This post is older than 2 years and might not be relevant anymore
More Info: Consider searching for newer posts

HID over GATT

Hi,

I'm referring to -

1. Custom HID over GATT device

2. nRF51422 HID example modification

So for now, I just used the descriptor mentioned in above links. But "hello" is not getting printed on the notepad. Here is my code

#include <stdint.h>
#include <string.h>
#include "nordic_common.h"
#include "nrf.h"
#include "nrf_assert.h"
#include "app_error.h"
#include "ble.h"
#include "ble_err.h"
#include "ble_hci.h"
#include "ble_srv_common.h"
#include "ble_advertising.h"
#include "ble_advdata.h"
#include "ble_hids.h"
#include "ble_bas.h"
#include "ble_dis.h"
#include "ble_conn_params.h"
#include "sensorsim.h"
#include "bsp_btn_ble.h"
#include "app_scheduler.h"
#include "nrf_sdh.h"
#include "nrf_sdh_soc.h"
#include "nrf_sdh_ble.h"
#include "app_timer.h"
#include "peer_manager.h"
#include "fds.h"
#include "ble_conn_state.h"
#include "nrf_ble_gatt.h"
#include "nrf_ble_qwr.h"
#include "nrf_pwr_mgmt.h"
#include "nrf_log.h"
#include "nrf_log_ctrl.h"
#include "nrf_log_default_backends.h"

#define SHIFT_BUTTON_ID                     1                                          /**< Button used as 'SHIFT' Key. */
#define DEVICE_NAME                         "Nordic_Keyboard"                          /**< 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 BATTERY_LEVEL_MEAS_INTERVAL         APP_TIMER_TICKS(2000)                      /**< Battery level measurement interval (ticks). */
#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 PNP_ID_VENDOR_ID_SOURCE             0x02                                       /**< Vendor ID Source. */
#define PNP_ID_VENDOR_ID                    0x1915                                     /**< Vendor ID. */
#define PNP_ID_PRODUCT_ID                   0xEEEE                                     /**< Product ID. */
#define PNP_ID_PRODUCT_VERSION              0x0001                                     /**< Product Version. */
#define APP_ADV_FAST_INTERVAL               0x0028                                     /**< Fast advertising interval (in units of 0.625 ms. This value corresponds to 25 ms.). */
#define APP_ADV_SLOW_INTERVAL               0x0C80                                     /**< Slow advertising interval (in units of 0.625 ms. This value corrsponds to 2 seconds). */
#define APP_ADV_FAST_DURATION               3000                                       /**< The advertising duration of fast advertising in units of 10 milliseconds. */
#define APP_ADV_SLOW_DURATION               18000                                      /**< The advertising duration of slow advertising in units of 10 milliseconds. */

/*lint -emacro(524, MIN_CONN_INTERVAL) // Loss of precision */
#define MIN_CONN_INTERVAL                   MSEC_TO_UNITS(7.5, UNIT_1_25_MS)           /**< Minimum connection interval (7.5 ms) */
#define MAX_CONN_INTERVAL                   MSEC_TO_UNITS(30, UNIT_1_25_MS)            /**< Maximum connection interval (30 ms). */
#define SLAVE_LATENCY                       6                                          /**< Slave latency. */
#define CONN_SUP_TIMEOUT                    MSEC_TO_UNITS(430, UNIT_10_MS)             /**< Connection supervisory timeout (430 ms). */

#define FIRST_CONN_PARAMS_UPDATE_DELAY      APP_TIMER_TICKS(5000)                      /**< Time from initiating event (connect or start of notification) to first time sd_ble_gap_conn_param_update is called (5 seconds). */
#define NEXT_CONN_PARAMS_UPDATE_DELAY       APP_TIMER_TICKS(30000)                     /**< Time between each call to sd_ble_gap_conn_param_update after the first call (30 seconds). */
#define MAX_CONN_PARAMS_UPDATE_COUNT        3                                          /**< Number of attempts before giving up the connection parameter negotiation. */
#define SEC_PARAM_BOND                      1                                          /**< Perform bonding. */
#define SEC_PARAM_MITM                      0                                          /**< Man In The Middle protection not required. */
#define SEC_PARAM_LESC                      0                                          /**< LE Secure Connections not enabled. */
#define SEC_PARAM_KEYPRESS                  0                                          /**< Keypress notifications not enabled. */
#define SEC_PARAM_IO_CAPABILITIES           BLE_GAP_IO_CAPS_NONE                       /**< No I/O capabilities. */
#define SEC_PARAM_OOB                       0                                          /**< Out Of Band data not available. */
#define SEC_PARAM_MIN_KEY_SIZE              7                                          /**< Minimum encryption key size. */
#define SEC_PARAM_MAX_KEY_SIZE              16                                         /**< Maximum encryption key size. */
#define OUTPUT_REPORT_INDEX                 0                                          /**< Index of Output Report. */
#define OUTPUT_REPORT_MAX_LEN               1//22                                          /**< Maximum length of Output Report. */
#define INPUT_REPORT_KEYS_INDEX             0                                          /**< Index of Input Report. */
#define OUTPUT_REPORT_BIT_MASK_CAPS_LOCK    0x02                                       /**< CAPS LOCK bit in Output Report (based on 'LED Page (0x08)' of the Universal Serial Bus HID Usage Tables). */
#define INPUT_REP_REF_ID                    0                                          /**< Id of reference to Keyboard Input Report. */
#define OUTPUT_REP_REF_ID                   0                                          /**< Id of reference to Keyboard Output Report. */
#define MAX_BUFFER_ENTRIES                  5                                          /**< Number of elements that can be enqueued */
#define BASE_USB_HID_SPEC_VERSION           0x0101                                     /**< Version number of base USB HID Specification implemented by this application. */
#define INPUT_REPORT_KEYS_MAX_LEN           8//20                                          /**< Maximum length of the Input Report characteristic. */
#define DEAD_BEEF                           0xDEADBEEF                                 /**< Value used as error code on stack dump, can be used to identify stack location on stack unwind. */
#define SCHED_MAX_EVENT_DATA_SIZE           APP_TIMER_SCHED_EVENT_DATA_SIZE            /**< Maximum size of scheduler events. */
#ifdef SVCALL_AS_NORMAL_FUNCTION
#define SCHED_QUEUE_SIZE                    20                                         /**< Maximum number of events in the scheduler queue. More is needed in case of Serialization. */
#else
#define SCHED_QUEUE_SIZE                    10                                         /**< Maximum number of events in the scheduler queue. */
#endif
#define MODIFIER_KEY_POS                    0                                          /**< Position of the modifier byte in the Input Report. */
#define SCAN_CODE_POS                       2                                          /**< The start position of the key scan code in a HID Report. */
#define SHIFT_KEY_CODE                      0x02                                       /**< Key code indicating the press of the Shift Key. */
#define MAX_KEYS_IN_ONE_REPORT              (INPUT_REPORT_KEYS_MAX_LEN - SCAN_CODE_POS)/**< Maximum number of key presses that can be sent in one Input Report. */

