nRF52832 Nus MultiLink Multirole Example Project Inquiry

[siltvm]

Hi,

We are currently planning to start a project using the nRF52832 as our controller, SEGGER Embedded Studio version 5.42a as the IDE, and nRF5 SDK version 17.0.2 as our SDK. Our requirement is to have an nRF52832 device that can behave as both a central and peripheral device.

Is there any  nus MultiLink Multirole example project available to start writing the firmware for our requirement?

We need the nRF52832 to be able to act as both a central and peripheral device, send and receive data to/from corresponding connected BLE devices, and connect to an nRF Connect app.

Project Details:

• SDK: nRF5 SDK 17.0.2
• IDE: SEGGER Embedded Studio 5.42a
• Controller: nRF52832

Thank you for your support.

Best regards, SILTVM

[Susheel Nuguru]

I would highly recommend you not to use deprecated SDKs to use on starting a newer project. 
If you want to still use it, then you can start with examples/ble_central/ble_app_multilink_central which uses NUS as central and you need to merge it with NUS peripheral yourself. That is, we do not have a sample exactly to match your requirement but above can be a starting point.

[siltvm]

I'm looking for an example project to start and found that the ble_app_hrs_rscs_relay example project is a good starting point. I'm unsure if this is the correct decision. I added some parts from the ble_nus_c and ble_nus examples from the ble_app_uart and ble_app_uart_c project to the ble_app_hrs_rscs_relay example code to handle central and peripheral NUS data. I initially encountered some memory-related issues, which I believe I've resolved. However, I'm not sure if my approach is correct.

Currently, I have two nRF52832 PCA10040 development boards. I've flashed the ble_app_hrs_rscs_relay example code onto one board and the ble_app_uart code onto the other. Initially, the ble_app_uart board advertises and connects to the modified relay code flashed board, and I can connect to the board(relay flashed board)  using the nRF Connect app.

issues :- 

1, if iam sending a data from apk to relay example code flashed board it print it on the console . when iam again sending another data from apk the console print nothing . i think the data is not received . 

2, i already told u that intially the uart flashed board is connected to relay flashed code . but if iam turn off the uart flashed board and then again powered on it connect but not observed the nus service .  

3, when the relay code flashed board power on after some time the log crash indication displays on the log console . 

doubts:-

1, is that a good approach for choosing ble_app_hrs_rscs_relay example project as a starting point .  

2, how can i connect to multiple periphrels at a time . is there any methods available for sending data to selected destination connected devices . 

i will attach my code for better understanding . 

 

/**
 * Copyright (c) 2014 - 2020, Nordic Semiconductor ASA
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form, except as embedded into a Nordic
 *    Semiconductor ASA integrated circuit in a product or a software update for
 *    such product, must reproduce the above copyright notice, this list of
 *    conditions and the following disclaimer in the documentation and/or other
 *    materials provided with the distribution.
 *
 * 3. Neither the name of Nordic Semiconductor ASA nor the names of its
 *    contributors may be used to endorse or promote products derived from this
 *    software without specific prior written permission.
 *
 * 4. This software, with or without modification, must only be used with a
 *    Nordic Semiconductor ASA integrated circuit.
 *
 * 5. Any software provided in binary form under this license must not be reverse
 *    engineered, decompiled, modified and/or disassembled.
 *
 * THIS SOFTWARE IS PROVIDED BY NORDIC SEMICONDUCTOR ASA "AS IS" AND ANY EXPRESS
 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY, NONINFRINGEMENT, AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL NORDIC SEMICONDUCTOR ASA OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
 * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */
/**
 * @brief BLE Heart Rate and Running Speed relay application main file.
 *
 * @detail This application demonstrates a simple relay, which passes on the values it receives.
 * By combining a collector part on one end and a sensor part on the other,
 * the s130 can function simultaneously as a central and a peripheral device.
 * 
 * The following figure shows how the sensor ble_app_hrs connects and interacts with the relay
 * in the same manner it would connect to a Heart Rate Collector. In this case, the relay
 * application acts as a central.
 *
 * On the other side, a collector (such as Master Control Panel or ble_app_hrs_c) connects
 * and interacts with the relay in the same manner it would connect to a heart rate sensor peripheral.
 *
 * LED layout:
 * LED 1: Central side is scanning.       LED 2: Central side is connected to a peripheral.
 * LED 3: Peripheral side is advertising. LED 4: Peripheral side is connected to a central.
 *
 * @note While testing, make sure that the Sensor and Collector are actually connecting to the relay,
 *       and not directly to each other!
 *
 *    Peripheral                  Relay                    Central
 *    +--------+        +-----------|----------+        +-----------+
 *    | Heart  |        | Heart     |   Heart  |        |           |
 *    | Rate   | -----> | Rate     -|-> Rate   | -----> | Collector |
 *    | Sensor |        | Collector |   Sensor |        |           |
 *    +--------+        +-----------|   and    |        +-----------+
 *                      | Running   |   Running|
 *    +--------+        | Speed    -|-> Speed  |
 *    | Running|------> | Collector |   Sensor |
 *    | Speed  |        +-----------|----------+
 *    | Sensor |
 *    +--------+
 */

#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include "nordic_common.h"
#include "nrf_sdh.h"
#include "nrf_sdh_soc.h"
#include "nrf_sdh_ble.h"
#include "peer_manager.h"
#include "peer_manager_handler.h"
#include "app_timer.h"
#include "bsp_btn_ble.h"
#include "ble.h"
#include "ble_advdata.h"
#include "ble_advertising.h"
#include "ble_conn_params.h"
#include "ble_db_discovery.h"
#include "ble_hrs.h"
#include "ble_rscs.h"
#include "ble_hrs_c.h"
#include "ble_rscs_c.h"
#include "ble_conn_state.h"
#include "ble_nus.h"
#include "ble_nus_c.h"
#include "nrf_fstorage.h"
#include "fds.h"
#include "nrf_ble_gatt.h"
#include "nrf_ble_qwr.h"
#include "nrf_pwr_mgmt.h"
#include "nrf_ble_scan.h"

