one_lead_electrocardiograph/app/main.c

/**
 * Copyright (c) 2014 - 2021, 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.
 *
 */
/** @file
 *
 * @defgroup ble_sdk_uart_over_ble_main main.c
 * @{
 * @ingroup  ble_sdk_app_nus_eval
 * @brief    UART over BLE application main file.
 *
 * This file contains the source code for a sample application that uses the Nordic UART service.
 * This application uses the @ref srvlib_conn_params module.
 */

#include <stdint.h>
#include <string.h>

#include "app_timer.h"
#include "app_uart.h"
#include "app_util_platform.h"
#include "ble_advdata.h"
#include "ble_advertising.h"
#include "ble_conn_params.h"
#include "ble_hci.h"
#include "ble_nus.h"
#include "bsp_btn_ble.h"
#include "nordic_common.h"
#include "nrf.h"
#include "nrf_ble_gatt.h"
#include "nrf_ble_qwr.h"
#include "nrf_pwr_mgmt.h"
#include "nrf_sdh.h"
#include "nrf_sdh_ble.h"
#include "nrf_sdh_soc.h"

#if defined(UART_PRESENT)
#include "nrf_uart.h"
#endif
#if defined(UARTE_PRESENT)
#include "nrf_uarte.h"
#endif

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

#define APP_BLE_CONN_CFG_TAG 1 /**< A tag identifying the SoftDevice BLE configuration. */

#define DEVICE_NAME           "Nordic_UART"              /**< Name of device. Will be included in the advertising data. */
#define NUS_SERVICE_UUID_TYPE BLE_UUID_TYPE_VENDOR_BEGIN /**< UUID type for the Nordic UART Service (vendor specific). */

#define APP_BLE_OBSERVER_PRIO 3 /**< Application's BLE observer priority. You shouldn't need to modify this value. */

#define APP_ADV_INTERVAL 64 /**< The advertising interval (in units of 0.625 ms. This value corresponds to 40 ms). */

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

#define MIN_CONN_INTERVAL              MSEC_TO_UNITS(20, UNIT_1_25_MS) /**< Minimum acceptable connection interval (20 ms), Connection interval uses 1.25 ms units. */
#define MAX_CONN_INTERVAL              MSEC_TO_UNITS(75, UNIT_1_25_MS) /**< Maximum acceptable connection interval (75 ms), Connection interval uses 1.25 ms units. */
#define SLAVE_LATENCY                  0                               /**< Slave latency. */
#define CONN_SUP_TIMEOUT               MSEC_TO_UNITS(4000, UNIT_10_MS) /**< Connection supervisory timeout (4 seconds), Supervision Timeout uses 10 ms units. */
#define FIRST_CONN_PARAMS_UPDATE_DELAY APP_TIMER_TICKS(5000)           /**< Time from initiating event (connect or start of notification) to first time sd_ble_gap_conn_param_update is called (5 seconds). */
#define NEXT_CONN_PARAMS_UPDATE_DELAY  APP_TIMER_TICKS(30000)          /**< Time between each call to sd_ble_gap_conn_param_update after the first call (30 seconds). */
#define MAX_CONN_PARAMS_UPDATE_COUNT   3                               /**< Number of attempts before giving up the connection parameter negotiation. */

#define DEAD_BEEF 0xDEADBEEF /**< Value used as error code on stack dump, can be used to identify stack location on stack unwind. */

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

BLE_NUS_DEF(m_nus, NRF_SDH_BLE_TOTAL_LINK_COUNT); /**< BLE NUS 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 uint16_t   m_ble_nus_max_data_len = BLE_GATT_ATT_MTU_DEFAULT - 3; /**< Maximum length of data (in bytes) that can be transmitted to the peer by the Nordic UART service module. */
static ble_uuid_t m_adv_uuids[]          =                               /**< Universally unique service identifier. */
    {{BLE_UUID_NUS_SERVICE, NUS_SERVICE_UUID_TYPE}};

/**@brief Function for assert macro callback.
 *
 * @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 analyse
 *          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(DEAD_BEEF, line_num, p_file_name); }

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

/**@brief Function for the GAP initialization.
 *
 * @details This function will set up all the necessary GAP (Generic Access Profile) parameters of
 *          the device. It also sets the permissions and appearance.
 */
static void gap_params_init(void) {
  uint32_t                err_code;
  ble_gap_conn_params_t   gap_conn_params;
  ble_gap_conn_sec_mode_t sec_mode;

  BLE_GAP_CONN_SEC_MODE_SET_OPEN(&sec_mode);