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

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

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

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

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

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

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

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

APP_TIMER_DEF(m_battery_timer_id);                                  /**< Battery timer. */
BLE_HIDS_DEF(m_hids,                                                /**< Structure used to identify the HID service. */
             NRF_SDH_BLE_TOTAL_LINK_COUNT,
             INPUT_REPORT_KEYS_MAX_LEN,
             OUTPUT_REPORT_MAX_LEN);
BLE_BAS_DEF(m_bas);                                                 /**< Structure used to identify the battery service. */
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 bool              m_in_boot_mode = false;                    /**< Current protocol mode. */
static uint16_t          m_conn_handle  = BLE_CONN_HANDLE_INVALID;  /**< Handle of the current connection. */
static sensorsim_cfg_t   m_battery_sim_cfg;                         /**< Battery Level sensor simulator configuration. */
static sensorsim_state_t m_battery_sim_state;                       /**< Battery Level sensor simulator state. */
static bool              m_caps_on = false;                         /**< Variable to indicate if Caps Lock is turned on. */
static pm_peer_id_t      m_peer_id;                                 /**< Device reference handle to the current bonded central. */
static uint32_t          m_whitelist_peer_cnt;                      /**< Number of peers currently in the whitelist. */
static buffer_list_t     buffer_list;                               /**< List to enqueue not just data to be sent, but also related information like the handle, connection handle etc */
static pm_peer_id_t      m_whitelist_peers[BLE_GAP_WHITELIST_ADDR_MAX_COUNT];   /**< List of peers currently in the whitelist. */

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

static uint8_t m_sample_key_press_scan_str[] = /**< Key pattern to be sent when the key press button has been pushed. */
{
    0x0b,       /* Key h */
    0x08,       /* Key e */
    0x0f,       /* Key l */
    0x0f,       /* Key l */
    0x12,       /* Key o */
    0x28        /* Key Return */
};

static uint8_t m_caps_on_key_scan_str[] = /**< Key pattern to be sent when the output report has been written with the CAPS LOCK bit set. */
{
    0x06,       /* Key C */
    0x04,       /* Key a */
    0x13,       /* Key p */
    0x16,       /* Key s */
    0x12,       /* Key o */
    0x11,       /* Key n */
};

static uint8_t m_caps_off_key_scan_str[] = /**< Key pattern to be sent when the output report has been written with the CAPS LOCK bit cleared. */
{
    0x06,       /* Key C */
    0x04,       /* Key a */
    0x13,       /* Key p */
    0x16,       /* Key s */
    0x12,       /* Key o */
    0x09,       /* Key f */
};

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

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

/**@brief Fetch the list of peer manager peer IDs.
 * @param[inout] p_peers   The buffer where to store the list of peer IDs.
 * @param[inout] p_size    In: The size of the @p p_peers buffer.
 *                         Out: The number of peers copied in the buffer. */
static void peer_list_get(pm_peer_id_t * p_peers, uint32_t * p_size)
{
    pm_peer_id_t peer_id;
    uint32_t     peers_to_copy;
    peers_to_copy = (*p_size < BLE_GAP_WHITELIST_ADDR_MAX_COUNT) ? *p_size : BLE_GAP_WHITELIST_ADDR_MAX_COUNT;
    peer_id = pm_next_peer_id_get(PM_PEER_ID_INVALID);
    *p_size = 0;
    while ((peer_id != PM_PEER_ID_INVALID) && (peers_to_copy--))
    {
        p_peers[(*p_size)++] = peer_id;
        peer_id = pm_next_peer_id_get(peer_id);
    }
}

/**@brief Clear bond information from persistent storage. */
static void delete_bonds(void)
{
    ret_code_t err_code;
    NRF_LOG_INFO("Erase bonds!");
    err_code = pm_peers_delete();
    APP_ERROR_CHECK(err_code);
}

/**@brief Function for starting advertising. */
static void advertising_start(bool erase_bonds)
{
    if (erase_bonds == true)
    {
        delete_bonds();         // Advertising is started by PM_EVT_PEERS_DELETE_SUCCEEDED event.
    }
    else
    {
        ret_code_t ret;
        memset(m_whitelist_peers, PM_PEER_ID_INVALID, sizeof(m_whitelist_peers));
        m_whitelist_peer_cnt = (sizeof(m_whitelist_peers) / sizeof(pm_peer_id_t));
        peer_list_get(m_whitelist_peers, &m_whitelist_peer_cnt);
        ret = pm_whitelist_set(m_whitelist_peers, m_whitelist_peer_cnt);
        APP_ERROR_CHECK(ret);
        // Setup the device identies list.
        // Some SoftDevices do not support this feature.
        ret = pm_device_identities_list_set(m_whitelist_peers, m_whitelist_peer_cnt);
        if (ret != NRF_ERROR_NOT_SUPPORTED)
        {
            APP_ERROR_CHECK(ret);
        }
        ret = ble_advertising_start(&m_advertising, BLE_ADV_MODE_FAST);
        APP_ERROR_CHECK(ret);
    }
}

