Application behavior and functionality

This section describes the general functioning of the Asset Tracker v2 application.

Data types

Data from multiple sensor sources are collected to construct information about the location, environment, and the health of the nRF9160-based device. The data types that are collected by the application are listed in the following table:

Data type	Description	Identifiers	String identifier for NOD list
Location	Position coordinates	APP_DATA_LOCATION	`gnss`, `ncell`
Environmental	Temperature, humidity	APP_DATA_ENVIRONMENTAL	NA
Movement	Acceleration	APP_DATA_MOVEMENT	NA
Modem	LTE link data, device data	APP_DATA_MODEM_DYNAMIC, APP_DATA_MODEM_STATIC	NA
Battery	Voltage	APP_DATA_BATTERY	NA

Additionally, the following data types are supported that provide some asynchronous data:

Data type	Description
Button	ID of pressed Button
Impact	Magnitude of impact in gravitational constant (G)

Real-time configurations

You can alter the behavior of the application at run time by updating the application’s real-time configurations through the cloud service. The real-time configurations supported by the application are listed in the following table:

Real-time Configurations		Description	Default values
Device mode		Either in active or passive mode.	Active
Active		Cloud updates occur at regular intervals.
Active	Active wait time	Number of seconds between each cloud update in active mode.	120 seconds
Passive		Cloud updates occur upon movement.
	Movement resolution	Number of seconds between each cloud update in passive mode, given that the device is moving.	120 seconds
	Movement timeout	Number of seconds between each cloud update in passive mode, regardless of movement.	3600 seconds
Location timeout		Timeout for location retrieval during data sampling.	120 seconds
Accelerometer activity threshold		Accelerometer activity threshold in m/s². Minimal absolute value for accelerometer readings to be considered valid movement.	4 m/s²
Accelerometer inactivity threshold		Accelerometer inactivity threshold in m/s². Maximal absolute value for accelerometer readings to be considered stillness.	4 m/s²
Accelerometer inactivity timeout		Accelerometer inactivity timeout in seconds. Minimum time for lack of movement to be considered stillness.	1 second
No Data List (NOD)		A list of strings that references data types, which will not be sampled by the application. Used to disable sampling from sensor sources. For instance, when GNSS should be disabled in favor of location based on neighbor cell measurements, the string identifier `GNSS` must be added to this list. The supported string identifiers for each data type can be found in the data types table.	No entries (Request all)

You can alter the default values of the real-time configurations at compile time by setting the options listed in Default device configuration options. However, note that these are only the default values. If a different value set has been set through the cloud service, it takes precedence. The application also stores its configuration values to non-volatile memory.

The application receives new configurations in one of the following three ways:

Upon every established connection to the cloud service.
When the device sends an update to cloud.
From non-volatile flash memory after boot.

The following flow charts show the operation of the application in the active and passive modes. The charts show the relationship between data sampling, sending of data, and the real-time configurations. All configurations that are not essential to this relationship are not included.

In the active mode, the application samples and sends data at regular intervals that are set by the Active wait timeout configuration.

In the passive mode, the application samples and sends data upon two occurrences:

When the timer controlled by the Movement resolution configuration expires and movement is detected.
When the timer controlled by the Movement timeout configuration expires. This timer acts as failsafe if no movement is detected for extended periods of time. Essentially, it makes sure that the application always sends data at some rate, regardless of movement.

User interface

The application supports basic UI elements to visualize its operating state and to notify the cloud using button presses. This functionality is implemented in the UI module and the supported LED patterns are documented in the UI module LED indication section.

A-GPS and P-GPS

The application supports processing of incoming A-GPS and P-GPS data to reduce the GNSS Time-To-First-Fix (TTFF). Requesting and processing of A-GPS data is a default feature of the application. See nRF Cloud A-GPS and P-GPS for further details. To enable support for P-GPS, add the parameter -DOVERLAY_CONFIG=overlay-pgps.conf to your build command.

Note

Enabling support for P-GPS creates a new flash partition in the image for storing P-GPS data. To ensure that the resulting binary can be deployed using FOTA, you must make sure that the new partition layout is compatible with layout of the old image. See static partitioning for more details.

Note

For more information on the various trade-offs of using A-GPS compared to using P-GPS, see the nRF Cloud Location Services documentation.