#include "nrf_log.h"
#include "nrf_log_ctrl.h"
#include "nrf_log_default_backends.h"


char Bledatabuff[64];

#define PERIPHERAL_ADVERTISING_LED      BSP_BOARD_LED_2
#define PERIPHERAL_CONNECTED_LED        BSP_BOARD_LED_3
#define CENTRAL_SCANNING_LED            BSP_BOARD_LED_0
#define CENTRAL_CONNECTED_LED           BSP_BOARD_LED_1

#define DEVICE_NAME                     "nRF Relay"                                 /**< Name of device used for advertising. */
#define MANUFACTURER_NAME               "NordicSemiconductor"                       /**< Manufacturer. Passed to Device Information Service. */
#define APP_ADV_INTERVAL                300                                         /**< The advertising interval (in units of 0.625 ms). This value corresponds to 187.5 ms. */

#define APP_ADV_DURATION                18000                                       /**< The advertising duration (180 seconds) in units of 10 milliseconds. */

#define APP_BLE_CONN_CFG_TAG            1                                           /**< Tag that identifies the SoftDevice BLE configuration. */

#define FIRST_CONN_PARAMS_UPDATE_DELAY  APP_TIMER_TICKS(5000)                       /**< Time from initiating event (connect or start of notification) to the 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 in octets. */
#define SEC_PARAM_MAX_KEY_SIZE          16                                          /**< Maximum encryption key size in octets. */

#define HART_RATE_SERVICE_UUID_IDX      0                                           /**< Hart Rate service UUID index in array. */
#define RSCS_SERVICE_UUID_IDX           1                                           /**< RSCS service UUID index in array. */

#define NUS_SERVICE_UUID_TYPE   BLE_UUID_TYPE_VENDOR_BEGIN              /**< UUID type for the Nordic UART Service (vendor specific). */
/**@brief   Priority of the application BLE event handler.
 * @note    You shouldn't need to modify this value.
 */
#define APP_BLE_OBSERVER_PRIO           3

#define DB_DISCOVERY_INSTANCE_CNT       2  /**< Number of DB Discovery instances. */

static ble_hrs_t m_hrs;                                             /**< Heart Rate Service instance. */
static ble_rscs_t m_rscs;                                           /**< Running Speed and Cadence Service instance. */
static ble_hrs_c_t m_hrs_c;                                         /**< Heart Rate Service client instance. */
static ble_rscs_c_t m_rscs_c; 
                                      /**< Running Speed and Cadence Service client instance. */
BLE_NUS_C_DEF(m_ble_nus_c);                                        /**< BLE Nordic UART Service (NUS) client instance. */
BLE_NUS_DEF(m_nus, NRF_SDH_BLE_TOTAL_LINK_COUNT);                   // peripherel instance of NUS  ( modified )

NRF_BLE_GQ_DEF(m_ble_gatt_queue,                                    /**< BLE GATT Queue instance. */
               NRF_SDH_BLE_CENTRAL_LINK_COUNT,
               NRF_BLE_GQ_QUEUE_SIZE);
NRF_BLE_GATT_DEF(m_gatt);                                              /**< GATT module instance. */
NRF_BLE_QWRS_DEF(m_qwr, NRF_SDH_BLE_TOTAL_LINK_COUNT);                 /**< Context for the Queued Write module.*/
BLE_ADVERTISING_DEF(m_advertising);                                    /**< Advertising module instance. */
BLE_DB_DISCOVERY_ARRAY_DEF(m_db_discovery, 2);                         /**< Database discovery module instances. */
NRF_BLE_SCAN_DEF(m_scan);                                           /**< Scanning module instance. */

static uint16_t m_conn_handle_hrs_c  = BLE_CONN_HANDLE_INVALID;     /**< Connection handle for the HRS central application */
static uint16_t m_conn_handle_rscs_c = BLE_CONN_HANDLE_INVALID;     /**< Connection handle for the RSC central application */
static uint16_t m_conn_handle_nus_c  = BLE_CONN_HANDLE_INVALID;     /**< Handle of the current connection for the nus  */
static uint16_t m_ble_nus_max_data_len = BLE_GATT_ATT_MTU_DEFAULT - OPCODE_LENGTH - HANDLE_LENGTH; /**< Maximum length of data (in bytes) that can be transmitted to the peer by the Nordic UART service module. */
/**@brief Names that the central application scans for, and that are advertised by the peripherals.
 *  If these are set to empty strings, the UUIDs defined below are used.
 */
static char const m_target_periph_name[] = "";

/**@brief UUIDs that the central application scans for if the name above is set to an empty string,
 * and that are to be advertised by the peripherals.
 */
static ble_uuid_t m_adv_uuids[] =
{
    {BLE_UUID_HEART_RATE_SERVICE,        BLE_UUID_TYPE_BLE},
    {BLE_UUID_RUNNING_SPEED_AND_CADENCE, BLE_UUID_TYPE_BLE}
};


/**@brief NUS UUID. */
static ble_uuid_t const m_nus_uuid =
{
    .uuid = BLE_UUID_NUS_SERVICE,
    .type = NUS_SERVICE_UUID_TYPE
};


static ble_gap_scan_params_t m_scan_param =                 /**< Scan parameters requested for scanning and connection. */
{
    .active        = 0x01,
    .interval      = NRF_BLE_SCAN_SCAN_INTERVAL,
    .window        = NRF_BLE_SCAN_SCAN_WINDOW,
    .filter_policy = BLE_GAP_SCAN_FP_ACCEPT_ALL,
    .timeout       = NRF_BLE_SCAN_SCAN_DURATION,
    .scan_phys     = BLE_GAP_PHY_1MBPS,
    .extended      = true,
};


/**@brief Function for handling asserts in the SoftDevice.
 *
 * @details This function is called in case of an assert in the SoftDevice.
 *
 * @warning This handler is an example only and is not meant for the 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] p_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(0xDEADBEEF, line_num, p_file_name);
}


