Access raw sensor data

AI-generated Key Takeaways

• The Sensors API enables real-time access to raw sensor data from a device and connected wearables, offering functionalities to list data sources, register data listeners, and manage these listeners.

• Developers can identify available data sources, such as step count, using SensorsClient.findDataSources, with the option to filter by data type and device for targeted data retrieval.

• Real-time data updates can be received by attaching a listener using SensorsClient.add, defining data types, sources, and sampling rates, for immediate data processing or visualization within the app.

• To stop data updates, developers can detach a listener using SensorsClient.remove, ceasing the flow of raw sensor data to the specified listener, freeing resources, and halting real-time processing.

• It is important to note that sensor data is not automatically stored; the Recording API is recommended for background data recording, while the Sensors API is best suited for immediate display and processing of sensor data.

The Sensors API lets you read raw sensor data in your app in real time. Use this API to do the following:

• List data sources that are available on the device and on companion devices.
• Register listeners to receive raw sensor data.
• Unregister listeners so that they no longer receive raw sensor data.

Caution: The Sensors API doesn't automatically store sensor readings in the fitness store, and sensor registrations created with the Sensors API aren't persisted when the system restarts. It's typical to use the Recording API to record data in the background with persistent subscriptions; use the Sensors API to display or process sensor readings in real time. In many cases, both of these APIs need to be used in an app.

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

List available data sources

To obtain a list of all available data sources on the device and on companion devices, use the SensorsClient.findDataSources method:

Kotlin

private val fitnessOptions = FitnessOptions.builder().addDataType(DataType.TYPE_STEP_COUNT_DELTA).build()

// Note: Fitness.SensorsApi.findDataSources() requires the
// ACCESS_FINE_LOCATION permission.
Fitness.getSensorsClient(requireContext(), GoogleSignIn.getAccountForExtension(requireContext(), fitnessOptions))
    .findDataSources(
        DataSourcesRequest.Builder()
            .setDataTypes(DataType.TYPE_STEP_COUNT_DELTA)
            .setDataSourceTypes(DataSource.TYPE_RAW)
            .build())
    .addOnSuccessListener { dataSources ->
        dataSources.forEach {
            Log.i(TAG, "Data source found: ${it.streamIdentifier}")
            Log.i(TAG, "Data Source type: ${it.dataType.name}")

            if (it.dataType == DataType.TYPE_STEP_COUNT_DELTA) {
                Log.i(TAG, "Data source for STEP_COUNT_DELTA found!")

                ...
            }
        }
    }
    .addOnFailureListener { e ->
        Log.e(TAG, "Find data sources request failed", e)
    }

Java

FitnessOptions fitnessOptions = FitnessOptions.builder().addDataType(DataType.TYPE_STEP_COUNT_DELTA).build();

// Note: Fitness.SensorsApi.findDataSources() requires the
// ACCESS_FINE_LOCATION permission.
Fitness.getSensorsClient(getApplicationContext(), GoogleSignIn.getAccountForExtension(getApplicationContext(), fitnessOptions))
        .findDataSources(
                new DataSourcesRequest.Builder()
                        .setDataTypes(DataType.TYPE_STEP_COUNT_DELTA)
                        .setDataSourceTypes(DataSource.TYPE_RAW)
                        .build())
        .addOnSuccessListener(dataSources -> {
            dataSources.forEach(dataSource -> {
                Log.i(TAG, "Data source found: ${it.streamIdentifier}");
                Log.i(TAG, "Data Source type: ${it.dataType.name}");

                if (dataSource.getDataType() == DataType.TYPE_STEP_COUNT_DELTA) {
                    Log.i(TAG, "Data source for STEP_COUNT_DELTA found!");
                    ...
                }
            })})
        .addOnFailureListener(e ->
            Log.e(TAG, "Find data sources request failed", e));

To get information about the device for a data source, use the DataSource.getDevice method. The device information is useful to distinguish from similar sensors on different devices, show the device information from a sensor to the user, or process data differently based on the device. For example, you might be interested in reading data specifically from the sensor on a wearable device but not from the same type of sensor on a phone.

To get a Device instance for the device that's running your activity, use the Device.getLocalDevice method. This is useful when you want to check whether a data source is on the same device that your app is running on.

Add a listener

To add a listener to receive raw data of a particular fitness data type or from a specific data source, use the SensorsClient.add method:

Kotlin

val listener = OnDataPointListener { dataPoint ->
        for (field in dataPoint.dataType.fields) {
            val value = dataPoint.getValue(field)
            Log.i(TAG, "Detected DataPoint field: ${field.name}")
            Log.i(TAG, "Detected DataPoint value: $value")
        }
    }

Fitness.getSensorsClient(this, GoogleSignIn.getAccountForExtension(this, fitnessOptions))
    .add(
        SensorRequest.Builder()
            .setDataSource(dataSource) // Optional but recommended for custom
            // data sets.
            .setDataType(dataType) // Can't be omitted.
            .setSamplingRate(10, TimeUnit.SECONDS)
            .build(),
        listener
    )
    .addOnSuccessListener {
    	Log.i(TAG, "Listener registered!")
    }
    .addOnFailureListener {
    	Log.e(TAG, "Listener not registered.", task.exception)
    }

Java

OnDataPointListener listener = dataPoint -> {
    for (Field field : dataPoint.getDataType().getFields()) {
        Value value = dataPoint.getValue(field);
        Log.i(TAG, "Detected DataPoint field: ${field.getName()}");
        Log.i(TAG, "Detected DataPoint value: $value");
    }
};
Fitness.getSensorsClient(this, GoogleSignIn.getAccountForExtension(this, fitnessOptions))
        .add(
                new SensorRequest.Builder()
                        .setDataSource(dataSource) // Optional but recommended
                        // for custom data sets.
                        .setDataType(dataType) // Can't be omitted.
                        .setSamplingRate(10, TimeUnit.SECONDS)
                        .build(),
                listener
        )
        .addOnSuccessListener(unused ->
                Log.i(TAG, "Listener registered!"))
        .addOnFailureListener(task ->
    Log.e(TAG, "Listener not registered.", task.getCause()));
}

Remove a listener

To remove a listener from raw data updates, use the SensorsClient.remove method:

Kotlin

Fitness.getSensorsClient(this, GoogleSignIn.getAccountForExtension(this, fitnessOptions))
    .remove(listener)
    .addOnSuccessListener {
    	Log.i(TAG, "Listener was removed!")
    }
    .addOnFailureListener {
    	Log.i(TAG, "Listener was not removed.")
    }

Java

Fitness.getSensorsClient(this, GoogleSignIn.getAccountForExtension(this, fitnessOptions))
        .remove(listener)
        .addOnSuccessListener(unused ->
                Log.i(TAG, "Listener was removed!"))
        .addOnFailureListener(e ->
                Log.i(TAG, "Listener was not removed."));