Peripheral device: Keep advertising during connection

[CY]

Hi ,

The device required to keep advertising during the connection established.

It is human interface device which mean it is peripheral device as well.

I would like to know whether there is any sample I could take as reference for the structure.

Or it is possible to keep the keyboard_sample for development? If yes, which API or function I should integrate?

In further, I would like to know is it possible to proceed connectable advertisement.

Currently, I just understand that is possible to do non-connectable advertisement.

Thanks.

[Jimmy Wong]

HI,

I did the example (https://github.com/jimmywong2003/nrf5-bond-with-2nd-central-example).

You can find the details in the readme (LINK).

It uses 2 peripheral roles on the device.

[CY]

Hi Jimmy,

Thanks for the reply. But it seem a little be different from my requirement.

Based on your program, it seems that it is still need to interrupt the host A then start advertising again to connect with host B. It is pretty much like the multiperipheral_keyboard does.

However, the mechanism I would like to achieve is keep the advertise function during the device is still connecting with the host A.

You can imaging that it is a keyboard with beacon service.

Thanks.

[Sigurd]

Take a look at the ble_app_multiperipheral example. It will continue to advertise also after connecting to the first central.

[CY]

Hi Sigurd, 

May I know could it support connectable advertisement? I know it might interrupt the connection with first central.

So the next question is "Is it possible to connect with 2 centrals at the same time?"

(The development is based on SDK15.2)

Thanks.

[Sigurd]

CY said:

May I know could it support connectable advertisement?

 Yes, that is supported. You can have 20 concurrent connections.

CY said:

So the next question is "Is it possible to connect with 2 centrals at the same time?"

Yes, you do connectable advertising and device #1 connects. After device #1 connects, you start connectable advertising again, and device #2 connects.

[CY]

Hi Sigurd,

I have viewed the sample and found that it doesn't use peer manager.

However, the peer manager, whitelist and bond are used in keyboard sample.

Thus, I would like to know if I remove the function will it cause any effect to the HID service?

Besides that, I also found out the structure of advertising_init (on_adv_evt) and advertising_start is different from keyboard and multi-peripheral sample.

Could you give me some guide, which parts are necessary to add in the keyboard sample to support multi-peripheral sample?

Thanks.

[CY]

Is it possible to proceed the different service for each host? 

For instance, run HID service with host A and run HRS service with host B at the same time?

[Sigurd]

CY said:

Thus, I would like to know if I remove the function will it cause any effect to the HID service?

 You should keep the Peer Manager if you are developing a HID keyboard.

CY said:

Could you give me some guide, which parts are necessary to add in the keyboard sample to support multi-peripheral sample?

I don't have a guide for this, but start by setting NRF_SDH_BLE_PERIPHERAL_LINK_COUNT and NRF_SDH_BLE_TOTAL_LINK_COUNT in sdk_config.h to 2. You should then replace:

NRF_BLE_QWR_DEF(m_qwr);                                             /**< Context for the Queued Write module.*/

with

NRF_BLE_QWRS_DEF(m_qwr, NRF_SDH_BLE_TOTAL_LINK_COUNT);                          /**< Context for the Queued Write module.*/

 in qwr_init(), replace

err_code = nrf_ble_qwr_init(&m_qwr, &qwr_init_obj);

with

    for (uint32_t i = 0; i < NRF_SDH_BLE_TOTAL_LINK_COUNT; i++)
    {
        err_code = nrf_ble_qwr_init(&m_qwr[i], &qwr_init_obj);
        APP_ERROR_CHECK(err_code);
    }

Add the ble_conn_state Connection state module, and call 

ble_conn_state_init(); in your service init code.

Add the on_connected() and on_disconnected() functions found in  ble_app_multiperipheral to your keyboard project.

CY said:

For instance, run HID service with host A and run HRS service with host B at the same time?

Yes, it's possible. But note that the service attribute table is shared, so a master/central has potentially access to both services.

[CY]

Hi Sigurd,

After I trying to implant the program into my main.c as below code.

#define HID_MULT 1

#define DEVICE_NAME                         "HID_MULTI"                                 /**< Name of device. Will be included in the advertising data. */
#define MANUFACTURER_NAME                   "CY"                               /**< Manufacturer. Will be passed to Device Information Service. */

#define APP_BLE_OBSERVER_PRIO               3                                          /**< Application's BLE observer priority. You shouldn't need to modify this value. */
#define APP_BLE_CONN_CFG_TAG                1                                          /**< A tag identifying the SoftDevice BLE configuration. */

#define BATTERY_LEVEL_MEAS_INTERVAL         APP_TIMER_TICKS(2000)                      /**< Battery level measurement interval (ticks). */
#define MIN_BATTERY_LEVEL                   5                                          /**< Minimum simulated battery level.*/
#define MAX_BATTERY_LEVEL                   100                                        /**< Maximum simulated battery level. */
#define BATTERY_LEVEL_INCREMENT             5                                          /**< Increment between each simulated battery level measurement. */

#define PNP_ID_VENDOR_ID_SOURCE             0x02                                       /**< Vendor ID Source. */
#define PNP_ID_VENDOR_ID                    0x413C			                               /**< Vendor ID. */
#define PNP_ID_PRODUCT_ID                   0x81D5 						                         /**< Product ID.*/
#define PNP_ID_PRODUCT_VERSION              0x0001                                     /**< Product Version. */


#define APP_ADV_FAST_INTERVAL               0x0028                                     /**< Fast advertising interval (in units of 0.625 ms. This value corresponds to 25 ms.). */
#define APP_ADV_SLOW_INTERVAL               0x00A0                                     /**< Slow advertising interval (in units of 0.625 ms. This value corrsponds to 100 ms). */

#define APP_ADV_FAST_DURATION               0                                     		 /**< The advertising duration of fast advertising in units of 10 milliseconds. */
#define APP_ADV_SLOW_DURATION               18000                                      /**< The advertising duration of slow advertising in units of 10 milliseconds. */


/*lint -emacro(524, MIN_CONN_INTERVAL) // Loss of precision */
#define MIN_CONN_INTERVAL                   MSEC_TO_UNITS(7.5, UNIT_1_25_MS)           /**< Minimum connection interval (7.5 ms) */
#define MAX_CONN_INTERVAL                   MSEC_TO_UNITS(15, UNIT_1_25_MS)            /**< Maximum connection interval (15 ms). */
#define SLAVE_LATENCY                       20                                          /**< Slave latency. */
#define CONN_SUP_TIMEOUT                    MSEC_TO_UNITS(3000, UNIT_10_MS)             /**< Connection supervisory timeout (3000 ms). */

#define FIRST_CONN_PARAMS_UPDATE_DELAY      APP_TIMER_TICKS(5000)                      /**< Time from initiating event (connect or start of notification) to first time sd_ble_gap_conn_param_update is called (5 seconds). */
#define NEXT_CONN_PARAMS_UPDATE_DELAY       APP_TIMER_TICKS(30000)                     /**< Time between each call to sd_ble_gap_conn_param_update after the first call (30 seconds). */
#define MAX_CONN_PARAMS_UPDATE_COUNT        3                                          /**< Number of attempts before giving up the connection parameter negotiation. */

#define SEC_PARAM_BOND                      1                                          /**< Perform bonding. */
#define SEC_PARAM_MITM                      0                                          /**< Man In The Middle protection not required. */
#define SEC_PARAM_LESC                      0                                          /**< LE Secure Connections not enabled. */
#define SEC_PARAM_KEYPRESS                  0                                          /**< Keypress notifications not enabled. */
#define SEC_PARAM_IO_CAPABILITIES           BLE_GAP_IO_CAPS_NONE                       /**< No I/O capabilities. */
#define SEC_PARAM_OOB                       0                                          /**< Out Of Band data not available. */
#define SEC_PARAM_MIN_KEY_SIZE              7                                          /**< Minimum encryption key size. */
#define SEC_PARAM_MAX_KEY_SIZE              16                                         /**< Maximum encryption key size. */


