how to get the RRSI of the central device? i am using sdk 17.1.0 and s140 soft device

[venkatesha kj]

static void ble_evt_handler(ble_evt_t const * p_ble_evt, void * p_context)
{
uint32_t err_code;

switch (p_ble_evt->header.evt_id)
{
case BLE_GAP_EVT_CONNECTED:
NRF_LOG_INFO("Connected");
err_code = bsp_indication_set(BSP_INDICATE_CONNECTED);
APP_ERROR_CHECK(err_code);
m_conn_handle = p_ble_evt->evt.gap_evt.conn_handle;
sd_ble_gap_rssi_start(m_conn_handle,1,0);
err_code = nrf_ble_qwr_conn_handle_assign(&m_qwr, m_conn_handle);
APP_ERROR_CHECK(err_code);
err_code = sd_ble_gap_tx_power_set(BLE_GAP_TX_POWER_ROLE_CONN, m_conn_handle, 4);
APP_ERROR_CHECK(err_code);
break;

case BLE_GAP_EVT_DISCONNECTED:
NRF_LOG_INFO("Disconnected");
// LED indication will be changed when advertising starts.
m_conn_handle = BLE_CONN_HANDLE_INVALID;
break;

case BLE_GAP_EVT_PHY_UPDATE_REQUEST:
{
NRF_LOG_DEBUG("PHY update request.");
ble_gap_phys_t const phys =
{
.rx_phys = BLE_GAP_PHY_AUTO,
.tx_phys = BLE_GAP_PHY_AUTO,
};
err_code = sd_ble_gap_phy_update(p_ble_evt->evt.gap_evt.conn_handle, &phys);
APP_ERROR_CHECK(err_code);
} break;

case BLE_GAP_EVT_SEC_PARAMS_REQUEST:
// Pairing not supported
err_code = sd_ble_gap_sec_params_reply(m_conn_handle, BLE_GAP_SEC_STATUS_PAIRING_NOT_SUPP, NULL, NULL);
APP_ERROR_CHECK(err_code);
break;

case BLE_GATTS_EVT_SYS_ATTR_MISSING:
// No system attributes have been stored.
err_code = sd_ble_gatts_sys_attr_set(m_conn_handle, NULL, 0, 0);
APP_ERROR_CHECK(err_code);
break;

case BLE_GATTC_EVT_TIMEOUT:
// Disconnect on GATT Client timeout event.
err_code = sd_ble_gap_disconnect(p_ble_evt->evt.gattc_evt.conn_handle,
BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION);
APP_ERROR_CHECK(err_code);
break;

case BLE_GATTS_EVT_TIMEOUT:
// Disconnect on GATT Server timeout event.
err_code = sd_ble_gap_disconnect(p_ble_evt->evt.gatts_evt.conn_handle,
BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION);
APP_ERROR_CHECK(err_code);
break;

case BLE_GAP_EVT_RSSI_CHANGED:
rssi = p_ble_evt->evt.gap_evt.params.rssi_changed.rssi;
break;

default:
// No implementation needed.
break;
}
}

i try to get the rssi of the central device that is my phone but it shows 0xffffcd

[venkatesha kj]

not cleared is it if i want to measure the rssi of central device it needs to be connected to pheripheral?

[Einar Thorsrud]

Let me try to clarify. To measure RSSI you need to receive a signal from the device you want to measure. As you are a peripheral device and the other is a central there are no advertisement packets. The only packets the central sends to you is when in a connection (starting with the connection indication packet), and if the central performs active scanning (which means that it sends a scan resquest packet, asking for the peripheral to reply with a scan response packet). There are no other situations where the central sends data to you, and thus no other situations where you can measure the RSSI (which by definition is the signal strengt you receive).