About BLE_GAP_EVT_ADV_REPORT

[sdi_kei]

Hello.
I am developing using nrf52832 (S132 v7.0.1, SDK v16.0.0) as a central device and an Android device (Bluetooth 4.2, nRF Connect) as a peripheral.

I want to get Scan Response data.
Therefore, I used scan_response of the ble_gap_adv_report_type_t structure in BLE_GAP_EVT_ADV_REPORT to check if it could be obtained.
However, during the verification, the scan_response was retrieved before sending the advertisement on nRF Connect.
In addition, scan_response was acquired multiple times after the start of transmission, or could not be acquired even once.

It is filtered by UUID at the start of scan, and nRF Connect has UUID set for advertisement and scan response. Therefore, I think that the event will not occur unless the UUID matches BLE_GAP_EVT_ADV_REPORT.

① Is the UUID filter irrelevant to BLE_GAP_EVT_ADV_REPORT?
② Why is scan_response acquired multiple times or not even once after the advertisement is sent?

Thank you.

[Sigurd]

Hi,

sdi_kei said:

① Is the UUID filter irrelevant to BLE_GAP_EVT_ADV_REPORT?

Yes. I assume you're using the scan module here(nrf_ble_scan.c). The scan module's does filtering based on BLE_GAP_EVT_ADV_REPORT, and then forwards the filter match to the application.

sdi_kei said:

② Why is scan_response acquired multiple times or not even once after the advertisement is sent?

I'm not sure I understand the question, but you could be getting scan responses from other Bluetooth devices nearby.

[sdi_kei]

thank you for your answer.

My purpose is to receive the Scan Response of the advertised device. This is because you later want to receive advice from multiple devices and see the packet information for each device. Therefore, I would like to link it with the device that received the advice.

①Is there any place other than BLE_GAP_EVT_ADV_REPORT that can be judged to have received Scan Response?
②Is there a way to determine that the device has received the advertisement? I am in trouble because the MAC address of the device cannot be obtained correctly without pairing.

Thank you.

[sdi_kei]

Hello.

sdi_kei said:

①Is there any place other than BLE_GAP_EVT_ADV_REPORT that can be judged to have received Scan Response?

The place to confirm that the Scan Response was received was done in "NRF_BLE_SCAN_EVT_FILTER_MATCH". At that time, I was able to determine whether the Scan Response was received from p_scan_evt.

sdi_kei said:

②Is there a way to determine that the device has received the advertisement? I am in trouble because the MAC address of the device cannot be obtained correctly without pairing.

I haven't been able to get the MAC address yet.

Thank you for your cooperation in ①. Thank you for answering ②.

[Sigurd]

sdi_kei said:

I haven't been able to get the MAC address yet.

The MAC address can be found in peer_addr field,

https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.s132.api.v7.0.1/structble__gap__evt__adv__report__t.html

Using the scan module, and you get a filter match(NRF_BLE_SCAN_EVT_FILTER_MATCH), you can find it in the p_adv_report

https://infocenter.nordicsemi.com/topic/sdk_nrf5_v16.0.0/structnrf__ble__scan__evt__filter__match__t.html

 Snippets:

/**@brief Function for displaying an address in HEX format.
 */
static void hex_addr_display(uint8_t const * p_addr, size_t size)
{
    NRF_LOG_RAW_INFO("Address: ");

    for (uint8_t i = 0; i < size; ++i)
    {
        NRF_LOG_RAW_INFO("%.2X ", p_addr[size - (i + 1)]);
    }

    NRF_LOG_RAW_INFO("\r\n");
}

..
..
..
scan_evt_handler

        case NRF_BLE_SCAN_EVT_FILTER_MATCH:
        
                    hex_addr_display(p_scan_evt->params.filter_match.p_adv_report->peer_addr.addr,
                             BLE_GAP_ADDR_LEN);
                    break;

[sdi_kei]

Hello.

Sorry for the late reply.

Although it is a MAC address, what I can get at this point was "BLE_GAP_ADDR_TYPE_RANDOM_PRIVATE_RESOLVABLE".
I couldn't get "BLE_GAP_ADDR_TYPE_PUBLIC" without bonding. Is there any way to get it?

Thank you.

[Sigurd]

sdi_kei said:

Although it is a MAC address, what I can get at this point was "BLE_GAP_ADDR_TYPE_RANDOM_PRIVATE_RESOLVABLE".
I couldn't get "BLE_GAP_ADDR_TYPE_PUBLIC" without bonding. Is there any way to get it?

 No, not without bonding. (If you want to read more about BLE MAC addresses, I recommend this article: https://www.novelbits.io/bluetooth-address-privacy-ble/ )