How to let the advertisement device know that which centrals have received its advertisement

[Tom.Fu]

Dear Support Team

Is there any way to let a advertisement device know which centrals have received the advertisement?

I know that a central can send the scan request to the advertisement device for the scan respond data after the central scan a advertisement.  In this case, is there any application layer event for informing the advertisement device the scan request is received?  If it supports, I don't know whether this is the best way that to let a advertisement device know which centrals have received the advertisement. Is there any other better way?  Many thanks.

[Maria Gilje]

Hello,

I have been assigned this ticket, and I will get back to you with an answer soon. Thank you for your patience.

Best regards,

Maria

[Tom.Fu]

Hi Maria

Many thanks for supporting and looking forward to your getting back. 

[Maria Gilje]

Hello,

Thank you for your patience.

Is there any way to let a advertisement device know which centrals have received the advertisement?

This depends on what type of advertising you are using. Most of the below points are covered in Lesson 2 of from the Bluetooth LE fundamentals course.

• For legacy advertisement, the scan request and scan response does not trigger an application level event.
• For extended advertisement, the application is notified through the bt_le_ext_adv_start_param struct in the bt_gap group of  the GAP API.
• For directed advertising, the scanner will not send a scan request, only connect to the advertising device. The case is also that the advertising device directly advertises to the scanner, so it already knows which central it has sent advertisements to, and if the connection is reestablished it knows that the advertisement was successful.
• Periodic Advertisement with Responses (PAwR) (from Bluetooth v5.4) enables the scanner to respond in one of the response slots for each subevent. (Technical overview of new features in Bluetooth v5.4)

Let me know if you need more details on anything.

BR,

Maria

[Tom.Fu]

Dear Maria

Many thanks for supporting.

Is it meant that Observer devices would respond to the Broadcaster after receiving the extended advertisement sent by the Broadcaster and the Broadcaster would get a corresponding event and it would call which callback member in the bt_conn_cb structure in the below picture?

In the PAwR, is there a limit to the number of observers for a broadcaster in the NCS?

Many thanks.

[Maria Gilje]

Hello,

Tom.Fu said:

Is it meant that Observer devices would respond to the Broadcaster after receiving the extended advertisement sent by the Broadcaster and the Broadcaster would get a corresponding event and it would call which callback member in the bt_conn_cb structure in the below picture?

Sorry, I referred to the wrong struct.

It is the scanned member of bt_le_ext_adv_cb which is called when the Advertiser receives a scan request from a Scanner.

Tom.Fu said:

In the PAwR, is there a limit to the number of observers for a broadcaster in the NCS?

The limit is caused by the periodic advertising event interval duration, the amount of subevents in the PAwR event, and the amount of response slots in the subevents.

BR,

Maria