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

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

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

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

/**@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 handling the data from the Nordic UART Service.
 *
 * @details This function will process the data received from the Nordic UART BLE Service and send
 *          it to the UART module.
 *
 * @param[in] p_evt       Nordic UART Service event.
 */
/**@snippet [Handling the data received over BLE] */
static void nus_data_handler(ble_nus_evt_t *p_evt) {
  if (p_evt->type == BLE_NUS_EVT_RX_DATA) {
    uint32_t err_code;

    NRF_LOG_DEBUG("Received data from BLE NUS. Writing data on UART.");
    NRF_LOG_HEXDUMP_DEBUG(p_evt->params.rx_data.p_data, p_evt->params.rx_data.length);

    for (uint32_t i = 0; i < p_evt->params.rx_data.length; i++) {
      do {
        err_code = app_uart_put(p_evt->params.rx_data.p_data[i]);
        if ((err_code != NRF_SUCCESS) && (err_code != NRF_ERROR_BUSY)) {
          NRF_LOG_ERROR("Failed receiving NUS message. Error 0x%x. ", err_code);
          APP_ERROR_CHECK(err_code);
        }
      } while (err_code == NRF_ERROR_BUSY);
    }
    if (p_evt->params.rx_data.p_data[p_evt->params.rx_data.length - 1] == '\r') {
      while (app_uart_put('\n') == NRF_ERROR_BUSY)
        ;
    }
  }
}
/**@snippet [Handling the data received over BLE] */

/**@brief Function for initializing services that will be used by the application.
 */
static void services_init(void) {
  uint32_t           err_code;
  ble_nus_init_t     nus_init;
  nrf_ble_qwr_init_t qwr_init = {0};

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

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

  // Initialize NUS.
  memset(&nus_init, 0, sizeof(nus_init));

  nus_init.data_handler = nus_data_handler;

  err_code = ble_nus_init(&m_nus, &nus_init);
  APP_ERROR_CHECK(err_code);
}

/**@brief Function for handling an event from 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) {
  uint32_t err_code;

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

/**@brief Function for 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); }

/**@brief Function for initializing the Connection Parameters module.
 */
static void conn_params_init(void) {
  uint32_t               err_code;
  ble_conn_params_init_t cp_init;

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

  cp_init.p_conn_params                  = NULL;
  cp_init.first_conn_params_update_delay = FIRST_CONN_PARAMS_UPDATE_DELAY;
  cp_init.next_conn_params_update_delay  = NEXT_CONN_PARAMS_UPDATE_DELAY;
  cp_init.max_conn_params_update_count   = MAX_CONN_PARAMS_UPDATE_COUNT;
  cp_init.start_on_notify_cccd_handle    = BLE_GATT_HANDLE_INVALID;
  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) {
  uint32_t 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:
      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");
      // LED indication will be changed when advertising starts.
      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_GAP_EVT_SEC_PARAMS_REQUEST:
      // Pairing not supported
      err_code = sd_ble_gap_sec_params_reply(m_conn_handle, BLE_GAP_SEC_STATUS_PAIRING_NOT_SUPP, NULL, NULL);
      APP_ERROR_CHECK(err_code);
      break;

    case BLE_GATTS_EVT_SYS_ATTR_MISSING:
      // No system attributes have been stored.
      err_code = sd_ble_gatts_sys_attr_set(m_conn_handle, NULL, 0, 0);
      APP_ERROR_CHECK(err_code);
      break;

    case BLE_GATTC_EVT_TIMEOUT:
      // Disconnect on GATT Client timeout event.
      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.
      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 the SoftDevice initialization.
 *
 * @details This function 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 GATT library. */
void gatt_evt_handler(nrf_ble_gatt_t *p_gatt, nrf_ble_gatt_evt_t const *p_evt) {
  if ((m_conn_handle == p_evt->conn_handle) && (p_evt->evt_id == NRF_BLE_GATT_EVT_ATT_MTU_UPDATED)) {
    m_ble_nus_max_data_len = p_evt->params.att_mtu_effective - OPCODE_LENGTH - HANDLE_LENGTH;
    NRF_LOG_INFO("Data len is set to 0x%X(%d)", m_ble_nus_max_data_len, m_ble_nus_max_data_len);
  }
  NRF_LOG_DEBUG("ATT MTU exchange completed. central 0x%x peripheral 0x%x", p_gatt->att_mtu_desired_central, p_gatt->att_mtu_desired_periph);
}

/**@brief Function for initializing the GATT library. */
void gatt_init(void) {
  ret_code_t err_code;

  err_code = nrf_ble_gatt_init(&m_gatt, gatt_evt_handler);
  APP_ERROR_CHECK(err_code);

  err_code = nrf_ble_gatt_att_mtu_periph_set(&m_gatt, NRF_SDH_BLE_GATT_MAX_MTU_SIZE);
  APP_ERROR_CHECK(err_code);
}