#define OUTPUT_REPORT_INDEX                 0                                          /**< Index of Output Report. */
#define OUTPUT_REPORT_MAX_LEN               1                                          /**< Maximum length of Output Report. */
#define INPUT_REPORT_KEYS_INDEX             0                                          /**< Index of Input Report. */
#define OUTPUT_REPORT_BIT_MASK_CAPS_LOCK    0x02                                       /**< CAPS LOCK bit in Output Report (based on 'LED Page (0x08)' of the Universal Serial Bus HID Usage Tables). */
#define INPUT_REP_REF_ID                    0                                          /**< Id of reference to Keyboard Input Report. */
#define OUTPUT_REP_REF_ID                   0                                          /**< Id of reference to Keyboard Output Report. */
#define FEATURE_REP_REF_ID                  0                                          /**< ID of reference to Keyboard Feature Report. */
#define FEATURE_REPORT_MAX_LEN              2                                          /**< Maximum length of Feature Report. */
#define FEATURE_REPORT_INDEX                0                                          /**< Index of Feature Report. */

#define MAX_BUFFER_ENTRIES                  5                                          /**< Number of elements that can be enqueued */

#define BASE_USB_HID_SPEC_VERSION           0x0101                                     /**< Version number of base USB HID Specification implemented by this application. */

#define INPUT_REPORT_KEYS_MAX_LEN           8                                          /**< Maximum length of the Input Report characteristic. */
#define DEAD_BEEF                           0xDEADBEEF                                 /**< Value used as error code on stack dump, can be used to identify stack location on stack unwind. */

#define SCHED_MAX_EVENT_DATA_SIZE           APP_TIMER_SCHED_EVENT_DATA_SIZE            /**< Maximum size of scheduler events. */
#ifdef SVCALL_AS_NORMAL_FUNCTION
#define SCHED_QUEUE_SIZE                    20                                         /**< Maximum number of events in the scheduler queue. More is needed in case of Serialization. */
#else
#define SCHED_QUEUE_SIZE                    10                                         /**< Maximum number of events in the scheduler queue. */
#endif


#define MODIFIER_KEY_POS                    0                                          /**< Position of the modifier byte in the Input Report. */
#define SCAN_CODE_POS                       2                                          /**< The start position of the key scan code in a HID Report. */
#define MAX_KEYS_IN_ONE_REPORT              (INPUT_REPORT_KEYS_MAX_LEN - SCAN_CODE_POS)/**< Maximum number of key presses that can be sent in one Input Report. */

// General application timer settings.
#define APP_TIMER_PRESCALER             16    // RTC PRESCALER register value.
#define APP_TIMER_OP_QUEUE_SIZE         2     // Size of timer operation queues.

#define UART_TX_BUF_SIZE                256                                         /**< UART TX buffer size. */
#define UART_RX_BUF_SIZE                256                                         /**< UART RX buffer size. */

/**Buffer queue access macros
 *
 * @{ */
/** Initialization of buffer list */
#define BUFFER_LIST_INIT()     \
    do                         \
    {                          \
        buffer_list.rp    = 0; \
        buffer_list.wp    = 0; \
        buffer_list.count = 0; \
    } while (0)

/** Provide status of data list is full or not */
#define BUFFER_LIST_FULL() \
    ((MAX_BUFFER_ENTRIES == buffer_list.count - 1) ? true : false)

/** Provides status of buffer list is empty or not */
#define BUFFER_LIST_EMPTY() \
    ((0 == buffer_list.count) ? true : false)

#define BUFFER_ELEMENT_INIT(i)                 \
    do                                         \
    {                                          \
        buffer_list.buffer[(i)].p_data = NULL; \
    } while (0)

/** @} */

/** Abstracts buffer element */
typedef struct hid_key_buffer
{
    uint8_t      data_offset; /**< Max Data that can be buffered for all entries */
    uint8_t      data_len;    /**< Total length of data */
    uint8_t    * p_data;      /**< Scanned key pattern */
    ble_hids_t * p_instance;  /**< Identifies peer and service instance */
} buffer_entry_t;

STATIC_ASSERT(sizeof(buffer_entry_t) % 4 == 0);

/** Circular buffer list */
typedef struct
{
    buffer_entry_t buffer[MAX_BUFFER_ENTRIES]; /**< Maximum number of entries that can enqueued in the list */
    uint8_t        rp;                         /**< Index to the read location */
    uint8_t        wp;                         /**< Index to write location */
    uint8_t        count;                      /**< Number of elements in the list */
} buffer_list_t;

STATIC_ASSERT(sizeof(buffer_list_t) % 4 == 0);


APP_TIMER_DEF(m_battery_timer_id);                                  /**< Battery timer. */

BLE_HIDS_DEF(m_hids,                                                /**< Structure used to identify the HID service. */
             NRF_SDH_BLE_TOTAL_LINK_COUNT,
             INPUT_REPORT_KEYS_MAX_LEN,
             OUTPUT_REPORT_MAX_LEN,
             FEATURE_REPORT_MAX_LEN);
BLE_BAS_DEF(m_bas);                                                 /**< Structure used to identify the battery service. */
NRF_BLE_GATT_DEF(m_gatt);                                           /**< GATT module instance. */

#if HID_MULT == 0
NRF_BLE_QWR_DEF(m_qwr);                                             /**< Context for the Queued Write module.*/
#else
NRF_BLE_QWRS_DEF(m_qwr, NRF_SDH_BLE_TOTAL_LINK_COUNT);
static uint8_t m_adv_handle = BLE_GAP_ADV_SET_HANDLE_NOT_SET;
#endif
BLE_ADVERTISING_DEF(m_advertising);                                 /**< Advertising module instance. */
APP_TIMER_DEF(m_button_action);																			/**<press button event.  */

static bool              m_in_boot_mode = false;                    /**< Current protocol mode. */
static uint16_t          m_conn_handle  = BLE_CONN_HANDLE_INVALID;  /**< Handle of the current connection. */
static sensorsim_cfg_t   m_battery_sim_cfg;                         /**< Battery Level sensor simulator configuration. */
static sensorsim_state_t m_battery_sim_state;                       /**< Battery Level sensor simulator state. */
static pm_peer_id_t      m_peer_id;                                 /**< Device reference handle to the current bonded central. */
static buffer_list_t     buffer_list;                               /**< List to enqueue not just data to be sent, but also related information like the handle, connection handle etc */

static ble_uuid_t m_adv_uuids[] = {
																		{BLE_UUID_HUMAN_INTERFACE_DEVICE_SERVICE, BLE_UUID_TYPE_BLE},
																	};



static void on_hids_evt(ble_hids_t * p_hids, ble_hids_evt_t * p_evt);

/**@brief Callback function for asserts in the SoftDevice.
 *
 * @details This function will be called in case of an assert in the SoftDevice.
 *
 * @warning This handler is an example only and does not fit a final product. You need to analyze
 *          how your product is supposed to react in case of Assert.
 * @warning On assert from the SoftDevice, the system can only recover on reset.
 *
 * @param[in]   line_num   Line number of the failing ASSERT call.
 * @param[in]   file_name  File name of the failing ASSERT call.
 */
void assert_nrf_callback(uint16_t line_num, const uint8_t * p_file_name)
{
    app_error_handler(DEAD_BEEF, line_num, p_file_name);
}