/**@brief Function for handling the Heart Rate Service Client
 *        Running Speed and Cadence Service Client.
 *
 * @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 errors from the Connection Parameters module.
 *
 * @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);
}


static void scan_evt_handler(scan_evt_t const * p_scan_evt)
{
    ret_code_t err_code;
    ble_gap_evt_adv_report_t const * p_adv = 
                   p_scan_evt->params.filter_match.p_adv_report;
    ble_gap_scan_params_t    const * p_scan_param = 
                   p_scan_evt->p_scan_params;

    switch(p_scan_evt->scan_evt_id)
    {
        case NRF_BLE_SCAN_EVT_FILTER_MATCH:
        {
            // Initiate connection.
            err_code = sd_ble_gap_connect(&p_adv->peer_addr,
                                          p_scan_param,
                                          &m_scan.conn_params,
                                          APP_BLE_CONN_CFG_TAG);
            APP_ERROR_CHECK(err_code);
        } break;

        case NRF_BLE_SCAN_EVT_CONNECTING_ERROR:
        {
            err_code = p_scan_evt->params.connecting_err.err_code;
            APP_ERROR_CHECK(err_code);
        } break;

        case NRF_BLE_SCAN_EVT_CONNECTED:
        {
            ble_gap_evt_connected_t const * p_connected = p_scan_evt->params.connected.p_connected;
            NRF_LOG_INFO("Connected to target %02x%02x%02x%02x%02x%02x",
                         p_connected->peer_addr.addr[0],
                         p_connected->peer_addr.addr[1],
                         p_connected->peer_addr.addr[2],
                         p_connected->peer_addr.addr[3],
                         p_connected->peer_addr.addr[4],
                         p_connected->peer_addr.addr[5]);
        } break;


        default:
            break;
    }
}


/**@brief Function for initialization the scanning and setting the filters.
 */
static void scan_init(void)
{
    ret_code_t          err_code;
    nrf_ble_scan_init_t init_scan;

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

    init_scan.p_scan_param = &m_scan_param;
    //init_scan.connect_if_match = true;
    //init_scan.conn_cfg_tag     = APP_BLE_CONN_CFG_TAG;

    err_code = nrf_ble_scan_init(&m_scan, &init_scan, scan_evt_handler);
    APP_ERROR_CHECK(err_code);
    NRF_LOG_INFO("nrf_ble_scan_init : %d\n",err_code);

    if (strlen(m_target_periph_name) != 0)
    {
        err_code = nrf_ble_scan_filter_set(&m_scan, 
                                           SCAN_NAME_FILTER, 
                                           m_target_periph_name);
        NRF_LOG_INFO("SCAN_NAME_FILTER : %d\n",err_code);
        APP_ERROR_CHECK(err_code);
    }

    err_code = nrf_ble_scan_filter_set(&m_scan, 
                                       SCAN_UUID_FILTER, 
                                       &m_adv_uuids[HART_RATE_SERVICE_UUID_IDX]);
    NRF_LOG_INFO("scan filter init HART_RATE_SERVICE_UUID_IDX : %d\n",err_code);
    APP_ERROR_CHECK(err_code);

    err_code = nrf_ble_scan_filter_set(&m_scan, 
                                       SCAN_UUID_FILTER, 
                                       &m_adv_uuids[RSCS_SERVICE_UUID_IDX]);
    NRF_LOG_INFO("scan filter init RSCS_SERVICE_UUID_IDX : %d\n",err_code);
    APP_ERROR_CHECK(err_code);

    err_code = nrf_ble_scan_filter_set(&m_scan, SCAN_UUID_FILTER, &m_nus_uuid);
    NRF_LOG_INFO("scan filter init NUS : %d\n",err_code);
    APP_ERROR_CHECK(err_code);

    err_code = nrf_ble_scan_filters_enable(&m_scan, 
                                           NRF_BLE_SCAN_ALL_FILTER, 
                                           false);
    NRF_LOG_INFO("nrf_ble_scan_filters_enable : %d\n",err_code);
    APP_ERROR_CHECK(err_code);

}


/**@brief Function for initializing the scanning.
 */
static void scan_start(void)
{
    ret_code_t err_code;

    err_code = nrf_ble_scan_start(&m_scan);
    APP_ERROR_CHECK(err_code);
    NRF_LOG_INFO("nrf_ble_scan_start : %d\n",err_code);
    NRF_LOG_INFO("SCAN START");
}


/**@brief Function for initializing the advertising and the scanning.
 */
static void adv_scan_start(void)
{
    ret_code_t err_code;

    //check if there are no flash operations in progress
    if (!nrf_fstorage_is_busy(NULL))
    {
        // Start scanning for peripherals and initiate connection to devices which
        // advertise Heart Rate or Running speed and cadence UUIDs.
        scan_start();

        // Turn on the LED to signal scanning.
        bsp_board_led_on(CENTRAL_SCANNING_LED);

        // Start advertising.
        err_code = ble_advertising_start(&m_advertising, BLE_ADV_MODE_FAST);
        APP_ERROR_CHECK(err_code);
    }
}


/**@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_disconnect_on_sec_failure(p_evt);
    pm_handler_flash_clean(p_evt);

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

        default:
            break;
    }
}


/**@brief Function for changing filter settings after establishing the connection.
 */
static void filter_settings_change(void)
{
    ret_code_t err_code;

    err_code = nrf_ble_scan_all_filter_remove(&m_scan);
    APP_ERROR_CHECK(err_code);

    if (strlen(m_target_periph_name) != 0)
    {
        err_code = nrf_ble_scan_filter_set(&m_scan, 
                                           SCAN_NAME_FILTER, 
                                           m_target_periph_name);
        APP_ERROR_CHECK(err_code);
    }

    if ((m_conn_handle_hrs_c != BLE_CONN_HANDLE_INVALID) && 
        (m_conn_handle_rscs_c == BLE_CONN_HANDLE_INVALID))
    {
        err_code = nrf_ble_scan_filter_set(&m_scan, 
                                           SCAN_UUID_FILTER, 
                                           &m_adv_uuids[RSCS_SERVICE_UUID_IDX]);
    }

    if ((m_conn_handle_rscs_c != BLE_CONN_HANDLE_INVALID) && 
         m_conn_handle_hrs_c == BLE_CONN_HANDLE_INVALID)
    {
        err_code = nrf_ble_scan_filter_set(&m_scan, 
                                           SCAN_UUID_FILTER, 
                                           &m_adv_uuids[HART_RATE_SERVICE_UUID_IDX]);
    }

