NORDIC softDevice 蓝牙协议栈初始化程序分析(蓝牙从机,ble_peripheral)

基于 NORDIC softDevice 蓝牙协议栈 S132

蓝牙角色: 从机,ble_peripheral

---

应用主函数 main() 中必须的函数:

ble_stack_init();
gap_params_init();
gatt_init();
services_init();
advertising_init();
advertising_start();

/**@brief Function for application main entry.*/
int main(void)
{
    // Initialize.
    log_init();
    leds_init();
    timers_init();
    buttons_init();
    power_management_init();
    ble_stack_init();
    gap_params_init();
    gatt_init();
    services_init();
    advertising_init();
    conn_params_init();

    // Start execution.
    NRF_LOG_INFO("Blinky example started.");
    advertising_start();

	application_timers_start();		
    // Enter main loop.
    for (;;)
    {
        idle_state_handle();
    }
}

---

ble_stack_init()

NRF_SDH_BLE_OBSERVER(m_ble_observer, APP_BLE_OBSERVER_PRIO, ble_evt_handler, NULL);  语句中, ble_evt_handler 为 BLE 事件回调函数 (handler for BLE events).

/**@brief Function for initializing the BLE stack.
 * @details Initializes the SoftDevice and the BLE event interrupt.
 */
static void ble_stack_init(void)
{
    ret_code_t err_code;

    err_code = nrf_sdh_enable_request();
    APP_ERROR_CHECK(err_code);

    // Configure the BLE stack using the default settings.
    // Fetch the start address of the application RAM.
    uint32_t ram_start = 0;
    err_code = nrf_sdh_ble_default_cfg_set(APP_BLE_CONN_CFG_TAG, &ram_start);
    APP_ERROR_CHECK(err_code);

    // Enable BLE stack.
    err_code = nrf_sdh_ble_enable(&ram_start);
    APP_ERROR_CHECK(err_code);

    // Register a handler for BLE events.
    NRF_SDH_BLE_OBSERVER(m_ble_observer, APP_BLE_OBSERVER_PRIO, ble_evt_handler, NULL);
}

BLE 事件回调函数,ble_evt_handler

/**@brief Function for handling BLE events.
 * @param[in]   p_ble_evt   Bluetooth stack event.
 * @param[in]   p_context   Unused.
 */
static void ble_evt_handler(ble_evt_t const * p_ble_evt, void * p_context)
{
    ret_code_t err_code;

    switch (p_ble_evt->header.evt_id)
    {
        case BLE_GAP_EVT_CONNECTED:
            NRF_LOG_INFO("Connected");				
            bsp_board_led_on(CONNECTED_LED);
            bsp_board_led_off(ADVERTISING_LED);
				
            m_conn_handle = p_ble_evt->evt.gap_evt.conn_handle;
            err_code = nrf_ble_qwr_conn_handle_assign(&m_qwr, m_conn_handle);
            APP_ERROR_CHECK(err_code);
            err_code = app_button_enable();
            APP_ERROR_CHECK(err_code);
            break;

        case BLE_GAP_EVT_DISCONNECTED:
            NRF_LOG_INFO("Disconnected");
            bsp_board_led_off(CONNECTED_LED);
            m_conn_handle = BLE_CONN_HANDLE_INVALID;
            err_code = app_button_disable();
            APP_ERROR_CHECK(err_code);
            advertising_start();
            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_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_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.
            NRF_LOG_DEBUG("GATT Client Timeout.");
            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.
            NRF_LOG_DEBUG("GATT Server Timeout.");
            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;

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

BLE GAP 事件列表 (GAP Event IDs.);  (BLE 事件回调函数 ble_evt_handler 中常处理的事件)

enum BLE_GAP_EVTS

GAP Event IDs. IDs that uniquely identify an event coming from the stack to the application.