/**@brief Function for setting filtered whitelist.
 *
 * @param[in] skip  Filter passed to @ref pm_peer_id_list.
 */
static void whitelist_set(pm_peer_id_list_skip_t skip)
{
    pm_peer_id_t peer_ids[BLE_GAP_WHITELIST_ADDR_MAX_COUNT];
    uint32_t     peer_id_count = BLE_GAP_WHITELIST_ADDR_MAX_COUNT;

    ret_code_t err_code = pm_peer_id_list(peer_ids, &peer_id_count, PM_PEER_ID_INVALID, skip);
    APP_ERROR_CHECK(err_code);

    NRF_LOG_INFO("\tm_whitelist_peer_cnt %d, MAX_PEERS_WLIST %d",
                   peer_id_count + 1,
                   BLE_GAP_WHITELIST_ADDR_MAX_COUNT);

    err_code = pm_whitelist_set(peer_ids, peer_id_count);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for setting filtered device identities.
 *
 * @param[in] skip  Filter passed to @ref pm_peer_id_list.
 */
static void identities_set(pm_peer_id_list_skip_t skip)
{
    pm_peer_id_t peer_ids[BLE_GAP_DEVICE_IDENTITIES_MAX_COUNT];
    uint32_t     peer_id_count = BLE_GAP_DEVICE_IDENTITIES_MAX_COUNT;

    ret_code_t err_code = pm_peer_id_list(peer_ids, &peer_id_count, PM_PEER_ID_INVALID, skip);
    APP_ERROR_CHECK(err_code);

    err_code = pm_device_identities_list_set(peer_ids, peer_id_count);
    APP_ERROR_CHECK(err_code);
}


/**@brief Clear bond information from persistent storage.
 */
static void delete_bonds(void)
{
    ret_code_t err_code;

    NRF_LOG_INFO("Erase bonds!");

    err_code = pm_peers_delete();
    APP_ERROR_CHECK(err_code);
}



/**@brief Function for starting advertising.
 */
static void advertising_start(bool erase_bonds)
{
    if (erase_bonds == true)
    {
        delete_bonds();
        // Advertising is started by PM_EVT_PEERS_DELETE_SUCCEEDED event.
    }
    else
    {
        whitelist_set(PM_PEER_ID_LIST_SKIP_NO_ID_ADDR);

        ret_code_t ret = ble_advertising_start(&m_advertising, BLE_ADV_MODE_FAST);
        APP_ERROR_CHECK(ret);
    }
}


/**@brief Function for handling Peer Manager events.
 *
 * @param[in] p_evt  Peer Manager event.
 */
static void pm_evt_handler(pm_evt_t const * p_evt)
{
    pm_handler_on_pm_evt(p_evt);
    pm_handler_flash_clean(p_evt);

    switch (p_evt->evt_id)
    {
        case PM_EVT_PEERS_DELETE_SUCCEEDED:
            advertising_start(false);
            break;

        case PM_EVT_PEER_DATA_UPDATE_SUCCEEDED:
            if (     p_evt->params.peer_data_update_succeeded.flash_changed
                 && (p_evt->params.peer_data_update_succeeded.data_id == PM_PEER_DATA_ID_BONDING))
            {
                NRF_LOG_INFO("New Bond, add the peer to the whitelist if possible");
                // Note: You should check on what kind of white list policy your application should use.

                whitelist_set(PM_PEER_ID_LIST_SKIP_NO_ID_ADDR);
            }
            break;

        default:
            break;
    }
}


/**@brief Function for handling Service errors.
 *
 * @details A pointer to this function will be passed to each service which may need to inform the
 *          application about an error.
 *
 * @param[in]   nrf_error   Error code containing information about what went wrong.
 */
static void service_error_handler(uint32_t nrf_error)
{
    APP_ERROR_HANDLER(nrf_error);
}


/**@brief Function for handling advertising errors.
 *
 * @param[in] nrf_error  Error code containing information about what went wrong.
 */
static void ble_advertising_error_handler(uint32_t nrf_error)
{
    APP_ERROR_HANDLER(nrf_error);
}


/**@brief Function for performing a battery measurement, and update the Battery Level characteristic in the Battery Service.
 */
static void battery_level_update(void)
{
    ret_code_t err_code;
    uint8_t  battery_level;

    battery_level = (uint8_t)sensorsim_measure(&m_battery_sim_state, &m_battery_sim_cfg);

    err_code = ble_bas_battery_level_update(&m_bas, battery_level, BLE_CONN_HANDLE_ALL);
    if ((err_code != NRF_SUCCESS) &&
        (err_code != NRF_ERROR_BUSY) &&
        (err_code != NRF_ERROR_RESOURCES) &&
        (err_code != NRF_ERROR_FORBIDDEN) &&
        (err_code != NRF_ERROR_INVALID_STATE) &&
        (err_code != BLE_ERROR_GATTS_SYS_ATTR_MISSING)
       )
    {
        APP_ERROR_HANDLER(err_code);
    }
}


/**@brief Function for handling the Battery measurement timer timeout.
 *
 * @details This function will be called each time the battery level measurement timer expires.
 *
 * @param[in]   p_context   Pointer used for passing some arbitrary information (context) from the
 *                          app_start_timer() call to the timeout handler.
 */
static void battery_level_meas_timeout_handler(void * p_context)
{
    UNUSED_PARAMETER(p_context);
    battery_level_update();
}




/**@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);

    err_code = sd_ble_gap_appearance_set(BLE_APPEARANCE_HID_KEYBOARD); 
    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);
}


/**@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);
}


/**@brief Function for handling Queued Write Module errors.
 *
 * @details A pointer to this function will be passed to each service which may need to inform the
 *          application about an error.
 *
 * @param[in]   nrf_error   Error code containing information about what went wrong.
 */
static void nrf_qwr_error_handler(uint32_t nrf_error)
{
    APP_ERROR_HANDLER(nrf_error);
}


/**@brief Function for initializing the Queued Write Module.
 */
static void qwr_init(void)
{
    ret_code_t         err_code;
    nrf_ble_qwr_init_t qwr_init_obj = {0};

    qwr_init_obj.error_handler = nrf_qwr_error_handler;
		
	#if HID_MULT ==0
    err_code = nrf_ble_qwr_init(&m_qwr, &qwr_init_obj);
    APP_ERROR_CHECK(err_code);
	#else
    for (uint32_t i = 0; i < NRF_SDH_BLE_TOTAL_LINK_COUNT; i++)
    {
        err_code = nrf_ble_qwr_init(&m_qwr[i], &qwr_init_obj);
        APP_ERROR_CHECK(err_code);
    }
	#endif
}


/**@brief Function for initializing Device Information Service.
 */
static void dis_init(void)
{
    ret_code_t       err_code;
    ble_dis_init_t   dis_init_obj;
    ble_dis_pnp_id_t pnp_id;

    pnp_id.vendor_id_source = PNP_ID_VENDOR_ID_SOURCE;
    pnp_id.vendor_id        = PNP_ID_VENDOR_ID;
    pnp_id.product_id       = PNP_ID_PRODUCT_ID;
    pnp_id.product_version  = PNP_ID_PRODUCT_VERSION;

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

    ble_srv_ascii_to_utf8(&dis_init_obj.manufact_name_str, MANUFACTURER_NAME);
    dis_init_obj.p_pnp_id = &pnp_id;

    dis_init_obj.dis_char_rd_sec = SEC_OPEN;

    err_code = ble_dis_init(&dis_init_obj);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for initializing Battery Service.
 */
static void bas_init(void)
{
    ret_code_t     err_code;
    ble_bas_init_t bas_init_obj;

