Use BLE_GAP_EVT_ADV_REPORT to scan for beacon

[Max]

Setup:

Module: nRF51822.

SDK version:nRF5_SDK_11.0.0_89a8197.

Example: ble_app_uart.

Softdevice: S130.

I use ble_nus_string_send on the BLE_GAP_EVT_ADV_REPORT in on_ble_evt tring to scan for

beacon and found that it only outputs strings less than 20 bytes. Dig a little further, I found it's

because of

if (length > BLE_NUS_MAX_DATA_LEN)
{
return NRF_ERROR_INVALID_PARAM;
}

in ble_nus.c while BLE_NUS_MAX_DATA_LEN is defined as (GATT_MTU_SIZE_DEFAULT - 3) and

GATT_MTU_SIZE_DEFAULT is defined to be 23.

My question is how to modify so I can scan for beacon whose data length is about 30? Or it's just

not supported in S130 to scan for beacons this way?

[Hung Bui]

Hi Max, 
I assume you are using S130. 

Unfortunately larger ATT_MTU and longer Datalengh is not supported by S130. 

So if you want to send via notification more than 23 bytes, you need to segment the data send it in multiple packets. 

On S132 (for nRF52) it's supported up to 247 byte ATT_MTU that you can use to send notification. 

[Max]

Hi Bui,

Yes, I am using S130. The thing is that I am not trying to send beacon signals. Instead, I want to scan for it. is there a workaround in BLE_GAP_EVT_ADV_REPROT?

Also, I am targeting nrf51822 module and S132 is not applicable.

[Hung Bui]

Hi Max, 

Yes I understood that you want to scan and then send the beacon signal to the peer device. But the way you are sending the beacon data to the peer device is via notification (ble_nus_string_send ) 
So you have 3 options. 
1. Use notification but segment the beacon data into 2 packets. So for example if you need to send 30 bytes. You can send first 20 bytes, then send the last 10 bytes on a second call ble_nus_string_send  . 

2. You can send a notification telling the central to do a read. With read request there is no restriction on 20 bytes payload size (read response is automatically segmented to multiple packets on the ATT layer)

3. You can implement a server on the central, and do a write from the peripheral to the central, with this you can write more than 20 bytes (write response is also automatically segmented). 

[Max]

Hi Bui,

My problem is not sending beacon signals. Just scanning. What I want to achieve is to scan for a specific beacon signal and wake up from BLE idle to advertising.

[Hung Bui]

Could you explain why you call ble_nus_string_send() ? I have no idea why it's related to BLE_GAP_EVT_ADV_REPORT and to scanning. 
Please provide your full code. 

[Max]

It's for inspection of received packets only.

Fullscreen 6014.main.c Download

/* Copyright (c) 2014 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.
 *
 */

/** @file
 *
 * @defgroup ble_sdk_uart_over_ble_main main.c
 * @{
 * @ingroup  ble_sdk_app_nus_eval
 * @brief    UART over BLE application main file.
 *
 * This file contains the source code for a sample application that uses the Nordic UART service.
 * This application uses the @ref srvlib_conn_params module.
 */

#include <stdint.h>
#include <string.h>
#include "nordic_common.h"
#include "nrf.h"
#include "ble_hci.h"
#include "ble_advdata.h"
#include "ble_advertising.h"
#include "ble_conn_params.h"
#include "softdevice_handler.h"
#include "app_timer.h"
#include "app_button.h"
#include "ble_nus.h"
#include "app_uart.h"
#include "app_util_platform.h"
#include "bsp.h"
#include "bsp_btn_ble.h"

// 20210714
// Max Lu
#include "nrf_delay.h"
#include "scanner_beacon.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              0                                           /**< 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*/

#ifdef living_room
#define DEVICE_NAME                     "iot_livingroom"                               /**< Name of device. Will be included in the advertising data. */
#define BEACON_LOC                      0xf4                        //Identify Beacons. 0xf4 is in living room.
#else
#define DEVICE_NAME                     "Not_defined"                               /**< Name of device. Will be included in the advertising data. */
#define BEACON_LOC                      0xff
#endif

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

#define APP_ADV_INTERVAL                64                                          /**< The advertising interval (in units of 0.625 ms. This value corresponds to 40 ms). */
//#define APP_ADV_TIMEOUT_IN_SECONDS      180                                         /**< The advertising timeout (in units of seconds). */
#define APP_ADV_TIMEOUT_IN_SECONDS      20                                         /**< The advertising timeout (in units of seconds). */