Enumerator
BLE_GAP_EVT_CONNECTED	GAP BLE Event base.
BLE_GAP_EVT_DISCONNECTED	GAP BLE Event base. Disconnected from peer.  See ble_gap_evt_disconnected_t.
BLE_GAP_EVT_CONN_PARAM_UPDATE	GAP BLE Event base. Connection Parameters updated.  See ble_gap_evt_conn_param_update_t.
BLE_GAP_EVT_SEC_PARAMS_REQUEST	GAP BLE Event base. Request to provide security parameters.  Reply with sd_ble_gap_sec_params_reply.  See ble_gap_evt_sec_params_request_t.
BLE_GAP_EVT_SEC_INFO_REQUEST	GAP BLE Event base. Request to provide security information.  Reply with sd_ble_gap_sec_info_reply.  See ble_gap_evt_sec_info_request_t.
BLE_GAP_EVT_PASSKEY_DISPLAY	GAP BLE Event base. Request to display a passkey to the user.  In LESC Numeric Comparison, reply with sd_ble_gap_auth_key_reply.  See ble_gap_evt_passkey_display_t.
BLE_GAP_EVT_KEY_PRESSED	GAP BLE Event base. Notification of a keypress on the remote device. See ble_gap_evt_key_pressed_t
BLE_GAP_EVT_AUTH_KEY_REQUEST	GAP BLE Event base. Request to provide an authentication key.  Reply with sd_ble_gap_auth_key_reply.  See ble_gap_evt_auth_key_request_t.
BLE_GAP_EVT_LESC_DHKEY_REQUEST	GAP BLE Event base. Request to calculate an LE Secure Connections DHKey.  Reply with sd_ble_gap_lesc_dhkey_reply.  See ble_gap_evt_lesc_dhkey_request_t
BLE_GAP_EVT_AUTH_STATUS	GAP BLE Event base. Authentication procedure completed with status.  See ble_gap_evt_auth_status_t.
BLE_GAP_EVT_CONN_SEC_UPDATE	GAP BLE Event base. Connection security updated.  See ble_gap_evt_conn_sec_update_t.
BLE_GAP_EVT_TIMEOUT	GAP BLE Event base. Timeout expired.  See ble_gap_evt_timeout_t.
BLE_GAP_EVT_RSSI_CHANGED	GAP BLE Event base. RSSI report.  See ble_gap_evt_rssi_changed_t.
BLE_GAP_EVT_ADV_REPORT	GAP BLE Event base. Advertising report.  See ble_gap_evt_adv_report_t.
BLE_GAP_EVT_SEC_REQUEST	GAP BLE Event base. Security Request.  See ble_gap_evt_sec_request_t.
BLE_GAP_EVT_CONN_PARAM_UPDATE_REQUEST	GAP BLE Event base. Connection Parameter Update Request.  Reply with sd_ble_gap_conn_param_update.  See ble_gap_evt_conn_param_update_request_t.
BLE_GAP_EVT_SCAN_REQ_REPORT	GAP BLE Event base. Scan request report.  See ble_gap_evt_scan_req_report_t.
BLE_GAP_EVT_PHY_UPDATE_REQUEST	GAP BLE Event base. PHY Update Request.  Reply with sd_ble_gap_phy_update.  See ble_gap_evt_phy_update_request_t.
BLE_GAP_EVT_PHY_UPDATE	GAP BLE Event base. PHY Update Procedure is complete.  See ble_gap_evt_phy_update_t.
BLE_GAP_EVT_DATA_LENGTH_UPDATE_REQUEST	GAP BLE Event base. Data Length Update Request.  Reply with sd_ble_gap_data_length_update. See ble_gap_evt_data_length_update_request_t.
BLE_GAP_EVT_DATA_LENGTH_UPDATE	GAP BLE Event base. LL Data Channel PDU payload length updated.  See ble_gap_evt_data_length_update_t.
BLE_GAP_EVT_QOS_CHANNEL_SURVEY_REPORT	GAP BLE Event base. Channel survey report.  See ble_gap_evt_qos_channel_survey_report_t.
BLE_GAP_EVT_ADV_SET_TERMINATED	GAP BLE Event base. Advertising set terminated.  See ble_gap_evt_adv_set_terminated_t.

BLE GATT Server 事件列表 (GATT Server Event IDs.)(BLE 事件回调函数 ble_evt_handler 中常处理的事件)

enum BLE_GATTS_EVTS

GATT Server Event IDs.

