text: /**
   * Copyright (c) 2014 - 2019, 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.
   *
   */
  // Board/nrf6310/ble/ble_app_hrs_rtx/main.c
  /**
   *
   * @brief Heart Rate Service Sample Application with RTX main file.
   *
   * This file contains the source code for a sample application using RTX and the
   * Heart Rate service (and also Battery and Device Information services).
   * This application uses the @ref srvlib_conn_params module.
   */
  
  #include <stdint.h>
  #include <string.h>
  #include "nordic_common.h"
  #include "nrf.h"
  #include "app_error.h"
  #include "ble.h"
  #include "ble_hci.h"
  #include "ble_srv_common.h"
  #include "ble_advdata.h"
  #include "ble_advertising.h"
  #include "ble_bas.h"
  #include "ble_hrs.h"
  #include "ble_dis.h"
  #include "ble_conn_params.h"
  #include "sensorsim.h"
  #include "nrf_sdh.h"
  #include "nrf_sdh_soc.h"
  #include "nrf_sdh_ble.h"
  #include "nrf_sdh_freertos.h"
  #include "app_timer.h"
  #include "peer_manager.h"
  #include "peer_manager_handler.h"
  #include "bsp_btn_ble.h"
  #include "FreeRTOS.h"
  #include "task.h"
  #include "timers.h"
  #include "semphr.h"
  #include "fds.h"
  #include "ble_conn_state.h"
  #include "nrf_drv_clock.h"
  #include "nrf_ble_gatt.h"
  #include "nrf_ble_qwr.h"
  
  #include "nrf_log.h"
  #include "nrf_log_ctrl.h"
  #include "nrf_log_default_backends.h"
  
  
  #define DEVICE_NAME                         "Nordic_HRM"                            /**< Name of device. Will be included in the advertising data. */
  #define MANUFACTURER_NAME                   "NordicSemiconductor"                   /**< 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 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 BATTERY_LEVEL_MEAS_INTERVAL         2000                                    /**< Battery level measurement interval (ms). */
  #define MIN_BATTERY_LEVEL                   81                                      /**< Minimum simulated battery level. */
  #define MAX_BATTERY_LEVEL                   100                                     /**< Maximum simulated battery level. */
  #define BATTERY_LEVEL_INCREMENT             1                                       /**< Increment between each simulated battery level measurement. */
  
  #define HEART_RATE_MEAS_INTERVAL            1000                                    /**< Heart rate measurement interval (ms). */
  #define MIN_HEART_RATE                      140                                     /**< Minimum heart rate as returned by the simulated measurement function. */
  #define MAX_HEART_RATE                      300                                     /**< Maximum heart rate as returned by the simulated measurement function. */
  #define HEART_RATE_INCREMENT                10                                      /**< Value by which the heart rate is incremented/decremented for each call to the simulated measurement function. */
  
  #define RR_INTERVAL_INTERVAL                300                                     /**< RR interval interval (ms). */
  #define MIN_RR_INTERVAL                     100                                     /**< Minimum RR interval as returned by the simulated measurement function. */
  #define MAX_RR_INTERVAL                     500                                     /**< Maximum RR interval as returned by the simulated measurement function. */
  #define RR_INTERVAL_INCREMENT               1                                       /**< Value by which the RR interval is incremented/decremented for each call to the simulated measurement function. */
  
  #define SENSOR_CONTACT_DETECTED_INTERVAL    5000                                    /**< Sensor Contact Detected toggle interval (ms). */
  
  #define MIN_CONN_INTERVAL                   MSEC_TO_UNITS(400, UNIT_1_25_MS)        /**< Minimum acceptable connection interval (0.4 seconds). */
  #define MAX_CONN_INTERVAL                   MSEC_TO_UNITS(650, UNIT_1_25_MS)        /**< Maximum acceptable connection interval (0.65 second). */
  #define SLAVE_LATENCY                       0                                       /**< Slave latency. */
  #define CONN_SUP_TIMEOUT                    MSEC_TO_UNITS(4000, UNIT_10_MS)         /**< Connection supervisory time-out (4 seconds). */
  