#define APP_TIMER_PRESCALER             0                                           /**< Value of the RTC1 PRESCALER register. */
#define APP_TIMER_OP_QUEUE_SIZE         4                                           /**< Size of timer operation queues. */

#define MIN_CONN_INTERVAL               MSEC_TO_UNITS(20, UNIT_1_25_MS)             /**< Minimum acceptable connection interval (20 ms), Connection interval uses 1.25 ms units. */
#define MAX_CONN_INTERVAL               MSEC_TO_UNITS(75, UNIT_1_25_MS)             /**< Maximum acceptable connection interval (75 ms), Connection interval uses 1.25 ms units. */
#define SLAVE_LATENCY                   0                                           /**< Slave latency. */
#define CONN_SUP_TIMEOUT                MSEC_TO_UNITS(4000, UNIT_10_MS)             /**< Connection supervisory timeout (4 seconds), Supervision Timeout uses 10 ms units. */
#define FIRST_CONN_PARAMS_UPDATE_DELAY  APP_TIMER_TICKS(5000, APP_TIMER_PRESCALER)  /**< Time from initiating event (connect or start of notification) to first time sd_ble_gap_conn_param_update is called (5 seconds). */
#define NEXT_CONN_PARAMS_UPDATE_DELAY   APP_TIMER_TICKS(30000, APP_TIMER_PRESCALER) /**< Time between each call to sd_ble_gap_conn_param_update after the first call (30 seconds). */
#define MAX_CONN_PARAMS_UPDATE_COUNT    3                                           /**< Number of attempts before giving up the connection parameter negotiation. */

#define DEAD_BEEF                       0xDEADBEEF                                  /**< Value used as error code on stack dump, can be used to identify stack location on stack unwind. */

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

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. */

// 20210714
// Max Lu
#define BLE_IDLE 0
#define BLE_ADVERTISING 1
#define BLE_CONNECTED 2
#define SEARCHED_MAJOR                          0x1234  // Decimal 13330
#define SEARCHED_MINOR                          0x5678  // Decimal 30806
#define APP_COMPANY_IDENTIFIER                  0x004C                                  /**< Company identifier for Nordic Semiconductor ASA. as per www.bluetooth.org. */
#define MAX_IDENTIFIER                  0x0617                                  /**< Company identifier for Nordic Semiconductor ASA. as per www.bluetooth.org. */
#define APP_BEACON_UUID                  0xe2, 0xc5, 0x6d, 0xb5, \
                                         0xdf, 0xfb, 0x48, 0xd2, \
                                         0xb0, 0x60, 0xd0, 0xf5, \
                                         0xa7, 0x10, 0x96, 0xe0            /**< Proprietary UUID for Beacon. */

static ble_gap_adv_params_t m_adv_params;                                  /**< Parameters to be passed to the stack when starting advertising. */
static bool beacon_broadcast = false;
uint8_t ble_state = BLE_IDLE;
uint16_t raw_temp;

void beacon_start(uint16_t manu_id, uint16_t major_value, uint16_t minor_value);
void sensor_start();
static ble_beacon_scanner_init_t m_beacon_scanner_init;


APP_TIMER_DEF(m_xs_timer_id);
APP_TIMER_DEF(m_xm_timer_id);
#define XS_INTERVAL          APP_TIMER_TICKS(3000, APP_TIMER_PRESCALER) 
#define XM_INTERVAL          APP_TIMER_TICKS(3600000, APP_TIMER_PRESCALER) 
#define BROADCAST_TIME      3000

/**@brief Function for assert macro callback.
 *
 * @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 analyse 
 *          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(DEAD_BEEF, line_num, p_file_name);
}


/**@brief Function for the GAP initialization.
 *
 * @details This function will set up all the necessary GAP (Generic Access Profile) parameters of 
 *          the device. It also sets the permissions and appearance.
 */
static void gap_params_init(void)
{
    uint32_t                err_code;
    ble_gap_conn_params_t   gap_conn_params;
    ble_gap_conn_sec_mode_t sec_mode;

