NRF52 db discovery event has all characteristic uuids 0

[ryan]

when performing db discovering using a peripheral nrf52832 (running sample dfu project) from sdk 13 from a nrf32832 central on sdk 14 I notice that the db discovery event handler has each characteristic UUID of 0.

it is not possible to update either SDK at this moment for reasons i cannot get into. 

my central side code for initializing the db discovery...:

ble_uuid128_t base_uuid        = { .uuid128 = DFU_SERVICE_UUID_128bit };    
ble_uuid_t    dfu_service_uuid = { .uuid    = DFU_SERVICE_UUID_16bit };     
                                                                                 
uint32_t err_code = sd_ble_uuid_vs_add(&base_uuid, &dfu_service_uuid.type); 
NRF_LOG_INFO("uuid vs add returned: %d/%04X", err_code, err_code);          
APP_ERROR_CHECK(err_code);                                                  
                                                                                 
/* register to get db discovery events for the dfu service */               
ble_db_discovery_evt_register(&dfu_service_uuid);                           

ble_db_discovery_start(db_disc_handle, dfu_target->conn_handle);            

and in my event handler:

uint32_t dfu_db_disc_evt_handler( ble_ript_acc_client_t *dfu_target,            
                                  const ble_db_discovery_evt_t * const p_evt)   
{                                                                               
    if (p_evt->evt_type != BLE_DB_DISCOVERY_COMPLETE)                           
    {                                                                           
        return 0;                                                               
    }                                                                           
                                                                             
    // we only care about the dfu service UUIDs                                 
    if (p_evt->params.discovered_db.srv_uuid.uuid == DFU_SERVICE_UUID_16bit)    
    {                                                                           
        for (int i = 0; i < p_evt->params.discovered_db.char_count; i++)        
        {                                                                       
            const ble_gatt_db_char_t *const disc_char = &p_evt->params.discovered_db.charateristics[i];
            NRF_LOG_INFO("%d: uuid: %04X cccd:%04X. value:%04X\n",              
                    i,                                                          
                    disc_char->characteristic.uuid.uuid,                        
                    disc_char->cccd_handle,                                     
                    disc_char->characteristic.handle_value);                    
       }                                         
    }
}

when i run this, my output on RTT Client looks like this:

<info> app: uuid vs add returned: 0/0000

<info> app: 0: uuid: 0000 cccd:0000. value:0010

<info> app: 1: uuid: 0000 cccd:0013. value:0012

<info> app: 0: uuid: 0000 cccd:0000. value:0010

<info> app: 1: uuid: 0000 cccd:0013. value:0012

<info> app: 0: uuid: 0000 cccd:0000. value:0010

<info> app: 1: uuid: 0000 cccd:0013. value:0012

<info> app: 0: uuid: 0000 cccd:0000. value:0010

<info> app: 1: uuid: 0000 cccd:0013. value:0012

<info> app: 0: uuid: 0000 cccd:0000. value:0010

<info> app: 1: uuid: 0000 cccd:0013. value:0012

<info> app: 0: uuid: 0000 cccd:0000. value:0010

<info> app: 1: uuid: 0000 cccd:0013. value:0012

<info> app: 0: uuid: 0000 cccd:0000. value:0010

<info> app: 1: uuid: 0000 cccd:0013. value:0012

<info> app: 0: uuid: 0000 cccd:0000. value:0010

<info> app: 1: uuid: 0000 cccd:0013. value:0012

My 2 questions are:
1. Why are the characteristic UUIDs always 0?
2. why do i get 7 events for the same service?

[Vidar Berg]

Hi,

Noticed that you call ble_db_discovery_start() after ble_db_discovery_evt_register(). Please try to only call ble_db_discovery_start() from the BLE_GAP_EVT_CONNECTED to ensure that the service is discovered once. 

