Service not discovered at peer. Custom 128 UUID

[Daniela_A]

Hello all, 

Currently I am developing a code for a BLE central device that is supposed to receive data from a weight scale (peer). The peer has a service with a custom 128-bit UUID.
I am initializing the service like this:

uint32_t ble_wss_c_init(ble_wss_c_t * p_ble_wss_c, ble_wss_c_init_t * p_ble_wss_c_init)
{
    uint32_t      err_code;
    ble_uuid_t    wss_uuid;
    ble_uuid128_t wss_base_uuid =  {0x8B, 0x7D, 0x29, 0x78, 0xFF, 0x00, 0xCB, 0x80, \
                                      0xFF, 0x1E, 0xE4, 0x1F, 0x00, 0x41, 0x43, 0x23};
    VERIFY_PARAM_NOT_NULL(p_ble_wss_c);
    VERIFY_PARAM_NOT_NULL(p_ble_wss_c_init);
    VERIFY_PARAM_NOT_NULL(p_ble_wss_c_init->evt_handler);

    p_ble_wss_c->conn_handle                = BLE_CONN_HANDLE_INVALID;
    p_ble_wss_c->peer_wss_db.wm_cccd_handle = BLE_GATT_HANDLE_INVALID;
    p_ble_wss_c->peer_wss_db.wm_handle      = BLE_GATT_HANDLE_INVALID;
    p_ble_wss_c->evt_handler                = p_ble_wss_c_init->evt_handler;

    err_code = sd_ble_uuid_vs_add(&wss_base_uuid, &p_ble_wss_c->uuid_type);
    if (err_code != NRF_SUCCESS)
    {
        
    }
    VERIFY_SUCCESS(err_code);

    wss_uuid.type                = p_ble_wss_c->uuid_type;

    wss_uuid.uuid                = BLE_UUID_WEIGHT_SCALE_SERVICE;
    
    return ble_db_discovery_evt_register(&wss_uuid);
}

I am being able to connect to the device. However, when the program reaches the function ble_wss_on_db_disc_evt() to confirm that the service was discovered, I get that the ble_db_discovery_evt_t is BLE_DB_DISCOVERY_SRV_NOT_FOUND. 

void ble_wss_on_db_disc_evt(ble_wss_c_t * p_ble_wss_c, const ble_db_discovery_evt_t * p_evt)
{   

    if (p_evt->evt_type == BLE_DB_DISCOVERY_COMPLETE
        &&
        p_evt->params.discovered_db.srv_uuid.uuid == BLE_UUID_WEIGHT_SCALE_SERVICE
        &&
        p_evt->params.discovered_db.srv_uuid.type == p_ble_wss_c->uuid_type)
    {
        // Find the CCCD Handle of the WSS characteristic.
        uint8_t i;

        ble_wss_c_evt_t evt;
        evt.evt_type    = BLE_WSS_C_EVT_DISCOVERY_COMPLETE;
        evt.conn_handle = p_evt->conn_handle;
        NRF_LOG_INFO("Number of characteristics: %x", p_evt->params.discovered_db.char_count);
        for (i = 0; i < p_evt->params.discovered_db.char_count; i++)
        {
            //NRF_LOG_INFO("Characteristic: %02x", p_evt->params.discovered_db.charateristics[i].characteristic.uuid.uuid);
            if (p_evt->params.discovered_db.charateristics[i].characteristic.uuid.uuid ==
                BLE_UUID_WEIGHT_MEASUREMENT_CHAR)
            {
                NRF_LOG_INFO("Found Weight Measurement characteristic");
                // Found WSS characteristic. Store CCCD handle and break.
                evt.params.peer_db.wm_cccd_handle =
                    p_evt->params.discovered_db.charateristics[i].cccd_handle;
                evt.params.peer_db.wm_handle =
                    p_evt->params.discovered_db.charateristics[i].characteristic.handle_value;
                
                p_ble_wss_c->peer_wss_db.wm_handle = p_evt->params.discovered_db.charateristics[i].characteristic.handle_value;
                p_ble_wss_c->conn_handle = p_evt->conn_handle;
                NRF_LOG_INFO("gm_handle: %02x",p_ble_wss_c->peer_wss_db.wm_handle);
                NRF_LOG_INFO("conn_handle: %02x",p_ble_wss_c->conn_handle);
                break;
            }

        }

        NRF_LOG_INFO("Weight Service discovered at peer.");

        //If the instance has been assigned prior to db_discovery, assign the db_handles
        if (p_ble_wss_c->conn_handle != BLE_CONN_HANDLE_INVALID)
        {
            if ((p_ble_wss_c->peer_wss_db.wm_cccd_handle == BLE_GATT_HANDLE_INVALID)&&
                (p_ble_wss_c->peer_wss_db.wm_handle      == BLE_GATT_HANDLE_INVALID))
            {
                p_ble_wss_c->peer_wss_db = evt.params.peer_db;
            }
        }
        p_ble_wss_c->evt_handler(p_ble_wss_c, &evt);
    }
    else
    {
        NRF_LOG_INFO("Weight Service discovery failure at peer. ");
        printf("\nWeight Service discovery failure at peer. ");
    }    
     
}

Any ideas on why this might be happening? I have followed examples and everything seems to be correct, that is why I don´t know what is causing the issue.

Thanks in advance

[Einar Thorsrud]

Hi,

Looking at your code snippets I do not see any obvious errors (this looks very much like the LBS client implementation in the SDK, which is a good reference for a simple custom service client -components/ble/ble_services/ble_lbs_c/ble_lbs_c.c).

Could there be a problem with the UUID, either the 16 bit part of the base? Could you post the full UUID of the service so that we can double check that?

[Daniela_A]

Hi,

Yes, sure.

The full UUID of the service is: 23434100-1fe4-1eff-80cb-00ff78297d8b
The 16-bit address of the service is 0x4100

The full UUID of the characteristic (don`t know it is really relevant here) is: 23434101-1fe4-1eff-80cb-00ff78297d8b
The 16-bit address of the characteristic is 0x4001

Thanks

[Daniela_A]

Hi Einar,

Apparently I was misunderstanding the message that I was getting while debugging. It was nothing related to the service discovery. It was about the way I was handling the notifications of the service. 

Thank you very much for your time

[Einar Thorsrud]

Ah, I see. Does that mean you got it working?

[Daniela_A]

Yes.