    BLE_GAP_CONN_SEC_MODE_SET_OPEN(&sec_mode);
    
    err_code = sd_ble_gap_device_name_set(&sec_mode,
                                          (const uint8_t *) DEVICE_NAME,
                                          strlen(DEVICE_NAME));
    APP_ERROR_CHECK(err_code);

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

    gap_conn_params.min_conn_interval = MIN_CONN_INTERVAL;
    gap_conn_params.max_conn_interval = MAX_CONN_INTERVAL;
    gap_conn_params.slave_latency     = SLAVE_LATENCY;
    gap_conn_params.conn_sup_timeout  = CONN_SUP_TIMEOUT;

    err_code = sd_ble_gap_ppcp_set(&gap_conn_params);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for 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 an event from the Connection Parameters Module.
 *
 * @details This function will be called for all events in the Connection Parameters Module
 *          which are passed to the application.
 *
 * @note All this function does is to disconnect. This could have been done by simply setting
 *       the disconnect_on_fail config parameter, but instead we use the event handler
 *       mechanism to demonstrate its use.
 *
 * @param[in] p_evt  Event received from the Connection Parameters Module.
 */
static void on_conn_params_evt(ble_conn_params_evt_t * p_evt)
{
    uint32_t err_code;
    
    if(p_evt->evt_type == BLE_CONN_PARAMS_EVT_FAILED)
    {
        err_code = sd_ble_gap_disconnect(m_conn_handle, BLE_HCI_CONN_INTERVAL_UNACCEPTABLE);
        APP_ERROR_CHECK(err_code);
    }
}


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


/**@brief Function for initializing the Connection Parameters module.
 */
static void conn_params_init(void)
{
    uint32_t               err_code;
    ble_conn_params_init_t cp_init;
    
    memset(&cp_init, 0, sizeof(cp_init));

    cp_init.p_conn_params                  = NULL;
    cp_init.first_conn_params_update_delay = FIRST_CONN_PARAMS_UPDATE_DELAY;
    cp_init.next_conn_params_update_delay  = NEXT_CONN_PARAMS_UPDATE_DELAY;
    cp_init.max_conn_params_update_count   = MAX_CONN_PARAMS_UPDATE_COUNT;
    cp_init.start_on_notify_cccd_handle    = BLE_GATT_HANDLE_INVALID;
    cp_init.disconnect_on_fail             = false;
    cp_init.evt_handler                    = on_conn_params_evt;
    cp_init.error_handler                  = conn_params_error_handler;
    
    err_code = ble_conn_params_init(&cp_init);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for putting the chip into sleep mode.
 *
 * @note This function will not return.
 */
static void sleep_mode_enter(void)
{
    uint32_t err_code = bsp_indication_set(BSP_INDICATE_IDLE);
    APP_ERROR_CHECK(err_code);

    // Prepare wakeup buttons.
    err_code = bsp_btn_ble_sleep_mode_prepare();
    APP_ERROR_CHECK(err_code);

    // Go to system-off mode (this function will not return; wakeup will cause a reset).
    err_code = sd_power_system_off();
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for handling advertising events.
 *
 * @details This function will be called for advertising events which are passed to the application.
 *
 * @param[in] ble_adv_evt  Advertising event.
 */
static void on_adv_evt(ble_adv_evt_t ble_adv_evt)
{
    uint32_t err_code;

    switch (ble_adv_evt)
    {
        case BLE_ADV_EVT_FAST:
            err_code = bsp_indication_set(BSP_INDICATE_ADVERTISING);
            APP_ERROR_CHECK(err_code);
            break;
        case BLE_ADV_EVT_IDLE:
            // 20210714
            // Max
            //sleep_mode_enter();
            break;
        default:
            break;
    }
}


/**@brief Function for the application's SoftDevice event handler.
 *
 * @param[in] p_ble_evt SoftDevice event.
 */
static void on_ble_evt(ble_evt_t * p_ble_evt)
{
    uint32_t                         err_code;
    //ble_gap_evt_adv_report_t        * p_adv_report = &p_ble_evt->evt.gap_evt.params.adv_report;
    
    switch (p_ble_evt->header.evt_id)
    {
        case BLE_GAP_EVT_CONNECTED:
            err_code = bsp_indication_set(BSP_INDICATE_CONNECTED);
            APP_ERROR_CHECK(err_code);
            m_conn_handle = p_ble_evt->evt.gap_evt.conn_handle;
            ble_state = BLE_CONNECTED;
            break;
            
        case BLE_GAP_EVT_DISCONNECTED:
            err_code = bsp_indication_set(BSP_INDICATE_IDLE);
            APP_ERROR_CHECK(err_code);
            m_conn_handle = BLE_CONN_HANDLE_INVALID;
            ble_state = BLE_IDLE;
            break;

        case BLE_GAP_EVT_TIMEOUT:
            ble_state = BLE_IDLE;
            break;

        case BLE_GAP_EVT_ADV_REPORT:
            {
                //uint16_t length;
                