I couldn't tell from the code snippets you provided, but did you set dfu_service_uuid.type to BLE_UUID_TYPE_BLE? I was unable to replicate this with the code below. 

void dfu_c_init()
{
    uint32_t      err_code;
    ble_uuid_t    dfu_uuid;
    uint8_t       uuid_type = BLE_UUID_TYPE_VENDOR_BEGIN;
    
    /*Base UUIDs for DFU service characteristics*/
    ble_uuid128_t dfu_base_uuid = 
    {
        {
            0x50, 0xEA, 0xDA, 0x30, 0x88, 0x83, 0xB8, 0x9F,
            0x60, 0x4F, 0x15, 0xF3,  0x00, 0x00, 0xC9, 0x8E
        }
    };


    dfu_uuid.type = BLE_UUID_TYPE_BLE;
    dfu_uuid.uuid = 0xFE59;

    err_code = sd_ble_uuid_vs_add(&dfu_base_uuid, &uuid_type);
    APP_ERROR_CHECK(err_code);


    err_code = ble_db_discovery_evt_register(&dfu_uuid);
    APP_ERROR_CHECK(err_code);
}

 

[ryan]

I know that I'm calling ble_db_discovery_start only once... otherwise my output would display "<info> app: uuid vs add returned: 0/0000" more than once, which it does not. 

regarding the uuid type, sd_ble_uuid_vs_add()'s 2nd parameter is and output, storing the uuid type into the unit8_t that is passed by adress on your code's line 20. so your assignment in line 17 is without impact per the documentation.  -- in my implementation, on line 4 i do the exact same thing as your reference so i'm not sure why you're asking about it... can you elaborate a bit more on your question?

ble_uuid_t    dfu_service_uuid = { .uuid    = DFU_SERVICE_UUID_16bit };     
                                                                                 
uint32_t err_code = sd_ble_uuid_vs_add(&base_uuid, &dfu_service_uuid.type); 

can you confirm the SDK version of the peripheral you were connecting with?

[Vidar Berg]

You're right, the 2nd parameter is an output. I just assumed it was input argument. Sorry for the confusion.

I did not manage to reproduce the issues. I used the pre-compiled bootloader hex in sdk 13 and modified the uart central example to discover the DFU service. So I'm not sure what the problem is.  Suggest that you do a comparison of your implementation with attached main.c and see if you can spot any relevant differences (verify that we are using same UUIDs etc). 

<info> app: Connected to target
<info> app: 0: uuid: 0002 cccd:0000. value:0010

<info> app: 1: uuid: 0001 cccd:0013. value:0012

 

Fullscreen main.c Download

/**
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 * 
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 * 
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
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 *    list of conditions and the following disclaimer.
 * 
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 *    contributors may be used to endorse or promote products derived from this
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 *    Nordic Semiconductor ASA integrated circuit.
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 * DISCLAIMED. IN NO EVENT SHALL NORDIC SEMICONDUCTOR ASA OR CONTRIBUTORS BE
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 * 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.
 * 
 */
#include <stdio.h>
#include <stdint.h>
#include <stdbool.h>
#include "nordic_common.h"
#include "app_error.h"
#include "app_uart.h"
#include "ble_db_discovery.h"
#include "app_timer.h"
#include "app_util.h"
#include "bsp_btn_ble.h"
#include "ble.h"
#include "ble_gap.h"
#include "ble_hci.h"
#include "nrf_sdh.h"
#include "nrf_sdh_ble.h"
#include "nrf_sdh_soc.h"
#include "nrf_pwr_mgmt.h"
#include "ble_advdata.h"
#include "ble_nus_c.h"
#include "nrf_ble_gatt.h"

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


#define APP_BLE_CONN_CFG_TAG    1                                       /**< A tag that refers to the BLE stack configuration we set with @ref sd_ble_cfg_set. Default tag is @ref BLE_CONN_CFG_TAG_DEFAULT. */
#define APP_BLE_OBSERVER_PRIO   3                                       /**< Application's BLE observer priority. You shoulnd't need to modify this value. */

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

#define NUS_SERVICE_UUID_TYPE   BLE_UUID_TYPE_VENDOR_BEGIN              /**< UUID type for the Nordic UART Service (vendor specific). */

#define SCAN_INTERVAL           0x00A0                                  /**< Determines scan interval in units of 0.625 millisecond. */
#define SCAN_WINDOW             0x0050                                  /**< Determines scan window in units of 0.625 millisecond. */
#define SCAN_TIMEOUT            0x0000                                  /**< Timout when scanning. 0x0000 disables timeout. */

