Bluetooth LE advertising module

In nRF Desktop, the Bluetooth® LE advertising module is responsible for controlling the Bluetooth LE advertising for the nRF Desktop peripheral device.

Module events

Source Module	Input Event	This Module	Output Event	Sink Module
Bluetooth LE advertising module	ble_peer_event	ble_adv
Bluetooth LE state module
Bluetooth LE bond module	ble_peer_operation_event
Source modules for module_state_event	module_state_event
Power manager module	power_down_event
Bluetooth LE advertising module	wake_up_event
Buttons module
HID forward module
Motion module
Power manager module
Wheel module
			ble_peer_event	Sink modules for ble_peer_event
			ble_peer_search_event	LED state module
			module_state_event	Sink modules for module_state_event
			wake_up_event	Sink modules for wake_up_event

Note

See the Overview: Firmware architecture for more information about the event-based communication in the nRF Desktop application and about how to read this table.

Implementation details

nRF Desktop uses the Bluetooth® LE advertising module from Common Application Framework (CAF). See the CAF Bluetooth LE advertising page for implementation details.

For more information about Bluetooth configuration in nRF Desktop, see Bluetooth in nRF Desktop.

Avoiding connection requests from unbonded centrals when bonded

If the Bluetooth local identity currently in use already has a bond and the nRF Desktop device uses indirect advertising, the device will not set the General Discoverable flag. The nRF Desktop devices also enable CONFIG_CAF_BLE_ADV_FILTER_ACCEPT_LIST to filter incoming scan response data requests and connection requests. This is done to prevent Bluetooth Centrals other than the bonded one from connecting with the device. The nRF Desktop dongle scans for peripheral devices using the Bluetooth device name, which is provided in the scan response data.

Advertised data

The CAF: Bluetooth LE advertising module relies on Bluetooth LE advertising providers to manage advertising data and scan response data. nRF Desktop application configures the data providers in src/modules/Kconfig.caf_ble_adv.default. By default, the application enables a set of data providers available in the nRF Connect SDK and adds a custom provider of UUID16 values of Battery Service (BAS) and Human Interface Device Service (HIDS). The UUID16 of a given GATT Service is added to the advertising data only if the service is enabled in the configuration and the Bluetooth local identity in use has no bond.