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Connect two nordic devices and send data via UART to PC

Hi all Nordic developers,

I am currently working on an application using a sensor (the temperature sensor) on a Smart beacon kit, which must connect and send data to a nRF51 DK; for this no problem, i already have done everything using some code (ble app multilink in particular) and it's working. After this, i want the received data by the DK to be sent via UART to the PC, which is of course connected by USB to my DK board. How can i do this? I have already tried to implement some part of the ble_app_uart example, just the part that should initialize the uart service and send data via the function "uart put", but i must be missing something because if i launch it, it conflicts with the multilink part of the code and the DK board doesn't even connect to the beacon, if i comment the "uart_init" function in main, everything returns functional. What am i missing in implementing the UART part? I post the full code, but the uart portion is just the last quarter of the code, i wrote a comment when it starts. Thanks in advance!

/*
 * Copyright (c) 2014 Nordic Semiconductor. All Rights Reserved.
 *
 * The information contained herein is confidential property of Nordic Semiconductor. The use,
 * copying, transfer or disclosure of such information is prohibited except by express written
 * agreement with Nordic Semiconductor.
 *
 */
 
/**
 * @brief BLE LED Button Service central and client application main file.
 *
 * This example can be a central for up to 8 peripherals.
 * The peripheral is called ble_app_blinky and can be found in the ble_peripheral
 * folder.
 */
 
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include "nordic_common.h"
#include "softdevice_handler.h"
#include "app_timer.h"
#include "app_trace.h"
#include "boards.h"
#include "bsp.h"
#include "bsp_btn_ble.h"
#include "ble.h"
#include "app_uart.h"
#include "ble_advdata.h"
#include "ble_advertising.h"
#include "ble_conn_params.h"
#include "ble_db_discovery.h"
#include "ble_lbs_c.h"
#include "ble_conn_state.h"
#include "nrf_log.h"
 
#include "nrf.h"
#include "ble_hci.h"
#include "app_button.h"
#include "ble_nus.h"
#include "app_util_platform.h"
 
#define IS_SRVC_CHANGED_CHARACT_PRESENT 0                                           /**< Include the service_changed characteristic. If not enabled, the server's database cannot be changed for the lifetime of the device. */
 
#define CENTRAL_LINK_COUNT        1                                          /**< Number of central links used by the application. When changing this number remember to adjust the RAM settings*/
#define PERIPHERAL_LINK_COUNT     1                                          /**< Number of peripheral links used by the application. When changing this number remember to adjust the RAM settings*/
#define TOTAL_LINK_COUNT          CENTRAL_LINK_COUNT + PERIPHERAL_LINK_COUNT /**< Total number of links used by the application. */
#define APPL_LOG                  app_trace_log                              /**< Macro used to log debug information over UART. */
 
#define CENTRAL_SCANNING_LED      BSP_LED_0_MASK
#define CENTRAL_CONNECTED_LED     BSP_LED_1_MASK
 
#define APP_TIMER_PRESCALER       0                                          /**< Value of the RTC1 PRESCALER register. */
#define APP_TIMER_MAX_TIMERS      (2+BSP_APP_TIMERS_NUMBER)                  /**< Maximum number of timers used by the application. */
#define APP_TIMER_OP_QUEUE_SIZE   2                                          /**< Size of timer operation queues. */
 
#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 SCAN_REQUEST              0                                          /**< Active scannin is not set. */
#define SCAN_WHITELIST_ONLY       0                                          /**< We will not ignore unknown devices. */
                                                                              
#define MIN_CONNECTION_INTERVAL   MSEC_TO_UNITS(7.5, UNIT_1_25_MS)           /**< Determines minimum connection interval in milliseconds. */
#define MAX_CONNECTION_INTERVAL   MSEC_TO_UNITS(30, UNIT_1_25_MS)            /**< Determines maximum connection interval in milliseconds. */
#define SLAVE_LATENCY             0                                          /**< Determines slave latency in terms of connection events. */
#define SUPERVISION_TIMEOUT       MSEC_TO_UNITS(4000, UNIT_10_MS)            /**< Determines supervision time-out in units of 10 milliseconds. */
 