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

    bas_init_obj.evt_handler          = NULL;
    bas_init_obj.support_notification = true;
    bas_init_obj.p_report_ref         = NULL;
    bas_init_obj.initial_batt_level   = 100;

    bas_init_obj.bl_rd_sec        = SEC_OPEN;
    bas_init_obj.bl_cccd_wr_sec   = SEC_OPEN;
    bas_init_obj.bl_report_rd_sec = SEC_OPEN;

    err_code = ble_bas_init(&m_bas, &bas_init_obj);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for initializing HID Service.
 */
static void hids_init(void)
{
    ret_code_t                    err_code;
    ble_hids_init_t               hids_init_obj;
    ble_hids_inp_rep_init_t     * p_input_report;
    ble_hids_outp_rep_init_t    * p_output_report;
    ble_hids_feature_rep_init_t * p_feature_report;
    uint8_t                       hid_info_flags;

    static ble_hids_inp_rep_init_t     input_report_array[1];
    static ble_hids_outp_rep_init_t    output_report_array[1];
    static ble_hids_feature_rep_init_t feature_report_array[1];
    static uint8_t                     report_map_data[] =
    {
        0x05, 0x01,       // Usage Page (Generic Desktop)
        0x09, 0x06,       // Usage (Keyboard)
        0xA1, 0x01,       // Collection (Application)

		0x05, 0x07,       // Usage Page (Key Codes)
        0x19, 0xe0,       // Usage Minimum (224)
        0x29, 0xe7,       // Usage Maximum (231)
        0x15, 0x00,       // Logical Minimum (0)
        0x25, 0x01,       // Logical Maximum (1)
        0x75, 0x01,       // Report Size (1)
        0x95, 0x08,       // Report Count (8)
        0x81, 0x02,       // Input (Data, Variable, Absolute)

        0x95, 0x01,       // Report Count (1)
        0x75, 0x08,       // Report Size (8)
        0x81, 0x01,       // Input (Constant) reserved byte(1)

        0x95, 0x05,       // Report Count (5)
        0x75, 0x01,       // Report Size (1)
        0x05, 0x08,       // Usage Page (Page# for LEDs)
        0x19, 0x01,       // Usage Minimum (1)
        0x29, 0x05,       // Usage Maximum (5)
        0x91, 0x02,       // Output (Data, Variable, Absolute), Led report
        0x95, 0x01,       // Report Count (1)
        0x75, 0x03,       // Report Size (3)
        0x91, 0x01,       // Output (Data, Variable, Absolute), Led report padding

        0x95, 0x06,       // Report Count (6)
        0x75, 0x08,       // Report Size (8)
        0x15, 0x00,       // Logical Minimum (0)
        
        0x25, 0x65,       // Logical Maximum (101)
        
        0x05, 0x07,       // Usage Page (Key codes)
        0x19, 0x00,       // Usage Minimum (0)
        
        0x29, 0x65,       // Usage Maximum (101)

        
        0x81, 0x00,       // Input (Data, Array) Key array(6 bytes)

        0x09, 0x05,       // Usage (Vendor Defined)
        0x15, 0x00,       // Logical Minimum (0)
        0x26, 0xFF, 0x00, // Logical Maximum (255)
        0x75, 0x08,       // Report Size (8 bit)
        0x95, 0x02,       // Report Count (2)
        0xB1, 0x02,       // Feature (Data, Variable, Absolute)

        0xC0,              // End Collection (Application)
};

    memset((void *)input_report_array, 0, sizeof(ble_hids_inp_rep_init_t));
    memset((void *)output_report_array, 0, sizeof(ble_hids_outp_rep_init_t));
    memset((void *)feature_report_array, 0, sizeof(ble_hids_feature_rep_init_t));

    // Initialize HID Service
    p_input_report                      = &input_report_array[INPUT_REPORT_KEYS_INDEX];
    p_input_report->max_len             = INPUT_REPORT_KEYS_MAX_LEN;
    p_input_report->rep_ref.report_id   = INPUT_REP_REF_ID;
    p_input_report->rep_ref.report_type = BLE_HIDS_REP_TYPE_INPUT;


    p_input_report->sec.cccd_wr = SEC_OPEN;
    p_input_report->sec.wr      = SEC_OPEN;
    p_input_report->sec.rd      = SEC_OPEN;

    p_output_report                      = &output_report_array[OUTPUT_REPORT_INDEX];
    p_output_report->max_len             = OUTPUT_REPORT_MAX_LEN;
    p_output_report->rep_ref.report_id   = OUTPUT_REP_REF_ID;
    p_output_report->rep_ref.report_type = BLE_HIDS_REP_TYPE_OUTPUT;

    p_output_report->sec.wr = SEC_OPEN;
    p_output_report->sec.rd = SEC_OPEN;

    p_feature_report                      = &feature_report_array[FEATURE_REPORT_INDEX];
    p_feature_report->max_len             = FEATURE_REPORT_MAX_LEN;
    p_feature_report->rep_ref.report_id   = FEATURE_REP_REF_ID;
    p_feature_report->rep_ref.report_type = BLE_HIDS_REP_TYPE_FEATURE;

    p_feature_report->sec.rd              = SEC_OPEN;
    p_feature_report->sec.wr              = SEC_OPEN;

    hid_info_flags = HID_INFO_FLAG_REMOTE_WAKE_MSK | HID_INFO_FLAG_NORMALLY_CONNECTABLE_MSK;

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

    hids_init_obj.evt_handler                    = on_hids_evt;
    hids_init_obj.error_handler                  = service_error_handler;
    hids_init_obj.is_kb                          = true;
    hids_init_obj.is_mouse                       = false;
	hids_init_obj.inp_rep_count                  = 1;

    hids_init_obj.p_inp_rep_array                = input_report_array;
    hids_init_obj.outp_rep_count                 = 1;
    hids_init_obj.p_outp_rep_array               = output_report_array;
    hids_init_obj.feature_rep_count              = 1;
    hids_init_obj.p_feature_rep_array            = feature_report_array;
    hids_init_obj.rep_map.data_len               = sizeof(report_map_data);
    hids_init_obj.rep_map.p_data                 = report_map_data;
    hids_init_obj.hid_information.bcd_hid        = BASE_USB_HID_SPEC_VERSION;
    hids_init_obj.hid_information.b_country_code = 0;
    hids_init_obj.hid_information.flags          = hid_info_flags;
    hids_init_obj.included_services_count        = 0;
    hids_init_obj.p_included_services_array      = NULL;

    hids_init_obj.rep_map.rd_sec         = SEC_OPEN;
    hids_init_obj.hid_information.rd_sec = SEC_OPEN;

    hids_init_obj.boot_kb_inp_rep_sec.cccd_wr = SEC_OPEN;
    hids_init_obj.boot_kb_inp_rep_sec.rd      = SEC_OPEN;

    hids_init_obj.boot_kb_outp_rep_sec.rd = SEC_OPEN;
    hids_init_obj.boot_kb_outp_rep_sec.wr = SEC_OPEN;

    hids_init_obj.protocol_mode_rd_sec = SEC_OPEN;
    hids_init_obj.protocol_mode_wr_sec = SEC_OPEN;
    hids_init_obj.ctrl_point_wr_sec    = SEC_OPEN;

    err_code = ble_hids_init(&m_hids, &hids_init_obj);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for initializing services that will be used by the application.
 */
static void services_init(void)
{
    qwr_init();
    dis_init();
    bas_init();
    hids_init();
	