#define MIN_CONNECTION_INTERVAL MSEC_TO_UNITS(20, UNIT_1_25_MS)         /**< Determines minimum connection interval in millisecond. */
#define MAX_CONNECTION_INTERVAL MSEC_TO_UNITS(75, UNIT_1_25_MS)         /**< Determines maximum connection interval in millisecond. */
#define SLAVE_LATENCY           0                                       /**< Determines slave latency in counts of connection events. */
#define SUPERVISION_TIMEOUT     MSEC_TO_UNITS(4000, UNIT_10_MS)         /**< Determines supervision time-out in units of 10 millisecond. */

#define UUID16_SIZE             2                                       /**< Size of 16 bit UUID */
#define UUID32_SIZE             4                                       /**< Size of 32 bit UUID */
#define UUID128_SIZE            16                                      /**< Size of 128 bit UUID */

#define ECHOBACK_BLE_UART_DATA  1                                       /**< Echo the UART data that is received over the Nordic UART Service back to the sender. */


BLE_NUS_C_DEF(m_ble_nus_c);                                             /**< BLE NUS service client instance. */
NRF_BLE_GATT_DEF(m_gatt);                                               /**< GATT module instance. */
BLE_DB_DISCOVERY_DEF(m_db_disc);                                        /**< DB discovery module instance. */

static uint16_t m_ble_nus_max_data_len = BLE_GATT_ATT_MTU_DEFAULT - OPCODE_LENGTH - HANDLE_LENGTH; /**< Maximum length of data (in bytes) that can be transmitted to the peer by the Nordic UART service module. */

/**@brief Connection parameters requested for connection. */
static ble_gap_conn_params_t const m_connection_param =
{
    (uint16_t)MIN_CONNECTION_INTERVAL,  // Minimum connection
    (uint16_t)MAX_CONNECTION_INTERVAL,  // Maximum connection
    (uint16_t)SLAVE_LATENCY,            // Slave latency
    (uint16_t)SUPERVISION_TIMEOUT       // Supervision time-out
};

/** @brief Parameters used when scanning. */
static ble_gap_scan_params_t const m_scan_params =
{
    .active   = 1,
    .interval = SCAN_INTERVAL,
    .window   = SCAN_WINDOW,
    .timeout  = SCAN_TIMEOUT,
    #if (NRF_SD_BLE_API_VERSION <= 2)
        .selective   = 0,
        .p_whitelist = NULL,
    #endif
    #if (NRF_SD_BLE_API_VERSION >= 3)
        .use_whitelist = 0,
    #endif
};

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


/**@brief 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] p_file_name  File name of the failing ASSERT call.
 */
void assert_nrf_callback(uint16_t line_num, const uint8_t * p_file_name)
{
    app_error_handler(0xDEADBEEF, line_num, p_file_name);
}


/**@brief Function to start scanning. */
static void scan_start(void)
{
    ret_code_t ret;

    ret = sd_ble_gap_scan_start(&m_scan_params);
    APP_ERROR_CHECK(ret);

    ret = bsp_indication_set(BSP_INDICATE_SCANNING);
    APP_ERROR_CHECK(ret);
}


/**@brief Function for handling database discovery events.
 *
 * @details This function is callback function to handle events from the database discovery module.
 *          Depending on the UUIDs that are discovered, this function should forward the events
 *          to their respective services.
 *
 * @param[in] p_event  Pointer to the database discovery event.
 */
static void db_disc_handler(ble_db_discovery_evt_t * p_evt)
{
    //ble_nus_c_on_db_disc_evt(&m_ble_nus_c, p_evt);

        if (p_evt->evt_type != BLE_DB_DISCOVERY_COMPLETE)                           
    {                                                                           
        return;                                                               
    }                                                                           
                                                                             
    // we only care about the dfu service UUIDs                                 
    if (p_evt->params.discovered_db.srv_uuid.uuid == 0xFE59)    
    {                                                                           
        for (int i = 0; i < p_evt->params.discovered_db.char_count; i++)        
        {                                                                       
            const ble_gatt_db_char_t *const disc_char = &p_evt->params.discovered_db.charateristics[i];
            NRF_LOG_INFO("%d: uuid: %04X cccd:%04X. value:%04X\n",              
                    i,                                                          
                    disc_char->characteristic.uuid.uuid,                        
                    disc_char->cccd_handle,                                     
                    disc_char->characteristic.handle_value);                    
       }                                         
    }

