2. Return those as a list of DataSource objects.
    }

    override fun onRegister(request: FitnessSensorServiceRequest): Boolean {
        // 1. Determine which sensor to register with request.dataSource.
        // 2. If a registration for this sensor already exists, replace it with
        //    this one.
        // 3. Keep (or update) a reference to the request object.
        // 4. Configure your sensor according to the request parameters.
        // 5. When the sensor has new data, deliver it to the platform by
        //    calling request.dispatcher.publish(dataPoints)
    }

    override fun onUnregister(dataSource: DataSource): Boolean {
        // 1. Configure this sensor to stop delivering data to the platform
        // 2. Discard the reference to the registration request object
    }
}

Java

public class MySensorService extends FitnessSensorService {
    @Override
    public void onCreate() {
        super.onCreate();
        // 1. Initialize your software sensor(s).
        // 2. Create DataSource representations of your software sensor(s).
        // 3. Initialize some data structure to keep track of a registration
        //    for each sensor.
    }

    @NonNull
    @Override
    public List<DataSource> onFindDataSources(@NonNull List<DataType> list) {
        // 1. Find which of your software sensors provide the data types
        //    requested.
        // 2. Return those as a list of DataSource objects.
    }

    @Override
    public boolean onRegister(
            @NonNull FitnessSensorServiceRequest fitnessSensorServiceRequest) {
        // 1. Determine which sensor to register with request.dataSource.
        // 2. If a registration for this sensor already exists, replace it with
        //    this one.
        // 3. Keep (or update) a reference to the request object.
        // 4. Configure your sensor according to the request parameters.
        // 5. When the sensor has new data, deliver it to the platform by
        //    calling request.getDispatcher.publish(dataPoints);
    }

    @Override
    public boolean onUnregister(@NonNull DataSource dataSource) {
        // 1. Configure this sensor to stop delivering data to the platform
        // 2. Discard the reference to the registration request object
    }
}