	#if HID_MULT==1
	ble_conn_state_init();
	#endif
	
}

static void on_conn_params_evt(ble_conn_params_evt_t * p_evt)
{
    uint32_t err_code;

    if (p_evt->evt_type == BLE_CONN_PARAMS_EVT_FAILED)
    {
        err_code = sd_ble_gap_disconnect(m_conn_handle, BLE_HCI_CONN_INTERVAL_UNACCEPTABLE);
        APP_ERROR_CHECK(err_code);
    }
}

/**@brief Function for initializing the battery sensor simulator.
 */
static void sensor_simulator_init(void)
{
    m_battery_sim_cfg.min          = MIN_BATTERY_LEVEL;
    m_battery_sim_cfg.max          = MAX_BATTERY_LEVEL;
    m_battery_sim_cfg.incr         = BATTERY_LEVEL_INCREMENT;
    m_battery_sim_cfg.start_at_max = true;

    sensorsim_init(&m_battery_sim_state, &m_battery_sim_cfg);
}

/**@brief Function for handling a Connection Parameters error.
 *
 * @param[in]   nrf_error   Error code containing information about what went wrong.
 */
static void conn_params_error_handler(uint32_t nrf_error)
{
    APP_ERROR_HANDLER(nrf_error);
}


/**@brief Function for initializing the Connection Parameters module.
 */
static void conn_params_init(void)
{
    ret_code_t             err_code;
    ble_conn_params_init_t cp_init;

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

    cp_init.p_conn_params                  = NULL;
    cp_init.first_conn_params_update_delay = FIRST_CONN_PARAMS_UPDATE_DELAY;
    cp_init.next_conn_params_update_delay  = NEXT_CONN_PARAMS_UPDATE_DELAY;
    cp_init.max_conn_params_update_count   = MAX_CONN_PARAMS_UPDATE_COUNT;
    cp_init.start_on_notify_cccd_handle    = BLE_GATT_HANDLE_INVALID;
    #if HID_MULT==1
    cp_init.disconnect_on_fail             = true;
    cp_init.evt_handler                    = on_conn_params_evt;
    #else
    cp_init.disconnect_on_fail             = false;
    cp_init.evt_handler                    = NULL;
    #endif
    cp_init.error_handler                  = conn_params_error_handler;

    err_code = ble_conn_params_init(&cp_init);
    APP_ERROR_CHECK(err_code);
}


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

    err_code = app_timer_start(m_battery_timer_id, BATTERY_LEVEL_MEAS_INTERVAL, NULL);
    APP_ERROR_CHECK(err_code);
}


/**@brief   Function for transmitting a key scan Press & Release Notification.
 *
 * @warning This handler is an example only. You need to analyze how you wish to send the key
 *          release.
 *
 * @param[in]  p_instance     Identifies the service for which Key Notifications are requested.
 * @param[in]  p_key_pattern  Pointer to key pattern.
 * @param[in]  pattern_len    Length of key pattern. 0 < pattern_len < 7.
 * @param[in]  pattern_offset Offset applied to Key Pattern for transmission.
 * @param[out] actual_len     Provides actual length of Key Pattern transmitted, making buffering of
 *                            rest possible if needed.
 * @return     NRF_SUCCESS on success, NRF_ERROR_RESOURCES in case transmission could not be
 *             completed due to lack of transmission buffer or other error codes indicating reason
 *             for failure.
 */
static uint32_t send_key_scan_press_release(ble_hids_t * p_hids,
                                            uint8_t    * p_key_pattern,
                                            uint16_t     pattern_len,
                                            uint16_t     pattern_offset,
                                            uint16_t   * p_actual_len)
{
    ret_code_t err_code;
    uint16_t offset;
    uint16_t data_len;
    uint8_t  data[INPUT_REPORT_KEYS_MAX_LEN];

    // HID Report Descriptor enumerates an array of size 6, the pattern hence shall not be any
    // longer than this.
    STATIC_ASSERT((INPUT_REPORT_KEYS_MAX_LEN - 2) == 6);

    ASSERT(pattern_len <= (INPUT_REPORT_KEYS_MAX_LEN - 2));

    offset   = pattern_offset;
    data_len = pattern_len;

    do
    {
        // Reset the data buffer.
        memset(data, 0, sizeof(data));

        // Copy the scan code.
        memcpy(data + SCAN_CODE_POS + offset, p_key_pattern + offset, data_len - offset);

        if (!m_in_boot_mode)
        {
            err_code = ble_hids_inp_rep_send(p_hids,
                                             INPUT_REPORT_KEYS_INDEX,
                                             INPUT_REPORT_KEYS_MAX_LEN,
                                             data,
                                             m_conn_handle);
        }
        else
        {
            err_code = ble_hids_boot_kb_inp_rep_send(p_hids,
                                                     INPUT_REPORT_KEYS_MAX_LEN,
                                                     data,
                                                     m_conn_handle);
        }

        if (err_code != NRF_SUCCESS)
        {
            break;
        }

        offset++;
    }
    while (offset <= data_len);

    *p_actual_len = offset;

    return err_code;
}


/**@brief   Function for initializing the buffer queue used to key events that could not be
 *          transmitted
 *
 * @warning This handler is an example only. You need to analyze how you wish to buffer or buffer at
 *          all.
 *
 * @note    In case of HID keyboard, a temporary buffering could be employed to handle scenarios
 *          where encryption is not yet enabled or there was a momentary link loss or there were no
 *          Transmit buffers.
 */
static void buffer_init(void)
{
    uint32_t buffer_count;

    BUFFER_LIST_INIT();

    for (buffer_count = 0; buffer_count < MAX_BUFFER_ENTRIES; buffer_count++)
    {
        BUFFER_ELEMENT_INIT(buffer_count);
    }
}


/**@brief Function for enqueuing key scan patterns that could not be transmitted either completely
 *        or partially.
 *
 * @warning This handler is an example only. You need to analyze how you wish to send the key
 *          release.
 *
 * @param[in]  p_hids         Identifies the service for which Key Notifications are buffered.
 * @param[in]  p_key_pattern  Pointer to key pattern.
 * @param[in]  pattern_len    Length of key pattern.
 * @param[in]  offset         Offset applied to Key Pattern when requesting a transmission on
 *                            dequeue, @ref buffer_dequeue.
 * @return     NRF_SUCCESS on success, else an error code indicating reason for failure.
 */
static uint32_t buffer_enqueue(ble_hids_t * p_hids,
                               uint8_t    * p_key_pattern,
                               uint16_t     pattern_len,
                               uint16_t     offset)
{
    buffer_entry_t * element;
    uint32_t         err_code = NRF_SUCCESS;

    if (BUFFER_LIST_FULL())
    {
        // Element cannot be buffered.
        err_code = NRF_ERROR_NO_MEM;
    }
    else
    {
        // Make entry of buffer element and copy data.
        element              = &buffer_list.buffer[(buffer_list.wp)];
        element->p_instance  = p_hids;
        element->p_data      = p_key_pattern;
        element->data_offset = offset;
        element->data_len    = pattern_len;

        buffer_list.count++;
        buffer_list.wp++;

        if (buffer_list.wp == MAX_BUFFER_ENTRIES)
        {
            buffer_list.wp = 0;
        }
    }

    return err_code;
}


/**@brief   Function to dequeue key scan patterns that could not be transmitted either completely of
 *          partially.
 *
 * @warning This handler is an example only. You need to analyze how you wish to send the key
 *          release.
 *
 * @param[in]  tx_flag   Indicative of whether the dequeue should result in transmission or not.
 * @note       A typical example when all keys are dequeued with transmission is when link is
 *             disconnected.
 *
 * @return     NRF_SUCCESS on success, else an error code indicating reason for failure.
 */
static uint32_t buffer_dequeue(bool tx_flag)
{
    buffer_entry_t * p_element;
    uint32_t         err_code = NRF_SUCCESS;
    uint16_t         actual_len;

