RSSI without connection

Question

Simple question: 
 Is possible a central to evaluate RSSI before connecting to a peripheral? 
 The idea is to make central device connect and bond to a peripheral only if a determined RSSI is achieved. 
 Cheers 
 Fávero

Anders Strand · Accepted Answer

See the scanning section of the BLE Central Tutorial . 
 In most SDK examples you will have the following function handling BLE events: 
 static void on_ble_evt(ble_evt_t * p_ble_evt)
{
 uint32_t err_code;
 const ble_gap_evt_t * p_gap_evt = &p_ble_evt->evt.gap_evt;	

 switch (p_ble_evt->header.evt_id)
 {
 case BLE_GAP_EVT_ADV_REPORT:
 {
 const ble_gap_evt_adv_report_t *p_adv_report = &p_gap_evt->params.adv_report;
 
 The p_adv_report contains all the received advertisement data. You will find the rssi at p_adv_report->rssi. 
 See the documentation on the type ble_gap_evt_adv_report_t

mabensur · Answer

Complementing Anders Strand answer, when using SDK 15, things are a little different. 
 
 You can use examples\ble_central\ ble_app_multilink_central as an starting point. 
 
 First you need to disable auto connect in scan_init() function: 
 
 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 = false; // I CHANGED
 init_scan.conn_cfg_tag = APP_BLE_CONN_CFG_TAG;

 //continues... 
} 
 
 Then on scan_evt_handler(scan_evt_t const * p_scan_evt) function you need to add a "case" on the "switch case" to look for 
 
 "NRF_BLE_SCAN_EVT_FILTER_MATCH" events. 
 
 This event will happen every time the scanner finds an device with advertising data accordingly to the filter set on scan_init() . In our case, devices advertising with "Nordic_Blinky" name. 
 
 Inside this "case" you can do the following: 
 
 static void scan_evt_handler(scan_evt_t const * p_scan_evt)
{
 ret_code_t err_code;

 switch(p_scan_evt->scan_evt_id)
 {
 case NRF_BLE_SCAN_EVT_CONNECTING_ERROR:
 {
 err_code = p_scan_evt->params.connecting_err.err_code;
 APP_ERROR_CHECK(err_code);
 } break;

 case NRF_BLE_SCAN_EVT_FILTER_MATCH: //CASE ADDED
 {
 int read_rssi = p_scan_evt->params.filter_match.p_adv_report->rssi;
 
 //PRINTS PEER ID OF THE CURRENT SCAN
 NRF_LOG_RAW_INFO("PEER ID = ")
 for (int i = 0; i < BLE_GAP_ADDR_LEN; i++){
 NRF_LOG_RAW_INFO("%02x", p_scan_evt->params.connected.p_connected->peer_addr.addr[i]);
 }
 NRF_LOG_RAW_INFO("
");
 
 //PRINTS RSSI VALUE
 NRF_LOG_RAW_INFO("RSSI = %d", read_rssi);
 NRF_LOG_RAW_INFO("
");
 NRF_LOG_RAW_INFO("
");
 
 
 //NRF_LOG_INFO("RSSI = %d", read_rssi);
 break;
 }

 default:
 break;
 }
}

RSSI without connection

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