BLE_GAP_EVT_SEC_REQUEST event missing?

[vctrvlad]

Hello everyone, 

1st of all, thank you for taking your time to have a look over my "problem".

I have a device that I am working on, that acts as aperipheral, it is a non NRF one.

I also have a NRF52DK that I am using to develop the central device for my peripheral.

In the central (NRF52DK), for connection, I am scanning for Local Name (shortened local name never works for me).

Immediately after a connection is estabilished, from peripheral I issue a BLE_GAP_EVT_SEC_REQUEST, that is visible on the sniffer log, but I seem to get no event in the central device at ble_evt_handler level.

Probably I am completely missing something, but please, can anyone help me out finding out what am I missing?

Thank you in advance, 

Victor 

[vctrvlad]

also, for what is worth mentioning, the PM is not enabled, and I am expecting for the event to show up in ble_evt_handler.

[Susheel Nuguru]

Heard such behavior for the first time. Normally a successful security request from the peripheral to central should be visible on the central side as BLE_GAP_EVT_SEC_REQUEST. Can you make s simplistic project for me to be able to replicate  this on my side?

[vctrvlad]

well, I am just using the ble_app_blinky_c example for this, and modified it a little bit, just as much as I could test some basic things on my peripheral.

This is my main.c in the mentioned example project. 

/**
 * Copyright (c) 2014 - 2020, Nordic Semiconductor ASA
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form, except as embedded into a Nordic
 *    Semiconductor ASA integrated circuit in a product or a software update for
 *    such product, must reproduce the above copyright notice, this list of
 *    conditions and the following disclaimer in the documentation and/or other
 *    materials provided with the distribution.
 *
 * 3. Neither the name of Nordic Semiconductor ASA nor the names of its
 *    contributors may be used to endorse or promote products derived from this
 *    software without specific prior written permission.
 *
 * 4. This software, with or without modification, must only be used with a
 *    Nordic Semiconductor ASA integrated circuit.
 *
 * 5. Any software provided in binary form under this license must not be reverse
 *    engineered, decompiled, modified and/or disassembled.
 *
 * THIS SOFTWARE IS PROVIDED BY NORDIC SEMICONDUCTOR ASA "AS IS" AND ANY EXPRESS
 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY, NONINFRINGEMENT, AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL NORDIC SEMICONDUCTOR ASA OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
 * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */
/**
 * @brief BLE LED Button Service central and client application main file.
 *
 * This file contains the source code for a sample client application using the LED Button service.
 */

#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include "nrf_sdh.h"
#include "nrf_sdh_ble.h"
#include "nrf_sdh_soc.h"
#include "nrf_pwr_mgmt.h"
#include "app_timer.h"
#include "boards.h"
#include "bsp.h"
#include "bsp_btn_ble.h"
#include "ble.h"
#include "ble_hci.h"
#include "ble_advertising.h"
#include "ble_conn_params.h"
#include "ble_db_discovery.h"
#include "ble_lbs_c.h"
#include "nrf_ble_gatt.h"
#include "nrf_ble_scan.h"

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


#define CENTRAL_SCANNING_LED            BSP_BOARD_LED_0                     /**< Scanning LED will be on when the device is scanning. */
#define CENTRAL_CONNECTED_LED           BSP_BOARD_LED_1                     /**< Connected LED will be on when the device is connected. */
#define LEDBUTTON_LED                   BSP_BOARD_LED_2                     /**< LED to indicate a change of state of the the Button characteristic on the peer. */
#define DEBUG_LED                       BSP_BOARD_LED_3                     /*VVL LED to debug*/

#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_DURATION                   0x0000                              /**< Timout when scanning. 0x0000 disables timeout. */

#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 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)                 /**< Delay from a GPIOTE event until a button is reported as pushed (in number of timer ticks). */

#define APP_BLE_CONN_CFG_TAG            1                                   /**< A tag identifying the SoftDevice BLE configuration. */
#define APP_BLE_OBSERVER_PRIO           3                                   /**< Application's BLE observer priority. You shouldn't need to modify this value. */