#define UUID16_SIZE               2                                          /**< Size of a UUID, in bytes. */
 
#define LEDBUTTON_LED             BSP_LED_2_MASK                             /**< LED to indicate a change of state of the the Button characteristic on the peer. */
 
#define LEDBUTTON_BUTTON_PIN      BSP_BUTTON_0                               /**< Button that will write to the LED characteristic of the peer */
#define BUTTON_DETECTION_DELAY    APP_TIMER_TICKS(50, APP_TIMER_PRESCALER)   /**< Delay from a GPIOTE event until a button is reported as pushed (in number of timer ticks). */
 
#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). */
 
 
static const char m_target_periph_name[] = "Macaque";                  /**< Name of the device we try to connect to. This name is searched for in the scan report data*/
 
static ble_nus_t                        m_nus;                                      /**< Structure to identify the Nordic UART Service. */
static uint16_t                         m_conn_handle = BLE_CONN_HANDLE_INVALID;    /**< Handle of the current connection. */
static ble_uuid_t                       m_adv_uuids[] = {{BLE_UUID_NUS_SERVICE, NUS_SERVICE_UUID_TYPE}};  /**< Universally unique service identifier. */
 
 
/** @brief Scan parameters requested for scanning and connection. */
static const ble_gap_scan_params_t m_scan_param =
{
    SCAN_REQUEST,
    SCAN_WHITELIST_ONLY,
    NULL,
    (uint16_t)SCAN_INTERVAL,
    (uint16_t)SCAN_WINDOW,
    SCAN_TIMEOUT
};
 
/**@brief Connection parameters requested for connection. */
static const ble_gap_conn_params_t m_connection_param =
{
    (uint16_t)MIN_CONNECTION_INTERVAL,
    (uint16_t)MAX_CONNECTION_INTERVAL,
    (uint16_t)SLAVE_LATENCY,
    (uint16_t)SUPERVISION_TIMEOUT
};
 
static ble_lbs_c_t        m_ble_lbs_c[TOTAL_LINK_COUNT];           /**< Main structures used by the LED Button client module. */
static uint8_t            m_ble_lbs_c_count;                       /**< Keeps track of how many instances of LED Button client module have been initialized. >*/
static ble_db_discovery_t m_ble_db_discovery[TOTAL_LINK_COUNT];    /**< list of DB structures used by the database discovery module. */
 
/**@brief Function to handle 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 for the LEDs initialization.
 *
 * @details Initializes all LEDs used by the application.
 */
static void leds_init(void)
{
    LEDS_CONFIGURE(CENTRAL_SCANNING_LED | CENTRAL_CONNECTED_LED | LEDBUTTON_LED);
    LEDS_OFF(CENTRAL_SCANNING_LED | CENTRAL_CONNECTED_LED | LEDBUTTON_LED);
}
 
 
/**
 * @brief Parses advertisement data, providing length and location of the field in case
 *        matching data is found.
 *
 * @param[in]  type       Type of data to be looked for in advertisement data.
 * @param[in]  p_advdata  Advertisement report length and pointer to report.
 * @param[out] p_typedata 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, uint8_array_t * p_advdata, uint8_array_t * p_typedata)
{
    uint32_t  index = 0;
    uint8_t * p_data;
 
    p_data = p_advdata->p_data;
 
    while (index < p_advdata->size)
    {
        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->size   = field_length - 1;
            return NRF_SUCCESS;
        }
        index += field_length + 1;
    }
    return NRF_ERROR_NOT_FOUND;
}
 
 
/**@brief Function to start scanning.
 */
static void scan_start(void)
{
    ret_code_t err_code;
 
    err_code = sd_ble_gap_scan_stop();
    // It is okay to ignore this error since we are stopping the scan anyway.
    if (err_code != NRF_ERROR_INVALID_STATE)
    {
        APP_ERROR_CHECK(err_code);
    }
 
    NRF_LOG_PRINTF("[APP]: start scanning for device name %s\r\n", m_target_periph_name);
    err_code = sd_ble_gap_scan_start(&m_scan_param);
    APP_ERROR_CHECK(err_code);
 