  #define FIRST_CONN_PARAMS_UPDATE_DELAY      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       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 DEAD_BEEF                           0xDEADBEEF                              /**< Value used as error code on stack dump, can be used to identify stack location on stack unwind. */
  
  #define OSTIMER_WAIT_FOR_QUEUE              2                                       /**< Number of ticks to wait for the timer queue to be ready */
  
  
  BLE_BAS_DEF(m_bas);                                                 /**< Battery service instance. */
  BLE_HRS_DEF(m_hrs);                                                 /**< Heart rate service instance. */
  NRF_BLE_GATT_DEF(m_gatt);                                           /**< GATT module instance. */
  NRF_BLE_QWR_DEF(m_qwr);                                             /**< Context for the Queued Write module.*/
  BLE_ADVERTISING_DEF(m_advertising);                                 /**< Advertising module instance. */
  
  static uint16_t m_conn_handle         = BLE_CONN_HANDLE_INVALID;    /**< Handle of the current connection. */
  static bool     m_rr_interval_enabled = true;                       /**< Flag for enabling and disabling the registration of new RR interval measurements (the purpose of disabling this is just to test sending HRM without RR interval data. */
  
  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 sensorsim_cfg_t   m_heart_rate_sim_cfg;                      /**< Heart Rate sensor simulator configuration. */
  static sensorsim_state_t m_heart_rate_sim_state;                    /**< Heart Rate sensor simulator state. */
  static sensorsim_cfg_t   m_rr_interval_sim_cfg;                     /**< RR Interval sensor simulator configuration. */
  static sensorsim_state_t m_rr_interval_sim_state;                   /**< RR Interval sensor simulator state. */
  
  static ble_uuid_t m_adv_uuids[] =                                   /**< Universally unique service identifiers. */
  {
      {BLE_UUID_HEART_RATE_SERVICE, BLE_UUID_TYPE_BLE},
      {BLE_UUID_BATTERY_SERVICE, BLE_UUID_TYPE_BLE},
      {BLE_UUID_DEVICE_INFORMATION_SERVICE, BLE_UUID_TYPE_BLE}
  };
  
  static TimerHandle_t m_battery_timer;                               /**< Definition of battery timer. */
  static TimerHandle_t m_heart_rate_timer;                            /**< Definition of heart rate timer. */
  static TimerHandle_t m_rr_interval_timer;                           /**< Definition of RR interval timer. */
  static TimerHandle_t m_sensor_contact_timer;                        /**< Definition of sensor contact detected timer. */
  
  #if NRF_LOG_ENABLED
  static TaskHandle_t m_logger_thread;                                /**< Definition of Logger thread. */
  #endif
  
  static void advertising_start(void * p_erase_bonds);
  
  
  /**@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 handling Peer Manager events.
   *
   * @param[in] p_evt  Peer Manager event.
   */
  static void pm_evt_handler(pm_evt_t const * p_evt)
  {
      bool delete_bonds = false;
  
      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(&delete_bonds);
              break;
  
          default:
              break;
      }
  }
  
  
  /**@brief Function for performing battery measurement and updating the Battery Level characteristic
   *        in 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_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 Battery measurement timer time-out.
   *
   * @details This function will be called each time the battery level measurement timer expires.
   *
   * @param[in] xTimer Handler to the timer that called this function.
   *                   You may get identifier given to the function xTimerCreate using pvTimerGetTimerID.
   */
  static void battery_level_meas_timeout_handler(TimerHandle_t xTimer)
  {
      UNUSED_PARAMETER(xTimer);
      battery_level_update();
  }
  
  
  /**@brief Function for handling the Heart rate measurement timer time-out.
   *
   * @details This function will be called each time the heart rate measurement timer expires.
   *          It will exclude RR Interval data from every third measurement.
   *
   * @param[in] xTimer Handler to the timer that called this function.
   *                   You may get identifier given to the function xTimerCreate using pvTimerGetTimerID.
   */
  static void heart_rate_meas_timeout_handler(TimerHandle_t xTimer)
  {
      static uint32_t cnt = 0;
      ret_code_t      err_code;
      uint16_t        heart_rate;
  