/**@brief Function for handling Peer Manager events.
 * @param[in] p_evt  Peer Manager event.*/
static void pm_evt_handler(pm_evt_t const * p_evt)
{
    ret_code_t err_code;
    switch (p_evt->evt_id)
    {
        case PM_EVT_BONDED_PEER_CONNECTED:
        {
            NRF_LOG_INFO("Connected to a previously bonded device.");
        } break;
        case PM_EVT_CONN_SEC_SUCCEEDED:
        {
            NRF_LOG_INFO("Connection secured: role: %d, conn_handle: 0x%x, procedure: %d.", ble_conn_state_role(p_evt->conn_handle), p_evt->conn_handle, p_evt->params.conn_sec_succeeded.procedure);
            m_peer_id = p_evt->peer_id;
        } break;
        case PM_EVT_CONN_SEC_FAILED:
        {
            /* Often, when securing fails, it shouldn't be restarted, for security reasons.
             * Other times, it can be restarted directly.
             * Sometimes it can be restarted, but only after changing some Security Parameters.
             * Sometimes, it cannot be restarted until the link is disconnected and reconnected.
             * Sometimes it is impossible, to secure the link, or the peer device does not support it.
             * How to handle this error is highly application dependent. */
        } break;
        case PM_EVT_CONN_SEC_CONFIG_REQ:
        {
            // Reject pairing request from an already bonded peer.
            pm_conn_sec_config_t conn_sec_config = {.allow_repairing = false};
            pm_conn_sec_config_reply(p_evt->conn_handle, &conn_sec_config);
        } break;
        case PM_EVT_STORAGE_FULL:
        {
            // Run garbage collection on the flash.
            err_code = fds_gc();
            if (err_code == FDS_ERR_NO_SPACE_IN_QUEUES)
            {
                // Retry.
            }
            else
            {
                APP_ERROR_CHECK(err_code);
            }
        } break;
        case PM_EVT_PEERS_DELETE_SUCCEEDED:
        {
            advertising_start(false);
        } break;
        case PM_EVT_PEER_DATA_UPDATE_SUCCEEDED:
        {
            if (p_evt->params.peer_data_update_succeeded.flash_changed && (p_evt->params.peer_data_update_succeeded.data_id == PM_PEER_DATA_ID_BONDING))
            {
                NRF_LOG_INFO("New Bond, add the peer to the whitelist if possible");
                NRF_LOG_INFO("\tm_whitelist_peer_cnt %d, MAX_PEERS_WLIST %d", m_whitelist_peer_cnt + 1, BLE_GAP_WHITELIST_ADDR_MAX_COUNT);
                // Note: You should check on what kind of white list policy your application should use.
                if (m_whitelist_peer_cnt < BLE_GAP_WHITELIST_ADDR_MAX_COUNT)
                {
                    // Bonded to a new peer, add it to the whitelist.
                    m_whitelist_peers[m_whitelist_peer_cnt++] = m_peer_id;
                    // The whitelist has been modified, update it in the Peer Manager.
                    err_code = pm_device_identities_list_set(m_whitelist_peers, m_whitelist_peer_cnt);
                    if (err_code != NRF_ERROR_NOT_SUPPORTED)
                    {
                        APP_ERROR_CHECK(err_code);
                    }
                    err_code = pm_whitelist_set(m_whitelist_peers, m_whitelist_peer_cnt);
                    APP_ERROR_CHECK(err_code);
                }
            }
        } break;
        case PM_EVT_PEER_DATA_UPDATE_FAILED:
        {
            // Assert.
            APP_ERROR_CHECK(p_evt->params.peer_data_update_failed.error);
        } break;
        case PM_EVT_PEER_DELETE_FAILED:
        {
            // Assert.
            APP_ERROR_CHECK(p_evt->params.peer_delete_failed.error);
        } break;
        case PM_EVT_PEERS_DELETE_FAILED:
        {
            // Assert.
            APP_ERROR_CHECK(p_evt->params.peers_delete_failed_evt.error);
        } break;
        case PM_EVT_ERROR_UNEXPECTED:
        {
            // Assert.
            APP_ERROR_CHECK(p_evt->params.error_unexpected.error);
        } break;
        case PM_EVT_CONN_SEC_START:
        case PM_EVT_PEER_DELETE_SUCCEEDED:
        case PM_EVT_LOCAL_DB_CACHE_APPLIED:
        case PM_EVT_LOCAL_DB_CACHE_APPLY_FAILED:
            // This can happen when the local DB has changed.
        case PM_EVT_SERVICE_CHANGED_IND_SENT:
        case PM_EVT_SERVICE_CHANGED_IND_CONFIRMED:
        default:
            break;
    }
}

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

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

/**@brief Function for performing a battery measurement, and update the Battery Level characteristic in the Battery Service. */
static void battery_level_update(void)
{
    ret_code_t err_code;
    uint8_t  battery_level;
    battery_level = (uint8_t)sensorsim_measure(&m_battery_sim_state, &m_battery_sim_cfg);
    err_code = ble_bas_battery_level_update(&m_bas, battery_level, BLE_CONN_HANDLE_ALL);//LAST ARGUMENT NOT INCLUDED
    if ((err_code != NRF_SUCCESS) && 
        (err_code != NRF_ERROR_BUSY) &&
        (err_code != NRF_ERROR_RESOURCES) &&
        (err_code != NRF_ERROR_FORBIDDEN) &&
        (err_code != NRF_ERROR_INVALID_STATE) &&
        (err_code != BLE_ERROR_GATTS_SYS_ATTR_MISSING)
       )
    {
        APP_ERROR_HANDLER(err_code);
    }
}

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

/**@brief Function for the Timer initialization.
 * @details Initializes the timer module. */
static void timers_init(void)
{
    ret_code_t err_code;
    err_code = app_timer_init();
    APP_ERROR_CHECK(err_code);
    // Create battery timer.
    err_code = app_timer_create(&m_battery_timer_id, APP_TIMER_MODE_REPEATED, battery_level_meas_timeout_handler);
    APP_ERROR_CHECK(err_code);
}

/**@brief Function for the GAP initialization.
 * @details This function sets up all the necessary GAP (Generic Access Profile) parameters of the device including the device name, appearance, and the preferred connection parameters. */
static void gap_params_init(void)
{
    ret_code_t              err_code;
    ble_gap_conn_params_t   gap_conn_params;
    ble_gap_conn_sec_mode_t sec_mode;
    BLE_GAP_CONN_SEC_MODE_SET_OPEN(&sec_mode);
    err_code = sd_ble_gap_device_name_set(&sec_mode, (const uint8_t *)DEVICE_NAME, strlen(DEVICE_NAME));
    APP_ERROR_CHECK(err_code);
    err_code = sd_ble_gap_appearance_set(BLE_APPEARANCE_HID_KEYBOARD);
    APP_ERROR_CHECK(err_code);
    memset(&gap_conn_params, 0, sizeof(gap_conn_params));
    gap_conn_params.min_conn_interval = MIN_CONN_INTERVAL;
    gap_conn_params.max_conn_interval = MAX_CONN_INTERVAL;
    gap_conn_params.slave_latency     = SLAVE_LATENCY;
    gap_conn_params.conn_sup_timeout  = CONN_SUP_TIMEOUT;
    err_code = sd_ble_gap_ppcp_set(&gap_conn_params);
    APP_ERROR_CHECK(err_code);
}

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

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

/**@brief Function for initializing the Queued Write Module. */
static void qwr_init(void)
{
    ret_code_t         err_code;
    nrf_ble_qwr_init_t qwr_init_obj = {0};
    qwr_init_obj.error_handler = nrf_qwr_error_handler;
    err_code = nrf_ble_qwr_init(&m_qwr, &qwr_init_obj);
    APP_ERROR_CHECK(err_code);
}

/**@brief Function for initializing Device Information Service. */
static void dis_init(void)
{
    ret_code_t       err_code;
    ble_dis_init_t   dis_init_obj;
    ble_dis_pnp_id_t pnp_id;
    pnp_id.vendor_id_source = PNP_ID_VENDOR_ID_SOURCE;
    pnp_id.vendor_id        = PNP_ID_VENDOR_ID;
    pnp_id.product_id       = PNP_ID_PRODUCT_ID;
    pnp_id.product_version  = PNP_ID_PRODUCT_VERSION;
    memset(&dis_init_obj, 0, sizeof(dis_init_obj));
    ble_srv_ascii_to_utf8(&dis_init_obj.manufact_name_str, MANUFACTURER_NAME);
    dis_init_obj.p_pnp_id = &pnp_id;
    BLE_GAP_CONN_SEC_MODE_SET_ENC_NO_MITM(&dis_init_obj.dis_attr_md.read_perm);
    BLE_GAP_CONN_SEC_MODE_SET_NO_ACCESS(&dis_init_obj.dis_attr_md.write_perm);
    err_code = ble_dis_init(&dis_init_obj);
    APP_ERROR_CHECK(err_code);
}