}
 
 
/**@brief Handles events coming from the LED Button central module.
 *
 * @param[in] p_lbs_c     The instance of LBS_C that triggered the event.
 * @param[in] p_lbs_c_evt The LBS_C event.
 */
static void lbs_c_evt_handler(ble_lbs_c_t * p_lbs_c, ble_lbs_c_evt_t * p_lbs_c_evt)
{
    const uint16_t conn_handle = p_lbs_c_evt->conn_handle;
    switch (p_lbs_c_evt->evt_type)
    {
        case BLE_LBS_C_EVT_DISCOVERY_COMPLETE:
        {
            ret_code_t err_code;
 
            NRF_LOG_PRINTF("[APP]: LED Button service discovered on conn_handle 0x%x\r\n", 
                            conn_handle);
             
            err_code = app_button_enable();
            APP_ERROR_CHECK(err_code);
 
            // LED Button service discovered. Enable notification of Button.
            err_code = ble_lbs_c_button_notif_enable(p_lbs_c);
            APP_ERROR_CHECK(err_code);
        } break; // BLE_LBS_C_EVT_DISCOVERY_COMPLETE
 
        case BLE_LBS_C_EVT_BUTTON_NOTIFICATION:
        {
            NRF_LOG_PRINTF("[APP]: Link 0x%x, Button state changed on peer to 0x%x\r\n", 
                           conn_handle,
                           p_lbs_c_evt->params.button.button_state);
            if (p_lbs_c_evt->params.button.button_state)
            {
                LEDS_ON(LEDBUTTON_LED);
            }
            else
            {
                LEDS_OFF(LEDBUTTON_LED);
            }
        } break; // BLE_LBS_C_EVT_BUTTON_NOTIFICATION
 
        default:
            // No implementation needed.
            break;
    }
}
 
/**@brief Function for handling the advertising report BLE event.
 *
 * @param[in] p_ble_evt  Bluetooth stack event.
 */
static void on_adv_report(const ble_evt_t * const p_ble_evt)
{
    uint32_t      err_code;
    uint8_array_t adv_data;
    uint8_array_t dev_name;
    bool          do_connect = false;
 
    // For readibility.
    const ble_gap_evt_t * const p_gap_evt    = &p_ble_evt->evt.gap_evt;
    const ble_gap_addr_t  * const peer_addr  = &p_gap_evt->params.adv_report.peer_addr;
 
    // Initialize advertisement report for parsing
    adv_data.p_data = (uint8_t *)p_gap_evt->params.adv_report.data;
    adv_data.size   = p_gap_evt->params.adv_report.dlen;
 
 
    //search for advertising names
    bool found_name = false;
    err_code = adv_report_parse(BLE_GAP_AD_TYPE_COMPLETE_LOCAL_NAME,
                                &adv_data,
                                &dev_name);
    if (err_code != NRF_SUCCESS)
    {
        // Look for the short local name if it was not found as complete
        err_code = adv_report_parse(BLE_GAP_AD_TYPE_SHORT_LOCAL_NAME, &adv_data, &dev_name);
        if (err_code != NRF_SUCCESS)
        {
            // If we can't parse the data, then exit
            return;
        }
        else
        {
            found_name = true;
        }
    }
    else
    {
        found_name = true;
    }
    if (found_name)
    {
        if (strlen(m_target_periph_name) != 0)
        {
            if(memcmp(m_target_periph_name, dev_name.p_data, dev_name.size) == 0)
            {
                do_connect = true;
            }
        }
    }
 
    if (do_connect)
    {
        // Initiate connection.
        err_code = sd_ble_gap_connect(peer_addr, &m_scan_param, &m_connection_param);
        if (err_code != NRF_SUCCESS)
        {
            APPL_LOG("[APPL]: Connection Request Failed, reason %d\r\n", err_code);
        }
    }
}
 
