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

[Einar Thorsrud]

Hi,

What has the value0xffffcd? How do you get the RSSI and which type does your rss variable have, and how do you print/interpret it? The rssi field in the ble_gap_evt_rssi_changed_t struct is a signed 8 bit integer (int8_t).

I suggest you do something like this, which should give you correct values (something like "<info> app: RSSI: -33" in the log):

        case BLE_GAP_EVT_RSSI_CHANGED:
        {
            int8_t rssi = p_ble_evt->evt.gap_evt.params.rssi_changed.rssi;
            NRF_LOG_INFO("RSSI: %d", rssi);
        } break;

Values are in dBm.

[venkatesha kj]

static void timeout_handler(void *timeoutpointer)
{
            uint8_t rssi;
            uint8_t channel;

            uint32_t err_code = sd_ble_gap_rssi_get(m_conn_handle,&rssi,&channel);
            APP_ERROR_CHECK(err_code);
            NRF_LOG_INFO("RSSI: %d", rssi);
}

i have initialise the rssi variable as int right?

[Einar Thorsrud]

venkatesha kj said:

i have initialise the rssi variable as int right?

No, it is not right. You are using uint8_t, which is unsigned. But the data here is signed, so rssi should be int8_t (not starting with "u"). The channel is uint_t, so that is correct.

[venkatesha kj]

if i want to know the rrsi of the central device when the device was not connected then how do i get that?

[Einar Thorsrud]

That is only possible if the central does active scanning. In that case you get a BLE_GAP_EVT_SCAN_REQ_REPORT if scanned by the central, which contains the rssi (see ble_gap_evt_scan_req_report_t).