/**@brief Function for initializing Battery Service. */
static void bas_init(void)
{
    ret_code_t     err_code;
    ble_bas_init_t bas_init_obj;
    memset(&bas_init_obj, 0, sizeof(bas_init_obj));
    bas_init_obj.evt_handler          = NULL;
    bas_init_obj.support_notification = true;
    bas_init_obj.p_report_ref         = NULL;
    bas_init_obj.initial_batt_level   = 100;
    BLE_GAP_CONN_SEC_MODE_SET_ENC_NO_MITM(&bas_init_obj.battery_level_char_attr_md.cccd_write_perm);
    BLE_GAP_CONN_SEC_MODE_SET_ENC_NO_MITM(&bas_init_obj.battery_level_char_attr_md.read_perm);
    BLE_GAP_CONN_SEC_MODE_SET_NO_ACCESS(&bas_init_obj.battery_level_char_attr_md.write_perm);
    BLE_GAP_CONN_SEC_MODE_SET_ENC_NO_MITM(&bas_init_obj.battery_level_report_read_perm);
    err_code = ble_bas_init(&m_bas, &bas_init_obj);
    APP_ERROR_CHECK(err_code);
}

/**@brief Function for initializing HID Service. */
static void hids_init(void)
{
    ret_code_t                 err_code;
    ble_hids_init_t            hids_init_obj;
    ble_hids_inp_rep_init_t  * p_input_report;
    ble_hids_outp_rep_init_t * p_output_report;
    uint8_t                    hid_info_flags;
    static ble_hids_inp_rep_init_t  input_report_array[1]; //2
    static ble_hids_outp_rep_init_t output_report_array[1];
    static uint8_t                  report_map_data[] =
    {
		0x06, 0x00, 0xFF,       // Usage Page = 0xFF00 (Vendor Defined Page 1)
		0x09, 0x01,             // Usage (Vendor Usage 1)
		0xA1, 0x01,             // Collection (Application)
		0x19, 0x01,             // Usage Minimum 
		0x29, INPUT_REPORT_KEYS_MAX_LEN, // Usage Maximum 
		0x15, 0x00,             // Logical Minimum (data bytes in the report may have minimum value = 0x00)
		0x26, 0xFF, 0x00,       // Logical Maximum (data bytes in the report may have maximum value = 0x00FF = unsigned 255)
		0x75, 0x08,             // Report Size: 8-bit field size
		0x95, INPUT_REPORT_KEYS_MAX_LEN, // Report Count: Make sixty-four 8-bit fields (the next time the parser hits an "Input", "Output", or "Feature" item)
		0x81, 0x00,             // Input (Data, Array, Abs): Instantiates input packet fields based on the above report size, count, logical min/max, and usage.
		0x19, 0x01,             // Usage Minimum
		0x29, OUTPUT_REPORT_MAX_LEN, // Usage Maximum
		0x91, 0x00,             // Output (Data, Array, Abs): Instantiates output packet fields.  Uses same report size and count as "Input" fields, since nothing new/different was specified to the parser since the "Input" item.
		0xC0                    // End Collection
//        0x05, 0x01,       // Usage Page (Generic Desktop)
//        0x09, 0x06,       // Usage (Keyboard)
//        0xA1, 0x01,       // Collection (Application)
//        0x05, 0x07,       // Usage Page (Key Codes)
//        0x19, 0xe0,       // Usage Minimum (224)
//        0x29, 0xe7,       // Usage Maximum (231)
//        0x15, 0x00,       // Logical Minimum (0)
//        0x25, 0x01,       // Logical Maximum (1)
//        0x75, 0x01,       // Report Size (1)
//        0x95, 0x08,       // Report Count (8)
//        0x81, 0x02,       // Input (Data, Variable, Absolute)

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

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

//        0x95, 0x06,       // Report Count (6)
//        0x75, 0x08,       // Report Size (8)
//        0x15, 0x00,       // Logical Minimum (0)
//        0x25, 0x65,       // Logical Maximum (101)
//        0x05, 0x07,       // Usage Page (Key codes)
//        0x19, 0x00,       // Usage Minimum (0)
//        0x29, 0x65,       // Usage Maximum (101)
//        0x81, 0x00,       // Input (Data, Array) Key array(6 bytes)

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

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

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

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

    BLE_GAP_CONN_SEC_MODE_SET_ENC_NO_MITM(&p_input_report->security_mode.cccd_write_perm);
    BLE_GAP_CONN_SEC_MODE_SET_ENC_NO_MITM(&p_input_report->security_mode.read_perm);
    BLE_GAP_CONN_SEC_MODE_SET_ENC_NO_MITM(&p_input_report->security_mode.write_perm);

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

    BLE_GAP_CONN_SEC_MODE_SET_ENC_NO_MITM(&p_output_report->security_mode.read_perm);
    BLE_GAP_CONN_SEC_MODE_SET_ENC_NO_MITM(&p_output_report->security_mode.write_perm);

    hid_info_flags = HID_INFO_FLAG_REMOTE_WAKE_MSK | HID_INFO_FLAG_NORMALLY_CONNECTABLE_MSK;

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

    hids_init_obj.evt_handler                    = on_hids_evt;
    hids_init_obj.error_handler                  = service_error_handler;
    hids_init_obj.is_kb                          = true;
    hids_init_obj.is_mouse                       = false;
    hids_init_obj.inp_rep_count                  = 1;
    hids_init_obj.p_inp_rep_array                = input_report_array;
    hids_init_obj.outp_rep_count                 = 1;
    hids_init_obj.p_outp_rep_array               = output_report_array;
    hids_init_obj.feature_rep_count              = 0;
    hids_init_obj.p_feature_rep_array            = NULL;
    hids_init_obj.rep_map.data_len               = sizeof(report_map_data);
    hids_init_obj.rep_map.p_data                 = report_map_data;
    hids_init_obj.hid_information.bcd_hid        = BASE_USB_HID_SPEC_VERSION;
    hids_init_obj.hid_information.b_country_code = 0;
    hids_init_obj.hid_information.flags          = hid_info_flags;
    hids_init_obj.included_services_count        = 0;
    hids_init_obj.p_included_services_array      = NULL;