      UNUSED_PARAMETER(xTimer);
  
      heart_rate = (uint16_t)sensorsim_measure(&m_heart_rate_sim_state, &m_heart_rate_sim_cfg);
  
      cnt++;
      err_code = ble_hrs_heart_rate_measurement_send(&m_hrs, heart_rate);
      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);
      }
  
      // Disable RR Interval recording every third heart rate measurement.
      // NOTE: An application will normally not do this. It is done here just for testing generation
      // of messages without RR Interval measurements.
      m_rr_interval_enabled = ((cnt % 3) != 0);
  }
  
  
  /**@brief Function for handling the RR interval timer time-out.
   *
   * @details This function will be called each time the RR interval timer expires.
   *
   * @param[in] xTimer Handler to the timer that called this function.
   *                   You may get identifier given to the function xTimerCreate using pvTimerGetTimerID.
   */
  static void rr_interval_timeout_handler(TimerHandle_t xTimer)
  {
      UNUSED_PARAMETER(xTimer);
  
      if (m_rr_interval_enabled)
      {
          uint16_t rr_interval;
  
          rr_interval = (uint16_t)sensorsim_measure(&m_rr_interval_sim_state,
                                                    &m_rr_interval_sim_cfg);
          ble_hrs_rr_interval_add(&m_hrs, rr_interval);
      }
  }
  
  
  /**@brief Function for handling the Sensor Contact Detected timer time-out.
   *
   * @details This function will be called each time the Sensor Contact Detected timer expires.
   *
   * @param[in] xTimer Handler to the timer that called this function.
   *                   You may get identifier given to the function xTimerCreate using pvTimerGetTimerID.
   */
  static void sensor_contact_detected_timeout_handler(TimerHandle_t xTimer)
  {
      static bool sensor_contact_detected = false;
  
      UNUSED_PARAMETER(xTimer);
  
      sensor_contact_detected = !sensor_contact_detected;
      ble_hrs_sensor_contact_detected_update(&m_hrs, sensor_contact_detected);
  }
  
  
  /**@brief Function for the Timer initialization.
   *
   * @details Initializes the timer module. This creates and starts application timers.
   */
  static void timers_init(void)
  {
      // Initialize timer module.
      ret_code_t err_code = app_timer_init();
      APP_ERROR_CHECK(err_code);
  
      // Create timers.
      m_battery_timer = xTimerCreate("BATT",
                                     BATTERY_LEVEL_MEAS_INTERVAL,
                                     pdTRUE,
                                     NULL,
                                     battery_level_meas_timeout_handler);
      m_heart_rate_timer = xTimerCreate("HRT",
                                        HEART_RATE_MEAS_INTERVAL,
                                        pdTRUE,
                                        NULL,
                                        heart_rate_meas_timeout_handler);
      m_rr_interval_timer = xTimerCreate("RRT",
                                         RR_INTERVAL_INTERVAL,
                                         pdTRUE,
                                         NULL,
                                         rr_interval_timeout_handler);
      m_sensor_contact_timer = xTimerCreate("SCT",
                                            SENSOR_CONTACT_DETECTED_INTERVAL,
                                            pdTRUE,
                                            NULL,
                                            sensor_contact_detected_timeout_handler);
  
      /* Error checking */
      if ( (NULL == m_battery_timer)
           || (NULL == m_heart_rate_timer)
           || (NULL == m_rr_interval_timer)
           || (NULL == m_sensor_contact_timer) )
      {
          APP_ERROR_HANDLER(NRF_ERROR_NO_MEM);
      }
  }
  
  
  /**@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_HEART_RATE_SENSOR_HEART_RATE_BELT);
      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 services that will 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_bas_init_t     bas_init;
      ble_dis_init_t     dis_init;
      nrf_ble_qwr_init_t qwr_init = {0};
      uint8_t            body_sensor_location;
  
      // Initialize Queued Write Module.
      qwr_init.error_handler = nrf_qwr_error_handler;
  
      err_code = nrf_ble_qwr_init(&m_qwr, &qwr_init);
      APP_ERROR_CHECK(err_code);
  
      // Initialize 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/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);
  
      // Initialize Battery Service.
      memset(&bas_init, 0, sizeof(bas_init));
  