    APP_ERROR_CHECK(err_code);
}


/**@brief Handles events coming from the Heart Rate central module.
 */
static void hrs_c_evt_handler(ble_hrs_c_t * p_hrs_c, ble_hrs_c_evt_t * p_hrs_c_evt)
{
    switch (p_hrs_c_evt->evt_type)
    {
        case BLE_HRS_C_EVT_DISCOVERY_COMPLETE:
        {
            if (m_conn_handle_hrs_c == BLE_CONN_HANDLE_INVALID)
            {
                ret_code_t err_code;

                m_conn_handle_hrs_c = p_hrs_c_evt->conn_handle;
                NRF_LOG_INFO("HRS discovered on conn_handle 0x%x", m_conn_handle_hrs_c);

                filter_settings_change();

                err_code = ble_hrs_c_handles_assign(p_hrs_c,
                                                    m_conn_handle_hrs_c,
                                                    &p_hrs_c_evt->params.peer_db);
                APP_ERROR_CHECK(err_code);
                // Initiate bonding.
                err_code = pm_conn_secure(m_conn_handle_hrs_c, false);
                if (err_code != NRF_ERROR_BUSY)
                {
                    APP_ERROR_CHECK(err_code);
                }

                // Heart rate service discovered. Enable notification of Heart Rate Measurement.
                err_code = ble_hrs_c_hrm_notif_enable(p_hrs_c);
                APP_ERROR_CHECK(err_code);
            }
        } break; // BLE_HRS_C_EVT_DISCOVERY_COMPLETE

        case BLE_HRS_C_EVT_HRM_NOTIFICATION:
        {
            ret_code_t err_code;

            NRF_LOG_INFO("Heart Rate = %d", p_hrs_c_evt->params.hrm.hr_value);

            err_code = ble_hrs_heart_rate_measurement_send(&m_hrs, p_hrs_c_evt->params.hrm.hr_value);
            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);
            }
        } break; // BLE_HRS_C_EVT_HRM_NOTIFICATION

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


/**@brief Handles events coming from  Running Speed and Cadence central module.
 */
static void rscs_c_evt_handler(ble_rscs_c_t * p_rscs_c, ble_rscs_c_evt_t * p_rscs_c_evt)
{
    switch (p_rscs_c_evt->evt_type)
    {
        case BLE_RSCS_C_EVT_DISCOVERY_COMPLETE:
        {
            if (m_conn_handle_rscs_c == BLE_CONN_HANDLE_INVALID)
            {
                ret_code_t err_code;

                m_conn_handle_rscs_c = p_rscs_c_evt->conn_handle;
                NRF_LOG_INFO("Running Speed and Cadence service discovered on conn_handle 0x%x",
                             m_conn_handle_rscs_c);

                filter_settings_change();

                err_code = ble_rscs_c_handles_assign(p_rscs_c,
                                                    m_conn_handle_rscs_c,
                                                    &p_rscs_c_evt->params.rscs_db);
                APP_ERROR_CHECK(err_code);

                // Initiate bonding.
                err_code = pm_conn_secure(m_conn_handle_rscs_c, false);
                if (err_code != NRF_ERROR_BUSY)
                {
                    APP_ERROR_CHECK(err_code);
                }

                // Running Speed Cadence Service discovered. Enable notifications.
                err_code = ble_rscs_c_rsc_notif_enable(p_rscs_c);
                APP_ERROR_CHECK(err_code);
            }
        } break; // BLE_RSCS_C_EVT_DISCOVERY_COMPLETE:

        case BLE_RSCS_C_EVT_RSC_NOTIFICATION:
        {
            ret_code_t      err_code;
            ble_rscs_meas_t rscs_measurment;

            NRF_LOG_INFO("Speed      = %d", p_rscs_c_evt->params.rsc.inst_speed);

            rscs_measurment.is_running                  = p_rscs_c_evt->params.rsc.is_running;
            rscs_measurment.is_inst_stride_len_present  = p_rscs_c_evt->params.rsc.is_inst_stride_len_present;
            rscs_measurment.is_total_distance_present   = p_rscs_c_evt->params.rsc.is_total_distance_present;

            rscs_measurment.inst_stride_length = p_rscs_c_evt->params.rsc.inst_stride_length;
            rscs_measurment.inst_cadence       = p_rscs_c_evt->params.rsc.inst_cadence;
            rscs_measurment.inst_speed         = p_rscs_c_evt->params.rsc.inst_speed;
            rscs_measurment.total_distance     = p_rscs_c_evt->params.rsc.total_distance;

            err_code = ble_rscs_measurement_send(&m_rscs, &rscs_measurment);
            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);
            }
        } break; // BLE_RSCS_C_EVT_RSC_NOTIFICATION

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


/**@brief Function for assigning new connection handle to available instance of QWR module.
 *
 * @param[in] conn_handle New connection handle.
 */
static void multi_qwr_conn_handle_assign(uint16_t conn_handle)
{
    for (uint32_t i = 0; i < NRF_SDH_BLE_TOTAL_LINK_COUNT; i++)
    {
        if (m_qwr[i].conn_handle == BLE_CONN_HANDLE_INVALID)
        {
            ret_code_t err_code = nrf_ble_qwr_conn_handle_assign(&m_qwr[i], conn_handle);
            APP_ERROR_CHECK(err_code);
            break;
        }
    }
}