    BLE_GAP_CONN_SEC_MODE_SET_ENC_NO_MITM(&hids_init_obj.rep_map.security_mode.read_perm);
    BLE_GAP_CONN_SEC_MODE_SET_NO_ACCESS(&hids_init_obj.rep_map.security_mode.write_perm);
    BLE_GAP_CONN_SEC_MODE_SET_ENC_NO_MITM(&hids_init_obj.hid_information.security_mode.read_perm);
    BLE_GAP_CONN_SEC_MODE_SET_NO_ACCESS(&hids_init_obj.hid_information.security_mode.write_perm);

    BLE_GAP_CONN_SEC_MODE_SET_ENC_NO_MITM(&hids_init_obj.security_mode_boot_kb_inp_rep.cccd_write_perm);
    BLE_GAP_CONN_SEC_MODE_SET_ENC_NO_MITM(&hids_init_obj.security_mode_boot_kb_inp_rep.read_perm);
    BLE_GAP_CONN_SEC_MODE_SET_NO_ACCESS(&hids_init_obj.security_mode_boot_kb_inp_rep.write_perm);
    BLE_GAP_CONN_SEC_MODE_SET_ENC_NO_MITM(&hids_init_obj.security_mode_boot_kb_outp_rep.read_perm);
    BLE_GAP_CONN_SEC_MODE_SET_ENC_NO_MITM(&hids_init_obj.security_mode_boot_kb_outp_rep.write_perm);

    BLE_GAP_CONN_SEC_MODE_SET_ENC_NO_MITM(&hids_init_obj.security_mode_protocol.read_perm);
    BLE_GAP_CONN_SEC_MODE_SET_ENC_NO_MITM(&hids_init_obj.security_mode_protocol.write_perm);
    BLE_GAP_CONN_SEC_MODE_SET_NO_ACCESS(&hids_init_obj.security_mode_ctrl_point.read_perm);
    BLE_GAP_CONN_SEC_MODE_SET_ENC_NO_MITM(&hids_init_obj.security_mode_ctrl_point.write_perm);

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

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

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

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

/**@brief Function for initializing the Connection Parameters module. */
static void conn_params_init(void)
{
    ret_code_t             err_code;
    ble_conn_params_init_t cp_init;
    memset(&cp_init, 0, sizeof(cp_init));
    cp_init.p_conn_params                  = NULL;
    cp_init.first_conn_params_update_delay = FIRST_CONN_PARAMS_UPDATE_DELAY;
    cp_init.next_conn_params_update_delay  = NEXT_CONN_PARAMS_UPDATE_DELAY;
    cp_init.max_conn_params_update_count   = MAX_CONN_PARAMS_UPDATE_COUNT;
    cp_init.start_on_notify_cccd_handle    = BLE_GATT_HANDLE_INVALID;
    cp_init.disconnect_on_fail             = false;
    cp_init.evt_handler                    = NULL;
    cp_init.error_handler                  = conn_params_error_handler;
    err_code = ble_conn_params_init(&cp_init);
    APP_ERROR_CHECK(err_code);
}

/**@brief Function for starting timers. */
static void timers_start(void)
{
    ret_code_t err_code;
    err_code = app_timer_start(m_battery_timer_id, BATTERY_LEVEL_MEAS_INTERVAL, NULL);
    APP_ERROR_CHECK(err_code);
}

/**@brief   Function for transmitting a key scan Press & Release Notification.
 * @warning This handler is an example only. You need to analyze how you wish to send the key release.
 * @param[in]  p_instance     Identifies the service for which Key Notifications are requested.
 * @param[in]  p_key_pattern  Pointer to key pattern.
 * @param[in]  pattern_len    Length of key pattern. 0 < pattern_len < 7.
 * @param[in]  pattern_offset Offset applied to Key Pattern for transmission.
 * @param[out] actual_len     Provides actual length of Key Pattern transmitted, making buffering of rest possible if needed.
 * @return     NRF_SUCCESS on success, NRF_ERROR_RESOURCES in case transmission could not be completed due to lack of transmission buffer or other error codes indicating reason for failure.
 * @note       In case of NRF_ERROR_RESOURCES, remaining pattern that could not be transmitted can be enqueued \ref buffer_enqueue function.
 *             In case a pattern of 'cofFEe' is the p_key_pattern, with pattern_len as 6 and pattern_offset as 0, the notifications as observed on the peer side would be
 *             1>    'c', 'o', 'f', 'F', 'E', 'e'
 *             2>    -  , 'o', 'f', 'F', 'E', 'e'
 *             3>    -  ,   -, 'f', 'F', 'E', 'e'
 *             4>    -  ,   -,   -, 'F', 'E', 'e'
 *             5>    -  ,   -,   -,   -, 'E', 'e'
 *             6>    -  ,   -,   -,   -,   -, 'e'
 *             7>    -  ,   -,   -,   -,   -,  -
 *             Here, '-' refers to release, 'c' refers to the key character being transmitted.
 *             Therefore 7 notifications will be sent.
 *             In case an offset of 4 was provided, the pattern notifications sent will be from 5-7 will be transmitted. */
static uint32_t send_key_scan_press_release(ble_hids_t * p_hids, uint8_t    * p_key_pattern, uint16_t     pattern_len, uint16_t     pattern_offset, uint16_t   * p_actual_len)
{
    ret_code_t err_code;
    uint16_t offset;
    uint16_t data_len;
    uint8_t  data[INPUT_REPORT_KEYS_MAX_LEN];//="ABCDEFGHIJKLMNOPQR";

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

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

    offset   = pattern_offset;
    data_len = pattern_len;

    do
    {
        // Reset the data buffer.
        memset(data, 0, sizeof(data));
        // Copy the scan code.
        memcpy(data + SCAN_CODE_POS + offset, p_key_pattern + offset, data_len - offset);
        if (bsp_button_is_pressed(SHIFT_BUTTON_ID))
        {
            data[MODIFIER_KEY_POS] |= SHIFT_KEY_CODE;
        }
        if (!m_in_boot_mode)
        {
            //err_code = ble_hids_inp_rep_send(p_hids, INPUT_REPORT_KEYS_INDEX, INPUT_REPORT_KEYS_MAX_LEN, data, m_conn_handle);
			err_code = ble_hids_inp_rep_send(p_hids, INPUT_REPORT_KEYS_INDEX, INPUT_REPORT_KEYS_MAX_LEN, data, m_conn_handle);
        }
        else
        {
            //err_code = ble_hids_boot_kb_inp_rep_send(p_hids, INPUT_REPORT_KEYS_MAX_LEN, data, m_conn_handle);
			err_code = ble_hids_boot_kb_inp_rep_send(p_hids, INPUT_REPORT_KEYS_MAX_LEN, data, m_conn_handle);
        }
        if (err_code != NRF_SUCCESS)
        {
            break;
        }
        offset++;
    }
    while (offset <= data_len);
    *p_actual_len = offset;
    return err_code;
}

