nRF52840 Dongle with Raspberry Pi B+ for Beacon scanning

Question

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 · Answer

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

nRF52840 Dongle with Raspberry Pi B+ for Beacon scanning

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