/**@brief   Function for handling BLE events from the central application.
 *
 * @details This function parses scanning reports and initiates a connection to peripherals when a
 *          target UUID is found. It updates the status of LEDs used to report the central application
 *          activity.
 *
 * @param[in]   p_ble_evt   Bluetooth stack event.
 */
static void on_ble_central_evt(ble_evt_t const * p_ble_evt)
{
    ret_code_t            err_code;
    ble_gap_evt_t const * p_gap_evt = &p_ble_evt->evt.gap_evt;

    switch (p_ble_evt->header.evt_id)
    {
        // Upon connection, check which peripheral is connected (HR or RSC), initiate DB
        // discovery, update LEDs status, and resume scanning, if necessary.
        case BLE_GAP_EVT_CONNECTED:
        {
            NRF_LOG_INFO("Central connected");
            // If no Heart Rate sensor or RSC sensor is currently connected, try to find them on this peripheral.
            if (   (m_conn_handle_hrs_c  == BLE_CONN_HANDLE_INVALID)
                || (m_conn_handle_rscs_c == BLE_CONN_HANDLE_INVALID)||(m_conn_handle_nus_c==BLE_CONN_HANDLE_INVALID)) //added an nus or operator checking here .
            {
                NRF_LOG_INFO("Attempt to find HRS or RSC or NUS conn_handle 0x%x", p_gap_evt->conn_handle);

                err_code = ble_db_discovery_start(&m_db_discovery[0], p_gap_evt->conn_handle);
                if (err_code == NRF_ERROR_BUSY)
                {
                    err_code = ble_db_discovery_start(&m_db_discovery[1], p_gap_evt->conn_handle);
                    APP_ERROR_CHECK(err_code);
                }
                else
                {
                    APP_ERROR_CHECK(err_code);
                }
            }

            // Assign connection handle to NUS Client
            err_code = ble_nus_c_handles_assign(&m_ble_nus_c, p_ble_evt->evt.gap_evt.conn_handle, NULL);  //added nus handle assigning 
            APP_ERROR_CHECK(err_code);

            // Assign connection handle to the QWR module.
            multi_qwr_conn_handle_assign(p_gap_evt->conn_handle);

            // Update LEDs status, and check whether to look for more peripherals to connect to.
            bsp_board_led_on(CENTRAL_CONNECTED_LED);
            if (ble_conn_state_central_conn_count() == NRF_SDH_BLE_CENTRAL_LINK_COUNT)
            {
                bsp_board_led_off(CENTRAL_SCANNING_LED);
            }
            else
            {
                // Resume scanning.
                bsp_board_led_on(CENTRAL_SCANNING_LED);
                scan_start();
            }
        } break; // BLE_GAP_EVT_CONNECTED

        // Upon disconnection, reset the connection handle of the peer that disconnected,
        // update the LEDs status and start scanning again.
        case BLE_GAP_EVT_DISCONNECTED:
        {

         NRF_LOG_INFO("Device disconnected, conn_handle: 0x%x, reason: 0x%x",
                         p_gap_evt->conn_handle,
                         p_gap_evt->params.disconnected.reason);

            if (p_gap_evt->conn_handle == m_conn_handle_hrs_c)
            {
                NRF_LOG_INFO("HRS central disconnected (reason: %d)",
                             p_gap_evt->params.disconnected.reason);

                m_conn_handle_hrs_c = BLE_CONN_HANDLE_INVALID;
                
                err_code = nrf_ble_scan_filter_set(&m_scan, 
                                                   SCAN_UUID_FILTER, 
                                                   &m_adv_uuids[HART_RATE_SERVICE_UUID_IDX]);
                NRF_LOG_INFO("HRS service disconnected.");
                APP_ERROR_CHECK(err_code);
            }

            if (p_gap_evt->conn_handle == m_conn_handle_rscs_c)
            {
                NRF_LOG_INFO("RSC central disconnected (reason: %d)",
                             p_gap_evt->params.disconnected.reason);

                m_conn_handle_rscs_c = BLE_CONN_HANDLE_INVALID;

                err_code = nrf_ble_scan_filter_set(&m_scan, 
                                                   SCAN_UUID_FILTER, 
                                                   &m_adv_uuids[RSCS_SERVICE_UUID_IDX]);
                                              
                NRF_LOG_INFO("RSCS service disconnected.");
                APP_ERROR_CHECK(err_code);
            }


            if (p_gap_evt->conn_handle == m_conn_handle_nus_c)
            {
                m_conn_handle_nus_c = BLE_CONN_HANDLE_INVALID;
                NRF_LOG_INFO("NUS service disconnected.");
            }


            if (   (m_conn_handle_rscs_c == BLE_CONN_HANDLE_INVALID)
                || (m_conn_handle_hrs_c  == BLE_CONN_HANDLE_INVALID)||(m_conn_handle_nus_c==BLE_CONN_HANDLE_INVALID)) //added nus connection handle checking
            {
                // Start scanning.
                scan_start();

                // Update LEDs status.
                bsp_board_led_on(CENTRAL_SCANNING_LED);
            }

            if (ble_conn_state_central_conn_count() == 0)
            {
                bsp_board_led_off(CENTRAL_CONNECTED_LED);
            }
        } break; // BLE_GAP_EVT_DISCONNECTED

        case BLE_GAP_EVT_TIMEOUT:
        {
            // No timeout for scanning is specified, so only connection attemps can timeout.
            if (p_gap_evt->params.timeout.src == BLE_GAP_TIMEOUT_SRC_CONN)
            {
                NRF_LOG_INFO("Connection Request timed out.");
            }
        } break;

        case BLE_GAP_EVT_CONN_PARAM_UPDATE_REQUEST:
        {
            // Accept parameters requested by peer.
            err_code = sd_ble_gap_conn_param_update(p_gap_evt->conn_handle,
                                        &p_gap_evt->params.conn_param_update_request.conn_params);
            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_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 handling BLE events from peripheral applications.
 * @details Updates the status LEDs used to report the activity of the peripheral applications.
 *
 * @param[in]   p_ble_evt   Bluetooth stack event.
 */
static void on_ble_peripheral_evt(ble_evt_t const * p_ble_evt)
{
    ret_code_t            err_code;
    ble_gap_evt_t const * p_gap_evt = &p_ble_evt->evt.gap_evt;

    switch (p_ble_evt->header.evt_id)
    {
        case BLE_GAP_EVT_CONNECTED:
            NRF_LOG_INFO("Peripheral connected");
            bsp_board_led_off(PERIPHERAL_ADVERTISING_LED);
            bsp_board_led_on(PERIPHERAL_CONNECTED_LED);

