How to read Value if Service 128bit UUID is completely different from Characteristics 128 bit UUID ?

[Vipul2988]

I am able to pair a peripheral device using advertising 16bit UUID to the Central Device(nRF52840-DK board).

Also I am able to read the Battery level service and Device  information service using bas_c_init() and dis_c_inti(). That' Good.

Now device has Some other Custom Primary services with different 128bit service UUID & 128bit Characteristics UUID. See Image Below 

 

To read such values from Unknown Characteristics which function we need to use ? 

I am using nRF52840-DK with nRF5_SDK_17.0.2 and S140

[Einar Thorsrud]

Hi,

You need to implement your own client for that custom service. This is a service with a long (128 bit) UUID, so you should refer to one of the custom service client implementations in the SDK and adapt it to the service you want to use. I suspect the LBS service might be a good starting point here, so take a look at components\ble\ble_services\ble_lbs_c\ble_lbs_c.c and components\ble\ble_services\ble_lbs_c\ble_lbs_c.h.

[Vipul2988]

Hi Einar,

I am getting Fatal Error when I am changing the UUID base and  UUID Service like below.

Also I was not able to define both Service And Characteristics 128bit different as image shown in the primary question.   

[Einar Thorsrud]

Hi, 

Vipul2988 said:

how we can add different 128bit characteristic UUID. as in ble_lbs_c.h allow us to add only 16 bit characteristic UUID only.

In fact, the LBS is also a 128 bit characteristic, so you should do exactly as demonstrated there. The way it works is that you create a base UUID (referred to as uuid_type). So when you make a new base UUID, that is referred to by the type. When you then make a new characteristic and refer to the type of the base UUID, you only provide the extra 2 bytes / 16 bit, that are combined with the base UUID of the type to make the 128 bit UUID.

[Vipul2988]

HI Einar,

When I am trying to connect only service with 128bit UUID it is found and connected.

But when I am adding another 128bit UUID for Characteristics in ble_lbs_c_init() function, it is not giving any error but also not connecting to service and characteristics.

Please find attached zip file and open ble_central example. 

 

nRF5_SDK_15.3.0.zip

[Einar Thorsrud]

Hi,

I did not understand exactly what you meant, can you elaborate?

In any case I see something which does not look correct. You have two calls to sd_ble_uuid_vs_add() where you try to add two bases. But the ID is output to the same variable (&p_ble_lbs_c->uuid_type), so the first is overwritten. And then cannot be used. Please double check the code so that you avoid suck mistakes.

(Another detail I see is that you ignore the return value of the fist call to sd_ble_uuid_vs_add(). While it does not fail in this case, ignoring return value is never a good idea and typically prevents you from discovering issues early).

[Vipul2988]

HI Einar,

I means to say whey I am serching services with only 128bit base, it is working good.

but as and when I tried to add characteristics with diffferent128 bit, I am not getting any output and Error as well.   

Can you suggest how my ble_lbs_c_init() function should look like ?

uint32_t ble_lbs_c_init(ble_lbs_c_t * p_ble_lbs_c, ble_lbs_c_init_t * p_ble_lbs_c_init)
{
    uint32_t      err_code;

    ble_uuid_t    lbs_uuid;
    ble_uuid128_t lbs_base_uuid = {PRESS_SER_UUID_BASE};
    ble_uuid_t    lbs_char_uuid;
    ble_uuid128_t lbs_char_base_uuid = {PRESS_CHAR_UUID_BASE};

    VERIFY_PARAM_NOT_NULL(p_ble_lbs_c);
    VERIFY_PARAM_NOT_NULL(p_ble_lbs_c_init);
    VERIFY_PARAM_NOT_NULL(p_ble_lbs_c_init->evt_handler);

    p_ble_lbs_c->peer_lbs_db.button_cccd_handle = BLE_GATT_HANDLE_INVALID;
    p_ble_lbs_c->peer_lbs_db.button_handle      = BLE_GATT_HANDLE_INVALID;
    p_ble_lbs_c->peer_lbs_db.led_handle         = BLE_GATT_HANDLE_INVALID;
    p_ble_lbs_c->conn_handle                    = BLE_CONN_HANDLE_INVALID;
    p_ble_lbs_c->evt_handler                    = p_ble_lbs_c_init->evt_handler;

    err_code = sd_ble_uuid_vs_add(&lbs_base_uuid, &p_ble_lbs_c->uuid_type);
    err_code = sd_ble_uuid_vs_add(&lbs_char_base_uuid, &p_ble_lbs_c->uuid_type);

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

   lbs_uuid.type = p_ble_lbs_c->uuid_type;
   lbs_uuid.uuid = LBS_UUID_SERVICE;

    //lbs_uuid.type = p_ble_lbs_c->uuid_type;
    //lbs_uuid.uuid = PRESS_SER_UUID;

    lbs_char_uuid.type = p_ble_lbs_c->uuid_type;
    lbs_char_uuid.uuid = PRESS_CHAR_UUID;

    return ble_db_discovery_evt_register(&lbs_uuid);
    return ble_db_discovery_evt_register(&lbs_char_uuid);
}

[Einar Thorsrud]

It looks like it should be something like this (note the comment that you must also update ble_lbs_c_t in this case):

uint32_t ble_lbs_c_init(ble_lbs_c_t * p_ble_lbs_c, ble_lbs_c_init_t * p_ble_lbs_c_init)
{
    uint32_t      err_code;

    ble_uuid_t    lbs_uuid;
    ble_uuid128_t lbs_base_uuid = {PRESS_SER_UUID_BASE};
    ble_uuid_t    lbs_char_uuid;
    ble_uuid128_t lbs_char_base_uuid = {PRESS_CHAR_UUID_BASE};

    VERIFY_PARAM_NOT_NULL(p_ble_lbs_c);
    VERIFY_PARAM_NOT_NULL(p_ble_lbs_c_init);
    VERIFY_PARAM_NOT_NULL(p_ble_lbs_c_init->evt_handler);

    p_ble_lbs_c->peer_lbs_db.button_cccd_handle = BLE_GATT_HANDLE_INVALID;
    p_ble_lbs_c->peer_lbs_db.button_handle      = BLE_GATT_HANDLE_INVALID;
    p_ble_lbs_c->peer_lbs_db.led_handle         = BLE_GATT_HANDLE_INVALID;
    p_ble_lbs_c->conn_handle                    = BLE_CONN_HANDLE_INVALID;
    p_ble_lbs_c->evt_handler                    = p_ble_lbs_c_init->evt_handler;

    err_code = sd_ble_uuid_vs_add(&lbs_base_uuid, &p_ble_lbs_c->uuid_type);

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

    err_code = sd_ble_uuid_vs_add(&lbs_char_base_uuid, &p_ble_lbs_c->uuid_type_char); // You need to add uuid_type_char in the ble_lbs_c_t so that it exists

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

    lbs_uuid.type = p_ble_lbs_c->uuid_type;
    lbs_uuid.uuid = LBS_UUID_SERVICE;

    lbs_char_uuid.type = p_ble_lbs_c->uuid_type_char;
    lbs_char_uuid.uuid = PRESS_CHAR_UUID;

    return ble_db_discovery_evt_register(&lbs_uuid);
    return ble_db_discovery_evt_register(&lbs_char_uuid);
}