}


/**@brief Function for handling characters received by the Nordic UART Service.
 *
 * @details This function takes a list of characters of length data_len and prints the characters out on UART.
 *          If @ref ECHOBACK_BLE_UART_DATA is set, the data is sent back to sender.
 */
static void ble_nus_chars_received_uart_print(uint8_t * p_data, uint16_t data_len)
{
    ret_code_t ret_val;

    NRF_LOG_DEBUG("Receiving data.");
    NRF_LOG_HEXDUMP_DEBUG(p_data, data_len);

    for (uint32_t i = 0; i < data_len; i++)
    {
        do
        {
            ret_val = app_uart_put(p_data[i]);
            if ((ret_val != NRF_SUCCESS) && (ret_val != NRF_ERROR_BUSY))
            {
                NRF_LOG_ERROR("app_uart_put failed for index 0x%04x.", i);
                APP_ERROR_CHECK(ret_val);
            }
        } while (ret_val == NRF_ERROR_BUSY);
    }
    if (p_data[data_len-1] == '\r')
    {
        while (app_uart_put('\n') == NRF_ERROR_BUSY);
    }
    if (ECHOBACK_BLE_UART_DATA)
    {
        // Send data back to peripheral.
        do
        {
            ret_val = ble_nus_c_string_send(&m_ble_nus_c, p_data, data_len);
            if ((ret_val != NRF_SUCCESS) && (ret_val != NRF_ERROR_BUSY))
            {
                NRF_LOG_ERROR("Failed sending NUS message. Error 0x%x. ", ret_val);
                APP_ERROR_CHECK(ret_val);
            }
        } while (ret_val == NRF_ERROR_BUSY);
    }
}


/**@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.
 */
void uart_event_handle(app_uart_evt_t * p_event)
{
    static uint8_t data_array[BLE_NUS_MAX_DATA_LEN];
    static uint16_t index = 0;
    uint32_t ret_val;

    switch (p_event->evt_type)
    {
        /**@snippet [Handling data from UART] */
        case APP_UART_DATA_READY:
            UNUSED_VARIABLE(app_uart_get(&data_array[index]));
            index++;

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

                do
                {
                    ret_val = ble_nus_c_string_send(&m_ble_nus_c, data_array, index);
                    if ( (ret_val != NRF_ERROR_INVALID_STATE) && (ret_val != NRF_ERROR_BUSY) )
                    {
                        APP_ERROR_CHECK(ret_val);
                    }
                } while (ret_val == NRF_ERROR_BUSY);

                index = 0;
            }
            break;

        /**@snippet [Handling data from UART] */
        case APP_UART_COMMUNICATION_ERROR:
            NRF_LOG_ERROR("Communication error occurred while handling UART.");
            APP_ERROR_HANDLER(p_event->data.error_communication);
            break;

        case APP_UART_FIFO_ERROR:
            NRF_LOG_ERROR("Error occurred in FIFO module used by UART.");
            APP_ERROR_HANDLER(p_event->data.error_code);
            break;

        default:
            break;
    }
}


/**@brief Callback handling NUS Client events.
 *
 * @details This function is called to notify the application of NUS client events.
 *
 * @param[in]   p_ble_nus_c   NUS Client Handle. This identifies the NUS client
 * @param[in]   p_ble_nus_evt Pointer to the NUS Client event.
 */

/**@snippet [Handling events from the ble_nus_c module] */
static void ble_nus_c_evt_handler(ble_nus_c_t * p_ble_nus_c, ble_nus_c_evt_t const * p_ble_nus_evt)
{
    ret_code_t err_code;

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

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

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

        case BLE_NUS_C_EVT_DISCONNECTED:
            NRF_LOG_INFO("Disconnected.");
            scan_start();
            break;
    }
}
/**@snippet [Handling events from the ble_nus_c module] */


/**
 * @brief Function for shutdown events.
 *
 * @param[in]   event       Shutdown type.
 */
static bool shutdown_handler(nrf_pwr_mgmt_evt_t event)
{
    ret_code_t err_code;