/**@brief Function for handling BLE Stack events concerning central applications.
 *
 * @details This function keeps the connection handles of central applications up-to-date. It
 *          parses scanning reports, initiating a connection attempt to peripherals when a
 *          target UUID is found, and manages connection parameter update requests. Additionally,
 *          it updates the status of LEDs used to report central applications activity.
 *
 * @note Since this function updates connection handles, @ref BLE_GAP_EVT_DISCONNECTED events
 *       should be dispatched to the target application before invoking this function.
 *
 * @param[in] p_ble_evt  Bluetooth stack event.
 */
static void on_ble_evt(const ble_evt_t * const p_ble_evt)
{
    // For readability.
    const ble_gap_evt_t * const p_gap_evt = &p_ble_evt->evt.gap_evt;
 
    switch (p_ble_evt->header.evt_id)
    {
        // Upon connection, check which peripheral has connected, initiate DB
        // discovery, update LEDs status and resume scanning if necessary.
        case BLE_GAP_EVT_CONNECTED:
        {
            uint32_t err_code;
 
            NRF_LOG_PRINTF("[APP]: link 0x%x established, start discovery on it\r\n", 
                           p_gap_evt->conn_handle);
            APP_ERROR_CHECK_BOOL(p_gap_evt->conn_handle < TOTAL_LINK_COUNT);
            
            err_code = ble_lbs_c_handles_assign(&m_ble_lbs_c[p_gap_evt->conn_handle], 
                                                p_gap_evt->conn_handle, 
                                                NULL);
            APP_ERROR_CHECK(err_code);
 
            err_code = ble_db_discovery_start(&m_ble_db_discovery[p_gap_evt->conn_handle],
                                              p_gap_evt->conn_handle);
            if (err_code != NRF_ERROR_BUSY)
            {
                APP_ERROR_CHECK(err_code);
            }
 
            // Update LEDs status, and check if we should be looking for more
            // peripherals to connect to.
            LEDS_ON(CENTRAL_CONNECTED_LED);
            if (ble_conn_state_n_centrals() == CENTRAL_LINK_COUNT)
            {
                LEDS_OFF(CENTRAL_SCANNING_LED);
            }
            else
            {
                // Resume scanning.
                LEDS_ON(CENTRAL_SCANNING_LED);
                scan_start();
            }
        } break; // BLE_GAP_EVT_CONNECTED
 
        // Upon disconnection, reset the connection handle of the peer which disconnected, update
        // the LEDs status and start scanning again.
        case BLE_GAP_EVT_DISCONNECTED:
        {
            uint32_t central_link_cnt; // Number of central links.
 
            NRF_LOG_PRINTF("LBS central link 0x%x disconnected (reason: %d)\r\n",
                           p_gap_evt->conn_handle,
                           p_gap_evt->params.disconnected.reason);
 
            uint32_t err_code = app_button_disable();
            APP_ERROR_CHECK(err_code);
 
            // Start scanning
            scan_start();
 
            // Update LEDs status.
            LEDS_ON(CENTRAL_SCANNING_LED);
            central_link_cnt = ble_conn_state_n_centrals();
            if (central_link_cnt == 0)
            {
                LEDS_OFF(CENTRAL_CONNECTED_LED);
            }
        } break; // BLE_GAP_EVT_DISCONNECTED
 
        case BLE_GAP_EVT_ADV_REPORT:
            on_adv_report(p_ble_evt);
        break; // BLE_GAP_ADV_REPORT
 
        case BLE_GAP_EVT_TIMEOUT:
        {
            // We have not specified a timeout for scanning, so only connection attemps can timeout.
            if (p_gap_evt->params.timeout.src == BLE_GAP_TIMEOUT_SRC_CONN)
            {
                APPL_LOG("[APPL]: Connection Request timed out.\r\n");
            }
        } break; // BLE_GAP_EVT_TIMEOUT
 
        case BLE_GAP_EVT_CONN_PARAM_UPDATE_REQUEST:
        {
            // Accept parameters requested by peer.
            ret_code_t err_code;
            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; // BLE_GAP_EVT_CONN_PARAM_UPDATE_REQUEST
 
        default:
            // No implementation needed.
            break;
    }
}
 
 
/**@brief Function for dispatching a BLE stack event to all modules with a BLE stack event handler.
 *
 * @details This function is called from the scheduler in the main loop after a BLE stack event has
 * been received.
 *
 * @param[in] p_ble_evt  Bluetooth stack event.
 */
static void ble_evt_dispatch(ble_evt_t * p_ble_evt)
{
    uint16_t conn_handle;
    conn_handle = p_ble_evt->evt.gap_evt.conn_handle;
 
    ble_conn_state_on_ble_evt(p_ble_evt);
    on_ble_evt(p_ble_evt);
        ble_nus_on_ble_evt(&m_nus, p_ble_evt);
 