NRF_BLE_SCAN_DEF(m_scan);                                       /**< Scanning module instance. */
BLE_LBS_C_DEF(m_ble_lbs_c);                                     /**< Main structure used by the LBS client module. */
NRF_BLE_GATT_DEF(m_gatt);                                       /**< GATT module instance. */
BLE_DB_DISCOVERY_DEF(m_db_disc);                                /**< DB discovery module instance. */
NRF_BLE_GQ_DEF(m_ble_gatt_queue,                                /**< BLE GATT Queue instance. */
               NRF_SDH_BLE_CENTRAL_LINK_COUNT,
               NRF_BLE_GQ_QUEUE_SIZE);
//VVL
static char const m_target_periph_name[] = "MQBLG";     /**< Name of the device we try to connect to. This name is searched in the scan report data*/

//static const nrf_ble_scan_short_name_t m_target_periph_short_name = {"MQBLG", 5};//VVL



/**@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 handling the LED Button Service client errors.
 *
 * @param[in]   nrf_error   Error code containing information about what went wrong.
 */
static void lbs_error_handler(uint32_t nrf_error)
{
    APP_ERROR_HANDLER(nrf_error);
}


/**@brief Function for the LEDs initialization.
 *
 * @details Initializes all LEDs used by the application.
 */
static void leds_init(void)
{
    bsp_board_init(BSP_INIT_LEDS);
}


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

    err_code = nrf_ble_scan_start(&m_scan);
    APP_ERROR_CHECK(err_code);

    bsp_board_led_off(CENTRAL_CONNECTED_LED);
    bsp_board_led_on(CENTRAL_SCANNING_LED);
}


/**@brief Handles events coming from the LED Button central module.
 */
static void lbs_c_evt_handler(ble_lbs_c_t * p_lbs_c, ble_lbs_c_evt_t * p_lbs_c_evt)
{
    switch (p_lbs_c_evt->evt_type)
    {
        case BLE_LBS_C_EVT_DISCOVERY_COMPLETE:
        {
            ret_code_t err_code;

            err_code = ble_lbs_c_handles_assign(&m_ble_lbs_c,
                                                p_lbs_c_evt->conn_handle,
                                                &p_lbs_c_evt->params.peer_db);
            NRF_LOG_INFO("LED Button service discovered on conn_handle 0x%x.", p_lbs_c_evt->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_INFO("Button state changed on peer to 0x%x.", p_lbs_c_evt->params.button.button_state);
            if (p_lbs_c_evt->params.button.button_state)
            {
                bsp_board_led_on(LEDBUTTON_LED);
            }
            else
            {
                bsp_board_led_off(LEDBUTTON_LED);
            }
        } break; // BLE_LBS_C_EVT_BUTTON_NOTIFICATION

        default:
            // No implementation needed.
            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;

    // For readability.
    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 (HR or RSC), initiate DB
        // discovery, update LEDs status and resume scanning if necessary. */
        case BLE_GAP_EVT_CONNECTED:
        {
            NRF_LOG_INFO("Connected.");
            err_code = ble_lbs_c_handles_assign(&m_ble_lbs_c, p_gap_evt->conn_handle, NULL);
            APP_ERROR_CHECK(err_code);

            err_code = ble_db_discovery_start(&m_db_disc, p_gap_evt->conn_handle);
            APP_ERROR_CHECK(err_code);

            // Update LEDs status, and check if we should be looking for more
            // peripherals to connect to.
            bsp_board_led_on(CENTRAL_CONNECTED_LED);
            bsp_board_led_off(CENTRAL_SCANNING_LED);
        } break;

        // Upon disconnection, reset the connection handle of the peer which disconnected, update
        // the LEDs status and start scanning again.
        case BLE_GAP_EVT_DISCONNECTED:
        {
            NRF_LOG_INFO("Disconnected.");
            scan_start();
        } break;