    if (BUFFER_LIST_EMPTY())
    {
        err_code = NRF_ERROR_NOT_FOUND;
    }
    else
    {
        bool remove_element = true;

        p_element = &buffer_list.buffer[(buffer_list.rp)];

        if (tx_flag)
        {
            err_code = send_key_scan_press_release(p_element->p_instance,
                                                   p_element->p_data,
                                                   p_element->data_len,
                                                   p_element->data_offset,
                                                   &actual_len);
            // An additional notification is needed for release of all keys, therefore check
            // is for actual_len <= element->data_len and not actual_len < element->data_len
            if ((err_code == NRF_ERROR_RESOURCES) && (actual_len <= p_element->data_len))
            {
                // Transmission could not be completed, do not remove the entry, adjust next data to
                // be transmitted
                p_element->data_offset = actual_len;
                remove_element         = false;
            }
        }

        if (remove_element)
        {
            BUFFER_ELEMENT_INIT(buffer_list.rp);

            buffer_list.rp++;
            buffer_list.count--;

            if (buffer_list.rp == MAX_BUFFER_ENTRIES)
            {
                buffer_list.rp = 0;
            }
        }
    }

    return err_code;
}


/**@brief Function for sending sample key presses to the peer.
 *
 * @param[in]   key_pattern_len   Pattern length.
 * @param[in]   p_key_pattern     Pattern to be sent.
 */
static void keys_send(uint8_t key_pattern_len, uint8_t * p_key_pattern)
{
    ret_code_t err_code;
    uint16_t actual_len;

    err_code = send_key_scan_press_release(&m_hids,
                                           p_key_pattern,
                                           key_pattern_len,
                                           0,
                                           &actual_len);
    // An additional notification is needed for release of all keys, therefore check
    // is for actual_len <= key_pattern_len and not actual_len < key_pattern_len.
    if ((err_code == NRF_ERROR_RESOURCES) && (actual_len <= key_pattern_len))
    {
        // Buffer enqueue routine return value is not intentionally checked.
        // Rationale: Its better to have a a few keys missing than have a system
        // reset. Recommendation is to work out most optimal value for
        // MAX_BUFFER_ENTRIES to minimize chances of buffer queue full condition
        UNUSED_VARIABLE(buffer_enqueue(&m_hids, p_key_pattern, key_pattern_len, actual_len));
    }


    if ((err_code != NRF_SUCCESS) &&
        (err_code != NRF_ERROR_INVALID_STATE) &&
        (err_code != NRF_ERROR_RESOURCES) &&
        (err_code != NRF_ERROR_BUSY) &&
        (err_code != BLE_ERROR_GATTS_SYS_ATTR_MISSING)
       )
    {
        APP_ERROR_HANDLER(err_code);
    }
}


/**@brief Function for handling the HID Report Characteristic Write event.
 *
 * @param[in]   p_evt   HID service event.
 */
static void on_hid_rep_char_write(ble_hids_evt_t * p_evt)
{
    if (p_evt->params.char_write.char_id.rep_type == BLE_HIDS_REP_TYPE_OUTPUT)
    {
        ret_code_t err_code;
        uint8_t  report_val;
        uint8_t  report_index = p_evt->params.char_write.char_id.rep_index;

        if (report_index == OUTPUT_REPORT_INDEX)
        {
            // This code assumes that the output report is one byte long. Hence the following
            // static assert is made.
            STATIC_ASSERT(OUTPUT_REPORT_MAX_LEN == 1);

            err_code = ble_hids_outp_rep_get(&m_hids,
                                             report_index,
                                             OUTPUT_REPORT_MAX_LEN,
                                             0,
                                             m_conn_handle,
                                             &report_val);
            APP_ERROR_CHECK(err_code);
        }
    }
}


/**@brief Function for putting the chip into sleep mode.
 *
 * @note This function will not return.
 */
static void sleep_mode_enter(void)
{
    ret_code_t err_code;

    err_code = bsp_indication_set(BSP_INDICATE_IDLE);
    APP_ERROR_CHECK(err_code);

    // Prepare wakeup buttons.
    err_code = bsp_btn_ble_sleep_mode_prepare();
    APP_ERROR_CHECK(err_code);

    // Go to system-off mode (this function will not return; wakeup will cause a reset).
    err_code = sd_power_system_off();
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for handling HID events.
 *
 * @details This function will be called for all HID events which are passed to the application.
 *
 * @param[in]   p_hids  HID service structure.
 * @param[in]   p_evt   Event received from the HID service.
 */
static void on_hids_evt(ble_hids_t * p_hids, ble_hids_evt_t * p_evt)
{
    switch (p_evt->evt_type)
    {
        case BLE_HIDS_EVT_BOOT_MODE_ENTERED:
            m_in_boot_mode = true;
            break;

        case BLE_HIDS_EVT_REPORT_MODE_ENTERED:
            m_in_boot_mode = false;
            break;

        case BLE_HIDS_EVT_REP_CHAR_WRITE:
            on_hid_rep_char_write(p_evt);
            break;

        case BLE_HIDS_EVT_NOTIF_ENABLED:
            break;

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


/**@brief Function for handling advertising events.
 *
 * @details This function will be called for advertising events which are passed to the application.
 *
 * @param[in] ble_adv_evt  Advertising event.
 */
static void on_adv_evt(ble_adv_evt_t ble_adv_evt)
{
    ret_code_t err_code;

    switch (ble_adv_evt)
    {
        case BLE_ADV_EVT_DIRECTED_HIGH_DUTY:
            NRF_LOG_INFO("High Duty Directed advertising.");
            err_code = bsp_indication_set(BSP_INDICATE_ADVERTISING_DIRECTED);
            APP_ERROR_CHECK(err_code);
            break;

        case BLE_ADV_EVT_DIRECTED:
            NRF_LOG_INFO("Directed advertising.");
            err_code = bsp_indication_set(BSP_INDICATE_ADVERTISING_DIRECTED);
            APP_ERROR_CHECK(err_code);
            break;

        case BLE_ADV_EVT_FAST:
            NRF_LOG_INFO("Fast advertising.");

            err_code = bsp_indication_set(BSP_INDICATE_IDLE);
						//err_code = bsp_indication_set(BSP_INDICATE_ADVERTISING);
            APP_ERROR_CHECK(err_code);
            break;

        case BLE_ADV_EVT_SLOW:
            NRF_LOG_INFO("Slow advertising.");
            err_code = bsp_indication_set(BSP_INDICATE_ADVERTISING_SLOW);
            APP_ERROR_CHECK(err_code);
            break;

        case BLE_ADV_EVT_FAST_WHITELIST:
            NRF_LOG_INFO("Fast advertising with whitelist.");
            err_code = bsp_indication_set(BSP_INDICATE_ADVERTISING_WHITELIST);
            APP_ERROR_CHECK(err_code);
            break;

        case BLE_ADV_EVT_SLOW_WHITELIST:
            NRF_LOG_INFO("Slow advertising with whitelist.");
            err_code = bsp_indication_set(BSP_INDICATE_ADVERTISING_WHITELIST);
            APP_ERROR_CHECK(err_code);
            break;

        case BLE_ADV_EVT_IDLE:
            err_code = bsp_indication_set(BSP_INDICATE_IDLE);
            APP_ERROR_CHECK(err_code);
            
            sleep_mode_enter();
            break;

        case BLE_ADV_EVT_WHITELIST_REQUEST:
        {
            ble_gap_addr_t whitelist_addrs[BLE_GAP_WHITELIST_ADDR_MAX_COUNT];
            ble_gap_irk_t  whitelist_irks[BLE_GAP_WHITELIST_ADDR_MAX_COUNT];
            uint32_t       addr_cnt = BLE_GAP_WHITELIST_ADDR_MAX_COUNT;
            uint32_t       irk_cnt  = BLE_GAP_WHITELIST_ADDR_MAX_COUNT;

            err_code = pm_whitelist_get(whitelist_addrs, &addr_cnt,
                                        whitelist_irks,  &irk_cnt);
            APP_ERROR_CHECK(err_code);
            NRF_LOG_DEBUG("pm_whitelist_get returns %d addr in whitelist and %d irk whitelist",
                          addr_cnt, irk_cnt);