      // Here the sec level for the Battery Service can be changed/increased.
      bas_init.bl_rd_sec        = SEC_OPEN;
      bas_init.bl_cccd_wr_sec   = SEC_OPEN;
      bas_init.bl_report_rd_sec = SEC_OPEN;
  
      bas_init.evt_handler          = NULL;
      bas_init.support_notification = true;
      bas_init.p_report_ref         = NULL;
      bas_init.initial_batt_level   = 100;
  
      err_code = ble_bas_init(&m_bas, &bas_init);
      APP_ERROR_CHECK(err_code);
  
      // Initialize Device Information Service.
      memset(&dis_init, 0, sizeof(dis_init));
  
      ble_srv_ascii_to_utf8(&dis_init.manufact_name_str, (char *)MANUFACTURER_NAME);
  
      dis_init.dis_char_rd_sec = SEC_OPEN;
  
      err_code = ble_dis_init(&dis_init);
      APP_ERROR_CHECK(err_code);
  }
  
  
  /**@brief Function for initializing the sensor simulators. */
  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);
  
      m_heart_rate_sim_cfg.min          = MIN_HEART_RATE;
      m_heart_rate_sim_cfg.max          = MAX_HEART_RATE;
      m_heart_rate_sim_cfg.incr         = HEART_RATE_INCREMENT;
      m_heart_rate_sim_cfg.start_at_max = false;
  
      sensorsim_init(&m_heart_rate_sim_state, &m_heart_rate_sim_cfg);
  
      m_rr_interval_sim_cfg.min          = MIN_RR_INTERVAL;
      m_rr_interval_sim_cfg.max          = MAX_RR_INTERVAL;
      m_rr_interval_sim_cfg.incr         = RR_INTERVAL_INCREMENT;
      m_rr_interval_sim_cfg.start_at_max = false;
  
      sensorsim_init(&m_rr_interval_sim_state, &m_rr_interval_sim_cfg);
  }
  
  
  /**@brief   Function for starting application timers.
   * @details Timers are run after the scheduler has started.
   */
  static void application_timers_start(void)
  {
      // Start application timers.
      if (pdPASS != xTimerStart(m_battery_timer, OSTIMER_WAIT_FOR_QUEUE))
      {
          APP_ERROR_HANDLER(NRF_ERROR_NO_MEM);
      }
      if (pdPASS != xTimerStart(m_heart_rate_timer, OSTIMER_WAIT_FOR_QUEUE))
      {
          APP_ERROR_HANDLER(NRF_ERROR_NO_MEM);
      }
      if (pdPASS != xTimerStart(m_rr_interval_timer, OSTIMER_WAIT_FOR_QUEUE))
      {
          APP_ERROR_HANDLER(NRF_ERROR_NO_MEM);
      }
      if (pdPASS != xTimerStart(m_sensor_contact_timer, OSTIMER_WAIT_FOR_QUEUE))
      {
          APP_ERROR_HANDLER(NRF_ERROR_NO_MEM);
      }
  }
  
  
  /**@brief Function for handling the Connection Parameters Module.
   *
   * @details This function will be called for all events in the Connection Parameters Module which
   *          are passed to the application.
   *          @note All this function does is to disconnect. This could have been done by simply
   *                setting the disconnect_on_fail config parameter, but instead we use the event
   *                handler mechanism to demonstrate its use.
   *
   * @param[in]   p_evt   Event received from the Connection Parameters Module.
   */
  static void on_conn_params_evt(ble_conn_params_evt_t * p_evt)
  {
      ret_code_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 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    = m_hrs.hrm_handles.cccd_handle;
      cp_init.disconnect_on_fail             = false;
      cp_init.evt_handler                    = on_conn_params_evt;
      cp_init.error_handler                  = conn_params_error_handler;
  
      err_code = ble_conn_params_init(&cp_init);
      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 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)
  {
      uint32_t err_code;
  
      switch (ble_adv_evt)
      {
          case BLE_ADV_EVT_FAST:
              NRF_LOG_INFO("Fast advertising.");
              err_code = bsp_indication_set(BSP_INDICATE_ADVERTISING);
              APP_ERROR_CHECK(err_code);
              break;
  