    // Make sure taht an invalid connection handle are not passed since
    // our array of modules is bound to TOTAL_LINK_COUNT.
    if (conn_handle < TOTAL_LINK_COUNT)
    {
        ble_db_discovery_on_ble_evt(&m_ble_db_discovery[conn_handle], p_ble_evt);
        ble_lbs_c_on_ble_evt(&m_ble_lbs_c[conn_handle], p_ble_evt);
    }
}
 
 
/**@brief LED Button collector initialization.
 */
static void lbs_c_init(void)
{
    uint32_t         err_code;
    ble_lbs_c_init_t lbs_c_init_obj;
 
    lbs_c_init_obj.evt_handler = lbs_c_evt_handler;
 
    for(m_ble_lbs_c_count = 0; m_ble_lbs_c_count < TOTAL_LINK_COUNT; m_ble_lbs_c_count++)
    {
        err_code = ble_lbs_c_init(&m_ble_lbs_c[m_ble_lbs_c_count], &lbs_c_init_obj);
        APP_ERROR_CHECK(err_code);
    }
    m_ble_lbs_c_count = 0;
}
 
 
/**@brief Function for initializing the BLE stack.
 *
 * @details Initializes the SoftDevice and the BLE event interrupts.
 */
static void ble_stack_init(void)
{
    ret_code_t err_code;
     
    nrf_clock_lf_cfg_t clock_lf_cfg = NRF_CLOCK_LFCLKSRC;
     
    // Initialize the SoftDevice handler module.
    SOFTDEVICE_HANDLER_INIT(&clock_lf_cfg, NULL);
     
    ble_enable_params_t ble_enable_params;
    err_code = softdevice_enable_get_default_config(CENTRAL_LINK_COUNT,
                                                    PERIPHERAL_LINK_COUNT,
                                                    &ble_enable_params);
    APP_ERROR_CHECK(err_code);
     
    // Stack checks first if there are still entries in the table before checking if a vendor
    // specific UUID is already in the table thus to be able to call sd_ble_uuid_vs_add several
    // times with the same entry, vs_uuid_count has to be 1 bigger than what is actually needed.
    ble_enable_params.common_enable_params.vs_uuid_count = 2;
     
    // Check the ram settings against the used number of links
    CHECK_RAM_START_ADDR(CENTRAL_LINK_COUNT,PERIPHERAL_LINK_COUNT);
     
    // Enable BLE stack.
    err_code = softdevice_enable(&ble_enable_params);
    APP_ERROR_CHECK(err_code);
 
    // Register with the SoftDevice handler module for BLE events.
    err_code = softdevice_ble_evt_handler_set(ble_evt_dispatch);
    APP_ERROR_CHECK(err_code);
}
 
 
/**@brief Function to write to the LED characterestic of all connected clients.
 *
 * @details Based on if the button is pressed or released, we write a high or low LED status to
 *          the server.
 *
 * @param[in] button_action The button action (press/release).
 *            Determines if the LEDs of the servers will be ON or OFF.
 *
 * @return NRF_SUCCESS on success, else the error code from ble_lbs_led_status_send.
 */
static uint32_t led_status_send_to_all(uint8_t button_action)
{
    uint32_t err_code;
 
    for (uint32_t i = 0; i< CENTRAL_LINK_COUNT; i++)
    {
        err_code = ble_lbs_led_status_send(&m_ble_lbs_c[i], button_action);
        if (err_code != NRF_SUCCESS &&
            err_code != BLE_ERROR_INVALID_CONN_HANDLE &&
            err_code != NRF_ERROR_INVALID_STATE)
        {
            return err_code;
        }
    }
        return NRF_SUCCESS;
}
 
