What are the conditions for sending a scan request?

Hi. 

Currently, after receiving "Advertising data", "Scan Response data" can be obtained on rare occasions.

 What do you mean by rare occasions?

How often do you receive the advertising data, and how often do you receive the scan response data?

What are the advertising and scan parameters for your devices?

Br, 
Joakim

Hello.

Regarding the Scan time setting, interval is set to 0x320 (800ms) and window is set to 0x190 (400ms).
When the reception frequency of 4000ms was measured, the reception frequency of Advertise data was 8 times and the reception frequency of Scan Response was 2 times.
The device Advertise cycle is 100ms. Advertise parameters are Flags, 128bit UUID and Manufacturer Data, and Scan parameters are 128bit UUID and Manufacturer Data.

Thank you.

Hello.

Regarding the Scan time setting, interval is set to 0x320 (800ms) and window is set to 0x190 (400ms).
When the reception frequency of 4000ms was measured, the reception frequency of Advertise data was 8 times and the reception frequency of Scan Response was 2 times.
The device Advertise cycle is 100ms. Advertise parameters are Flags, 128bit UUID and Manufacturer Data, and Scan parameters are 128bit UUID and Manufacturer Data.

Thank you.

Hi,

Would you by any chance have an ellisys sniffer so you can capture the on air traffic? Or as an alternative place the scanner and advertiser in an RF chamber? It could be that there are also other scanners performing active scanning, which is "blocking" the scan requests from your scanner.

Hello.

I don't know the sample source from which my code is based.
As a confirmation method, NRF_BLE_SCAN_EVT_FILTER_MATCH of scan_evt_handler is confirmed whether scan_response is 1. (p_scan_evt-> params.filter_match.p_adv_report-> type.scan_response)
Therefore, I don't use ellisys sniffer.

user2112 said:

It could be that there are also other scanners performing active scanning, which is "blocking" the scan requests from your scanner.

In other words, is it not possible to get the advertisement of the Android device because it was picked up by two scans and both of them are making requests?

Isn't the scan response sent by the data contained in the advertisement packet?

Thank you.

The advertisement packet and scan response packets are two separate packages. First the scanner must receive the advertisement packet, then it must send a scan request, So the advertiser will only send the scan response if it first receives a scan request

Hello.

You must send a Scan Request from Central to have the advertisement send you a Scan Response.
I want to set Central to issue a Scan Request, what should I do?

Thank you.

Hi,

Check ble_gap_scan_params_t  and make sure that

This will enable active scanning. There might still be other active scanners in the area. These will potentially send a scan request at the same time as you do, potentially creating a CRC error on the Advertiser, which will cause it to not send the scan response.