RSSI Implementation with nRF52480 on BLE UART APK

RE: RSSI Implementation with nRF52480 on BLE UART APK

Dheeraj — Wed, 06 Nov 2019 07:35:55 GMT

Hi Einar,

Does this same works for asset tracker application to obtain RSSI values?

I am looking to perform BLE scan based on the timeout values and sort the result by RSSI implementation with nRF52840 for PCA20035 and pass the BLE_SCANLIST_ENTRIES over UART.

Thanks

RE: RSSI Implementation with nRF52480 on BLE UART APK

_OP — Thu, 10 Jan 2019 10:11:44 GMT

Hi,

I was using NRF_LOG_INFO instead of printf() 🙂

for some reason NRF_LOG_INFO doesn't work on putty.

Thanks for your help and time Einar, truly appreciate.

_OP

RE: RSSI Implementation with nRF52480 on BLE UART APK

Einar Thorsrud — Thu, 10 Jan 2019 09:46:08 GMT

Hi,

I did this modifications to the HRS example main.c file from SDK 14.2:

devzone.nordicsemi.com/.../main.c.diff

This resulted in the following log output (RSSI measurements are printed for as long as the connection is alive):

<info> app: Heart Rate Sensor example started.
<info> app: Fast advertising.
<info> app: Connected.
<info> app: rssi =-56 dBm
<info> app: rssi =-47 dBm
<info> app: rssi =-57 dBm
<info> app: rssi =-54 dBm
<info> app: rssi =-50 dBm
<info> app: GATT ATT MTU on connection 0x0 changed to 247.
<info> app: rssi =-49 dBm
<info> app: rssi =-47 dBm
<info> app: rssi =-50 dBm
<info> app: rssi =-54 dBm
<info> app: rssi =-51 dBm
<info> app: rssi =-50 dBm
<info> app: rssi =-46 dBm
<info> app: rssi =-49 dBm
<info> app: rssi =-54 dBm
<info> app: rssi =-53 dBm
<info> app: rssi =-50 dBm
<info> app: rssi =-53 dBm
<info> app: rssi =-48 dBm
<info> app: rssi =-49 dBm
<info> app: rssi =-46 dBm
<info> app: rssi =-51 dBm
<info> app: rssi =-54 dBm
<info> app: rssi =-51 dBm
<info> app: rssi =-49 dBm
<info> app: rssi =-47 dBm
<info> app: rssi =-51 dBm
<info> app: rssi =-54 dBm
<info> app: rssi =-51 dBm
<info> app: rssi =-49 dBm

You should get the same. Does your application work as expected without the RSSI logging?

RE: RSSI Implementation with nRF52480 on BLE UART APK

_OP — Wed, 09 Jan 2019 14:54:10 GMT

Thanks for your quick anser.

Indeed i don't get the 'disconected' msg from the BLE_GAP_EVT_DISCONNECTED event when i turn down the second card.

i'm using putty the output i'm getting is below:

So the sd_ble_gap_rssi_start() is called but the condition "case BLE_GAP_EVT_RSSI_CHANGED:" isn't ever valide (even if i move the cards.. i don't get the msg one single time).

how shoud i fix it ? Is it a good idea to use putty to debug ? Can i see your output with your debugger ?

Thx again Einar.

RE: RSSI Implementation with nRF52480 on BLE UART APK

Einar Thorsrud — Wed, 09 Jan 2019 13:53:35 GMT

Hi,

That's odd. It should work. In fact I copy-pasted your code into an SDK 14.2 example and it worked out of the box (I just had to declare your RSSI variable as int8_t). Have you verified by a debugger that you get the BLE_GAP_EVT_CONNECTED event (and thus call sd_ble_gap_rssi_start()), but you still don't get any BLE_GAP_EVT_RSSI_CHANGED events? Are there any other events instead (particularly BLE_GAP_EVT_DISCONNECTED, which would explain why you don't get any RSSI measurements)?

RE: RSSI Implementation with nRF52480 on BLE UART APK

_OP — Wed, 09 Jan 2019 09:32:09 GMT

Thanks a lot for your anser Einar,

I added theses lines to the example code in the ble_evt_handler function in main.c.

  case BLE_GAP_EVT_CONNECTED:
            printf("Connected!\r\n!");
						
            NRF_LOG_INFO("Connected to target");
            err_code = ble_nus_c_handles_assign(&m_ble_nus_c, p_ble_evt->evt.gap_evt.conn_handle, NULL);
            sd_ble_gap_rssi_start(p_ble_evt->evt.gap_evt.conn_handle, 1, 1); //added by _OP
						printf("It does pass by sd_ble_gap_rssi_start\n");
						APP_ERROR_CHECK(err_code);
            err_code = bsp_indication_set(BSP_INDICATE_CONNECTED);
            APP_ERROR_CHECK(err_code);
            // start discovery of services. The NUS Client waits for a discovery result
            err_code = ble_db_discovery_start(&m_db_disc, p_ble_evt->evt.gap_evt.conn_handle);
            APP_ERROR_CHECK(err_code);
            break;
				
				case BLE_GAP_EVT_RSSI_CHANGED:          //block added by _OP
						sd_ble_gap_rssi_get(p_ble_evt->evt.gap_evt.conn_handle, &RSSI);
						NRF_LOG_INFO("rssi =%d dBm",	RSSI);
						break;
						
        case BLE_GAP_EVT_TIMEOUT:
            if (p_gap_evt->params.timeout.src == BLE_GAP_TIMEOUT_SRC_SCAN)
            {
                NRF_LOG_INFO("Scan timed out.");
                scan_start();
            }
            else if (p_gap_evt->params.timeout.src == BLE_GAP_TIMEOUT_SRC_CONN)
            {
                NRF_LOG_INFO("Connection Request timed out.");
            }
            break;

it does pass by the sd_ble_gap_rssi_start function but not by the BLE_GAP_EVT_RSSI_CHANGED event

I'm on 14.2 SDK because i'm testing the long range app and it's not compatible with 15 (doesn't compile).

Thanks in advance.

_OP

RE: RSSI Implementation with nRF52480 on BLE UART APK

Einar Thorsrud — Tue, 08 Jan 2019 14:25:40 GMT

Hi,

You have to call sd_ble_gap_rssi_start() initially so that the SoftDevice will start to report the RSSI. Depending on the parameters, you will get an event every time the RSSI change or if it changes beyond a given threshold. You can also poll by calling sd_ble_gap_rssi_get(). These message sequence charts shows all variants:

As a side note, it seems you use the nRF52840 with DK 14.2. Please note that it is not recommended to use SDK 14.2 with the nRF52840. It was only supported experimentally. SDK 15.0.0 was the first SDK release with production quality support for the nRF52840.