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

    switch (event)
    {
        case NRF_PWR_MGMT_EVT_PREPARE_WAKEUP:
            // Prepare wakeup buttons.
            err_code = bsp_btn_ble_sleep_mode_prepare();
            APP_ERROR_CHECK(err_code);
            break;

        default:
            break;
    }

    return true;
}

NRF_PWR_MGMT_HANDLER_REGISTER(shutdown_handler, APP_SHUTDOWN_HANDLER_PRIORITY);

/**@brief Reads an advertising report and checks if a UUID is present in the service list.
 *
 * @details The function is able to search for 16-bit, 32-bit and 128-bit service UUIDs.
 *          To see the format of a advertisement packet, see
 *          https://www.bluetooth.org/Technical/AssignedNumbers/generic_access_profile.htm
 *
 * @param[in]   p_target_uuid The UUID to search for.
 * @param[in]   p_adv_report  Pointer to the advertisement report.
 *
 * @retval      true if the UUID is present in the advertisement report. Otherwise false
 */
static bool is_uuid_present(ble_uuid_t               const * p_target_uuid,
                            ble_gap_evt_adv_report_t const * p_adv_report)
{
    ret_code_t   err_code;
    ble_uuid_t   extracted_uuid;
    uint16_t     index  = 0;
    uint8_t    * p_data = (uint8_t *)p_adv_report->data;

    while (index < p_adv_report->dlen)
    {
        uint8_t field_length = p_data[index];
        uint8_t field_type   = p_data[index + 1];

        if (   (field_type == BLE_GAP_AD_TYPE_16BIT_SERVICE_UUID_MORE_AVAILABLE)
            || (field_type == BLE_GAP_AD_TYPE_16BIT_SERVICE_UUID_COMPLETE))
        {
            for (uint32_t i = 0; i < (field_length / UUID16_SIZE); i++)
            {
                err_code = sd_ble_uuid_decode(UUID16_SIZE,
                                              &p_data[i * UUID16_SIZE + index + 2],
                                              &extracted_uuid);

                if (err_code == NRF_SUCCESS)
                {
                    if (extracted_uuid.uuid == p_target_uuid->uuid)
                    {
                        return true;
                    }
                }
            }
        }
        else if (   (field_type == BLE_GAP_AD_TYPE_32BIT_SERVICE_UUID_MORE_AVAILABLE)
                 || (field_type == BLE_GAP_AD_TYPE_32BIT_SERVICE_UUID_COMPLETE))
        {
            for (uint32_t i = 0; i < (field_length / UUID32_SIZE); i++)
            {
                err_code = sd_ble_uuid_decode(UUID32_SIZE,
                                              &p_data[i * UUID32_SIZE + index + 2],
                                              &extracted_uuid);

                if (err_code == NRF_SUCCESS)
                {
                    if (   (extracted_uuid.uuid == p_target_uuid->uuid)
                        && (extracted_uuid.type == p_target_uuid->type))
                    {
                        return true;
                    }
                }
            }
        }

        else if (   (field_type == BLE_GAP_AD_TYPE_128BIT_SERVICE_UUID_MORE_AVAILABLE)
                 || (field_type == BLE_GAP_AD_TYPE_128BIT_SERVICE_UUID_COMPLETE))
        {
            err_code = sd_ble_uuid_decode(UUID128_SIZE, &p_data[index + 2], &extracted_uuid);
            if (err_code == NRF_SUCCESS)
            {
                if (   (extracted_uuid.uuid == p_target_uuid->uuid)
                    && (extracted_uuid.type == p_target_uuid->type))
                {
                    return true;
                }
            }
        }
        index += field_length + 1;
    }
    return false;
}

/**@brief Variable length data encapsulation in terms of length and pointer to data */
typedef struct
{
    uint8_t  * p_data;      /**< Pointer to data. */
    uint16_t   data_len;    /**< Length of data. */
} data_t;