Enumerator
BLE_GATTS_EVT_WRITE	GATTS BLE Event base. Write operation performed.  See ble_gatts_evt_write_t.
BLE_GATTS_EVT_RW_AUTHORIZE_REQUEST	Read/Write Authorization request.  Reply with sd_ble_gatts_rw_authorize_reply.  See ble_gatts_evt_rw_authorize_request_t.
BLE_GATTS_EVT_SYS_ATTR_MISSING	A persistent system attribute access is pending.  Respond with sd_ble_gatts_sys_attr_set.  See ble_gatts_evt_sys_attr_missing_t.
BLE_GATTS_EVT_HVC	Handle Value Confirmation.  See ble_gatts_evt_hvc_t.
BLE_GATTS_EVT_SC_CONFIRM	Service Changed Confirmation.  No additional event structure applies.
BLE_GATTS_EVT_EXCHANGE_MTU_REQUEST	Exchange MTU Request.  Reply with sd_ble_gatts_exchange_mtu_reply.  See ble_gatts_evt_exchange_mtu_request_t.
BLE_GATTS_EVT_TIMEOUT	Peer failed to respond to an ATT request in time.  See ble_gatts_evt_timeout_t.
BLE_GATTS_EVT_HVN_TX_COMPLETE	Handle Value Notification transmission complete.  See ble_gatts_evt_hvn_tx_complete_t.

BLE GATT Client 事件列表 (GATT Client Event IDs.)(BLE 事件回调函数 ble_evt_handler 中常处理的事件)

enum BLE_GATTC_EVTS

GATT Client Event IDs.

Enumerator
BLE_GATTC_EVT_PRIM_SRVC_DISC_RSP	GATTC BLE Event base. Primary Service Discovery Response event.  See ble_gattc_evt_prim_srvc_disc_rsp_t.
BLE_GATTC_EVT_REL_DISC_RSP	Relationship Discovery Response event.  See ble_gattc_evt_rel_disc_rsp_t.
BLE_GATTC_EVT_CHAR_DISC_RSP	Characteristic Discovery Response event.  See ble_gattc_evt_char_disc_rsp_t.
BLE_GATTC_EVT_DESC_DISC_RSP	Descriptor Discovery Response event.  See ble_gattc_evt_desc_disc_rsp_t.
BLE_GATTC_EVT_ATTR_INFO_DISC_RSP	Attribute Information Response event.  See ble_gattc_evt_attr_info_disc_rsp_t.
BLE_GATTC_EVT_CHAR_VAL_BY_UUID_READ_RSP	Read By UUID Response event.  See ble_gattc_evt_char_val_by_uuid_read_rsp_t.
BLE_GATTC_EVT_READ_RSP	Read Response event.  See ble_gattc_evt_read_rsp_t.
BLE_GATTC_EVT_CHAR_VALS_READ_RSP	Read multiple Response event.  See ble_gattc_evt_char_vals_read_rsp_t.
BLE_GATTC_EVT_WRITE_RSP	Write Response event.  See ble_gattc_evt_write_rsp_t.
BLE_GATTC_EVT_HVX	Handle Value Notification or Indication event.  Confirm indication with sd_ble_gattc_hv_confirm.  See ble_gattc_evt_hvx_t.
BLE_GATTC_EVT_EXCHANGE_MTU_RSP	Exchange MTU Response event.  See ble_gattc_evt_exchange_mtu_rsp_t.
BLE_GATTC_EVT_TIMEOUT	Timeout event.  See ble_gattc_evt_timeout_t.
BLE_GATTC_EVT_WRITE_CMD_TX_COMPLETE	Write without Response transmission complete.  See ble_gattc_evt_write_cmd_tx_complete_t.

---

gap_params_init()

/**@brief Function for the GAP initialization.
 * @details This function sets up all the necessary GAP (Generic Access Profile) parameters of the
 *          device including the device name, appearance, and the preferred connection parameters.
 */
static void gap_params_init(void)
{
    ret_code_t              err_code;
    ble_gap_conn_params_t   gap_conn_params;
    ble_gap_conn_sec_mode_t sec_mode;

