s140 Central and timeslots

[EGM dev]

Hello,

is it possible to use use timeslot API on s140 while BLE is in "central" mode?

I was able to use timeslot API when BLE was running as peripheral. However, same timeslot code does nothing in BLE central mode.

I am using "ble_app_blinky" as a basis for both peripheral / central and "nrf51-ble-gzll-device-uart" as a basis for timeslot API.

For some reason in BLE central my timeslot callback "m_radio_callback" does not seem to be called at all. However session open / request passes without any error.

Thank you.

[Jared]

Hi,

The timeslot feature should not be dependent on what BLE role you have implemented in your application. 

I'm seeing some inconsistent behavior of the logger module, as logs are printed only occasionally. I see that you have configured the logger module in deferred mode which means that the application will process the logger in Idle mode. It doesn't seem like the application has enough time to process the logs which makes it unpractical to debug with, turning off deferred mode would make the application process the logs in-place, which I also don't recommend for real time applications. Instead, I recommend using something as simple as the LEDS on the DK and toggle them each time the application increments one of the callback counters. I've implemented this in the included files. LED3 and LED4 is used for cb_counter and ev_counter respectively. 

The original project "nrf51-ble-gzll-device-uart" was written for SDK 10. Since then we have done some major changes in how modules subscribe to Softdevice events. From the SDK 14.0 migration guide:

"The scheme for dispatching events from the SoftDevice to the libraries and services has changed: the ble_evt_dispatch and sys_evt_dispatch functions have been removed, in favor of registering BLE and SoC event observers using the NRF_SDH_BLE_OBSERVER and NRF_SDH_SOC_OBSERVER macros, respectively".

Which means that you should register a observer with NRF_SDH_BLE_OBSERVER for the m_radio_callback and sys_evt_dispatch callback handlers to be called. I've implemented these changes in the included files below. The result is that the callback handlers are called which is shown by the toggling of LEDS.

best regards

Jared

/* Copyright (c) 2013 Nordic Semiconductor. All Rights Reserved.
 *
 * The information contained herein is property of Nordic Semiconductor ASA.
 * Terms and conditions of usage are described in detail in NORDIC
 * SEMICONDUCTOR STANDARD SOFTWARE LICENSE AGREEMENT.
 *
 * Licensees are granted free, non-transferable use of the information. NO
 * WARRANTY of ANY KIND is provided. This heading must NOT be removed from
 * the file.
 *
 */
 
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include "nrf_assert.h"
#include "nrf_soc.h"
#include "nrf_gzll.h"
#include "app_error.h"
#include "wireless_debug.h"
#include "app_util_platform.h"
#include "nrf_sdh_soc.h"

void sys_evt_dispatch(uint32_t evt_id,void * p_context); //Forward declaration
NRF_SDH_SOC_OBSERVER(m_sys_radio_signal_obs, 0, sys_evt_dispatch, NULL);//registering of observer for events

 
//void notification_cb(nrf_impl_notification_t notification);
/*lint -e526 "Symbol RADIO_IRQHandler not defined" */
void RADIO_IRQHandler(void);

#define PIPE_NUMBER          0
#define TX_PAYLOAD_LENGTH   32
#define ACK_PAYLOAD_LENGTH  32

static nrf_radio_request_t  m_timeslot_request;
static uint32_t             m_slot_length;
static volatile bool        m_cmd_received = false;
static volatile bool        m_gzll_initialized = false;

volatile uint32_t cb_counter;
volatile uint32_t ev_counter;

static nrf_radio_signal_callback_return_param_t signal_callback_return_param;
static uint8_t ack_payload[ACK_PAYLOAD_LENGTH];

