How can I create a custom 128 bit base uuid?

[Yadhu KP]

Hello,

Please give detailed steps to create a custom 128-bit base UUID for our custom service and characteristics.

[Einar Thorsrud]

Hi,

I recommend you refer to the ble_nus.c implementation which demonstrates usage of a custom 128 bit UUID. Referring to that what you need to add a 128 bit UUID is to fist add the base UUID:

    // Add a custom base UUID.
    err_code = sd_ble_uuid_vs_add(&nus_base_uuid, &p_nus->uuid_type);
    VERIFY_SUCCESS(err_code);

This adds the base and the "handle" for that base is put in the uuid_type varible, which is an output. This is essentially just a counter, and the first added base UUID will always be BLE_UUID_TYPE_VENDOR_BEGIN which is 2. . (This is why you see some example refer to BLE_UUID_TYPE_VENDOR_BEGIN instead of actually using the handle from the call to sd_ble_uuid_vs_add). If you add another custom base it will be 3 etc.

Later when adding the service UUID you refer to the type to get the correct base:

   ble_uuid.type = p_nus->uuid_type;
    ble_uuid.uuid = BLE_UUID_NUS_SERVICE;

    // Add the service.
    err_code = sd_ble_gatts_service_add(BLE_GATTS_SRVC_TYPE_PRIMARY,
                                        &ble_uuid,
                                        &p_nus->service_handle);

and the same when adding characteristics:

    // Add the TX Characteristic.
    /**@snippet [Adding proprietary characteristic to the SoftDevice] */
    memset(&add_char_params, 0, sizeof(add_char_params));
    add_char_params.uuid              = BLE_UUID_NUS_TX_CHARACTERISTIC;
    add_char_params.uuid_type         = p_nus->uuid_type;
    add_char_params.max_len           = BLE_NUS_MAX_TX_CHAR_LEN;
    add_char_params.init_len          = sizeof(uint8_t);
    add_char_params.is_var_len        = true;
    add_char_params.char_props.notify = 1;

    add_char_params.read_access       = SEC_OPEN;
    add_char_params.write_access      = SEC_OPEN;
    add_char_params.cccd_write_access = SEC_OPEN;

    return characteristic_add(p_nus->service_handle, &add_char_params, &p_nus->tx_handles);
    /**@snippet [Adding proprietary characteristic to the SoftDevice] */

Einar

[Yadhu KP]

Einar thanks for the reply, but what I really want is the method to create a 128bit base UUID 

[Einar Thorsrud]

Ah, I see. I misunderstood the question. See this post.

[Yadhu KP]

thank you einar