            // Set the correct identities list (no excluding peers with no Central Address Resolution).
            identities_set(PM_PEER_ID_LIST_SKIP_NO_IRK);

            // Apply the whitelist.
            err_code = ble_advertising_whitelist_reply(&m_advertising,
                                                       whitelist_addrs,
                                                       addr_cnt,
                                                       whitelist_irks,
                                                       irk_cnt);
            APP_ERROR_CHECK(err_code);
        } break; //BLE_ADV_EVT_WHITELIST_REQUEST

        case BLE_ADV_EVT_PEER_ADDR_REQUEST:
        {
            pm_peer_data_bonding_t peer_bonding_data;

            // Only Give peer address if we have a handle to the bonded peer.
            if (m_peer_id != PM_PEER_ID_INVALID)
            {
                err_code = pm_peer_data_bonding_load(m_peer_id, &peer_bonding_data);
                if (err_code != NRF_ERROR_NOT_FOUND)
                {
                    APP_ERROR_CHECK(err_code);

                    // Manipulate identities to exclude peers with no Central Address Resolution.
                    identities_set(PM_PEER_ID_LIST_SKIP_ALL);

                    ble_gap_addr_t * p_peer_addr = &(peer_bonding_data.peer_ble_id.id_addr_info);
                    err_code = ble_advertising_peer_addr_reply(&m_advertising, p_peer_addr);
                    APP_ERROR_CHECK(err_code);
                }
            }
        } break; //BLE_ADV_EVT_PEER_ADDR_REQUEST

        default:
            break;
    }
}

#if HID_MULT ==1
/**@brief Function for handling the Connected event.
 *
 * @param[in] p_gap_evt GAP event received from the BLE stack.
 */
static void on_connected(const ble_gap_evt_t * const p_gap_evt)
{
    ret_code_t  err_code;
    uint32_t    periph_link_cnt = ble_conn_state_peripheral_conn_count(); // Number of peripheral links.

    NRF_LOG_INFO("Connection with link 0x%x established.", p_gap_evt->conn_handle);

    // Assign connection handle to available instance of QWR module.
    for (uint32_t i = 0; i < NRF_SDH_BLE_PERIPHERAL_LINK_COUNT; i++)
    {
        if (m_qwr[i].conn_handle == BLE_CONN_HANDLE_INVALID)
        {
            err_code = nrf_ble_qwr_conn_handle_assign(&m_qwr[i], p_gap_evt->conn_handle);
            APP_ERROR_CHECK(err_code);
            break;
        }
    }
    // Update LEDs
    bsp_board_led_on(LED_3);
    if (periph_link_cnt == NRF_SDH_BLE_PERIPHERAL_LINK_COUNT)
    {
        bsp_board_led_off(LED_4);
    }
    else
    {
        // Continue advertising. More connections can be established because the maximum link count has not been reached.
        advertising_start(true);
    }

}


/**@brief Function for handling the Disconnected event.
 *
 * @param[in] p_gap_evt GAP event received from the BLE stack.
 */
static void on_disconnected(ble_gap_evt_t const * const p_gap_evt)
{
    ret_code_t  err_code;
    uint32_t    periph_link_cnt = ble_conn_state_peripheral_conn_count(); // Number of peripheral links.

    NRF_LOG_INFO("Connection 0x%x has been disconnected. Reason: 0x%X",
                 p_gap_evt->conn_handle,
                 p_gap_evt->params.disconnected.reason);

    if (periph_link_cnt == 0)
    {
		advertising_start(true);
        bsp_board_led_off(LED_3);
		APP_ERROR_CHECK(err_code);
    }

    if (periph_link_cnt == (NRF_SDH_BLE_PERIPHERAL_LINK_COUNT - 1))
    {
        // Advertising is not running when all connections are taken, and must therefore be started.
        advertising_start(true);
        }
}
#endif

/**@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");
			#if HID_MULT ==0
            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 = nrf_ble_qwr_conn_handle_assign(&m_qwr, m_conn_handle);
            APP_ERROR_CHECK(err_code);
			#else
			on_connected(&p_ble_evt->evt.gap_evt);
			#endif
            break;

        case BLE_GAP_EVT_DISCONNECTED:
            NRF_LOG_INFO("Disconnected");
            // Dequeue all keys without transmission.
            (void) buffer_dequeue(false);
			#if HID_MULT ==0
            m_conn_handle = BLE_CONN_HANDLE_INVALID;

            err_code = bsp_indication_set(BSP_INDICATE_ALERT_OFF);
            APP_ERROR_CHECK(err_code);
			#else
			on_disconnected(&p_ble_evt->evt.gap_evt);
			#endif
			delete_bonds();
				
            break; // BLE_GAP_EVT_DISCONNECTED

        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_HVN_TX_COMPLETE:
            // Send next key event
            (void) buffer_dequeue(true);
            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;
    }
}


/**@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);
}


/**@brief Function for the Event Scheduler initialization.
 */
static void scheduler_init(void)
{
    APP_SCHED_INIT(SCHED_MAX_EVENT_DATA_SIZE, SCHED_QUEUE_SIZE);
}


////////////////////////////////////////////////////////////////////////////////////////////
/**@brief Function for handling events from the BSP module.
 *
 * @param[in]   event   Event generated by button press.
 */
static void bsp_event_handler(bsp_event_t event)
{
    uint32_t         err_code;
    static uint8_t * p_key = 0;
    static uint8_t   size  = 0;

    switch (event)
    {
        case BSP_EVENT_SLEEP:
            sleep_mode_enter();
            break;

        case BSP_EVENT_DISCONNECT:
            err_code = sd_ble_gap_disconnect(m_conn_handle,
                                             BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION);
            if (err_code != NRF_ERROR_INVALID_STATE)
            {
                APP_ERROR_CHECK(err_code);
            }
            break;

        case BSP_EVENT_WHITELIST_OFF:
            if (m_conn_handle == BLE_CONN_HANDLE_INVALID)
            {
                err_code = ble_advertising_restart_without_whitelist(&m_advertising);
                if (err_code != NRF_ERROR_INVALID_STATE)
                {
                    APP_ERROR_CHECK(err_code);
                }
            }
            break;

        case BSP_EVENT_KEY_0:

            break;

        default:
            break;
    }
}


/**@brief Function for the Peer Manager initialization.
 */
static void peer_manager_init(void)
{
    ble_gap_sec_params_t sec_param;
    ret_code_t           err_code;

    err_code = pm_init();
    APP_ERROR_CHECK(err_code);

    memset(&sec_param, 0, sizeof(ble_gap_sec_params_t));

