Scanning module support for Coded PHY/Extended Advertisements

[Mohammad Afaneh]

Does the nRF5 SDK Scanning module support scanning extended advertising packets? For example to discover a Peripheral advertising using the Coded PHY?

When I try this, I get the following error:

ble_scan: sd_ble_gap_scan_start returned 0x9
app: ERROR 9 [NRF_ERROR_INVALID_LENGTH] at main.c:177
PC at: 0x0002D295

After looking through at the scan data structure, I see that scan_buffer_data has a length of NRF_BLE_SCAN_BUFFER which is equal to 31. Does that mean it cannot handle extended advertising packets since their size can be up to 255 bytes?

This is my code for scan_init():

// Scan parameters requested for scanning and connection.
static ble_gap_scan_params_t const m_scan_params =
{
    .extended      = 1,
    .active        = 0x00,
    .interval      = SCAN_INTERVAL,
    .window        = SCAN_WINDOW,
    .timeout       = 0x0000, // No timeout.
    .scan_phys     = BLE_GAP_PHY_CODED,
    .filter_policy = BLE_GAP_SCAN_FP_ACCEPT_ALL,
};

static char const m_target_periph_name[] = "Nordic_Blinky_Coded";     /**< Name of the device we try to connect to. This name is searched in the scan report data*/

static void scan_init(void)
{
    ret_code_t          err_code;
    nrf_ble_scan_init_t init_scan;

    memset(&init_scan, 0, sizeof(init_scan));

    init_scan.connect_if_match = true;
    init_scan.conn_cfg_tag     = APP_BLE_CONN_CFG_TAG;

    init_scan.p_scan_param = &m_scan_params;

    err_code = nrf_ble_scan_init(&m_scan, &init_scan, scan_evt_handler);
    APP_ERROR_CHECK(err_code);

    // Setting filters for scanning.
    err_code = nrf_ble_scan_filters_enable(&m_scan, NRF_BLE_SCAN_NAME_FILTER, false);
    APP_ERROR_CHECK(err_code);

    err_code = nrf_ble_scan_filter_set(&m_scan, SCAN_NAME_FILTER, m_target_periph_name);
    APP_ERROR_CHECK(err_code);
}


My goal is to discover a Peripheral that is using Coded PHY for advertising and connect to it whenver the device is discovered by the Central (via its advertised name).

[Vidar Berg]

Hi,

Yes, as you said, the scan buffer must be set to 255 when extended scanning is enabled (BLE_GAP_SCAN_BUFFER_EXTENDED_MIN). You can adjust the NRF_BLE_SCAN_BUFFER flag in sdk_config.h.

You can find a modified version of ble_app_uart and ble_app_uart_c that use CODED_PHY in this thread: https://devzone.nordicsemi.com/f/nordic-q-a/40476/unable-to-convert-to-long-range-after-looking-at-umpteen-examples--

Regards,

Vidar

[Mohammad Afaneh]

Thanks, Vidar.

For some reason, I missed that the NRF_BLE_SCAN_BUFFER is defined in sdk_config.h. I will modify its value and give a try.

[RMV]

I am using SDK v15.3.0.

I looked at ALL the config files provided as templates under the top level /config/ folder and none of them includes this symbol NRF_BLE_SCAN_BUFFER.

I had to scan (no pun intended) all the sdk_config.h under the examples to even figure out that I needed such a beast.

Why doesn't Nordic deem it important to publish a comprehensive version of the "sdk_config.h"?

[Jimmy Wong]

Hi,

i did the example at my github (https://github.com/jimmywong2003/nrf52811-ble-long-range-demo/blob/master/ble_app_uart_c/main.c).

you can use it as reference.

/**@brief Pointer to the buffer where advertising reports will be stored by the SoftDevice. */
static ble_data_t m_scan_buffer =
{
    m_scan_buffer_data,
    BLE_GAP_SCAN_BUFFER_EXTENDED_MIN
};

/**@brief Scan parameters requested for scanning and connection. */
static ble_gap_scan_params_t m_scan_params =
{
    .active   = 1,
    .interval = SCAN_INTERVAL,
    .window   = SCAN_WINDOW,
    .report_incomplete_evts = 0, 
    .extended = 1,
    .timeout           = SCAN_TIMEOUT,
    .scan_phys         = BLE_GAP_PHY_CODED,//BLE_GAP_PHY_1MBPS,
    .filter_policy     = BLE_GAP_SCAN_FP_ACCEPT_ALL,
    .channel_mask      = {0,0,0,0,0},
};


/**@brief NUS UUID. */
static ble_uuid_t const m_nus_uuid =
    {
        .uuid = BLE_UUID_NUS_SERVICE,
        .type = NUS_SERVICE_UUID_TYPE
    };