 
/**@brief Function for handling events from the button handler module.
 *
 * @param[in] pin_no        The pin that the event applies to.
 * @param[in] button_action The button action (press/release).
 */
static void button_event_handler(uint8_t pin_no, uint8_t button_action)
{
    uint32_t err_code;
 
    switch (pin_no)
    {
        case LEDBUTTON_BUTTON_PIN:
            err_code = led_status_send_to_all(button_action);
            if (err_code == NRF_SUCCESS)
            {
                NRF_LOG_PRINTF("LBS write LED state %d\r\n", button_action);
            }
            break;
 
        default:
            APP_ERROR_HANDLER(pin_no);
            break;
    }
}
 
 
/**@brief Function for initializing the button handler module.
 */
static void buttons_init(void)
{
    uint32_t err_code;
 
   //The array must be static because a pointer to it will be saved in the button handler module.
    static app_button_cfg_t buttons[] =
    {
        {LEDBUTTON_BUTTON_PIN, false, BUTTON_PULL, button_event_handler}
    };
 
    err_code = app_button_init(buttons, sizeof(buttons) / sizeof(buttons[0]),
                               BUTTON_DETECTION_DELAY);
    APP_ERROR_CHECK(err_code);
}
 
 
/**@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)
{
    NRF_LOG_PRINTF("[APP]: call to ble_lbs_on_db_disc_evt for instance %d and link 0x%x!\r\n", 
                    p_evt->conn_handle,
                    p_evt->conn_handle);
    ble_lbs_on_db_disc_evt(&m_ble_lbs_c[p_evt->conn_handle], p_evt);
}
 
 
/** @brief Database discovery initialization.
 */
static void db_discovery_init(void)
{
    ret_code_t err_code = ble_db_discovery_init(db_disc_handler);
    APP_ERROR_CHECK(err_code);
}
 
 
 
/** @brief Function to sleep until a BLE event is received by the application.
 */
static void power_manage(void)
{
    ret_code_t err_code = sd_app_evt_wait();
    APP_ERROR_CHECK(err_code);
}
 


***// HERE STARTS THE UART PART!!!!!***


/**@brief Function for handling the data from the Nordic UART Service.
 *
 * @details This function will process the data received from the Nordic UART BLE Service and send
 *          it to the UART module.
 *
 * @param[in] p_nus    Nordic UART Service structure.
 * @param[in] p_data   Data to be send to UART module.
 * @param[in] length   Length of the data.
 */
/**@snippet [Handling the data received over BLE] */
static void nus_data_handler(ble_nus_t * p_nus, uint8_t * p_data, uint16_t length)
{
    for (uint32_t i = 0; i < length; i++)
    {
        while(app_uart_put(p_data[i]) != NRF_SUCCESS);
    }
    while(app_uart_put('\n') != NRF_SUCCESS);
}
/**@snippet [Handling the data received over BLE] */
 
/**@brief Function for initializing services that will be used by the application.
 */
static void services_init(void)
{
    uint32_t       err_code;
    ble_nus_init_t nus_init;
     
    memset(&nus_init, 0, sizeof(nus_init));
 
    nus_init.data_handler = nus_data_handler;
     
    err_code = ble_nus_init(&m_nus, &nus_init);
    APP_ERROR_CHECK(err_code);
}
 
/**@brief   Function for handling 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' i.e '\n' (hex 0x0D) or if the string has reached a length of 
 *          @ref NUS_MAX_DATA_LENGTH.
 */
/**@snippet [Handling the data received over UART] */
void uart_event_handle(app_uart_evt_t * p_event)
{
    static uint8_t data_array[BLE_NUS_MAX_DATA_LEN];
    static uint8_t index = 0;
    uint32_t       err_code;
 
    switch (p_event->evt_type)
    {
        case APP_UART_DATA_READY:
            UNUSED_VARIABLE(app_uart_get(&data_array[index]));
            index++;
 
            if ((data_array[index - 1] == '\n') || (index >= (BLE_NUS_MAX_DATA_LEN)))
            {
                err_code = ble_nus_string_send(&m_nus, data_array, index);
                if (err_code != NRF_ERROR_INVALID_STATE)
                {
                    APP_ERROR_CHECK(err_code);
                }
                 
                index = 0;
            }
            break;
 
        case APP_UART_COMMUNICATION_ERROR:
            APP_ERROR_HANDLER(p_event->data.error_communication);
            break;
 
        case APP_UART_FIFO_ERROR:
            APP_ERROR_HANDLER(p_event->data.error_code);
            break;
 
        default:
            break;
    }
}
/**@snippet [Handling the data received over UART] */
 