/**@brief   Function for initializing the buffer queue used to key events that could not be transmitted
 * @warning This handler is an example only. You need to analyze how you wish to buffer or buffer at all.
 * @note    In case of HID keyboard, a temporary buffering could be employed to handle scenarios where encryption is not yet enabled or there was a momentary link loss or there were no Transmit buffers. */
static void buffer_init(void)
{
    uint32_t buffer_count;
    BUFFER_LIST_INIT();
    for (buffer_count = 0; buffer_count < MAX_BUFFER_ENTRIES; buffer_count++)
    {
        BUFFER_ELEMENT_INIT(buffer_count);
    }
}

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

        buffer_list.count++;
        buffer_list.wp++;
        if (buffer_list.wp == MAX_BUFFER_ENTRIES)
        {
            buffer_list.wp = 0;
        }
    }
    return err_code;
}

/**@brief   Function to dequeue key scan patterns that could not be transmitted either completely of partially.
 * @warning This handler is an example only. You need to analyze how you wish to send the key release.
 * @param[in]  tx_flag   Indicative of whether the dequeue should result in transmission or not.
 * @note       A typical example when all keys are dequeued with transmission is when link is disconnected.
 * @return     NRF_SUCCESS on success, else an error code indicating reason for failure. */
static uint32_t buffer_dequeue(bool tx_flag)
{
    buffer_entry_t * p_element;
    uint32_t         err_code = NRF_SUCCESS;
    uint16_t         actual_len;
    if (BUFFER_LIST_EMPTY())
    {
        err_code = NRF_ERROR_NOT_FOUND;
    }
    else
    {
        bool remove_element = true;
        p_element = &buffer_list.buffer[(buffer_list.rp)];
        if (tx_flag)
        {
            err_code = send_key_scan_press_release(p_element->p_instance, p_element->p_data, p_element->data_len, p_element->data_offset, &actual_len); 
			// An additional notification is needed for release of all keys, therefore check is for actual_len <= element->data_len and not actual_len < element->data_len
            if ((err_code == NRF_ERROR_RESOURCES) && (actual_len <= p_element->data_len))
            {
                // Transmission could not be completed, do not remove the entry, adjust next data to be transmitted
                p_element->data_offset = actual_len;
                remove_element         = false;
            }
        }
        if (remove_element)
        {
            BUFFER_ELEMENT_INIT(buffer_list.rp);
            buffer_list.rp++;
            buffer_list.count--;
            if (buffer_list.rp == MAX_BUFFER_ENTRIES)
            {
                buffer_list.rp = 0;
            }
        }
    }
    return err_code;
}

/**@brief Function for sending sample key presses to the peer.
 * @param[in]   key_pattern_len   Pattern length.
 * @param[in]   p_key_pattern     Pattern to be sent. */
static void keys_send(uint8_t key_pattern_len, uint8_t * p_key_pattern)
{
    ret_code_t err_code;
    uint16_t actual_len;
    err_code = send_key_scan_press_release(&m_hids, p_key_pattern, key_pattern_len, 0, &actual_len);
    // An additional notification is needed for release of all keys, therefore check is for actual_len <= key_pattern_len and not actual_len < key_pattern_len.
    if ((err_code == NRF_ERROR_RESOURCES) && (actual_len <= key_pattern_len))
    {
        // Buffer enqueue routine return value is not intentionally checked.
        // Rationale: Its better to have a a few keys missing than have a system reset. 
		// Recommendation is to work out most optimal value for MAX_BUFFER_ENTRIES to minimize chances of buffer queue full condition
        UNUSED_VARIABLE(buffer_enqueue(&m_hids, p_key_pattern, key_pattern_len, actual_len));
    }

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

/**@brief Function for handling the HID Report Characteristic Write event.
 * @param[in]   p_evt   HID service event. */
static void on_hid_rep_char_write(ble_hids_evt_t * p_evt)
{
    if (p_evt->params.char_write.char_id.rep_type == BLE_HIDS_REP_TYPE_OUTPUT)
    {
        ret_code_t err_code;
        uint8_t  report_val;
        uint8_t  report_index = p_evt->params.char_write.char_id.rep_index;
        if (report_index == OUTPUT_REPORT_INDEX)
        {
            // This code assumes that the output report is one byte long. Hence the following static assert is made.
            STATIC_ASSERT(OUTPUT_REPORT_MAX_LEN == 1);
            err_code = ble_hids_outp_rep_get(&m_hids, report_index, OUTPUT_REPORT_MAX_LEN, 0, m_conn_handle, &report_val);
            APP_ERROR_CHECK(err_code);
            if (!m_caps_on && ((report_val & OUTPUT_REPORT_BIT_MASK_CAPS_LOCK) != 0))
            {
                // Caps Lock is turned On.
                NRF_LOG_INFO("Caps Lock is turned On!");
                err_code = bsp_indication_set(BSP_INDICATE_ALERT_3);
                APP_ERROR_CHECK(err_code);
                keys_send(sizeof(m_caps_on_key_scan_str), m_caps_on_key_scan_str);
                m_caps_on = true;
            }
            else if (m_caps_on && ((report_val & OUTPUT_REPORT_BIT_MASK_CAPS_LOCK) == 0))
            {
                // Caps Lock is turned Off .
                NRF_LOG_INFO("Caps Lock is turned Off!");
                err_code = bsp_indication_set(BSP_INDICATE_ALERT_OFF);
                APP_ERROR_CHECK(err_code);
                keys_send(sizeof(m_caps_off_key_scan_str), m_caps_off_key_scan_str);
                m_caps_on = false;
            }
            else
            {
                // The report received is not supported by this application. Do nothing.
            }
        }
    }
}

/**@brief Function for putting the chip into sleep mode.
 * @note This function will not return. */
static void sleep_mode_enter(void)
{
    ret_code_t err_code;
    err_code = bsp_indication_set(BSP_INDICATE_IDLE);
    APP_ERROR_CHECK(err_code);
    // Prepare wakeup buttons.
    err_code = bsp_btn_ble_sleep_mode_prepare();
    APP_ERROR_CHECK(err_code);
    // Go to system-off mode (this function will not return; wakeup will cause a reset).
    err_code = sd_power_system_off();
    APP_ERROR_CHECK(err_code);
}

/**@brief Function for handling HID events.
 * @details This function will be called for all HID events which are passed to the application.
 * @param[in]   p_hids  HID service structure.
 * @param[in]   p_evt   Event received from the HID service. */
static void on_hids_evt(ble_hids_t * p_hids, ble_hids_evt_t * p_evt)
{
    switch (p_evt->evt_type)
    {
        case BLE_HIDS_EVT_BOOT_MODE_ENTERED:
            m_in_boot_mode = true;
            break;
        case BLE_HIDS_EVT_REPORT_MODE_ENTERED:
            m_in_boot_mode = false;
            break;
        case BLE_HIDS_EVT_REP_CHAR_WRITE:
            on_hid_rep_char_write(p_evt);
            break;
        case BLE_HIDS_EVT_NOTIF_ENABLED:
            break;
        default:
            // No implementation needed.
            break;
    }
}

