esp_event_handler_register() function

Register an event handler to the system event loop (legacy). This function can be used to register a handler for either: (1) specific events, (2) all events of a certain event base, or (3) all events known by the system event loop. - specific events: specify exact event_base and event_id - all events of a certain base: specify exact event_base and use ESP_EVENT_ANY_ID as the event_id - all events known by the loop: use ESP_EVENT_ANY_BASE for event_base and ESP_EVENT_ANY_ID as the event_id Registering multiple handlers to events is possible. Registering a single handler to multiple events is also possible. However, registering the same handler to the same event multiple times would cause the previous registrations to be overwritten.