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

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

Einar Thorsrud — Fri, 26 Nov 2021 10:09:55 GMT

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).

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

venkatesha kj — Fri, 26 Nov 2021 10:07:25 GMT

BLE_GAP_EVT_SCAN_REQ_REPORT:

in this event i am suppose to call rssi get function right?

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

venkatesha kj — Fri, 26 Nov 2021 10:05:05 GMT

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

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

Einar Thorsrud — Fri, 26 Nov 2021 09:35:27 GMT

No, this is not related to RSSI scanning. You always tet the RSSI together with a scan report. Note that this only works if you advertise and use a scan response, and the central does active scanning. In any other case, a central/observer that is not connected to you does not send you any data, and so you cannot measure the RSSI (which is the strength of the signal you received, and in this case you receive nothing).

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

venkatesha kj — Fri, 26 Nov 2021 09:29:06 GMT

case BLE_GAP_EVT_SCAN_REQ_REPORT:

err_code = sd_ble_gap_rssi_start(p_ble_evt->evt.gap_evt.conn_handle,BLE_GAP_RSSI_THRESHOLD_INVALID,0); //ADDED BY ME
APP_ERROR_CHECK(err_code); //ADDED BY ME

break;

i am suppose to call functio rssi start in scan request report event right?

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

Einar Thorsrud — Fri, 26 Nov 2021 09:18:37 GMT

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).

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

venkatesha kj — Fri, 26 Nov 2021 09:13:48 GMT

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

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

Einar Thorsrud — Fri, 26 Nov 2021 09:11:56 GMT

[quote user="venkatesha kj"]i have initialise the rssi variable as int right?[/quote]

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.

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

venkatesha kj — Fri, 26 Nov 2021 09:04:04 GMT

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?

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

Einar Thorsrud — Fri, 26 Nov 2021 08:59:57 GMT

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.

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

venkatesha kj — Fri, 26 Nov 2021 08:59:48 GMT

static void ble_evt_handler(ble_evt_t const * p_ble_evt, void * p_context)
{
uint32_t err_code;
ble_gap_evt_t const * p_gap_evt = &p_ble_evt->evt.gap_evt; // ADDED BY ME

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;
err_code = sd_ble_gap_rssi_start(p_ble_evt->evt.gap_evt.conn_handle,BLE_GAP_RSSI_THRESHOLD_INVALID,0); //ADDED BY ME
APP_ERROR_CHECK(err_code); //ADDED BY ME

err_code = app_timer_start(my_timer_id,APP_TIMER_TICKS(5000),0); //ADDED BY ME
APP_ERROR_CHECK(err_code); //ADDED BY ME
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 am trying to get the rssi value when the device is connected i am getting like below will it be in dbm or need to convert to dbm?