    BLE_GAP_CONN_SEC_MODE_SET_OPEN(&sec_mode);

    err_code = sd_ble_gap_device_name_set(&sec_mode,
                                          (const uint8_t *)DEVICE_NAME,
                                          strlen(DEVICE_NAME));
    APP_ERROR_CHECK(err_code);

    memset(&gap_conn_params, 0, sizeof(gap_conn_params));

    gap_conn_params.min_conn_interval = MIN_CONN_INTERVAL;
    gap_conn_params.max_conn_interval = MAX_CONN_INTERVAL;
    gap_conn_params.slave_latency     = SLAVE_LATENCY;
    gap_conn_params.conn_sup_timeout  = CONN_SUP_TIMEOUT;

    err_code = sd_ble_gap_ppcp_set(&gap_conn_params);
    APP_ERROR_CHECK(err_code);
}

---

gatt_init()

/**@brief Function for initializing the GATT module.*/
static void gatt_init(void)
{
    ret_code_t err_code = nrf_ble_gatt_init(&m_gatt, NULL);
    APP_ERROR_CHECK(err_code);
}

ret_code_t nrf_ble_gatt_init(nrf_ble_gatt_t * p_gatt, nrf_ble_gatt_evt_handler_t evt_handler)
{
    VERIFY_PARAM_NOT_NULL(p_gatt);

    p_gatt->evt_handler             = evt_handler;
    p_gatt->att_mtu_desired_periph  = NRF_SDH_BLE_GATT_MAX_MTU_SIZE;
    p_gatt->att_mtu_desired_central = NRF_SDH_BLE_GATT_MAX_MTU_SIZE;
    p_gatt->data_length             = NRF_SDH_BLE_GAP_DATA_LENGTH;

    for (uint32_t i = 0; i < NRF_BLE_GATT_LINK_COUNT; i++)
    {
        link_init(&p_gatt->links[i]);
    }

    return NRF_SUCCESS;
}

---

services_init()

本例 services_init() 中，实现的是 LED Button Service; 其具体内容根据应用需求修改。

/**@brief Function for initializing services that will be used by the application.
 */
static void services_init(void)
{
    ret_code_t         err_code;
    ble_lbs_init_t     init     = {0};
    nrf_ble_qwr_init_t qwr_init = {0};

    // Initialize Queued Write Module.
    qwr_init.error_handler = nrf_qwr_error_handler;

    err_code = nrf_ble_qwr_init(&m_qwr, &qwr_init);
    APP_ERROR_CHECK(err_code);

    // Initialize LBS.
    init.led_write_handler = led_write_handler;

    err_code = ble_lbs_init(&m_lbs, &init);
    APP_ERROR_CHECK(err_code);
}

/**@brief Function for handling write events to the LED characteristic.
 * @param[in] p_lbs     Instance of LED Button Service to which the write applies.
 * @param[in] led_state Written/desired state of the LED.
 */
static void led_write_handler(uint16_t conn_handle, ble_lbs_t * p_lbs, uint8_t led_state)
{
    if (led_state)
    {
        bsp_board_led_on(LEDBUTTON_LED);
        NRF_LOG_INFO("Received LED ON!");
    }
    else
    {
        bsp_board_led_off(LEDBUTTON_LED);
        NRF_LOG_INFO("Received LED OFF!");
    }
}

---

advertising_init()

/**@brief Function for initializing the Advertising functionality.
 * @details Encodes the required advertising data and passes it to the stack.
 *          Also builds a structure to be passed to the stack when starting advertising.
 */
static void advertising_init(void)
{
    ret_code_t    err_code;
    ble_advdata_t advdata;
    ble_advdata_t srdata;

    ble_uuid_t adv_uuids[] = {{LBS_UUID_SERVICE, m_lbs.uuid_type}};

    // Build and set advertising data.
    memset(&advdata, 0, sizeof(advdata));

    advdata.name_type          = BLE_ADVDATA_FULL_NAME;
    advdata.include_appearance = true;
    advdata.flags              = BLE_GAP_ADV_FLAGS_LE_ONLY_GENERAL_DISC_MODE;


    memset(&srdata, 0, sizeof(srdata));
    srdata.uuids_complete.uuid_cnt = sizeof(adv_uuids) / sizeof(adv_uuids[0]);
    srdata.uuids_complete.p_uuids  = adv_uuids;

    err_code = ble_advdata_encode(&advdata, m_adv_data.adv_data.p_data, &m_adv_data.adv_data.len);
    APP_ERROR_CHECK(err_code);

    err_code = ble_advdata_encode(&srdata, m_adv_data.scan_rsp_data.p_data, &m_adv_data.scan_rsp_data.len);
    APP_ERROR_CHECK(err_code);

    ble_gap_adv_params_t adv_params;

