nRF52840 Dongle with Raspberry Pi B+ for Beacon scanning

[Ashiq Mohammed]

Team,

For asset tracking I am using nRF52840 Beacons as tags in asserts and Raspberry Pi B+ for scanning Beacon's MAC, UID, Major, Minor, Tx,  and RSSI values.

To calculate Beacon distance with more accuracy I am planning to use 'Channel Diversity' approach, so I want to scan nRF52840 Beacons for any one of specific channel (from 37, 38, 39).  How I can use nRF52840 Dongle along with Raspberry Pi B+ to filter specific channel of nRF52840 Beacon advertisement data.

Ashiq Mohammed

[AndreasF]

Hi Ashiq.

Here is an example in using the ble_app_blinky example in the nRF5_SDK_15.2.0_9412b96\examples\ble_peripheral\ble_app_blinky\pca10059\s140 folder.

In the function static void advertising_init(void), channel masking can be done by adding one of the code snippets below:

adv_params.channel_mask[4] = 0x80; // Dont advertise on ch 39
adv_params.channel_mask[4] = 0x40; // Dont advertise on ch 38
adv_params.channel_mask[4] = 0x20; // Dont advertise on ch 37


adv_params.channel_mask[4] = 0xA0; // Dont advertise on ch 39 and 37
adv_params.channel_mask[4] = 0xC0; // Dont advertise on ch 38 and 39
adv_params.channel_mask[4] = 0x60; // Dont advertise on ch 37 and 38

If i want to for example mask channel 37 and 38 my static void advertising_init(void) function would look like this:

static void advertising_init(void)
{
    ret_code_t    err_code;
    ble_advdata_t advdata;
    ble_advdata_t srdata;

    ble_uuid_t adv_uuids[] = {{LBS_UUID_SERVICE, m_lbs.uuid_type}};

    // Build and set advertising data.
    memset(&advdata, 0, sizeof(advdata));

    advdata.name_type          = BLE_ADVDATA_FULL_NAME;
    advdata.include_appearance = true;
    advdata.flags              = BLE_GAP_ADV_FLAGS_LE_ONLY_GENERAL_DISC_MODE;


    memset(&srdata, 0, sizeof(srdata));
    srdata.uuids_complete.uuid_cnt = sizeof(adv_uuids) / sizeof(adv_uuids[0]);
    srdata.uuids_complete.p_uuids  = adv_uuids;

    err_code = ble_advdata_encode(&advdata, m_adv_data.adv_data.p_data, &m_adv_data.adv_data.len);
    APP_ERROR_CHECK(err_code);

    err_code = ble_advdata_encode(&srdata, m_adv_data.scan_rsp_data.p_data, &m_adv_data.scan_rsp_data.len);
    APP_ERROR_CHECK(err_code);

    ble_gap_adv_params_t adv_params;

    // Set advertising parameters.
    memset(&adv_params, 0, sizeof(adv_params));

    adv_params.primary_phy     = BLE_GAP_PHY_1MBPS;
    adv_params.duration        = APP_ADV_DURATION;
    adv_params.properties.type = BLE_GAP_ADV_TYPE_CONNECTABLE_SCANNABLE_UNDIRECTED;
    adv_params.p_peer_addr     = NULL;
    adv_params.filter_policy   = BLE_GAP_ADV_FP_ANY;
    adv_params.interval        = APP_ADV_INTERVAL;
    adv_params.channel_mask[4] = 0x60; //The code i added to mask channel 37 and 38

    err_code = sd_ble_gap_adv_set_configure(&m_adv_handle, &m_adv_data, &adv_params);
    APP_ERROR_CHECK(err_code);
}

Note that using RSSI to calculate distance is very inaccurate.

Hope this helps.

- Andreas

[Ashiq Mohammed]

Thanks Andreas. Do you have any idea How to communicate nRF52840 Dongle with Raspberry Pi B+.Assume nRF52840 Dongle placed in USB drive of Raspberry Pi B+. Please help.

[awneil]

AndreasF said:

Note that using RSSI to calculate distance is very inaccurate

Indeed.

See: https://devzone.nordicsemi.com/f/nordic-q-a/38857/how-to-calculate-the-distance-with-the-rssi-value-and-tx-power/150174#150174

[Ashiq Mohammed]

My question is, I want to send data from nRF52840 Dongle to Raspberry Pi B+, Assume nRF52840 Dongle placed in USB drive of Raspberry Pi B+. Please help with coding sample.

[AndreasF]

Hi Ashiq.

Could you please create a new post and post this question there, as this is another question and maybe other customers are interested in this, I will close this case. And please verify the answer i posted to your first question.

- Andreas