Data module
The data module gathers data that has been sampled by other modules in the system and stores it into ring buffers. It keeps track of data requested by the Application module and decides when data is sent to the cloud.
Features
This section documents the features implemented by the module.
Requested data types
The data module maintains a list of requested data types that is updated every time a sample request of type APP_EVT_DATA_GET is sent from the Application module.
When all the data types present in the list is received by the module, the event DATA_EVT_DATA_READY is sent out.
This event signifies that all data has been gathered for a sample request.
The available data can now be encoded and sent to the cloud.
The APP_EVT_DATA_GET event also carries a sample timeout.
This timeout is used by the data module to trigger a DATA_EVT_DATA_READY event, even if not all types in the requested list have been received.
This acts as a fail-safe in case some modules do not manage to sample the requested data in time.
For example, it is not always possible to acquire a GNSS fix.
Note
The module can decide not to send data after a sample request. If this happens, data is persisted in the ring buffers and sent to the cloud in batch messages after the next sample request, in case the application is connected to the cloud. The ring buffers in the module are implemented so that the oldest entry is always overwritten in case the buffer is filled.
Device configuration
When the application boots, the data module distributes the current values of the applications Real-time configurations to the rest of the application with the DATA_EVT_CONFIG_INIT event.
These value are persisted in flash between reboots using the Settings and updated each time the application receives a new configuration update.
If a new configuration update is received from the cloud, the data module distributes the new configuration values using the DATA_EVT_CONFIG_READY event.
You can alter the default values of the Real-time configurations compile time using the options listed in the Default device configuration options.
Connection evaluation
This is an experimental feature. The module can decide to hold off encoding and sending of sampled data based on evaluation of the LTE connection and estimated energy consumed to send the data. This feature is enabled by setting the CONFIG_DATA_GRANT_SEND_ON_CONNECTION_QUALITY Kconfig option. The module can deny the sending of data a number of times before it is sent regardless. This limit is configurable and set by the CONFIG_DATA_SEND_ATTEMPTS_COUNT_MAX Kconfig option. This feature is supported for regular updates that include neighbor cell measurements, generic (GNSS, sensor data, and so on), and historical batched data, which are scheduled based on the application’s Real-time configurations.
To adjust the minimum allowed energy threshold for a specific type, set the following Kconfig options:
The energy levels map directly to the LTE link control structure lte_lc_energy_estimate and the current energy level that is evaluated before sending of data is retrieved with the lte_lc_conn_eval_params_get() function call.
Configuration options
Options that alter the default values of the application’s real-time configurations:
- CONFIG_DATA_DEVICE_MODE_ACTIVE
This configuration sets the device in active mode. Default mode for nRF91 Series devices.
- CONFIG_DATA_DEVICE_MODE_PASSIVE
This configuration sets the device in passive mode. Default mode for the Thingy:91.
- CONFIG_DATA_ACTIVE_TIMEOUT_SECONDS
This configuration sets the active mode timeout value.
- CONFIG_DATA_MOVEMENT_RESOLUTION_SECONDS
This configuration sets the movement resolution timeout value.
- CONFIG_DATA_MOVEMENT_TIMEOUT_SECONDS
This configuration sets the movement timeout value.
- CONFIG_DATA_ACCELEROMETER_ACT_THRESHOLD
This configuration sets the upper accelerometer threshold value.
- CONFIG_DATA_ACCELEROMETER_INACT_THRESHOLD
This configuration sets the lower accelerometer threshold value.
- CONFIG_DATA_ACCELEROMETER_INACT_TIMEOUT_SECONDS
This configuration sets a timeout in seconds after which the accelerometer reports inactivity.
- CONFIG_DATA_LOCATION_TIMEOUT_SECONDS
This configuration sets the location timeout value.
- CONFIG_DATA_SAMPLE_GNSS_DEFAULT
This configuration includes GNSS during sampling. Enabled by default.
- CONFIG_DATA_SAMPLE_NEIGHBOR_CELLS_DEFAULT
This configuration includes neighbor cell measurements during sampling. Enabled by default.
- CONFIG_DATA_SAMPLE_WIFI_DEFAULT
This configuration includes Wi-Fi APs during sampling. Enabled by default.
Other options:
- CONFIG_DATA_GRANT_SEND_ON_CONNECTION_QUALITY
Grants or denies encoding and sending of data based on LTE connection quality.
- CONFIG_DATA_SEND_ATTEMPTS_COUNT_MAX
Maximum number of times sending can be denied due to connection quality before the data is sent regardless.
- CONFIG_DATA_GENERIC_UPDATES_ENERGY_THRESHOLD_MIN
Minimum energy threshold for generic updates.
- CONFIG_DATA_NEIGHBOR_CELL_UPDATES_ENERGY_THRESHOLD_MIN
Minimum energy threshold for neighbor cell updates.
- CONFIG_DATA_BATCH_UPDATES_ENERGY_THRESHOLD_MIN
Minimum energy threshold for batch updates.
Module states
The data module has an internal state machine with the following states:
STATE_CLOUD_DISCONNECTED- Cloud is disconnected. Data transmission is not attempted.STATE_CLOUD_CONNECTED- Cloud is connected. Data transmission is attempted.STATE_SHUTDOWN- The module has been shut down after receiving a request from the utility module.
Module events
The asset_tracker_v2/src/events/data_module_event.h header file contains a list of events sent by the module.
Dependencies
This module uses the following nRF Connect SDK libraries and drivers:
API documentation
asset_tracker_v2/src/events/data_module_event.hasset_tracker_v2/src/events/data_module_event.c, asset_tracker_v2/src/modules/data_module.c