                //length = p_adv_report->dlen;
                //if ((p_adv_report->dlen == 30 ) && (ble_state == BLE_CONNECTED) &&
                    //(p_adv_report->data[25] == 0x34) &&
                    //(p_adv_report->data[26] == 0x12) &&
                    //(p_adv_report->data[27] == 0x78) &&
                    //(p_adv_report->data[2] == 0x1a))
                    //ble_nus_string_send(&m_nus, p_adv_report->data, p_adv_report->dlen);
            }
            break;

        case BLE_GAP_EVT_SEC_PARAMS_REQUEST:
            // Pairing not supported
            err_code = sd_ble_gap_sec_params_reply(m_conn_handle, BLE_GAP_SEC_STATUS_PAIRING_NOT_SUPP, NULL, NULL);
            APP_ERROR_CHECK(err_code);
            break;

        case BLE_GATTS_EVT_SYS_ATTR_MISSING:
            // No system attributes have been stored.
            err_code = sd_ble_gatts_sys_attr_set(m_conn_handle, NULL, 0, 0);
            APP_ERROR_CHECK(err_code);
            break;

        default:
            // No implementation needed.
            break;
    }
}


/**@brief Function for dispatching a SoftDevice event to all modules with a SoftDevice 
 *        event handler.
 *
 * @details This function is called from the SoftDevice event interrupt handler after a 
 *          SoftDevice event has been received.
 *
 * @param[in] p_ble_evt  SoftDevice event.
 */
static void ble_evt_dispatch(ble_evt_t * p_ble_evt)
{
    ble_conn_params_on_ble_evt(p_ble_evt);
    ble_nus_on_ble_evt(&m_nus, p_ble_evt);
    on_ble_evt(p_ble_evt);
    ble_advertising_on_ble_evt(p_ble_evt);
    bsp_btn_ble_on_ble_evt(p_ble_evt);
    
}


/**@brief Function for the SoftDevice initialization.
 *
 * @details This function initializes the SoftDevice and the BLE event interrupt.
 */
static void ble_stack_init(void)
{
    uint32_t err_code;
    
    nrf_clock_lf_cfg_t clock_lf_cfg = NRF_CLOCK_LFCLKSRC;
    
    // Initialize SoftDevice.
    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);
        
    //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);
    
    // Subscribe for BLE events.
    err_code = softdevice_ble_evt_handler_set(ble_evt_dispatch);
    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)
{
    uint32_t err_code;
    switch (event)
    {
        case BSP_EVENT_SLEEP:
            sleep_mode_enter();
            break;

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

        case BSP_EVENT_WHITELIST_OFF:
            err_code = ble_advertising_restart_without_whitelist();
            if (err_code != NRF_ERROR_INVALID_STATE)
            {
                APP_ERROR_CHECK(err_code);
            }
            break;

        default:
            break;
    }
}


/**@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 - 2] == '\n') && (data_array[index - 1] == '\r')) || (index >= (BLE_NUS_MAX_DATA_LEN)))
            {
                raw_temp = ((data_array[index - 4] << 8) | data_array[index - 3]);
                if ((ble_state == BLE_CONNECTED) && !beacon_broadcast)
                {
                    err_code = ble_nus_string_send(&m_nus, data_array, index);
                    if (err_code != NRF_ERROR_INVALID_STATE)
                    {
                        APP_ERROR_CHECK(err_code);
                    }
                }
                
                if ((ble_state == BLE_IDLE) && !beacon_broadcast)
                    sensor_start();

                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_ENABLED,
        APP_UART_FLOW_CONTROL_DISABLED,
        false,
        UART_BAUDRATE_BAUDRATE_Baud115200
    };

    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] */


/**@brief Function for initializing the Advertising functionality.
 */
static void advertising_init(void)
{
    uint32_t      err_code;
    ble_advdata_t advdata;
    ble_advdata_t scanrsp;