    // Set advertising parameters.
    memset(&adv_params, 0, sizeof(adv_params));

    adv_params.primary_phy     = BLE_GAP_PHY_1MBPS;
    adv_params.duration        = APP_ADV_DURATION;
    adv_params.properties.type = BLE_GAP_ADV_TYPE_CONNECTABLE_SCANNABLE_UNDIRECTED;
    adv_params.p_peer_addr     = NULL;
    adv_params.filter_policy   = BLE_GAP_ADV_FP_ANY;
    adv_params.interval        = APP_ADV_INTERVAL;

    err_code = sd_ble_gap_adv_set_configure(&m_adv_handle, &m_adv_data, &adv_params);
    APP_ERROR_CHECK(err_code);
}

BLE 广播重要函数 sd_ble_advdata_encode

ret_code_t ble_advdata_encode	(	ble_advdata_t const *const	p_advdata,
		uint8_t *const	p_encoded_data,
		uint16_t *const	p_len
	)

Function for encoding data in the Advertising and Scan Response data format (AD structures).

This function encodes data into the Advertising and Scan Response data format (AD structures) based on the fields in the supplied structures. This function can be used to create a payload of Advertising packet or Scan Response packet, or a payload of NFC message intended for initiating the Out-of-Band pairing.

Parameters

[in]	p_advdata	Pointer to the structure for specifying the content of encoded data.
[out]	p_encoded_data	Pointer to the buffer where encoded data will be returned.
[in,out]	p_len	in: Size of p_encoded_data buffer. out: Length of encoded data.

Return values

NRF_SUCCESS	If the operation was successful.
NRF_ERROR_INVALID_PARAM	If the operation failed because a wrong parameter was provided in p_advdata.
NRF_ERROR_DATA_SIZE	If the operation failed because not all the requested data could fit into the provided buffer or some encoded AD structure is too long and its length cannot be encoded with one octet.

Warning

This API may override the application's request to use the long name and use a short name instead. This truncation will occur in case the long name does not fit the provided buffer size. The application can specify a preferred short name length if truncation is required. For example, if the complete device name is ABCD_HRMonitor, the application can specify the short name length to be 8, so that the short device name appears as ABCD_HRM instead of ABCD_HRMo or ABCD_HRMoni if the available size for the short name is 9 or 12 respectively, to have a more appropriate short name. However, it should be noted that this is just a preference that the application can specify, and if the preference is too large to fit in the provided buffer, the name can be truncated further.

BLE 广播重要函数 sd_ble_gap_adv_set_configure

uint32_t sd_ble_gap_adv_set_configure	(	uint8_t *	p_adv_handle,
		ble_gap_adv_data_t const *	p_adv_data,
		ble_gap_adv_params_t const *	p_adv_params
	)

Configure an advertising set. Set, clear or update advertising and scan response data.

Note

The format of the advertising data will be checked by this call to ensure interoperability. Limitations imposed by this API call to the data provided include having a flags data type in the scan response data and duplicating the local name in the advertising data and scan response data.

In order to update advertising data while advertising, new advertising buffers must be provided.

Relevant Message Sequence Charts

Advertising

Whitelist Sharing

Parameters

[in,out]	p_adv_handle	Provide a pointer to a handle containing BLE_GAP_ADV_SET_HANDLE_NOT_SET to configure a new advertising set. On success, a new handle is then returned through the pointer. Provide a pointer to an existing advertising handle to configure an existing advertising set.
[in]	p_adv_data	Advertising data. If set to NULL, no advertising data will be used. See ble_gap_adv_data_t.
[in]	p_adv_params	Advertising parameters. When this function is used to update advertising data while advertising, this parameter must be NULL. See ble_gap_adv_params_t.