void HardFault_Handler(uint32_t program_counter, uint32_t link_register)
{
}

void m_configure_next_event(void)
{
    m_slot_length                                  = 25000;
    m_timeslot_request.request_type                = NRF_RADIO_REQ_TYPE_EARLIEST;
    m_timeslot_request.params.earliest.hfclk       = NRF_RADIO_HFCLK_CFG_XTAL_GUARANTEED;
    m_timeslot_request.params.earliest.priority    = NRF_RADIO_PRIORITY_NORMAL;
    m_timeslot_request.params.earliest.length_us   = m_slot_length;
    m_timeslot_request.params.earliest.timeout_us  = 1000000;
}

void sys_evt_dispatch(uint32_t evt_id,void * p_context)
{
    uint32_t err_code;

    ev_counter++;
    
    switch (evt_id)
    {
        case NRF_EVT_RADIO_SIGNAL_CALLBACK_INVALID_RETURN:
            ASSERT(false);
            break;
        
        case NRF_EVT_RADIO_SESSION_IDLE:
            ASSERT(false);
            break;

        case NRF_EVT_RADIO_SESSION_CLOSED:
            ASSERT(false);
            break;

        case NRF_EVT_RADIO_BLOCKED:
            m_configure_next_event();
            err_code = sd_radio_request(&m_timeslot_request);
            APP_ERROR_CHECK(err_code);
            break;

        case NRF_EVT_RADIO_CANCELED:
            m_configure_next_event();
            err_code = sd_radio_request(&m_timeslot_request);
            APP_ERROR_CHECK(err_code);
            break;

        default:
            break;
    }
}

static void m_on_start(void)
{
    bool res;
    signal_callback_return_param.params.request.p_next = NULL;
    signal_callback_return_param.callback_action = NRF_RADIO_SIGNAL_CALLBACK_ACTION_NONE;
    
    if (!m_gzll_initialized)
    {
        res = nrf_gzll_init(NRF_GZLL_MODE_DEVICE);
        ASSERT(res);
        res = nrf_gzll_set_device_channel_selection_policy(NRF_GZLL_DEVICE_CHANNEL_SELECTION_POLICY_USE_CURRENT);
        ASSERT(res);
        res = nrf_gzll_set_xosc_ctl(NRF_GZLL_XOSC_CTL_MANUAL);
        ASSERT(res);
        /*res = */nrf_gzll_set_max_tx_attempts(0);
        //ASSERT(res);
        res = nrf_gzll_set_base_address_0(0xE7E7E7E7);
        ASSERT(res);
        res = nrf_gzll_enable();
        ASSERT(res);
        m_gzll_initialized = true;
    }
    else
    {
        res = nrf_gzll_set_mode(NRF_GZLL_MODE_DEVICE);
        ASSERT(res);
    }
    NRF_TIMER0->INTENSET = TIMER_INTENSET_COMPARE0_Msk;
    NRF_TIMER0->CC[0] = m_slot_length - 4000; // TODO: Use define instead of magic number
    NVIC_EnableIRQ(TIMER0_IRQn);    
}

static void m_on_multitimer(void)
{
    NRF_TIMER0->EVENTS_COMPARE[0] = 0;
    if (nrf_gzll_get_mode() != NRF_GZLL_MODE_SUSPEND)
    {
        signal_callback_return_param.params.request.p_next = NULL;
        signal_callback_return_param.callback_action = NRF_RADIO_SIGNAL_CALLBACK_ACTION_NONE;
        (void)nrf_gzll_set_mode(NRF_GZLL_MODE_SUSPEND);
        NRF_TIMER0->INTENSET = TIMER_INTENSET_COMPARE0_Msk;
        NRF_TIMER0->CC[0] = m_slot_length - 1000;
    }
    else
    {
        ASSERT(nrf_gzll_get_mode() == NRF_GZLL_MODE_SUSPEND);
        m_configure_next_event();
        signal_callback_return_param.params.request.p_next = &m_timeslot_request;
        signal_callback_return_param.callback_action = NRF_RADIO_SIGNAL_CALLBACK_ACTION_REQUEST_AND_END;
    }
}