    // Build advertising data struct to pass into @ref ble_advertising_init.
    memset(&advdata, 0, sizeof(advdata));
    advdata.name_type          = BLE_ADVDATA_FULL_NAME;
    advdata.include_appearance = false;
    advdata.flags              = BLE_GAP_ADV_FLAGS_LE_ONLY_LIMITED_DISC_MODE;

    memset(&scanrsp, 0, sizeof(scanrsp));
    scanrsp.uuids_complete.uuid_cnt = sizeof(m_adv_uuids) / sizeof(m_adv_uuids[0]);
    scanrsp.uuids_complete.p_uuids  = m_adv_uuids;

    ble_adv_modes_config_t options = {0};
    options.ble_adv_fast_enabled  = BLE_ADV_FAST_ENABLED;
    options.ble_adv_fast_interval = APP_ADV_INTERVAL;
    options.ble_adv_fast_timeout  = APP_ADV_TIMEOUT_IN_SECONDS;

    err_code = ble_advertising_init(&advdata, &scanrsp, &options, on_adv_evt, NULL);
    APP_ERROR_CHECK(err_code);
}


/**@brief Function for initializing buttons and leds.
 *
 * @param[out] p_erase_bonds  Will be true if the clear bonding button was pressed to wake the application up.
 */
/*static void buttons_leds_init(bool * p_erase_bonds)
{
    bsp_event_t startup_event;

    uint32_t err_code = bsp_init(BSP_INIT_LED | BSP_INIT_BUTTONS,
                                 APP_TIMER_TICKS(100, APP_TIMER_PRESCALER), 
                                 bsp_event_handler);
    APP_ERROR_CHECK(err_code);

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

    *p_erase_bonds = (startup_event == BSP_EVENT_CLEAR_BONDING_DATA);
}
*/

/**@brief Function for placing the application in low power state while waiting for events.
 */
static void power_manage(void)
{
    uint32_t err_code = sd_app_evt_wait();
    APP_ERROR_CHECK(err_code);
}

// 2015/11/27 Sending iBeacon for iot sensors detection
void beacon_start(uint16_t manu_id, uint16_t major_value, uint16_t minor_value)
{
    uint32_t err_code;
    ble_advdata_t   advdata;

    //app_beacon_scanner_stop();

    if (ble_state == BLE_IDLE)
    {
    ble_advdata_manuf_data_t manuf_specific_data;
    //manuf_specific_data.company_identifier = 0x004C;                            /**< Company identifier for Apple Inc. as per www.bluetooth.org. */
    manuf_specific_data.company_identifier = manu_id;                            /**< Company identifier for Apple Inc. as per www.bluetooth.org. */
	
uint8_t m_beacon_info[0x17] =                     /**< Information advertised by the Beacon. */
{
    0x02,     // Manufacturer specific information. Specifies the device type in this 
                         // implementation. 
    0x15, // Manufacturer specific information. Specifies the length of the 
                         // manufacturer specific data in this implementation.
    APP_BEACON_UUID,     // 128 bit UUID value. 
    major_value, major_value>>8,    // Major arbitrary value that can be used to distinguish between Beacons. 
    minor_value, minor_value>>8,    // Minor arbitrary value that can be used to distinguish between Beacons. 
    0xC8    // Manufacturer specific information. The Beacon's measured TX power in 
                         // this implementation. 
};
    manuf_specific_data.data.p_data        = (uint8_t *) m_beacon_info;                    
    manuf_specific_data.data.size          = 0x17;

    // Build and set advertising data.
    memset(&advdata, 0, sizeof(advdata));

    advdata.name_type               = BLE_ADVDATA_NO_NAME;
    advdata.flags                   = BLE_GAP_ADV_FLAG_BR_EDR_NOT_SUPPORTED;
    advdata.p_manuf_specific_data   = &manuf_specific_data;

    err_code = ble_advdata_set(&advdata, NULL);
    APP_ERROR_CHECK(err_code);

