Is it possible to see raw extended advertising packets?

[Damia]

Hi,

I'm a beginner trying to understand BLE extended advertising. I have modified the peripheral/ble_app_beacon example to broadcast extended advertising packets with PHY=Coded. I'm receiving the packets using the pc-ble-driver with a modified "heart_rate_collector" example. I'm using two nrf52840 dongles.

I'm currently able to read the entire data that I transmit on the advertising packet, and some other bytes like the source address using the following code:

static void on_adv_report(const ble_gap_evt_t *const p_ble_gap_evt)
{
    uint32_t err_code;
    uint8_t str[STRING_BUFFER_SIZE] = {0};

    // Log the Bluetooth device address of advertisement packet received.
    ble_address_to_string_convert(p_ble_gap_evt->params.adv_report.peer_addr, str);
    printf("Received advertisement report with device address: 0x%s\n", str);
    printf("Extended?: %d, channel: %d, data len:: %d\n",
           p_ble_gap_evt->params.adv_report.type.extended_pdu,
           p_ble_gap_evt->params.adv_report.ch_index, p_ble_gap_evt->params.adv_report.data.len);
    //Printar data:
    int i;
    for (i = 0; i < p_ble_gap_evt->params.adv_report.data.len; i++)
    {
        printf("%02X", p_ble_gap_evt->params.adv_report.data.p_data[i]);
    }
    printf("\n");
    fflush(stdout);
}

..but I would like to see all the raw packet that I'm receiving (both primary and secondary extended advertising packet). I think the raw packet should begin with a 0x3C (preamble) byte since I'm transmitting and receiving with coded phy. Is there any form to visualize all the bytes (including the preamble byte)?

Thanks in advance.

[Simonr]

Hi

If you're new to the Coded PHY, I would strongly suggest checking out this blog post explaining Coded PHY, what it is, how it's used, and the packet format in detail. What have you set the NRF_LOG_MSGPOOL_ELEMENT_SIZE and _COUNT to in your config header file(s)? This has been an issue previously when trying to log raw extended advertising data: https://devzone.nordicsemi.com/f/nordic-q-a/40367/unable-to-hexdump-complete-extended-advertisement-data 

Best regards,

Simon

[Damia]

NRF_LOG_MSGPOOL_ELEMENT_SIZE, _COUNT and NRF_LOG_RAW_HEXDUMP_INFO(...) are not defined in the pc-ble-driver I am currently using. Do you recommend me to program an nrf52840 with NRF_LOG_RAW_HEXDUMP_INFO() and log the raw packets to the pc somehow? Is it possible to use a nrf52840 dongle for this or I have to buy a DK?

[Simonr]

Hi again

I see, I didn't realize you were using the pc-ble-driver. It doesn't matter though, it seems. I dove into the firmware, and it seems you won't be able to get the raw data from Coded PHY advertisements, as it is the SoftDevice who's handling FEC decoding, and you won't be able to get raw data from there. The only way would be to use a Sniffer to tap into the connection and pick up the raw data. Unfortunately, the nRF Sniffer does not support sniffing the secondary advertising channels, so you will need a more expensive option like an Ellisys device or similar.

The other option would be to use the radio peripheral directly, without the SoftDevice, but that is quite a bit of work, and would be up to you I'm afraid.

Best regards,

Simon

[Damia]

OK thank you a lot!