Adding custom UUID in the advertisement packet

[Nabeel Ar]

Board: nRF52810

SoftDevice: s112

SDK version: 17.0.2

I'm trying to add a custom UUID in the advertisement packet and scan for the custom UUID in the central device to connect with it. I've followed the steps as given in the Tutorial. But my application gets asserted when entering the advertising_start() function. 

Is it necessary to add my custom UUID in service init because I am only using it for connection purposes?

How can solve this problem?

In central, how can I scan for the custom UUID?

Thanks in advance.

[Vidar Berg]

Hello,

Is it necessary to add my custom UUID in service init because I am only using it for connection purposes?

No, it's only if the central needs the UUID to recognize your device. The central may also recognize it from the device name, address, etc.

my application gets asserted when entering the advertising_start() function. 

Sure you are not getting the assert in advertising_init()? Either way, please include your code here so I can have a look.

[Nabeel Ar]

Hi Vidar,

Vidar Berg said:

Sure you are not getting the assert in advertising_init()?

Yes, It gets asserted when I try to add base uuid in the ble stack.

SVCALL(SD_BLE_UUID_VS_ADD, uint32_t, sd_ble_uuid_vs_add(ble_uuid128_t const *p_vs_uuid, uint8_t *p_uuid_type));

[Vidar Berg]

Does it return NRF_ERROR_NO_MEM? In that case, you have to increase the NRF_SDH_BLE_VS_UUID_COUNT in your sdk_config.h and probably adjust the RAM start address (see debug log for details).

[Nabeel Ar]

I've increased the count in sdl_config.h file NRF_SDH_BLE_VS_UUID_COUNT. Now it works fine. But in the advertisement packet the CUSTOM_SERVICE_UUID (16 bit UUID) is embedded into the UART base UUID (I'm also using this service but don't want to advertise it) but not my custom UUID that I've added.

How to add my custom UUID in the advertisement packet? 

[Vidar Berg]

Please post your main.c file.

[Nabeel Ar]

Hi,

This is my ble_cus.h file.

#include <stdint.h>
#include <stdbool.h>
#include "ble.h"
#include "ble_srv_common.h"

#define CUSTOM_SERVICE_UUID_BASE         {0xBC, 0x8A, 0xBF, 0x45, 0xCA, 0x05, 0x50, 0xBA, \
                                          0x40, 0x42, 0xB0, 0x00, 0xC9, 0xAD, 0x64, 0xF3}

#define CUSTOM_SERVICE_UUID               0x1400

/**@brief   Macro for defining a ble_cus instance.
 *
 * @param   _name   Name of the instance.
 * @hideinitializer
 */
#define BLE_CUS_DEF(_name)                                                                          \
static ble_cus_t _name;                                                                             \

/**@brief Custom Service init structure. This contains all options and data needed for
 *        initialization of the service.*/
typedef struct
{
    uint8_t                       initial_custom_value;           /**< Initial custom value */
    ble_srv_cccd_security_mode_t  custom_value_char_attr_md;     /**< Initial security level for Custom characteristics attribute */
} ble_cus_init_t;

/**@brief Custom Service structure. This contains various status information for the service. */
struct ble_cus_s
{
    uint16_t                      service_handle;                 /**< Handle of Custom Service (as provided by the BLE stack). */
    ble_gatts_char_handles_t      custom_value_handles;           /**< Handles related to the Custom Value characteristic. */
    uint16_t                      conn_handle;                    /**< Handle of the current connection (as provided by the BLE stack, is BLE_CONN_HANDLE_INVALID if not in a connection). */
    uint8_t                       uuid_type; 
};

// Forward declaration of the ble_cus_t type.
typedef struct ble_cus_s ble_cus_t;