        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)
            {
                NRF_LOG_DEBUG("Connection request timed out.");
            }
        } break;

        case BLE_GAP_EVT_CONN_PARAM_UPDATE_REQUEST:
        {
            // Accept 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;

        case BLE_GAP_EVT_PHY_UPDATE_REQUEST:
        {
            NRF_LOG_DEBUG("PHY update request.");
            ble_gap_phys_t const phys =
            {
                .rx_phys = BLE_GAP_PHY_AUTO,
                .tx_phys = BLE_GAP_PHY_AUTO,
            };
            err_code = sd_ble_gap_phy_update(p_ble_evt->evt.gap_evt.conn_handle, &phys);
            APP_ERROR_CHECK(err_code);
        } break;

        case BLE_GATTC_EVT_TIMEOUT:
        {
            // Disconnect on GATT Client timeout event.
            NRF_LOG_DEBUG("GATT Client Timeout.");
            err_code = sd_ble_gap_disconnect(p_ble_evt->evt.gattc_evt.conn_handle,
                                             BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION);
            APP_ERROR_CHECK(err_code);
        } break;

        case BLE_GATTS_EVT_TIMEOUT:
        {
            // Disconnect on GATT Server timeout event.
            NRF_LOG_DEBUG("GATT Server Timeout.");
            err_code = sd_ble_gap_disconnect(p_ble_evt->evt.gatts_evt.conn_handle,
                                             BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION);
            APP_ERROR_CHECK(err_code);
        } break;
        
        case BLE_GAP_EVT_SEC_REQUEST: 
        {
            NRF_LOG_DEBUG("security requested");
            err_code = err_code;
            APP_ERROR_CHECK(err_code);
        }
        break;


        default:
            NRF_LOG_DEBUG("unhandled event");
            APP_ERROR_CHECK(err_code);
            // No implementation needed.
            break;
    }
}


/**@brief LED Button client initialization.
 */
static void lbs_c_init(void)
{
    ret_code_t       err_code;
    ble_lbs_c_init_t lbs_c_init_obj;

    lbs_c_init_obj.evt_handler   = lbs_c_evt_handler;
    lbs_c_init_obj.p_gatt_queue  = &m_ble_gatt_queue;
    lbs_c_init_obj.error_handler = lbs_error_handler;

    err_code = ble_lbs_c_init(&m_ble_lbs_c, &lbs_c_init_obj);
    APP_ERROR_CHECK(err_code);
}


/**@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;

    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 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)
{
    ret_code_t err_code;

    switch (pin_no)
    {
        case LEDBUTTON_BUTTON_PIN:
            err_code = ble_lbs_led_status_send(&m_ble_lbs_c, button_action);
            if (err_code != NRF_SUCCESS &&
                err_code != BLE_ERROR_INVALID_CONN_HANDLE &&
                err_code != NRF_ERROR_INVALID_STATE)
            {
                APP_ERROR_CHECK(err_code);
            }
            if (err_code == NRF_SUCCESS)
            {
                NRF_LOG_INFO("LBS write LED state %d", button_action);
            }
            break;

        default:
            APP_ERROR_HANDLER(pin_no);
            break;
    }
}


/**@brief Function for handling Scaning events.
 *
 * @param[in]   p_scan_evt   Scanning event.
 */
static void scan_evt_handler(scan_evt_t const * p_scan_evt)
{
    ret_code_t err_code;
    switch(p_scan_evt->scan_evt_id)
    {
        case NRF_BLE_SCAN_EVT_FILTER_MATCH:
        {
          NRF_LOG_INFO("Shortened name found");
          bsp_board_led_off(DEBUG_LED);
        }
        break;
        case NRF_BLE_SCAN_EVT_NOT_FOUND:
        {
          ble_gap_evt_adv_report_t const * p_adv = p_scan_evt->params.p_not_found;
          bsp_board_led_on(DEBUG_LED);
          //NRF_LOG_INFO("Shortened name NOT found");
          
        }
        break;
        F_BLE_SCAN_EVT_CONNECTING_ERROR:
            err_code = p_scan_evt->params.connecting_err.err_code;
            APP_ERROR_CHECK(err_code);
            break;
        default:
          break;
    }
}


/**@brief Function for initializing the button handler module.
 */
static void buttons_init(void)
{
    ret_code_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, ARRAY_SIZE(buttons),
                               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)
{
    ble_lbs_on_db_disc_evt(&m_ble_lbs_c, p_evt);
}