/**@brief  Function for initializing the UART module.
 */
/**@snippet [UART Initialization] */
static void uart_init(void)
{
    uint32_t                     err_code;
    const app_uart_comm_params_t comm_params =
    {
        RX_PIN_NUMBER,
        TX_PIN_NUMBER,
        RTS_PIN_NUMBER,
        CTS_PIN_NUMBER,
        APP_UART_FLOW_CONTROL_DISABLED,
        false,
        UART_BAUDRATE_BAUDRATE_Baud38400
    };
 
    APP_UART_FIFO_INIT( &comm_params,
                       UART_RX_BUF_SIZE,
                       UART_TX_BUF_SIZE,
                       uart_event_handle,
                       APP_IRQ_PRIORITY_LOW,
                       err_code);
    APP_ERROR_CHECK(err_code);
}
/**@snippet [UART Initialization] */
 
 
 
 
int main(void)
{
    ret_code_t err_code;
         
        bool erase_bonds;
     
    err_code = NRF_LOG_INIT();
    APP_ERROR_CHECK(err_code);
    NRF_LOG_PRINTF("[APP]: Multilink Example\r\n");
    leds_init();
    APP_TIMER_INIT(APP_TIMER_PRESCALER, APP_TIMER_OP_QUEUE_SIZE, NULL);
    buttons_init();
    ble_stack_init();
     
        //uart_init();
        services_init();
 
    db_discovery_init();
    lbs_c_init();
 
    // Start scanning for peripherals and initiate connection to devices which
    // advertise.
    scan_start();
 
    // Turn on the LED to signal scanning.
    LEDS_ON(CENTRAL_SCANNING_LED);
 
    for (;;)
    {
        // Wait for BLE events.
        power_manage();
    }
}
  • I'm a bit confused. You are able to send the temperature from the peripheral (beacon) to the central (nRF51 DK). And you want to print the temperature in a terminal on the PC. Why are you adding uart service? This is for emulating uart over BLE, not uart to a PC. Can't you just use NRF_LOG_PRINTF() to print the temperature in a terminal?

  • Because i already used this example to send data similarly using a phone instead of the beacon as "data sender" (in this case of course i was the one triggering the connection from the control panel of the phone and it was easier), and i was able to visualize it. I'm using it because i want to read the values from the DK in Matlab saving them in an array while reading the serial port, not just visualize it, am i doing something unnecessary?

  • With that example you are a peripheral and the smart phone is a central that is discovering and using the uart service on the peripheral. Now you are putting the uart service on the central, which means that the peripheral has to do service discovery++ to use it. You don't need the uart service if you have already sent the temperature data over the BLE link. And even if you did, you would have the uart service on the peripheral (beacon) not the central (nRF51 DK). You can probably reuse uart_init() and some of the code in nus_data_handler(), but you first need to get some communication going. For example calling app_uart_put() and seeing something in a terminal (or Matlab), then use that with the temperature that you said that you receive from the peripheral.

  • Ok so if i estabilished a connection between central and peripheral by BLE (done with sd_ble_gap_connect after doing discovery and all the related stuff), i do NOT need UART service to send the data pushed from the beacon to the DK into Matlab, am i correct? To do this i just need the function app_uart_put if i understood correctly, like there is in the code i posted in the question, but how do i do it? I mean, how should i say to the DK that as soon as it receives a value of temperature by notification of the beacon, it must send it to the PC?

  • If you are already able to send the data to the nRF51 DK you don't need the UART service. You can have a look at the ble_app_uart_c example for how to send data received in a notification over uart to the PC. In short something like this: You will receive the BLE_GATTC_EVT_HVX event. Then you can find the data in p_ble_evt->evt.gattc_evt.params.hvx.data. Put this data into app_uart_put().

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