/**@brief Function for initializing the Custom Service.
 *
 * @param[out]  p_cus       Custom Service structure. This structure will have to be supplied by
 *                          the application. It will be initialized by this function, and will later
 *                          be used to identify this particular service instance.
 * @param[in]   p_cus_init  Information needed to initialize the service.
 *
 * @return      NRF_SUCCESS on successful initialization of service, otherwise an error code.
 */
uint32_t ble_cus_init(ble_cus_t * p_cus, const ble_cus_init_t * p_cus_init);

This is my ble_cus.c file

#include "sdk_common.h"
#include "ble_srv_common.h"
#include "ble_cus.h"
#include <string.h>
#include "nrf_gpio.h"
#include "boards.h"
#include "nrf_log.h"

uint32_t ble_cus_init(ble_cus_t * p_cus, const ble_cus_init_t * p_cus_init)
{
    if (p_cus == NULL || p_cus_init == NULL)
    {
        return NRF_ERROR_NULL;
    }

    uint32_t   err_code;
    ble_uuid_t ble_uuid;

    // Initialize service structure
    p_cus->conn_handle               = BLE_CONN_HANDLE_INVALID;

    // Add Custom Service UUID
    ble_uuid128_t base_uuid = {CUSTOM_SERVICE_UUID_BASE};
    err_code =  sd_ble_uuid_vs_add(&base_uuid, &p_cus->uuid_type);
    VERIFY_SUCCESS(err_code);
    
    ble_uuid.type = p_cus->uuid_type;
    ble_uuid.uuid = CUSTOM_SERVICE_UUID;

    // Add the Custom Service
    err_code = sd_ble_gatts_service_add(BLE_GATTS_SRVC_TYPE_PRIMARY, &ble_uuid, &p_cus->service_handle);
    if (err_code != NRF_SUCCESS)
    {
        return err_code;
    }
    return err_code;
}

I've added all these in my main.c

#include "ble_cus.h"

BLE_CUS_DEF(m_cus);

ble_uuid_t m_adv_uuids[] = {{CUSTOM_SERVICE_UUID, BLE_UUID_TYPE_VENDOR_BEGIN }}; /**< Universally unique service identifiers. */

/**@brief Function for initializing the Advertising functionality.
 */
static void advertising_init(void)
{
    uint32_t               err_code;
    ble_advertising_init_t init;
    ble_cus_init_t     cus_init;
    
    err_code = ble_cus_init(&m_cus, &cus_init);
    APP_ERROR_CHECK(err_code);

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

    init.advdata.name_type          = BLE_ADVDATA_FULL_NAME;
    init.advdata.include_appearance = false;
    init.advdata.flags              = BLE_GAP_ADV_FLAGS_LE_ONLY_LIMITED_DISC_MODE;

    init.srdata.uuids_complete.uuid_cnt = sizeof(m_adv_uuids) / sizeof(m_adv_uuids[0]);
    init.srdata.uuids_complete.p_uuids  = m_adv_uuids;

    init.config.ble_adv_fast_enabled  = true;
    init.config.ble_adv_fast_interval = APP_ADV_INTERVAL;
    init.config.ble_adv_fast_timeout  = APP_ADV_DURATION;
    init.evt_handler = on_adv_evt;

    err_code = ble_advertising_init(&m_advertising, &init);
    APP_ERROR_CHECK(err_code);
   
    ble_advertising_conn_cfg_tag_set(&m_advertising, APP_BLE_CONN_CFG_TAG);
}

 

I didn't add it to the services because I only need it to advertise it.

[Vidar Berg]

Hi,

You need to replace 'BLE_UUID_TYPE_VENDOR_BEGIN' with the 'p_uuid_type' value returned by sd_ble_uuid_vs_add() in ble_cus.c to ensure you're referencing the correct based UUID.

[Nabeel Ar]

I've changed the service and advertising initialization order in main.c. I initialize advertising first and then service. Now it works fine. 

Nabeel Ar said:

In central, how can I scan for the custom UUID?

Should I need to add the base uuid in ble stack in central too??

[Vidar Berg]

Yes, you need to specify the base UUID on the client side as well.