/**@brief Database discovery initialization.
 */
static void db_discovery_init(void)
{
    ble_db_discovery_init_t db_init;

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

    db_init.evt_handler  = db_disc_handler;
    db_init.p_gatt_queue = &m_ble_gatt_queue;

    ret_code_t err_code = ble_db_discovery_init(&db_init);
    APP_ERROR_CHECK(err_code);
}


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


/**@brief Function for initializing the Power manager. */
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 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)
{
    uint32_t err_code;    
	
#if 1 // change to public address
	ble_gap_addr_t gap_address;
	gap_address.addr_type = BLE_GAP_ADDR_TYPE_PUBLIC;
	memcpy(&gap_address.addr, "\x62\x52\x42\x32\x22\x12", sizeof(gap_address.addr));
	err_code = sd_ble_gap_addr_set(&gap_address);
	APP_ERROR_CHECK(err_code);
#endif

#if 0 // set random static address
	ble_gap_addr_t gap_address;
	gap_address.addr_type = BLE_GAP_ADDR_TYPE_RANDOM_STATIC;
	memcpy(&gap_address.addr, "\x62\x52\x42\x32\x22\x12", sizeof(gap_address.addr));
	gap_address.addr[5] |= 0xc0;
	err_code = sd_ble_gap_addr_set(&gap_address);
	APP_ERROR_CHECK(err_code);
#endif
	
}

static void scan_init(void)
{
    ret_code_t          err_code;
    nrf_ble_scan_init_t init_scan;

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

    init_scan.connect_if_match = true;
    init_scan.conn_cfg_tag     = APP_BLE_CONN_CFG_TAG;

    err_code = nrf_ble_scan_init(&m_scan, &init_scan, scan_evt_handler);
    APP_ERROR_CHECK(err_code);

    // Setting filters for scanning.
err_code = nrf_ble_scan_filters_enable(&m_scan, NRF_BLE_SCAN_NAME_FILTER, false);
//VVL       err_code = nrf_ble_scan_filters_enable(&m_scan, NRF_BLE_SCAN_SHORT_NAME_FILTER, false);
    APP_ERROR_CHECK(err_code);

err_code = nrf_ble_scan_filter_set(&m_scan, SCAN_NAME_FILTER, m_target_periph_name);
//VVL     err_code = nrf_ble_scan_filter_set(&m_scan, SCAN_SHORT_NAME_FILTER, &m_target_periph_short_name);
    
    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 the idle state (main loop).
 *
 * @details Handle any pending log operation(s), then sleep until the next event occurs.
 */
static void idle_state_handle(void)
{
    NRF_LOG_FLUSH();
    nrf_pwr_mgmt_run();
}


int main(void)
{
    // Initialize.
    log_init();
    timer_init();
    leds_init();
    buttons_init();
    power_management_init();
    ble_stack_init();
    gap_params_init();
    scan_init();
    gatt_init();
    db_discovery_init();
    lbs_c_init();

    // Start execution.
    NRF_LOG_INFO("Blinky CENTRAL example started.");
    scan_start();

    // Turn on the LED to signal scanning.
    bsp_board_led_on(CENTRAL_SCANNING_LED);

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

In order for NRF52DK with this example, to connect to peripheral, the peripheral should advertize the complete Local Name "MQBLG" no matter services and characteristics.

Immediately after connection request, the peripheral confirms it, and proceeds by requesting security:

Please let me know if I can offer anything more info in order for you to be able to help somehow.

I am also having realterm watching on the uart port of NRF52DK and displaying this:

I would have expected also "security requested" to be printed according to: 

       case BLE_GAP_EVT_SEC_REQUEST: 
        {
            NRF_LOG_DEBUG("security requested");
            err_code = err_code;
            APP_ERROR_CHECK(err_code);
        }
        break;

Please ignore the err_code = err_code; line, it was just a failed attempt to get the optimization out for the line below.

Regards, 

Victor

[vctrvlad]

hmmm, could this be because of me ignoring the "find by type value requests"?

[vctrvlad]

managed to get rid of DB_Discovery, but still, NRF does not reply/react to BLE_GAP_EVT_SEC_REQUEST