    // Security parameters to be used for all security procedures.
    sec_param.bond           = SEC_PARAM_BOND;
    sec_param.mitm           = SEC_PARAM_MITM;
    sec_param.lesc           = SEC_PARAM_LESC;
    sec_param.keypress       = SEC_PARAM_KEYPRESS;
    sec_param.io_caps        = SEC_PARAM_IO_CAPABILITIES;
    sec_param.oob            = SEC_PARAM_OOB;
    sec_param.min_key_size   = SEC_PARAM_MIN_KEY_SIZE;
    sec_param.max_key_size   = SEC_PARAM_MAX_KEY_SIZE;
    sec_param.kdist_own.enc  = 1;
    sec_param.kdist_own.id   = 1;
    sec_param.kdist_peer.enc = 1;
    sec_param.kdist_peer.id  = 1;

    err_code = pm_sec_params_set(&sec_param);
    APP_ERROR_CHECK(err_code);

    err_code = pm_register(pm_evt_handler);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for initializing the Advertising functionality.
 */
static void advertising_init(void)
{
    uint32_t               err_code;
    uint8_t                adv_flags;
    ble_advertising_init_t init;
	
    memset(&init, 0, sizeof(init));

    adv_flags                            = BLE_GAP_ADV_FLAGS_LE_ONLY_GENERAL_DISC_MODE;
    init.advdata.name_type               = BLE_ADVDATA_FULL_NAME;
    init.advdata.include_appearance      = true;
    init.advdata.flags                   = adv_flags;
    init.advdata.uuids_complete.uuid_cnt = sizeof(m_adv_uuids) / sizeof(m_adv_uuids[0]);
    init.advdata.uuids_complete.p_uuids  = m_adv_uuids;

    init.config.ble_adv_whitelist_enabled          = false; 
    init.config.ble_adv_directed_high_duty_enabled = false; 

    init.config.ble_adv_fast_enabled               = true;
    init.config.ble_adv_fast_interval              = APP_ADV_FAST_INTERVAL;
    init.config.ble_adv_fast_timeout               = APP_ADV_FAST_DURATION;

    init.evt_handler   = on_adv_evt;
    init.error_handler = ble_advertising_error_handler;

    err_code = ble_advertising_init(&m_advertising, &init);
    APP_ERROR_CHECK(err_code);
		
    ble_advertising_conn_cfg_tag_set(&m_advertising, APP_BLE_CONN_CFG_TAG);
}

/**@brief Function for initializing buttons and leds.
 *
 * @param[out] p_erase_bonds  Will be true if the clear bonding button was pressed to wake the application up.
 */
static void buttons_leds_init(bool * p_erase_bonds)
{
    ret_code_t err_code;
    bsp_event_t startup_event;
	
    err_code = bsp_init(BSP_INIT_LEDS | BSP_INIT_BUTTONS, bsp_event_handler);

    APP_ERROR_CHECK(err_code);

    err_code = bsp_btn_ble_init(NULL, &startup_event);
    APP_ERROR_CHECK(err_code);

    *p_erase_bonds = (startup_event == BSP_EVENT_CLEAR_BONDING_DATA);
}

/**@brief Function for the Timer initialization.
 *
 * @details Initializes the timer module.
 */
static void timers_init(void)
{
    ret_code_t err_code;

    err_code = app_timer_init();
    APP_ERROR_CHECK(err_code);

    // Create battery timer.
    err_code = app_timer_create(&m_battery_timer_id,
                                APP_TIMER_MODE_REPEATED,
                                battery_level_meas_timeout_handler);
    APP_ERROR_CHECK(err_code);

}

/**@brief Function for initializing the nrf log module.
 */
static void log_init(void)
{
    ret_code_t err_code = NRF_LOG_INIT(NULL);
    APP_ERROR_CHECK(err_code);

    NRF_LOG_DEFAULT_BACKENDS_INIT();
}

/**@brief Function for initializing power management.
 */
static void power_management_init(void)
{
    ret_code_t err_code;
    err_code = nrf_pwr_mgmt_init();
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for handling the idle state (main loop).
 *
 * @details If there is no pending log operation, then sleep until next the next event occurs.
 */
static void idle_state_handle(void)
{
    app_sched_execute();
    if (NRF_LOG_PROCESS() == false)
    {
        nrf_pwr_mgmt_run();
    }
}



/**@brief Function for application main entry.
 */
int main(void)
{
	ret_code_t err_code;
    
	bool erase_bonds;
	
    // Initialize.
    log_init();
    timers_init();

		
	buttons_leds_init(&erase_bonds);

    power_management_init();
    ble_stack_init();
    scheduler_init();
    gap_params_init();
    gatt_init();

		
    advertising_init();
    services_init();
    sensor_simulator_init();
    conn_params_init();
    buffer_init();
    peer_manager_init();

			
    // Start execution.
    NRF_LOG_INFO("HID MULTIPLE started.");
    timers_start();
    advertising_start(erase_bonds);
		
    // Enter main loop.
    for (;;)
    {
        idle_state_handle();
    }
}


/**
 * @}
 */

Though it could connect with 2 host by nRF connect it could not support windows HID service.

Whenever it connect with PC, it just dropped then reconnect and dropped again.

00> <info> app: HID MULTIPLE started.
00> <info> app: m_whitelist_peer_cnt 1, MAX_PEERS_WLIST 8
00> <info> app: Fast advertising.
00> <info> app: Connected
00> <info> app: Connection with link 0x0 established.
00> <info> app: Erase bonds!
00> <info> peer_manager_handler: All peers deleted.
00> <info> app: m_whitelist_peer_cnt 1, MAX_PEERS_WLIST 8
00> <info> app: Fast advertising.
00> <info> peer_manager_handler: Connection security failed: role: Peripheral, conn_handle: 0x0, procedure: Encryption, error: 4102
00> <error> app: Fatal error
00> <warning> app: System reset
00> <info> app: HID MULTIPLE started.
00> <info> app: m_whitelist_peer_cnt 1, MAX_PEERS_WLIST 8
00> <info> app: Fast advertising.
00> <info> app: Connected
00> <info> app: Connection with link 0x0 established.
00> <info> app: Erase bonds!
00> <info> peer_manager_handler: All peers deleted.
00> <info> app: m_whitelist_peer_cnt 1, MAX_PEERS_WLIST 8
00> <info> app: Fast advertising.
00> <error> app: Fatal error
00> <warning> app: System reset

Besides, when the device is connected with 2 host once the device disconnect with on of them. It will disconnect for all.

May I know how could I modified it? 

When I program the code, I found that start_advertising are different. 

Keyboard used the bond information  but multi-peripheral doesn't.

[CY]

Hi Sigurd,

I just tried to modified as below:

erase_bonds = false

set all related advertising_start(false) 

block the delete_bond() in the case BLE_GAP_EVT_DISCOONECTED

As the result, it could connect with windows without dropped and connect with nRF connect at the same time.

Somehow it show the message during I connect with PC.

00> <info> app: Connection with link 0x0 established.
00> <info> app: m_whitelist_peer_cnt 2, MAX_PEERS_WLIST 8
00> <info> app: Fast advertising.
00> <info> peer_manager_handler: Connection security failed: role: Peripheral, conn_handle: 0x0, procedure: Bonding, error: 133

And "when the device is connected with 2 host once the device disconnect with on of them. It will disconnect for all." It has been solved after the modification.

It show as below, 0x13 mean BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION, seem normal.

00> <info> app: Connected
00> <info> app: Connection with link 0x1 established.
00> <info> app: Fast advertising.
00> <info> app: Disconnected
00> <info> app: Connection 0x1 has been disconnected. Reason: 0x13
00> <info> app: Connected
00> <info> app: Connection with link 0x1 established.
00> <info> app: Fast advertising.
00> <info> app: Disconnected

However, after the disconnection the device could not be connectable anymore.

I suppose it cause by the bonding information.

Could you guide me how to fixed it?

Thanks.