/**@brief Function for handling events from the BSP module.
 *
 * @param[in]   event   Event generated by button press.
 */
void bsp_event_handler(bsp_event_t event) {
  uint32_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 handling app_uart events.
 *
 * @details This function will receive a single character from the app_uart module and append it to
 *          a string. The string will be be sent over BLE when the last character received was a
 *          'new line' '\n' (hex 0x0A) or if the string has reached the maximum data length.
 */
/**@snippet [Handling the data received over UART] */
void uart_event_handle(app_uart_evt_t *p_event) {
  static uint8_t data_array[BLE_NUS_MAX_DATA_LEN];
  static uint8_t index = 0;
  uint32_t       err_code;

  switch (p_event->evt_type) {
    case APP_UART_DATA_READY:
      UNUSED_VARIABLE(app_uart_get(&data_array[index]));
      index++;

      if ((data_array[index - 1] == '\n') || (data_array[index - 1] == '\r') || (index >= m_ble_nus_max_data_len)) {
        if (index > 1) {
          NRF_LOG_DEBUG("Ready to send data over BLE NUS");
          NRF_LOG_HEXDUMP_DEBUG(data_array, index);

          do {
            uint16_t length = (uint16_t)index;
            err_code        = ble_nus_data_send(&m_nus, data_array, &length, m_conn_handle);
            if ((err_code != NRF_ERROR_INVALID_STATE) && (err_code != NRF_ERROR_RESOURCES) && (err_code != NRF_ERROR_NOT_FOUND)) {
              APP_ERROR_CHECK(err_code);
            }
          } while (err_code == NRF_ERROR_RESOURCES);
        }

        index = 0;
      }
      break;

    case APP_UART_COMMUNICATION_ERROR:
      APP_ERROR_HANDLER(p_event->data.error_communication);
      break;

    case APP_UART_FIFO_ERROR:
      APP_ERROR_HANDLER(p_event->data.error_code);
      break;

    default:
      break;
  }
}
/**@snippet [Handling the data received over UART] */

/**@brief  Function for initializing the UART module.
 */
/**@snippet [UART Initialization] */
static void uart_init(void) {
  uint32_t                     err_code;
  app_uart_comm_params_t const comm_params = {
    .rx_pin_no    = RX_PIN_NUMBER,
    .tx_pin_no    = TX_PIN_NUMBER,
    .rts_pin_no   = RTS_PIN_NUMBER,
    .cts_pin_no   = CTS_PIN_NUMBER,
    .flow_control = APP_UART_FLOW_CONTROL_DISABLED,
    .use_parity   = false,
#if defined(UART_PRESENT)
    .baud_rate = NRF_UART_BAUDRATE_115200
#else
    .baud_rate = NRF_UARTE_BAUDRATE_115200
#endif
  };

  APP_UART_FIFO_INIT(&comm_params, UART_RX_BUF_SIZE, UART_TX_BUF_SIZE, uart_event_handle, APP_IRQ_PRIORITY_LOWEST, err_code);
  APP_ERROR_CHECK(err_code);
}
/**@snippet [UART Initialization] */

/**@brief Function for initializing the Advertising functionality.
 */
static void advertising_init(void) {
  uint32_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 = false;
  init.advdata.flags              = BLE_GAP_ADV_FLAGS_LE_ONLY_LIMITED_DISC_MODE;

  init.srdata.uuids_complete.uuid_cnt = sizeof(m_adv_uuids) / sizeof(m_adv_uuids[0]);
  init.srdata.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 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) {
  bsp_event_t startup_event;

  uint32_t 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 initializing the nrf log module.
 */
static void log_init(void) {
  ret_code_t err_code = NRF_LOG_INIT(NULL);
  APP_ERROR_CHECK(err_code);

  NRF_LOG_DEFAULT_BACKENDS_INIT();
}

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

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

/**@brief Function for starting advertising.
 */
static void advertising_start(void) {
  uint32_t err_code = ble_advertising_start(&m_advertising, BLE_ADV_MODE_FAST);
  APP_ERROR_CHECK(err_code);
}

/**@brief Application main function.
 */
int main(void) {
  bool erase_bonds;
  // Initialize.
  uart_init();
  log_init();

  timers_init();
  buttons_leds_init(&erase_bonds);
  power_management_init();
  ble_stack_init();
  gap_params_init();
  gatt_init();
  services_init();
  advertising_init();
  conn_params_init();

  // Start execution.
  printf("\r\nUART started.\r\n");
  NRF_LOG_INFO("Debug logging for UART over RTT started.");
  advertising_start();

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

/**
 * @}
 */