/**@brief Function for handling advertising events.
 * @details This function will be called for advertising events which are passed to the application.
 * @param[in] ble_adv_evt  Advertising event. */
static void on_adv_evt(ble_adv_evt_t ble_adv_evt)
{
    ret_code_t err_code;
    switch (ble_adv_evt)
    {
        case BLE_ADV_EVT_DIRECTED_HIGH_DUTY:
            NRF_LOG_INFO("High Duty Directed advertising.");
            err_code = bsp_indication_set(BSP_INDICATE_ADVERTISING_DIRECTED);
            APP_ERROR_CHECK(err_code);
            break;
        case BLE_ADV_EVT_DIRECTED: // NOT USED
            NRF_LOG_INFO("Directed advertising.");
            err_code = bsp_indication_set(BSP_INDICATE_ADVERTISING_DIRECTED);
            APP_ERROR_CHECK(err_code);
            break;
        case BLE_ADV_EVT_FAST: // NOT USED
            NRF_LOG_INFO("Fast advertising.");
            err_code = bsp_indication_set(BSP_INDICATE_ADVERTISING);
            APP_ERROR_CHECK(err_code);
            break;
        case BLE_ADV_EVT_SLOW: // NOT USED
            NRF_LOG_INFO("Slow advertising.");
            err_code = bsp_indication_set(BSP_INDICATE_ADVERTISING_SLOW);
            APP_ERROR_CHECK(err_code);
            break;
        case BLE_ADV_EVT_FAST_WHITELIST: // NOT USED
            NRF_LOG_INFO("Fast advertising with whitelist.");
            err_code = bsp_indication_set(BSP_INDICATE_ADVERTISING_WHITELIST);
            APP_ERROR_CHECK(err_code);
            break;
        case BLE_ADV_EVT_SLOW_WHITELIST: // NOT USED
            NRF_LOG_INFO("Slow advertising with whitelist.");
            err_code = bsp_indication_set(BSP_INDICATE_ADVERTISING_WHITELIST);
            APP_ERROR_CHECK(err_code);
            break;
        case BLE_ADV_EVT_IDLE: // NOT USED
            sleep_mode_enter();
            break;
        case BLE_ADV_EVT_WHITELIST_REQUEST:
        {
            ble_gap_addr_t whitelist_addrs[BLE_GAP_WHITELIST_ADDR_MAX_COUNT];
            ble_gap_irk_t  whitelist_irks[BLE_GAP_WHITELIST_ADDR_MAX_COUNT];
            uint32_t       addr_cnt = BLE_GAP_WHITELIST_ADDR_MAX_COUNT;
            uint32_t       irk_cnt  = BLE_GAP_WHITELIST_ADDR_MAX_COUNT;
            err_code = pm_whitelist_get(whitelist_addrs, &addr_cnt, whitelist_irks,  &irk_cnt);
            APP_ERROR_CHECK(err_code);
            NRF_LOG_DEBUG("pm_whitelist_get returns %d addr in whitelist and %d irk whitelist", addr_cnt, irk_cnt);

            // Apply the whitelist.
            err_code = ble_advertising_whitelist_reply(&m_advertising, whitelist_addrs, addr_cnt, whitelist_irks, irk_cnt);
            APP_ERROR_CHECK(err_code);
        } break; //BLE_ADV_EVT_WHITELIST_REQUEST
        case BLE_ADV_EVT_PEER_ADDR_REQUEST:
        {
            pm_peer_data_bonding_t peer_bonding_data;
            // Only Give peer address if we have a handle to the bonded peer.
            if (m_peer_id != PM_PEER_ID_INVALID)
            {
                err_code = pm_peer_data_bonding_load(m_peer_id, &peer_bonding_data);
                if (err_code != NRF_ERROR_NOT_FOUND)
                {
                    APP_ERROR_CHECK(err_code);
                    ble_gap_addr_t * p_peer_addr = &(peer_bonding_data.peer_ble_id.id_addr_info);
                    err_code = ble_advertising_peer_addr_reply(&m_advertising, p_peer_addr);
                    APP_ERROR_CHECK(err_code);
                }
            }
        } break; //BLE_ADV_EVT_PEER_ADDR_REQUEST
        default:
            break;
    }
}

/**@brief Function for handling BLE events.
 * @param[in]   p_ble_evt   Bluetooth stack event.
 * @param[in]   p_context   Unused. */
static void ble_evt_handler(ble_evt_t const * p_ble_evt, void * p_context)
{
    ret_code_t err_code;
    switch (p_ble_evt->header.evt_id)
    {
        case BLE_GAP_EVT_CONNECTED:
            NRF_LOG_INFO("Connected");
            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");
            // Dequeue all keys without transmission.
            (void) buffer_dequeue(false);
            m_conn_handle = BLE_CONN_HANDLE_INVALID;
            // Reset m_caps_on variable. Upon reconnect, the HID host will re-send the Output report containing the Caps lock state.
            m_caps_on = false;
            // disabling alert 3. signal - used for capslock ON
            err_code = bsp_indication_set(BSP_INDICATE_ALERT_OFF);
            APP_ERROR_CHECK(err_code);
            break; // BLE_GAP_EVT_DISCONNECTED
        case BLE_GAP_EVT_PHY_UPDATE_REQUEST:
        {
            NRF_LOG_DEBUG("PHY update request.");
            ble_gap_phys_t const phys =
            {
                .rx_phys = BLE_GAP_PHY_AUTO,
                .tx_phys = BLE_GAP_PHY_AUTO,
            };
            err_code = sd_ble_gap_phy_update(p_ble_evt->evt.gap_evt.conn_handle, &phys);
            APP_ERROR_CHECK(err_code);
        } break;
        case BLE_GATTS_EVT_HVN_TX_COMPLETE:
            // Send next key event
            (void) buffer_dequeue(true);
            break;
        case BLE_GATTC_EVT_TIMEOUT:
            // Disconnect on GATT Client timeout event.
            NRF_LOG_DEBUG("GATT Client Timeout.");
            err_code = sd_ble_gap_disconnect(p_ble_evt->evt.gattc_evt.conn_handle, BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION);
            APP_ERROR_CHECK(err_code);
            break;
        case BLE_GATTS_EVT_TIMEOUT:
            // Disconnect on GATT Server timeout event.
            NRF_LOG_DEBUG("GATT Server Timeout.");
            err_code = sd_ble_gap_disconnect(p_ble_evt->evt.gatts_evt.conn_handle, BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION);
            APP_ERROR_CHECK(err_code);
            break;
        default:
            // No implementation needed.
            break;
    }
}