nrf_radio_signal_callback_return_param_t * m_radio_callback(uint8_t signal_type)
{
    cb_counter++;
    switch(signal_type)
    {
        case NRF_RADIO_CALLBACK_SIGNAL_TYPE_START:
            m_on_start();
            break;

        case NRF_RADIO_CALLBACK_SIGNAL_TYPE_RADIO:
            signal_callback_return_param.params.request.p_next = NULL;
            signal_callback_return_param.callback_action = NRF_RADIO_SIGNAL_CALLBACK_ACTION_NONE;
            RADIO_IRQHandler();
            break;

        case NRF_RADIO_CALLBACK_SIGNAL_TYPE_TIMER0:
            m_on_multitimer();
            break;
    }
    return (&signal_callback_return_param);
}

uint32_t gazell_sd_radio_init(void)
{
    uint32_t err_code;

    err_code = sd_radio_session_open(m_radio_callback);
    if (err_code != NRF_SUCCESS)
        return err_code;
    m_configure_next_event();
    err_code = sd_radio_request(&m_timeslot_request);
    if (err_code != NRF_SUCCESS)
    {
        (void)sd_radio_session_close();
        return err_code;
    }
    return NRF_SUCCESS;
}


void nrf_gzll_device_tx_success(uint32_t pipe, nrf_gzll_device_tx_info_t tx_info)
{
    uint32_t ack_payload_length = ACK_PAYLOAD_LENGTH; 
    if (tx_info.payload_received_in_ack)
    {      
        if (nrf_gzll_fetch_packet_from_rx_fifo(pipe, ack_payload, &ack_payload_length))
        {
            ASSERT(ack_payload_length == 1);
            m_cmd_received = true;
        }
    }
}

void nrf_gzll_device_tx_failed(uint32_t pipe, nrf_gzll_device_tx_info_t tx_info)
{
}

void nrf_gzll_host_rx_data_ready(uint32_t pipe, nrf_gzll_host_rx_info_t rx_info)
{
}

void nrf_gzll_disabled(void)
{
}

bool debug_cmd_available(void)
{
    return m_cmd_received;
}

char get_debug_cmd(void)
{
    char cmd = ack_payload[0];
    m_cmd_received = false;
    return cmd;
}

/**
 * Copyright (c) 2014 - 2019, 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"

#include "wireless_debug.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 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);

static char const m_target_periph_name[] = "Nordic_Blinky";     /**< Name of the device we try to connect to. This name is searched in the scan report data*/

static uint32_t old_cb_counter;
static uint32_t old_ev_counter;

/**@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;

        default:
            // 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_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);
}


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);
    APP_ERROR_CHECK(err_code);

    err_code = nrf_ble_scan_filter_set(&m_scan, SCAN_NAME_FILTER, m_target_periph_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();
    NRF_LOG_INFO("Her");
    timer_init();
    leds_init();
    buttons_init();
    power_management_init();
    ble_stack_init();
    scan_init();
    gatt_init();
    db_discovery_init();
    lbs_c_init();

    if(gazell_sd_radio_init())
        NRF_LOG_ERROR("gazell_sd_radio_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 (;;)
    {
	bool updated = false;
	if(old_cb_counter != cb_counter)
	{
        bsp_board_led_invert(BSP_BOARD_LED_2);
		old_cb_counter = cb_counter;
		NRF_LOG_INFO("CB count %d", old_cb_counter);
		updated = true;
	}
	if(old_ev_counter != ev_counter)
	{
        bsp_board_led_invert(BSP_BOARD_LED_3);
		old_ev_counter = ev_counter;
		NRF_LOG_INFO("CB count %d", old_ev_counter);
		updated = true;
	}
	if(updated)
		NRF_LOG_FLUSH();

        idle_state_handle();
    }
}

[EGM dev]

Hi,

From your changes i figured out the thing that makes timeslots work again is use of NRF_SDH_SOC_OBSERVER.

There is no issue with log messages. It works even without LEDs.

Thank you for your help.