            // Assign connection handle to the QWR module.
            multi_qwr_conn_handle_assign(p_ble_evt->evt.gap_evt.conn_handle);
            break;

        case BLE_GAP_EVT_DISCONNECTED:
            NRF_LOG_INFO("Peripheral disconnected. conn_handle: 0x%x, reason: 0x%x",
                         p_gap_evt->conn_handle,
                         p_gap_evt->params.disconnected.reason);

            bsp_board_led_off(PERIPHERAL_CONNECTED_LED);
            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_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 handling advertising events.
 *
 * @param[in] ble_adv_evt  Advertising event.
 */
static void on_adv_evt(ble_adv_evt_t ble_adv_evt)
{
    switch (ble_adv_evt)
    {
        case BLE_ADV_EVT_FAST:
        {
            NRF_LOG_INFO("Fast advertising.");
            bsp_board_led_on(PERIPHERAL_ADVERTISING_LED);
        } break;

        case BLE_ADV_EVT_IDLE:
        {
            ret_code_t err_code = ble_advertising_start(&m_advertising, BLE_ADV_MODE_FAST);
            NRF_LOG_INFO("BLE ADV EVT IDLE\n");
            APP_ERROR_CHECK(err_code);
        } break;

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


/**@brief Function for checking whether a bluetooth stack event is an advertising timeout.
 *
 * @param[in] p_ble_evt Bluetooth stack event.
 */
static bool ble_evt_is_advertising_timeout(ble_evt_t const * p_ble_evt)
{
    return (p_ble_evt->header.evt_id == BLE_GAP_EVT_ADV_SET_TERMINATED);
}


/**@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)
{
    uint16_t conn_handle = p_ble_evt->evt.gap_evt.conn_handle;
    uint16_t role        = ble_conn_state_role(conn_handle);
    NRF_LOG_INFO("enter in ble evt handler \n ");
    // Based on the role this device plays in the connection, dispatch to the right handler.
    if (role == BLE_GAP_ROLE_PERIPH || ble_evt_is_advertising_timeout(p_ble_evt))
    {
        NRF_LOG_INFO("ble gap role peripherel  \n ");
        ble_hrs_on_ble_evt(p_ble_evt, &m_hrs);
        ble_rscs_on_ble_evt(p_ble_evt, &m_rscs);
        ble_nus_on_ble_evt(p_ble_evt, &m_nus);  // Adding this line for NUS peripheral handling
        on_ble_peripheral_evt(p_ble_evt);
    }
    else if ((role == BLE_GAP_ROLE_CENTRAL) || (p_ble_evt->header.evt_id == BLE_GAP_EVT_ADV_REPORT))
    {
        NRF_LOG_INFO("ble gap role central   \n ");
        ble_hrs_c_on_ble_evt(p_ble_evt, &m_hrs_c);
        ble_rscs_c_on_ble_evt(p_ble_evt, &m_rscs_c);
        ble_nus_c_on_ble_evt(p_ble_evt,&m_ble_nus_c);   // need to check this operation is neccesssary 
        on_ble_central_evt(p_ble_evt);
    }
}

/**@brief Function for handling the Nordic UART Service Client errors.
 *
 * @param[in]   nrf_error   Error code containing information about what went wrong.
 */
static void nus_error_handler(uint32_t nrf_error)
{
    APP_ERROR_HANDLER(nrf_error);
}

static void ble_nus_chars_received_log_print(uint8_t * p_data, uint16_t data_len)
{

  ret_code_t ret_val;
  char received_str[64];
   memset(received_str,0,sizeof(received_str));
   NRF_LOG_DEBUG("Receiving data.");
   NRF_LOG_HEXDUMP_DEBUG(p_data, data_len);
	
   for (uint32_t i = 0; i < data_len; i++)
    {
	 received_str[i]=p_data[i];
    }
	NRF_LOG_INFO("received_str_from_peripherel  : %s\n",received_str);

}


static void ble_nus_c_evt_handler(ble_nus_c_t * p_ble_nus_c, ble_nus_c_evt_t const * p_ble_nus_evt)
{

 ret_code_t err_code;
 switch (p_ble_nus_evt->evt_type)
 {
  
     case BLE_NUS_C_EVT_DISCOVERY_COMPLETE:
          NRF_LOG_INFO("Discovery complete");
          err_code = ble_nus_c_handles_assign(p_ble_nus_c, p_ble_nus_evt->conn_handle, &p_ble_nus_evt->handles);
          APP_ERROR_CHECK(err_code);

          err_code = ble_nus_c_tx_notif_enable(p_ble_nus_c);
          APP_ERROR_CHECK(err_code);
          NRF_LOG_INFO("Connected to device with Nordic UART Service.");
          break;

     case BLE_NUS_C_EVT_NUS_TX_EVT:
          ble_nus_chars_received_log_print(p_ble_nus_evt->p_data, p_ble_nus_evt->data_len);
          break;

     case BLE_NUS_C_EVT_DISCONNECTED:
          NRF_LOG_INFO("Disconnected");
          scan_start();
          break;


 }
}
/**@brief Function for initializing the Nordic UART Service (NUS) client. */
static void nus_c_init(void)
{
    ret_code_t       err_code;
    ble_nus_c_init_t init;

    init.evt_handler   = ble_nus_c_evt_handler;
    init.error_handler = nus_error_handler;
    init.p_gatt_queue  = &m_ble_gatt_queue;

    err_code = ble_nus_c_init(&m_ble_nus_c, &init);
    NRF_LOG_INFO("ble_nus_c_init : %d\n",err_code);
    APP_ERROR_CHECK(err_code);
}

