Bluetooth RTOS adaptation#

Bluetooth RTOS adaptation.

The Bluetooth RTOS adaptation component implements the relevant interfaces for running the Bluetooth stack in an RTOS. The component creates the required RTOS synchronization primitives and tasks for the Bluetooth stack and handles the inter-process communication (IPC) required when the application calls a BGAPI command.

If the Bluetooth Event System IPC component (bluetooth_event_system_ipc) is included in the application, Bluetooth events are delivered using the IPC mechanism provided by the event_system component. See Bluetooth Event System IPC for the description of that mechanism. In this configuration no event task is created by the RTOS adaptation.

If the Bluetooth Event System IPC component (bluetooth_event_system_ipc) is not included in the application, the RTOS adaptation component creates an event task that delivers the events to the application as direct callbacks to sl_bt_process_event() and sl_bt_on_event() functions.

To guarantee thread safety and avoid the risk of deadlocks, the Bluetooth RTOS adaptation implementation makes the following promises with regard to the locking mechanism provided in the API:

1. The stack will never directly call sl_bt_process_event() or sl_bt_on_event() from within the same callstack that is calling a command function. The callbacks always come from a processing loop in an event task created for this purpose.

2. The stack uses sl_bgapi_lock() and sl_bgapi_unlock() to synchronize the handling of individual BGAPI commands, and the application must never directly call these. Individual BGAPI commands are safe to be called from multiple threads without additional locking. See sl_bt_bluetooth_pend() for description of when an application needs to use additional locking to guarantee atomicity across multiple commands.

3. The stack will never internally obtain the sl_bt_bluetooth_pend() lock. It is safe for the application to obtain the lock also from within the sl_bt_on_event() callback.