          case BLE_ADV_EVT_IDLE:
              sleep_mode_enter();
              break;
  
          default:
              break;
      }
  }
  
  
  /**@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)
  {
      uint32_t err_code;
  
      switch (p_ble_evt->header.evt_id)
      {
          case BLE_GAP_EVT_CONNECTED:
              NRF_LOG_INFO("Connected");
              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);
              break;
  
          case BLE_GAP_EVT_DISCONNECTED:
              NRF_LOG_INFO("Disconnected");
              m_conn_handle = BLE_CONN_HANDLE_INVALID;
              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 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 handling events from the BSP module.
   *
   * @param[in]   event   Event generated by button press.
   */
  static void bsp_event_handler(bsp_event_t event)
  {
      ret_code_t err_code;
  
      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;
  
          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 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 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 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 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 starting advertising. */
  static void advertising_start(void * p_erase_bonds)
  {
      bool erase_bonds = *(bool*)p_erase_bonds;
  
      if (erase_bonds)
      {
          delete_bonds();
          // Advertising is started by PM_EVT_PEERS_DELETE_SUCCEEDED event.
      }
      else
      {
          ret_code_t err_code = ble_advertising_start(&m_advertising, BLE_ADV_MODE_FAST);
          APP_ERROR_CHECK(err_code);
      }
  }
  
  
  #if NRF_LOG_ENABLED
  /**@brief Thread for handling the logger.
   *
   * @details This thread is responsible for processing log entries if logs are deferred.
   *          Thread flushes all log entries and suspends. It is resumed by idle task hook.
   *
   * @param[in]   arg   Pointer used for passing some arbitrary information (context) from the
   *                    osThreadCreate() call to the thread.
   */
  static void logger_thread(void * arg)
  {
      UNUSED_PARAMETER(arg);
  
      while (1)
      {
          NRF_LOG_FLUSH();
  
          vTaskSuspend(NULL); // Suspend myself
      }
  }
  #endif //NRF_LOG_ENABLED
  
  /**@brief A function which is hooked to idle task.
   * @note Idle hook must be enabled in FreeRTOS configuration (configUSE_IDLE_HOOK).
   */
  void vApplicationIdleHook( void )
  {
  #if NRF_LOG_ENABLED
       vTaskResume(m_logger_thread);
  #endif
  }
  
  
  /**@brief Function for initializing the clock.
   */
  static void clock_init(void)
  {
      ret_code_t err_code = nrf_drv_clock_init();
      APP_ERROR_CHECK(err_code);
  }
  
  
  /**@brief Function for application main entry.
   */
  int main(void)
  {
      bool erase_bonds;
  
      // Initialize modules.
      log_init();
      clock_init();
  
      // Do not start any interrupt that uses system functions before system initialisation.
      // The best solution is to start the OS before any other initalisation.
  
  #if NRF_LOG_ENABLED
      // Start execution.
      if (pdPASS != xTaskCreate(logger_thread, "LOGGER", 256, NULL, 1, &m_logger_thread))
      {
          APP_ERROR_HANDLER(NRF_ERROR_NO_MEM);
      }
  #endif
  
      // Activate deep sleep mode.
      SCB->SCR |= SCB_SCR_SLEEPDEEP_Msk;
  
      // Configure and initialize the BLE stack.
      ble_stack_init();
  
      // Initialize modules.
      timers_init();
      buttons_leds_init(&erase_bonds);
      gap_params_init();
      gatt_init();
      advertising_init();
      services_init();
      sensor_simulator_init();
      conn_params_init();
      peer_manager_init();
      application_timers_start();
  
      // Create a FreeRTOS task for the BLE stack.
      // The task will run advertising_start() before entering its loop.
      nrf_sdh_freertos_init(advertising_start, &erase_bonds);
  
      NRF_LOG_INFO("HRS FreeRTOS example started.");
      // Start FreeRTOS scheduler.
      vTaskStartScheduler();
  
      for (;;)
      {
          APP_ERROR_HANDLER(NRF_ERROR_FORBIDDEN);
      }
  }
  
  
  