    // Initialize advertising parameters (used when starting advertising).
    memset(&m_adv_params, 0, sizeof(m_adv_params));

    m_adv_params.type        = BLE_GAP_ADV_TYPE_ADV_NONCONN_IND;
    m_adv_params.p_peer_addr = NULL;                             // Undirected advertisement.
    m_adv_params.fp          = BLE_GAP_ADV_FP_ANY;
    m_adv_params.interval    = MSEC_TO_UNITS(100, UNIT_0_625_MS); /**< The advertising interval for non-connectable advertisement (100 ms). This value can vary between 100ms to 10.24s). */
    //m_adv_params.timeout     = 0;
    m_adv_params.timeout     = 2;           // In second

        beacon_broadcast = true;
        err_code = sd_ble_gap_adv_start(&m_adv_params);
        APP_ERROR_CHECK(err_code);
        //err_code = sd_ble_gap_adv_stop();
        //APP_ERROR_CHECK(err_code);
        nrf_delay_ms(BROADCAST_TIME);
        beacon_broadcast = false;
    }

    //app_beacon_scanner_start();
}

// 2021/07/18
// Max Lu
// Modified for beacon_start for sending sensor data
void sensor_start()
{
    uint32_t err_code;
    ble_advdata_t   advdata;
    uint8_t data[]                      = "123456789"; // Our data to adverise

    if (ble_state == BLE_IDLE)
    {
    ble_advdata_manuf_data_t manuf_specific_data;
    
    data[0] = BEACON_LOC ;	        // Sensor ID
    data[1] = raw_temp >> 4;		                // Temperature
    //data[2] = ach1;		                // Gas detector reading
    //data[3] = ach1 >> 8;
    manuf_specific_data.company_identifier = 0xAAAA; // Max ID
    manuf_specific_data.data.p_data        = data;                    
    manuf_specific_data.data.size          = sizeof(data);

    // Build and set advertising data.
    memset(&advdata, 0, sizeof(advdata));

    advdata.name_type               = BLE_ADVDATA_NO_NAME;
    advdata.flags                   = BLE_GAP_ADV_FLAG_BR_EDR_NOT_SUPPORTED;
    advdata.p_manuf_specific_data   = &manuf_specific_data;

    err_code = ble_advdata_set(&advdata, NULL);
    APP_ERROR_CHECK(err_code);

    // Initialize advertising parameters (used when starting advertising).
    memset(&m_adv_params, 0, sizeof(m_adv_params));

    m_adv_params.type        = BLE_GAP_ADV_TYPE_ADV_NONCONN_IND;
    m_adv_params.p_peer_addr = NULL;                             // Undirected advertisement.
    m_adv_params.fp          = BLE_GAP_ADV_FP_ANY;
    m_adv_params.interval    = MSEC_TO_UNITS(100, UNIT_0_625_MS); /**< The advertising interval for non-connectable advertisement (100 ms). This value can vary between 100ms to 10.24s). */
    //m_adv_params.timeout     = 0;
    m_adv_params.timeout     = 2;           // In second

        beacon_broadcast = true;
        err_code = sd_ble_gap_adv_start(&m_adv_params);
        APP_ERROR_CHECK(err_code);
        //err_code = sd_ble_gap_adv_stop();
        //APP_ERROR_CHECK(err_code);
        nrf_delay_ms(BROADCAST_TIME);
        beacon_broadcast = false;
    }
}

static void xs_timeout_handler(void * p_context)
{

    UNUSED_PARAMETER(p_context);

    if ((ble_state == BLE_IDLE) && (nrf_gpio_pin_read(LED_1) == 1))
    {
        beacon_start(APP_COMPANY_IDENTIFIER, 0x01, BEACON_LOC);
    }
    
}

static void xm_timeout_handler(void * p_context)
{

    UNUSED_PARAMETER(p_context);

    //if (nrf_gpio_pin_read(LED_4) == 0)
    {
        app_uart_put('t');
    }
}

/**@brief Function for the Timer initialization.
 *
 * @details Initializes the timer module. This creates and starts application timers.
 */
static void timers_init(void)
{
    uint32_t err_code;

    // Initialize timer module.
    APP_TIMER_INIT(APP_TIMER_PRESCALER, APP_TIMER_OP_QUEUE_SIZE, false);

    // 20210714
    // Max Lu
    // 2 seconds interval timer
    err_code = app_timer_create(&m_xs_timer_id,
                                APP_TIMER_MODE_REPEATED,
                                xs_timeout_handler);
    APP_ERROR_CHECK(err_code);
    
    err_code = app_timer_start(m_xs_timer_id, XS_INTERVAL, NULL);
    APP_ERROR_CHECK(err_code);

    err_code = app_timer_create(&m_xm_timer_id,
                                APP_TIMER_MODE_REPEATED,
                                xm_timeout_handler);
    APP_ERROR_CHECK(err_code);
    
    err_code = app_timer_start(m_xm_timer_id, XM_INTERVAL, NULL);
    APP_ERROR_CHECK(err_code);
}