/**@brief Heart Rate Collector initialization.
 */
static void hrs_c_init(void)
{
    ret_code_t       err_code;
    ble_hrs_c_init_t hrs_c_init_obj;

    hrs_c_init_obj.evt_handler   = hrs_c_evt_handler;
    hrs_c_init_obj.error_handler = service_error_handler;
    hrs_c_init_obj.p_gatt_queue  = &m_ble_gatt_queue;

    err_code = ble_hrs_c_init(&m_hrs_c, &hrs_c_init_obj);
    APP_ERROR_CHECK(err_code);
    NRF_LOG_INFO("ble_hrs_c_init : %d\n",err_code);
}


/**@brief RSC collector initialization.
 */
static void rscs_c_init(void)
{
    ret_code_t        err_code;
    ble_rscs_c_init_t rscs_c_init_obj;

    rscs_c_init_obj.evt_handler   = rscs_c_evt_handler;
    rscs_c_init_obj.error_handler = service_error_handler;
    rscs_c_init_obj.p_gatt_queue  = &m_ble_gatt_queue;

    err_code = ble_rscs_c_init(&m_rscs_c, &rscs_c_init_obj);
    APP_ERROR_CHECK(err_code);
    NRF_LOG_INFO("ble_rscs_c_init : %d\n",err_code);
}


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

    err_code = nrf_sdh_enable_request();
    APP_ERROR_CHECK(err_code);
    NRF_LOG_INFO("nrf_sdh_enable_request : %d\n",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);
    NRF_LOG_INFO("nrf_sdh_ble_default_cfg_set : %d\n",err_code);

    // Enable BLE stack.
    err_code = nrf_sdh_ble_enable(&ram_start);
    APP_ERROR_CHECK(err_code);
    NRF_LOG_INFO("nrf_sdh_ble_enable : %d\n",err_code);

    // Register a handler for BLE events.
    NRF_SDH_BLE_OBSERVER(m_ble_observer, APP_BLE_OBSERVER_PRIO, ble_evt_handler, NULL);
    NRF_LOG_INFO(" after nrf sdh ble observer \n");
}


/**@brief Function for initializing the Peer Manager.
 */
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);
    NRF_LOG_INFO("pm_init : %d\n",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);
    NRF_LOG_INFO("pm_sec_params_set : %d\n",err_code);

    err_code = pm_register(pm_evt_handler);
    APP_ERROR_CHECK(err_code);
    NRF_LOG_INFO("pm_register : %d\n",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 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, NULL);
    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 initializing the GAP.
 *
 * @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 = m_scan.conn_params.min_conn_interval;
    gap_conn_params.max_conn_interval = m_scan.conn_params.max_conn_interval;
    gap_conn_params.slave_latency     = m_scan.conn_params.slave_latency;
    gap_conn_params.conn_sup_timeout  = m_scan.conn_params.conn_sup_timeout;

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

/**@brief Function for handling events from the GATT library. */
void gatt_evt_handler(nrf_ble_gatt_t * p_gatt, nrf_ble_gatt_evt_t const * p_evt)
{
    if (p_evt->evt_id == NRF_BLE_GATT_EVT_ATT_MTU_UPDATED)
    {
        NRF_LOG_INFO("ATT MTU exchange completed.");

        m_ble_nus_max_data_len = p_evt->params.att_mtu_effective - OPCODE_LENGTH - HANDLE_LENGTH;
        NRF_LOG_INFO("Ble NUS max data length set to 0x%X(%d)", m_ble_nus_max_data_len, m_ble_nus_max_data_len);
    }
}

/**@brief Function for initializing the GATT module.
 */
static void gatt_init(void)
{
    ret_code_t err_code = nrf_ble_gatt_init(&m_gatt, gatt_evt_handler);
    APP_ERROR_CHECK(err_code);
    NRF_LOG_INFO("nrf_ble_gatt_init : %d\n",err_code);
    // Set the ATT MTU size for central role
    err_code = nrf_ble_gatt_att_mtu_central_set(&m_gatt, NRF_SDH_BLE_GATT_MAX_MTU_SIZE);
    APP_ERROR_CHECK(err_code);
    NRF_LOG_INFO("nrf_ble_gatt_att_mtu_central_set : %d\n",err_code);
    // Set the ATT MTU size for peripheral role
    err_code = nrf_ble_gatt_att_mtu_periph_set(&m_gatt, NRF_SDH_BLE_GATT_MAX_MTU_SIZE);
    APP_ERROR_CHECK(err_code);
    NRF_LOG_INFO("nrf_ble_gatt_att_mtu_periph_set : %d\n",err_code);


}


/**@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_CONN_HANDLE_INVALID; // Start upon connection.
    cp_init.disconnect_on_fail             = true;
    cp_init.evt_handler                    = NULL;  // Ignore events.
    cp_init.error_handler                  = conn_params_error_handler;

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


/**@brief Function for handling database discovery events.
 *
 * @details This function is a callback function to handle events from the database discovery module.
 *          Depending on the UUIDs that are discovered, this function forwards the events
 *          to their respective services.
 *
 * @param[in] p_event  Pointer to the database discovery event.
 */
static void db_disc_handler(ble_db_discovery_evt_t * p_evt)
{
    ble_db_discovery_t const * p_db = (ble_db_discovery_t *)p_evt->params.p_db_instance;

    ble_hrs_on_db_disc_evt(&m_hrs_c, p_evt);
    ble_rscs_on_db_disc_evt(&m_rscs_c, p_evt);
    ble_nus_c_on_db_disc_evt(&m_ble_nus_c, p_evt);     // nus central db disc evt handler . 

    if (p_evt->evt_type == BLE_DB_DISCOVERY_AVAILABLE) {
        NRF_LOG_INFO("DB Discovery instance %p available on conn handle: %d",
                     p_db,
                     p_evt->conn_handle);
        NRF_LOG_INFO("Found %d services on conn_handle: %d",
                     p_db->srv_count,
                     p_evt->conn_handle);
    }
}


