BLE Central: Unable to discover 128 bit UUID service having two characteristics with completely different 128 bit UUID.

[Nagma]

Hi Nordic Team,

My dev environment is as follow:

nRF52832 (Central) + S132+ SES 

At Peripheral side, I am using nRF connect app to advertise the service I want to discover.

The service I want to discover has 128 bit UUID. The two characteristics of that service have completely different 128 bit UUID.

Ambient Service UUID: 503d7513-99c6-f504-f3ea-7d2aa80cb92b

Ambient Light Characteristic UUID: c613cb6c-cd08-64b2-9b6a-8d6e6665f74e

Configuration Characteristic UUID: d502c51c-2f55-9e34-bfbc-e4fbf3e2ae70

I am trying to discover this service and its characteristics but I am unable to do so. 

I have added Ambient Light service UUID and both of the characteristics UUID to Attribute Table using sd_ble_uuid_vs_add() and have tried everything from various posts on this topic .

uint32_t ble_als_c_init(ble_als_c_t * p_ble_als_c, ble_als_c_init_t * p_ble_als_c_init)
{
    uint32_t      err_code;
    ble_uuid_t    uart_uuid;
    ble_uuid_t    uart_al_uuid;
    ble_uuid_t    uart_config_uuid;
    ble_uuid128_t als_base_uuid = ALS_BASE_UUID;
    ble_uuid128_t als_al_char_uuid = ALS_AL_CHARACTERISTIC_UUID;
    ble_uuid128_t als_config_char_uuid = ALS_CONFIG_CHARACTERISTIC_UUID;
    //ble_uuid128_t nus_base_uuid = NUS_SERVICE_BASE_UUID;
   

    VERIFY_PARAM_NOT_NULL(p_ble_als_c);
    VERIFY_PARAM_NOT_NULL(p_ble_als_c_init);
    VERIFY_PARAM_NOT_NULL(p_ble_als_c_init->p_gatt_queue);

  

    err_code = sd_ble_uuid_vs_add(&als_base_uuid, &p_ble_als_c->uuid_type);

    if (err_code != NRF_SUCCESS)
    {
    return err_code;
    }
    VERIFY_SUCCESS(err_code);

     err_code = sd_ble_uuid_vs_add(&als_al_char_uuid, &p_ble_als_c->uuid_type_al_char);

   if (err_code != NRF_SUCCESS)
    {
    return err_code;
    }

    VERIFY_SUCCESS(err_code);

     err_code = sd_ble_uuid_vs_add(&als_config_char_uuid, &p_ble_als_c->uuid_type_config_char);

   if (err_code != NRF_SUCCESS)
    {
    return err_code;
    }

    VERIFY_SUCCESS(err_code);

    uart_uuid.type = p_ble_als_c->uuid_type;
    uart_uuid.uuid = BLE_UUID_ALS_SERVICE ;

    uart_al_uuid.type = p_ble_als_c->uuid_type_al_char;
    uart_al_uuid.uuid = BLE_UUID_ALS_AL_CHARACTERISTIC;

    uart_config_uuid.type = p_ble_als_c->uuid_type_config_char;
    uart_config_uuid.uuid = BLE_UUID_ALS_CONFIG_CHARACTERISTIC;

    p_ble_als_c->conn_handle           = BLE_CONN_HANDLE_INVALID;
    p_ble_als_c->evt_handler           = p_ble_als_c_init->evt_handler;
    p_ble_als_c->error_handler         = p_ble_als_c_init->error_handler;
    p_ble_als_c->handles.als_al_handle = BLE_GATT_HANDLE_INVALID;
    p_ble_als_c->handles.als_config_handle = BLE_GATT_HANDLE_INVALID;
    p_ble_als_c->p_gatt_queue          = p_ble_als_c_init->p_gatt_queue;

    return ble_db_discovery_evt_register(&uart_uuid);
  
}

[Marjeris Romero]

Hi,

Sorry for the late reply.

Is the code you are sharing used in you peripheral device or in your central device? Your custom service and characteristics should be first added on your peripheral device in order for your central to be able to discover them. You can follow this 3-part tutorial in order to add your custom service to your peripheral device:

Bluetooth low energy advertising, a beginner's tutorial

Bluetooth low energy services, a beginner's tutorial

Bluetooth low energy characteristics, a beginner's tutorial

For implementing the central device to scan and discover your custom service and characteristic you can take a look at how the NUS central example is implemented, and how a scan filter is set to connect to the custom Nordic UART service. See also the Bluetooth low energy central tutorial for guidance.

Best regards,

Marjeris

[Nagma]

Hi,

This segment of code belongs to central. Actually for peripheral I am using Nrf connect app to advertise. 

I have went through NUS central. But NUS service 128 bit uuid and its characteristics 128 bit uuid is not completely different. Even I had implemented based on NUS central example. But fortunately I was able to solve this issue. I just used bas central example (sdk 17.0) and specifically used 

ble_bas_on_db_disc_evt() 

portion of code and changed things according to what I needed and it worked. 

The only thing that was important was while registering through sd_ble_uuid_vs_add() use 128 bit uuid of both service and characteristics but while registering for discovery only 16 bit uuid for both service and characteristics. 

Thank you for your reply!