/**@brief Function for handling a BeaconScanner event.
 *
 * @details This function will be called each time the scanner has found an advertiser with beacon data.
 *          In this simple implementation, it checks the Major and Minor and company ID fields from the beacon data,
 *          and if they match, @ref BSP_INDICATE_ALERT_3 is indicated. 
 *
 * @param[in]   p_evt   scanner event data.
 */
static void beacon_evt_handler(ble_scan_beacon_evt_t * p_evt)
{

    if((p_evt->rcv_adv_packet.adv_data.major    == SEARCHED_MAJOR)
     &&(p_evt->rcv_adv_packet.adv_data.minor    == SEARCHED_MINOR)
     &&(p_evt->rcv_adv_packet.adv_data.manuf_id == APP_COMPANY_IDENTIFIER))
    {
        //beacon_cnt++;
        advertising_init();
        ble_advertising_start(BLE_ADV_MODE_FAST);
    }
}

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

/**@brief Function for initializing the beacon scanner module.
 */
static void scanner_init()
{
    m_beacon_scanner_init.evt_handler   = beacon_evt_handler;
    m_beacon_scanner_init.error_handler = beacon_scanner_error_handler;
    app_beacon_scanner_init(&m_beacon_scanner_init);
}


/**@brief Function for starting the beacon scanner module.
 */
static void scanner_start()
{
    app_beacon_scanner_start();
}

/**@brief Application main function.
 */
int main(void)
{
    uint32_t err_code;
    //bool erase_bonds;

    // Initialize.
    APP_TIMER_INIT(APP_TIMER_PRESCALER, APP_TIMER_OP_QUEUE_SIZE, false);
    uart_init();
    
    //buttons_leds_init(&erase_bonds);
    ble_stack_init();
    gap_params_init();
    services_init();
    advertising_init();
    conn_params_init();

    // 20210714
    // Max Lu
    timers_init();
    nrf_gpio_cfg_input(LED_1, NRF_GPIO_PIN_NOPULL); // Motion detection
    //nrf_gpio_cfg_output(LED_4);
    //nrf_gpio_pin_clear(LED_4);
    nrf_gpio_cfg_input(LED_4, NRF_GPIO_PIN_PULLUP);
    scanner_init();
    scanner_start();
    
    // 2017/05/04 Max Lu
    // Set Tx power, available value -40, -30, -20, -16, -12, -8, -4, 0, 4 dBm
    sd_ble_gap_tx_power_set(4);

    printf("\r\nUART Start!\r\n");
    err_code = ble_advertising_start(BLE_ADV_MODE_FAST);
    APP_ERROR_CHECK(err_code);
    ble_state = BLE_ADVERTISING;
    
    // Enter main loop.
    for (;;)
    {
        power_manage();
    }
}


/** 
 * @}
 */

[Hung Bui]

Hi Max, 

Please explain why you call ble_nus_string_send() , what's it for ? 

So you want to see the beacon data on the phone ? correct ? 

[Max]

Yes, you can say that.

[Hung Bui]

Then please read my reply from the beginning. 
The way we send the data from the nRF52 to the phone is via notification. And there is a limitation of the notification compare to read/write. 

[Max]

My question is to scan for a specific beacon signal in nRF51. How to implement this in nRF51?

[Hung Bui]

Have you managed to scan for beacon ? 
You mentioned that you found if the beacon datasize is above 20 bytes you can't send it via ble_nus_string_send(). I assume that you have managed to scan for beacon with smaller than 20 bytes payload ? 
If you haven't implemented the code to scan, please look at the examples in ble_central folder. 

[Max]

The problem is how do I get the beacon data with more than 20 bytes in nRF51. Not sending, please.
In anther words, how to achieve the condition in BLE_GAP_EVT_ADV_REPORT events (line 336 of attached main.c)

if ((p_adv_report->dlen == 30 ) && (ble_state == BLE_CONNECTED) && ...

where p_adv_report->dlen could never be 30 due to S130 limitation.