info> app: RSSI: 198
<info> app: RSSI: 199
<info> app: RSSI: 202
<info> app: RSSI: 201
<info> app: RSSI: 199
<info> app: RSSI: 196
<info> app: RSSI: 200
<info> app: RSSI: 202
<info> app: RSSI: 198
<info> app: RSSI: 195
<info> app: RSSI: 198
<info> app: RSSI: 197
<info> app: RSSI: 191
<info> app: RSSI: 185
<info> app: RSSI: 191
<info> app: RSSI: 191
<info> app: RSSI: 191
<info> app: RSSI: 186
<info> app: RSSI: 188
<info> app: RSSI: 191
<info> app: RSSI: 190
<info> app: RSSI: 194
<info> app: RSSI: 193
<info> app: RSSI: 194
<info> app: RSSI: 191
<info> app: RSSI: 192
<info> app: RSSI: 191
<info> app: RSSI: 192
<info> app: RSSI: 187
<info> app: RSSI: 192
<info> app: RSSI: 196
<info> app: RSSI: 194
<info> app: RSSI: 183
<info> app: RSSI: 190
<info> app: RSSI: 191
<info> app: RSSI: 195
<info> app: RSSI: 192
<info> app: RSSI: 192
<info> app: RSSI: 192
<info> app: RSSI: 193
<info> app: RSSI: 193
<info> app: RSSI: 205
<info> app: RSSI: 199
<info> app: RSSI: 206
<info> app: RSSI: 194
<info> app: RSSI: 201
<info> app: RSSI: 200
<info> app: RSSI: 198
<info> app: RSSI: 193
<info> app: RSSI: 202
<info> app: RSSI: 199
<info> app: RSSI: 203
<info> app: RSSI: 198
<info> app: RSSI: 200
<info> app: RSSI: 203
<info> app: RSSI: 198
<info> app: RSSI: 199
<info> app: RSSI: 202
<info> app: RSSI: 194
<info> app: RSSI: 194
<info> app: RSSI: 200
<info> app: RSSI: 192
<info> app: RSSI: 193
<info> app: RSSI: 193
<info> app: RSSI: 198
<info> app: RSSI: 195
<info> app: RSSI: 198
<info> app: RSSI: 191
<info> app: RSSI: 199
<info> app: RSSI: 195
<info> app: RSSI: 194
<info> app: RSSI: 190
<info> app: RSSI: 191
<info> app: RSSI: 191
<info> app: RSSI: 192
<info> app: RSSI: 194
<info> app: RSSI: 195
<info> app: RSSI: 195
<info> app: RSSI: 197
<info> app: RSSI: 186
<info> app: RSSI: 188
<info> app: RSSI: 197
<info> app: RSSI: 191
<info> app: RSSI: 185
<info> app: RSSI: 190
<info> app: RSSI: 194
<info> app: RSSI: 199
<info> app: RSSI: 187
<info> app: RSSI: 192
<info> app: RSSI: 187
<info> app: RSSI: 196
<info> app: RSSI: 180
<info> app: RSSI: 199
<info> app: RSSI: 195
<info> app: RSSI: 190
<info> app: RSSI: 198
<info> app: RSSI: 193
<info> app: RSSI: 188
<info> app: RSSI: 199
<info> app: RSSI: 198
<info> app: RSSI: 190
<info> app: RSSI: 191
<info> app: RSSI: 197
<info> app: RSSI: 195
<info> app: RSSI: 198
<info> app: RSSI: 196
<info> app: RSSI: 178
<info> app: RSSI: 178
<info> app: RSSI: 198
<info> app: RSSI: 199
<info> app: RSSI: 199
<info> app: RSSI: 198
<info> app: RSSI: 198
<info> app: RSSI: 198
<info> app: RSSI: 198
<info> app: RSSI: 178
<info> app: RSSI: 195
<info> app: RSSI: 195
<info> app: RSSI: 181
<info> app: RSSI: 194
<info> app: RSSI: 187
<info> app: RSSI: 201
<info> app: RSSI: 200
<info> app: RSSI: 201
<info> app: RSSI: 196
<info> app: RSSI: 187
<info> app: RSSI: 188
<info> app: RSSI: 199
<info> app: RSSI: 201
<info> app: RSSI: 200
<info> app: RSSI: 196
<info> app: RSSI: 196
<info> app: RSSI: 199
<info> app: RSSI: 190
<info> app: RSSI: 201
<info> app: RSSI: 198
<info> app: RSSI: 201
<info> app: RSSI: 196
<info> app: RSSI: 201
<info> app: RSSI: 187
<info> app: RSSI: 199
<info> app: RSSI: 199
<info> app: RSSI: 200
<info> app: RSSI: 198
<info> app: RSSI: 199
<info> app: RSSI: 196
<info> app: RSSI: 198
<info> app: RSSI: 193
<info> app: RSSI: 192
<info> app: RSSI: 200
<info> app: RSSI: 201
<info> app: RSSI: 196
<info> app: RSSI: 195
<info> app: RSSI: 199
<info> app: RSSI: 200
<info> app: RSSI: 188
<info> app: RSSI: 195
<info> app: RSSI: 198
<info> app: RSSI: 193