/**
 * @brief Parses advertisement data, providing length and location of the field in case
 *        matching data is found.
 *
 * @param[in]  Type of data to be looked for in advertisement data.
 * @param[in]  Advertisement report length and pointer to report.
 * @param[out] If data type requested is found in the data report, type data length and
 *             pointer to data will be populated here.
 *
 * @retval NRF_SUCCESS if the data type is found in the report.
 * @retval NRF_ERROR_NOT_FOUND if the data type could not be found.
 */
static uint32_t adv_report_parse(uint8_t type, data_t * p_advdata, data_t * p_typedata)
{
    uint32_t  index = 0;
    uint8_t * p_data;

    p_data = p_advdata->p_data;

    while (index < p_advdata->data_len)
    {
        uint8_t field_length = p_data[index];
        uint8_t field_type   = p_data[index + 1];

        if (field_type == type)
        {
            p_typedata->p_data   = &p_data[index + 2];
            p_typedata->data_len = field_length - 1;
            return NRF_SUCCESS;
        }
        index += field_length + 1;
    }
    return NRF_ERROR_NOT_FOUND;
}

static bool find_adv_name(ble_gap_evt_adv_report_t const * p_adv_report, char const * name_to_find)
{
    ret_code_t err_code;
    data_t     adv_data;
    data_t     dev_name;

    // Initialize advertisement report for parsing
    adv_data.p_data   = (uint8_t *)p_adv_report->data;
    adv_data.data_len = p_adv_report->dlen;

    //search for advertising names
    err_code = adv_report_parse(BLE_GAP_AD_TYPE_COMPLETE_LOCAL_NAME, &adv_data, &dev_name);
    if (err_code == NRF_SUCCESS)
    {
        if (memcmp(name_to_find, dev_name.p_data, dev_name.data_len) == 0)
        {
            return true;
        }
    }

    return false;
}

/**@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;
    ble_gap_evt_t const * p_gap_evt = &p_ble_evt->evt.gap_evt;

    switch (p_ble_evt->header.evt_id)
    {
        case BLE_GAP_EVT_ADV_REPORT:
        {
            ble_gap_evt_adv_report_t const * p_adv_report = &p_gap_evt->params.adv_report;

            if (find_adv_name(p_adv_report, "DfuTarg"))
            {

                err_code = sd_ble_gap_connect(&p_adv_report->peer_addr,
                                              &m_scan_params,
                                              &m_connection_param,
                                              APP_BLE_CONN_CFG_TAG);

                if (err_code == NRF_SUCCESS)
                {
                    // scan is automatically stopped by the connect
                    err_code = bsp_indication_set(BSP_INDICATE_IDLE);
                    APP_ERROR_CHECK(err_code);
                    NRF_LOG_INFO("Connecting to target %02x%02x%02x%02x%02x%02x",
                             p_adv_report->peer_addr.addr[0],
                             p_adv_report->peer_addr.addr[1],
                             p_adv_report->peer_addr.addr[2],
                             p_adv_report->peer_addr.addr[3],
                             p_adv_report->peer_addr.addr[4],
                             p_adv_report->peer_addr.addr[5]
                             );
                }
            }
        }break; // BLE_GAP_EVT_ADV_REPORT

        case BLE_GAP_EVT_CONNECTED:
            NRF_LOG_INFO("Connected to target");
            err_code = ble_nus_c_handles_assign(&m_ble_nus_c, p_ble_evt->evt.gap_evt.conn_handle, NULL);
            APP_ERROR_CHECK(err_code);

            err_code = bsp_indication_set(BSP_INDICATE_CONNECTED);
            APP_ERROR_CHECK(err_code);

            // start discovery of services. The NUS Client waits for a discovery result
            err_code = ble_db_discovery_start(&m_db_disc, p_ble_evt->evt.gap_evt.conn_handle);
            APP_ERROR_CHECK(err_code);
            break;

        case BLE_GAP_EVT_TIMEOUT:
            if (p_gap_evt->params.timeout.src == BLE_GAP_TIMEOUT_SRC_SCAN)
            {
                NRF_LOG_INFO("Scan timed out.");
                scan_start();
            }
            else if (p_gap_evt->params.timeout.src == BLE_GAP_TIMEOUT_SRC_CONN)
            {
                NRF_LOG_INFO("Connection Request timed out.");
            }
            break;

        case BLE_GAP_EVT_SEC_PARAMS_REQUEST:
            // Pairing not supported
            err_code = sd_ble_gap_sec_params_reply(p_ble_evt->evt.gap_evt.conn_handle, BLE_GAP_SEC_STATUS_PAIRING_NOT_SUPP, NULL, NULL);
            APP_ERROR_CHECK(err_code);
            break;

        case BLE_GAP_EVT_CONN_PARAM_UPDATE_REQUEST:
            // Accepting parameters requested by peer.
            err_code = sd_ble_gap_conn_param_update(p_gap_evt->conn_handle,
                                                    &p_gap_evt->params.conn_param_update_request.conn_params);
            APP_ERROR_CHECK(err_code);
            break;