/**
 * @brief Database discovery initialization.
 */
static void db_discovery_init(void)
{
    ble_db_discovery_init_t db_init;

    memset(&db_init, 0, sizeof(ble_db_discovery_init_t));

    db_init.evt_handler  = db_disc_handler;
    db_init.p_gatt_queue = &m_ble_gatt_queue;

    ret_code_t err_code = ble_db_discovery_init(&db_init);
    APP_ERROR_CHECK(err_code);
    NRF_LOG_INFO("ble_db_discovery_init :%d\n",err_code);
}


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


static void nus_data_handler(ble_nus_evt_t * p_evt)
{

  memset(Bledatabuff,0,sizeof(Bledatabuff));
  // write the code for nus data handling .
   if (p_evt->type == BLE_NUS_EVT_RX_DATA)
    {
        NRF_LOG_DEBUG("Received data from BLE NUS.");

        // Copy received data to Bledatabuff array
        for (uint32_t i = 0; i < p_evt->params.rx_data.length; i++)
        {
            Bledatabuff[i] = p_evt->params.rx_data.p_data[i];
        }
    }
    NRF_LOG_INFO(" Received ble data : %s\n",Bledatabuff );

}
/**@brief Function for initializing services that are be used by the application.
 *
 * @details Initialize the Heart Rate, Battery and Device Information services.
 */
static void services_init(void)
{
    ret_code_t         err_code;
    ble_hrs_init_t     hrs_init;
    ble_rscs_init_t    rscs_init;
    ble_nus_init_t     nus_init;
    nrf_ble_qwr_init_t qwr_init = {0};
    uint8_t            body_sensor_location;

   

    // Initialize Queued Write module instances.
    qwr_init.error_handler = nrf_qwr_error_handler;

    for (uint32_t i = 0; i < NRF_SDH_BLE_TOTAL_LINK_COUNT; i++)
    {
        err_code = nrf_ble_qwr_init(&m_qwr[i], &qwr_init);
        APP_ERROR_CHECK(err_code);
        NRF_LOG_INFO("nrf_ble_qwr_init : %d\n",err_code);
    }

    // Initialize the Heart Rate Service.
    body_sensor_location = BLE_HRS_BODY_SENSOR_LOCATION_FINGER;

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

    hrs_init.evt_handler                 = NULL;
    hrs_init.is_sensor_contact_supported = true;
    hrs_init.p_body_sensor_location      = &body_sensor_location;

    // Here the sec level for the Heart Rate Service can be changed or increased.
    hrs_init.hrm_cccd_wr_sec = SEC_OPEN;
    hrs_init.bsl_rd_sec      = SEC_OPEN;

    err_code = ble_hrs_init(&m_hrs, &hrs_init);
    APP_ERROR_CHECK(err_code);
    NRF_LOG_INFO("ble_hrs_init : %d\n",err_code);

    // Initialize the Running Speed and Cadence Service.
    memset(&rscs_init, 0, sizeof(rscs_init));

    rscs_init.evt_handler = NULL;
    rscs_init.feature     = BLE_RSCS_FEATURE_INSTANT_STRIDE_LEN_BIT |
                            BLE_RSCS_FEATURE_WALKING_OR_RUNNING_STATUS_BIT;

    // Here the sec level for the Running Speed and Cadence Service can be changed or increased.
    rscs_init.rsc_feature_rd_sec   = SEC_OPEN;
    rscs_init.rsc_meas_cccd_wr_sec = SEC_OPEN;

    err_code = ble_rscs_init(&m_rscs, &rscs_init);
    APP_ERROR_CHECK(err_code);
    NRF_LOG_INFO("ble_rscs_init : %d\n ",err_code);

    memset(&nus_init, 0, sizeof(nus_init));     
    nus_init.data_handler = nus_data_handler;    //intialisation parts for the nus 
    err_code = ble_nus_init(&m_nus, &nus_init);
    APP_ERROR_CHECK(err_code);

    NRF_LOG_INFO(" ble_nus_init : %d\n",err_code);

}


/**@brief Function for initializing the advertising functionality.
 */
static void advertising_init(void)
{
    ret_code_t             err_code;
    ble_advertising_init_t init;

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

    init.advdata.name_type               = BLE_ADVDATA_FULL_NAME;
    init.advdata.include_appearance      = true;
    init.advdata.flags                   = BLE_GAP_ADV_FLAGS_LE_ONLY_GENERAL_DISC_MODE;
    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_fast_enabled  = true;
    init.config.ble_adv_fast_interval = APP_ADV_INTERVAL;
    init.config.ble_adv_fast_timeout  = APP_ADV_DURATION;

    init.evt_handler = on_adv_evt;

    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 logging.
 */
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). If there is no pending log operation,
          then sleeps until the next event occurs.
 */
static void idle_state_handle(void)
{
    if (NRF_LOG_PROCESS() == false)
    {
        nrf_pwr_mgmt_run();
    }
}


/**@brief Function for initializing the timer.
 */
static void timer_init(void)
{
    ret_code_t err_code = app_timer_init();
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for initializing the application main entry.
 */
int main(void)
{
    bool erase_bonds;

    // Initialize.
    log_init();
    timer_init();
    buttons_leds_init(&erase_bonds);
    power_management_init();
    ble_stack_init();
    scan_init();
    gap_params_init();
    gatt_init();
    conn_params_init();
    db_discovery_init();
    peer_manager_init();
    hrs_c_init();
    rscs_c_init();
    nus_c_init();
    services_init();
    advertising_init();

    // Start execution.
    NRF_LOG_INFO("Relay example started.");

    if (erase_bonds == true)
    {
        // Scanning and advertising is done upon PM_EVT_PEERS_DELETE_SUCCEEDED event.
        delete_bonds();
    }
    else
    {
        adv_scan_start();
    }

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

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