Return values

NRF_SUCCESS	Advertising set successfully configured.
NRF_ERROR_INVALID_PARAM	Invalid parameter(s) supplied: Invalid advertising data configuration specified. See ble_gap_adv_data_t. Invalid configuration of p_adv_params. See ble_gap_adv_params_t. Use of whitelist requested but whitelist has not been set, see sd_ble_gap_whitelist_set.
BLE_ERROR_GAP_INVALID_BLE_ADDR	ble_gap_adv_params_t::p_peer_addr is invalid.
NRF_ERROR_INVALID_STATE	Invalid state to perform operation. It is invalid to provide non-NULL advertising set parameters while advertising. It is invalid to provide the same data buffers while advertising. To update advertising data, provide new advertising buffers.
BLE_ERROR_GAP_DISCOVERABLE_WITH_WHITELIST	Discoverable mode and whitelist incompatible.
BLE_ERROR_INVALID_ADV_HANDLE	The provided advertising handle was not found. Use BLE_GAP_ADV_SET_HANDLE_NOT_SET to configure a new advertising handle.
NRF_ERROR_INVALID_ADDR	Invalid pointer supplied.
NRF_ERROR_INVALID_FLAGS	Invalid combination of advertising flags supplied.
NRF_ERROR_INVALID_DATA	Invalid data type(s) supplied. Check the advertising data format specification given in Bluetooth Specification Version 5.0, Volume 3, Part C, Chapter 11.
NRF_ERROR_INVALID_LENGTH	Invalid data length(s) supplied.
NRF_ERROR_NOT_SUPPORTED	Unsupported data length or advertising parameter configuration.
NRF_ERROR_NO_MEM	Not enough memory to configure a new advertising handle. Update an existing advertising handle instead.
BLE_ERROR_GAP_UUID_LIST_MISMATCH	Invalid UUID list supplied.

---

advertising_start()

/**@brief Function for starting advertising.
 */
static void advertising_start(void)
{
    ret_code_t           err_code;

    err_code = sd_ble_gap_adv_start(m_adv_handle, APP_BLE_CONN_CFG_TAG);
    APP_ERROR_CHECK(err_code);
    bsp_board_led_on( ADVERTISING_LED );	
}

BLE 广播重要函数 sd_ble_gap_adv_start

uint32_t sd_ble_gap_adv_start	(	uint8_t	adv_handle,
		uint8_t	conn_cfg_tag
	)

Start advertising (GAP Discoverable, Connectable modes, Broadcast Procedure).

Note

Only one advertiser may be active at any time.

Events generated

BLE_GAP_EVT_CONNECTED	Generated after connection has been established through connectable advertising.
BLE_GAP_EVT_ADV_SET_TERMINATED	Advertising set has terminated.
BLE_GAP_EVT_SCAN_REQ_REPORT	A scan request was received.

Relevant Message Sequence Charts

Advertising

Peripheral Connection Establishment with Private Peer

Directed Advertising

Whitelist Sharing

Parameters

[in]	adv_handle	Advertising handle to advertise on, received from sd_ble_gap_adv_set_configure.
[in]	conn_cfg_tag	Tag identifying a configuration set by sd_ble_cfg_set or BLE_CONN_CFG_TAG_DEFAULT to use the default connection configuration. For non-connectable advertising, this is ignored.

Return values

NRF_SUCCESS	The BLE stack has started advertising.
NRF_ERROR_INVALID_STATE	Invalid state to perform operation. adv_handle is not configured or already advertising.
NRF_ERROR_CONN_COUNT	The limit of available connections has been reached; connectable advertiser cannot be started.
BLE_ERROR_INVALID_ADV_HANDLE	Advertising handle not found. Configure a new adveriting handle with sd_ble_gap_adv_set_configure.
NRF_ERROR_NOT_FOUND	conn_cfg_tag not found.
NRF_ERROR_INVALID_PARAM	Invalid parameter(s) supplied: Invalid configuration of p_adv_params. See ble_gap_adv_params_t. Use of whitelist requested but whitelist has not been set, see sd_ble_gap_whitelist_set.
NRF_ERROR_RESOURCES	Either: adv_handle is configured with connectable advertising, but the event_length parameter associated with conn_cfg_tag is too small to be able to establish a connection on the selected advertising phys. Use sd_ble_cfg_set to increase the event length. Not enough BLE role slots available. Stop one or more currently active roles (Central, Peripheral, Broadcaster or Observer) and try again. p_adv_params is configured with connectable advertising, but the event_length parameter associated with conn_cfg_tag is too small to be able to establish a connection on the selected advertising phys. Use sd_ble_cfg_set to increase the event length.