Filter and multiple connection for many beacons simultaneously

[it0406]

Hello developers,

I am using nRF52840 feather from adafruit as a ble central board. 

FIrst of all, I tried to filter just only for my beacons with UUID. I saw a ble central example ble_app_hrs_c and needed a service UUID. 

So I gave it 0xFEAB in my code. But the board scans still many other bluetooth modules which are not beacons. 

How can I correctly filter only for beacons?

static char const test_periph_uuid[] = {0xab, 0xfe};

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;

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

    err_code = nrf_ble_scan_filter_set(&m_scan, SCAN_UUID_FILTER, test_periph_uuid);
    APP_ERROR_CHECK(err_code);

    err_code = nrf_ble_scan_filters_enable(&m_scan, NRF_BLE_SCAN_UUID_FILTER, false);
    APP_ERROR_CHECK(err_code);
}

Furthermore, I want to connect simultaneous many beacons (maybe 4 or more) with my board. But if I tried to connect 4 beacons at first, one of them can't be scanned and the other one could be rarely scanned. For example, first beacon is scanned 10 times, second beacon 0 times, third beacon 2 times and fourth beacon 42 times.

I saw the ble_app_multilink_central example for this problem and it didn't help well. 

Why does it randomly work? How can the board scan in order? I wrote it with if function in sequence from 1 to 4. 

#define NRF_SDH_BLE_CENTRAL_LINK_COUNT 8

/**@brief LED Button collector initialization. */
static void lbs_c_init(void)
{
    ret_code_t       err_code;
    ble_lbs_c_init_t lbs_c_init_obj;

    lbs_c_init_obj.evt_handler   = lbs_c_evt_handler;
    lbs_c_init_obj.p_gatt_queue  = &m_ble_gatt_queue;
    lbs_c_init_obj.error_handler = lbs_error_handler;

    for (uint32_t i = 0; i < NRF_SDH_BLE_CENTRAL_LINK_COUNT; i++)
    {
        err_code = ble_lbs_c_init(&m_lbs_c[i], &lbs_c_init_obj);
        APP_ERROR_CHECK(err_code);
    }
}

And one more question is the function lbs_c_init. As the explaination, it is actually a init function for LED Button collector. 

Why does it handle the number of bluetooth module for multilink?

Software specification:

Segger embedded studio for arm 5.50b

nRF5 SDK 17.0.2

Softdevice S140

Best regards, 

it0406

[Vidar Berg]

Hello,

The Scanning Module offers several filtering options, not just on the UUID. However, it does not include parsing of the manufacturer field used by most beacons. What kind of beacons do you have? Do they include a manufacturer field with a Beacon UUID in it like our ble_app_beacon sample? 

So I gave it 0xFEAB in my code. But the board scans still many other bluetooth modules which are not beacons. 

The RADIO will pick up all advertisment packets it see unless you scan with a whitelist. Still, only advertisment packets that meet the filtering critera will be notified through the NRF_BLE_SCAN_EVT_FILTER_MATCH event.

Furthermore, I want to connect simultaneous many beacons (maybe 4 or more) with my board. But if I tried to connect 4 beacons at first, one of them can't be scanned and the other one could be rarely scanned. For example, first beacon is scanned 10 times, second beacon 0 times, third beacon 2 times and fourth beacon 42 times.

What is meant with  "connect" in this context?

Best regards,

Vidar