#ifndef S140
        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;
#endif

        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:
            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 GATT library. */
void gatt_evt_handler(nrf_ble_gatt_t * p_gatt, nrf_ble_gatt_evt_t const * p_evt)
{
    if (p_evt->evt_id == NRF_BLE_GATT_EVT_ATT_MTU_UPDATED)
    {
        NRF_LOG_INFO("ATT MTU exchange completed.");

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


/**@brief Function for initializing the GATT 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_central_set(&m_gatt, 23);// 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)
{
    ret_code_t err_code;

    switch (event)
    {
        case BSP_EVENT_SLEEP:
            nrf_pwr_mgmt_shutdown(NRF_PWR_MGMT_SHUTDOWN_GOTO_SYSOFF);
            break;

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

        default:
            break;
    }
}

/**@brief Function for initializing the UART. */
static void uart_init(void)
{
    ret_code_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,
        .baud_rate    = UART_BAUDRATE_BAUDRATE_Baud115200
    };

    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);
}

/**@brief Function for initializing the NUS Client. */
static void nus_c_init(void)
{
    ret_code_t       err_code;
    ble_nus_c_init_t init;

    init.evt_handler = ble_nus_c_evt_handler;

    err_code = ble_nus_c_init(&m_ble_nus_c, &init);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for initializing buttons and leds. */
static void buttons_leds_init(void)
{
    ret_code_t err_code;
    bsp_event_t startup_event;

    err_code = bsp_init(BSP_INIT_LED, bsp_event_handler);
    APP_ERROR_CHECK(err_code);

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


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


/**@brief Function for initializing the 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 the Power manager. */
static void power_init(void)
{
    ret_code_t err_code = nrf_pwr_mgmt_init();
    APP_ERROR_CHECK(err_code);
}


/** @brief Function for initializing the Database Discovery Module. */
static void db_discovery_init(void)
{
    ret_code_t err_code = ble_db_discovery_init(db_disc_handler);
    APP_ERROR_CHECK(err_code);
}

void dfu_c_init()
{
    uint32_t      err_code;
    ble_uuid_t    dfu_uuid;
    uint8_t       uuid_type = BLE_UUID_TYPE_VENDOR_BEGIN;
    
    /*Base UUIDs for DFU service characteristics*/
    ble_uuid128_t dfu_base_uuid = 
    {
        {
            0x50, 0xEA, 0xDA, 0x30, 0x88, 0x83, 0xB8, 0x9F,
            0x60, 0x4F, 0x15, 0xF3,  0x00, 0x00, 0xC9, 0x8E
        }
    };


    dfu_uuid.type = BLE_UUID_TYPE_BLE;
    dfu_uuid.uuid = 0xFE59;

    err_code = sd_ble_uuid_vs_add(&dfu_base_uuid, &uuid_type);
    APP_ERROR_CHECK(err_code);


    err_code = ble_db_discovery_evt_register(&dfu_uuid);
    APP_ERROR_CHECK(err_code);
}


int main(void)
{
    log_init();
    timer_init();
    power_init();
    uart_init();
    buttons_leds_init();
    db_discovery_init();
    ble_stack_init();
    gatt_init();
    //nus_c_init();

    dfu_c_init();

    // Start scanning for peripherals and initiate connection
    // with devices that advertise NUS UUID.
    printf("BLE UART central example started.\r\n");
    NRF_LOG_INFO("BLE UART central example started.");
    scan_start();

    for (;;)
    {
        if (NRF_LOG_PROCESS() == false)
        {
            nrf_pwr_mgmt_run();
            //ble_db_discovery_start(&m_db_disc, 0);
        }
    }
}