About NUS connection

[Junichi]

I have implemented NUS on device A and confirmed that it can be connected from a PC by making it the advertising sender.

Device B can scan device A's advertisements and obtain values ​​from the advertisement data.

I would like to add an NUS function to device B so that device B can search for a specific Bluetooth ID from the advertisement and set it on device A via an NUS connection.

I am currently adding NUS_C to device B and trying to run it, but ble_nus_c_init() returns 14.

Please tell me what to do.

[Einar Thorsrud]

Hi,

I see you are using the nRF5 SDK. That incldues the Nordic UART Service Client example, which is a Central and does what you describe here (this works together with the UART/Serial Port Emulation over BLE peripehral example).

Regardign the -8 error you get, that is NRF_ERROR_INVALID_STATE. And you typically get this from sd_ble_gap_connect() if a connection is allready in progress. You will also get this error cod eif you call sd_ble_gap_scan_stop when it is not scanning (if you just wanted to terminate scanning if active you can shoose to ignore this error code, for instance by only calling APP_ERROR_CHECK if the error is different from NRF_ERROR_INVALID_STATE).

But as the description you have match well with the central NUS example linked above, I suggest you test with this first and either base your client on that or copy-past the relevant parts into your application as that i a known working implementation.

[Junichi]

Thank you for your answer.

By adding UART initialization, the NRF_ERROR_INVALID_STATE problem is resolved.

However, when I execute err_code2 = sd_ble_gap_connect(&addr, &scan_params, &conn_params, con_cfg_tag);, 0x05 (NRF_ERROR_NOT_FOUND) is returned and I cannot connect.

What could be the cause?

void scan_evt_handler(scan_evt_t const * p_scan_evt)
{
    switch (p_scan_evt->scan_evt_id)
    {
        case BLE_GAP_EVT_ADV_REPORT:
            break;
        case NRF_BLE_SCAN_EVT_SCAN_TIMEOUT:
            NRF_LOG_INFO("Scan timeout.");
            break;

        case NRF_BLE_SCAN_EVT_CONNECTING_ERROR:
            NRF_LOG_ERROR("Connection error.");
            break;

        case NRF_BLE_SCAN_EVT_CONNECTED:
            NRF_LOG_INFO("Connected to device.");
            break;

        case NRF_BLE_SCAN_EVT_FILTER_MATCH:
        {
            // Get Advertising Report
            ble_gap_evt_adv_report_t const * p_adv_report = p_scan_evt->params.filter_match.p_adv_report;

            // Get advertising data
            const uint8_t * p_data = p_adv_report->data.p_data; // Get p_data from ble_data_t
            uint16_t data_len = p_adv_report->data.len; 		// Get the data length from ble_data_t

            // Get Device Name
            char device_name[BLE_GAP_DEVNAME_MAX_LEN + 1]; 		// A buffer for the device name
            memset(device_name, 0, sizeof(device_name)); 		// Clear the buffer

            // Finding device names from advertising data
            uint8_t * p_name_data = ble_advdata_parse((uint8_t *)p_data, data_len, BLE_GAP_AD_TYPE_COMPLETE_LOCAL_NAME);
            if (p_name_data != NULL)
            {
                // Get the length of the device name
                uint8_t name_len = strlen((const char *)p_name_data);
                strncpy(device_name, (char *)p_name_data, name_len);
                device_name[name_len] = '\0'; 					// NULL terminated
                device_name[6] = '\0';
                // If the device names match, the connection is initiated.
                if (strcmp(device_name, TARGET_DEVICE_NAME) == 0)
                {
                    // Set the address of the destination device
                    Name_acquisition_flag = 1;
                    ble_gap_addr_t addr;
                    addr.addr_id_peer = 0; 												// 0 if not a private address
                    addr.addr_type = p_adv_report->peer_addr.addr_type; 				// Set the address type (0x01)
                    memcpy(addr.addr, p_adv_report->peer_addr.addr, BLE_GAP_ADDR_LEN); 	// Copy address

                    // Initialize scan parameters
                    ble_gap_scan_params_t scan_params;
                    memset(&scan_params, 0, sizeof(scan_params)); 						// Zero Initialization
                    scan_params.extended = 0; 											// 0 if you do not want to use extended scanning
                    scan_params.active = 1; 											// Enable Active Scanning
                    scan_params.report_incomplete_evts = 0; 							// Do not report incomplete events
                    scan_params.scan_phys = BLE_GAP_PHY_1MBPS; 							// Back PHY and feeling  (0x01)
                    scan_params.interval = 160; 										// Set the scan interval
                    scan_params.window = 72; 											// Set the scan window
                    scan_params.timeout = 0; 											// No timeout

                    // Initializing connection parameters
                    ble_gap_conn_params_t conn_params;
                    memset(&conn_params, 0, sizeof(conn_params)); 						// Zero Initialization
                    conn_params.min_conn_interval = MIN_CONN_INTERVAL; 					// Minimum Connection Interval (160)
                    conn_params.max_conn_interval = MAX_CONN_INTERVAL; 					// Maximum Connection Interval (320)
                    conn_params.slave_latency = SLAVE_LATENCY; 							// Slave Latency  (0)
                    conn_params.conn_sup_timeout = CONN_SUP_TIMEOUT; 					// Connection Supervision Timeout (MSEC_TO_UNITS(4000, UNIT_10_MS)
                    int attempts = 0;
//                    if (is_scanning)
//                    {
//                        err_code2 = sd_ble_gap_scan_stop();
//                        if (err_code2 != NRF_SUCCESS) 
//                        {
//                            is_scanning = true;
//                        }
//                        else
//                        {
//                            is_scanning = false; 
//                        }
//                    }
                    // Start a connection
                    if (!is_connected)
                    {
                        nrf_delay_ms(200);
                        err_code2 = sd_ble_gap_connect(&addr, &scan_params, &conn_params, con_cfg_tag);
                        if(err_code2 == NRF_ERROR_NOT_FOUND)
                        {
                            for(int i = 0 ; i < 5 ; i++)
                            {
                                nrf_delay_ms(1000);
                                err_code2 = sd_ble_gap_connect(&addr, &scan_params, &conn_params, con_cfg_tag);
                                if(err_code2 == 0)
                                {
                                    break;
                                }
                            }
                        }
                    }
                    device_name[6] = '\0';
                    if (err_code2 != NRF_SUCCESS) 
                    {
                        is_connected = true;
                    }
                }
            }
            break;
        }
        default:
            break;
    }
}

[Einar Thorsrud]

Hi,

sd_ble_gap_connect() will return NRF_ERROR_NOT_FOUND if conn_cfg_tag (the last parameter) cannot be found. Which value did you set it to, and did you call nrf_sdh_ble_default_cfg_set with that value (search for APP_BLE_CONN_CFG_TAG in the SDK to see examples of this)?