/**@brief Function for initializing the BLE stack.
 * @details Initializes the SoftDevice and the BLE event interrupt. */
static void ble_stack_init(void)
{
    ret_code_t err_code;
    err_code = nrf_sdh_enable_request();
    APP_ERROR_CHECK(err_code);
    // Configure the BLE stack using the default settings.
    // Fetch the start address of the application RAM.
    uint32_t ram_start = 0;
    err_code = nrf_sdh_ble_default_cfg_set(APP_BLE_CONN_CFG_TAG, &ram_start);
    APP_ERROR_CHECK(err_code);
    // Enable BLE stack.
    err_code = nrf_sdh_ble_enable(&ram_start);
    APP_ERROR_CHECK(err_code);
    // Register a handler for BLE events.
    NRF_SDH_BLE_OBSERVER(m_ble_observer, APP_BLE_OBSERVER_PRIO, ble_evt_handler, NULL);
}

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

/**@brief Function for handling events from the BSP module.
 * @param[in]   event   Event generated by button press. */
static void bsp_event_handler(bsp_event_t event)
{
    uint32_t         err_code;
    static uint8_t * p_key = m_sample_key_press_scan_str; // POINTER TO ARRAY OF LETTERS
    static uint8_t   size  = 0;
    switch (event)
    {
        case BSP_EVENT_SLEEP:
            sleep_mode_enter();
            break;
        case BSP_EVENT_DISCONNECT:
            err_code = sd_ble_gap_disconnect(m_conn_handle, BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION);
            if (err_code != NRF_ERROR_INVALID_STATE)
            {
                APP_ERROR_CHECK(err_code);
            }
            break;
        case BSP_EVENT_WHITELIST_OFF:
            if (m_conn_handle == BLE_CONN_HANDLE_INVALID)
            {
                err_code = ble_advertising_restart_without_whitelist(&m_advertising);
                if (err_code != NRF_ERROR_INVALID_STATE)
                {
                    APP_ERROR_CHECK(err_code);
                }
            }
            break;
        case BSP_EVENT_KEY_0:
            if (m_conn_handle != BLE_CONN_HANDLE_INVALID)
            {
                keys_send(1, p_key); // ARRAY OF LETTERS IS PASSED 
                p_key++; // INCREMENT ARRAY INDEX
                size++; // 
                if (size == MAX_KEYS_IN_ONE_REPORT) // IF IT REACHES TILL THE END
                {
                    p_key = m_sample_key_press_scan_str;//REINITIALIZE THE POINTER TO ORIGINAL ARRAY
                    size  = 0;
                }
            }
            break;
        default:
            break;
    }
}

/**@brief Function for the Peer Manager initialization. */
static void peer_manager_init(void)
{
    ble_gap_sec_params_t sec_param;
    ret_code_t           err_code;
    err_code = pm_init();
    APP_ERROR_CHECK(err_code);
    memset(&sec_param, 0, sizeof(ble_gap_sec_params_t));
    // Security parameters to be used for all security procedures.
    sec_param.bond           = SEC_PARAM_BOND;
    sec_param.mitm           = SEC_PARAM_MITM;
    sec_param.lesc           = SEC_PARAM_LESC;
    sec_param.keypress       = SEC_PARAM_KEYPRESS;
    sec_param.io_caps        = SEC_PARAM_IO_CAPABILITIES;
    sec_param.oob            = SEC_PARAM_OOB;
    sec_param.min_key_size   = SEC_PARAM_MIN_KEY_SIZE;
    sec_param.max_key_size   = SEC_PARAM_MAX_KEY_SIZE;
    sec_param.kdist_own.enc  = 1;
    sec_param.kdist_own.id   = 1;
    sec_param.kdist_peer.enc = 1;
    sec_param.kdist_peer.id  = 1;

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

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

/**@brief Function for initializing the Advertising functionality. */
static void advertising_init(void)
{
    uint32_t               err_code;
    uint8_t                adv_flags;
    ble_advertising_init_t init;
    memset(&init, 0, sizeof(init));
    adv_flags                            = BLE_GAP_ADV_FLAGS_LE_ONLY_GENERAL_DISC_MODE;
    init.advdata.name_type               = BLE_ADVDATA_FULL_NAME;
    init.advdata.include_appearance      = true;
    init.advdata.flags                   = adv_flags;
    init.advdata.uuids_complete.uuid_cnt = sizeof(m_adv_uuids) / sizeof(m_adv_uuids[0]);
    init.advdata.uuids_complete.p_uuids  = m_adv_uuids;
    init.config.ble_adv_whitelist_enabled          = true;
    init.config.ble_adv_directed_high_duty_enabled = true;
    init.config.ble_adv_directed_enabled           = false;
    init.config.ble_adv_directed_interval          = 0;
    init.config.ble_adv_directed_timeout           = 0;
    init.config.ble_adv_fast_enabled               = true;
    init.config.ble_adv_fast_interval              = APP_ADV_FAST_INTERVAL;
    init.config.ble_adv_fast_timeout               = APP_ADV_FAST_DURATION;
    init.config.ble_adv_slow_enabled               = true;
    init.config.ble_adv_slow_interval              = APP_ADV_SLOW_INTERVAL;
    init.config.ble_adv_slow_timeout               = APP_ADV_SLOW_DURATION;
    init.evt_handler   = on_adv_evt;
    init.error_handler = ble_advertising_error_handler;
    err_code = ble_advertising_init(&m_advertising, &init);
    APP_ERROR_CHECK(err_code);
    ble_advertising_conn_cfg_tag_set(&m_advertising, APP_BLE_CONN_CFG_TAG);
}

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

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

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

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

/**@brief Function for application main entry. */
int main(void)
{
    bool erase_bonds;
    log_init();
    timers_init();
    buttons_leds_init(&erase_bonds);
    power_management_init();
    ble_stack_init();
    scheduler_init();
    gap_params_init();
    gatt_init();
    advertising_init();
    services_init();
    sensor_simulator_init();
    conn_params_init();
    buffer_init();
    peer_manager_init();

    // Start execution.
    NRF_LOG_INFO("HID Keyboard example started.");
    timers_start();
    advertising_start(erase_bonds);

    for (;;)
    {
        idle_state_handle();
    }
}

  • So you suggest not to use HID? I'm able to connect with computer but not able to send values.

  • I am not sure the correct way of transferring data to an application is by pretending to be a keyboard. Because when you connect to the computer, it will start to write as if it was the keyboard connected. 

    I am not exactly sure why the HIDS keyboard isn't working with the parameters that you changed, but it should be easy to figure it out if you do some debugging, like I explained in the previous comment.

    However, I think it is better to go with something proprietary, like the ble_app_uart example. Note that you will not get the values from this in a window by default, but you can use a UART terminal, like Putty or Termite to see the data that you send. How to test the example is described here.

    Best regards,

    Edvin

Related