BLE Central - The Service and Characteristics have different base UUID

[Gaht]

I have trouble when discover the BLE Peripheral that have the base UUID of characteristics and service are different.
Then I followed several instructions in some cases, but it did not work.

Before I use sd_ble_uuid_vs_add() to add some base UUID of characteristics. The BLE Central still scan the BLE Peripheral but can not discover the characteristic, It returns some UUID = 0 and then crash.
After that, I add base UUID (I have changed NRF_SDH_BLE_VS_UUID_COUNT and size of RAM already), the BLE Central can not scan the BLE Peripheral anymore.

This is my code and the UUID of service and characteristics

//ble_nus_c.c
uint32_t ble_nus_c_init(ble_nus_c_t * p_ble_nus_c, ble_nus_c_init_t * p_ble_nus_c_init)
{
    uint32_t      err_code;
    ble_uuid_t    uart_uuid;
    ble_uuid128_t nus_base_uuid = NUS_BASE_UUID;
    ble_uuid128_t char1_base_uuid = CHAR1_BASE_UUID;
    ble_uuid128_t char2_base_uuid = CHAR2_BASE_UUID;
    ble_uuid128_t char3_base_uuid = CHAR3_BASE_UUID;
    VERIFY_PARAM_NOT_NULL(p_ble_nus_c);
    VERIFY_PARAM_NOT_NULL(p_ble_nus_c_init);

    err_code = sd_ble_uuid_vs_add(&char1_base_uuid, &p_ble_nus_c->uuid_type);
    VERIFY_SUCCESS(err_code);
    uart_uuid.type = p_ble_nus_c->uuid_type;
    uart_uuid.uuid = BLE_UUID_CHARACTERISTIC1;
    NRF_LOG_INFO("uart_uuid.uuid = %x, uart_uuid.type = %x",uart_uuid.uuid,p_ble_nus_c->uuid_type);
    
    err_code = sd_ble_uuid_vs_add(&char2_base_uuid, &p_ble_nus_c->uuid_type);
    VERIFY_SUCCESS(err_code);
    uart_uuid.type = p_ble_nus_c->uuid_type;
    uart_uuid.uuid = BLE_UUID_CHARACTERISTIC2;
    NRF_LOG_INFO("uart_uuid.uuid = %x, uart_uuid.type = %x",uart_uuid.uuid,p_ble_nus_c->uuid_type);

    err_code = sd_ble_uuid_vs_add(&char3_base_uuid, &p_ble_nus_c->uuid_type);
    VERIFY_SUCCESS(err_code);
    uart_uuid.type = p_ble_nus_c->uuid_type;
    uart_uuid.uuid = BLE_UUID_CHARACTERISTIC3;
    NRF_LOG_INFO("uart_uuid.uuid = %x, uart_uuid.type = %x",uart_uuid.uuid,p_ble_nus_c->uuid_type);

    err_code = sd_ble_uuid_vs_add(&nus_base_uuid, &p_ble_nus_c->uuid_type);
    VERIFY_SUCCESS(err_code);
    NRF_LOG_INFO("uart_uuid.uuid = %x, uart_uuid.type = %x",uart_uuid.uuid,p_ble_nus_c->uuid_type);
    uart_uuid.type = p_ble_nus_c->uuid_type;
    uart_uuid.uuid = BLE_UUID_NUS_SERVICE;
    NRF_LOG_INFO("uart_uuid.uuid = %x, uart_uuid.type = %x",uart_uuid.uuid,p_ble_nus_c->uuid_type);

    p_ble_nus_c->conn_handle           = BLE_CONN_HANDLE_INVALID;
    p_ble_nus_c->evt_handler           = p_ble_nus_c_init->evt_handler;
    p_ble_nus_c->handles.nus_tx_handle = BLE_GATT_HANDLE_INVALID;
    p_ble_nus_c->handles.nus_rx_handle = BLE_GATT_HANDLE_INVALID;
    return ble_db_discovery_evt_register(&uart_uuid);
}

//ble_nus_c.h
#define NUS_BASE_UUID                   {{0x8E,0x3F,0x28,0xB7,0xAA,0xA7,0x23,0xA9,0x88,0x49,0xCD,0xE4,0x70,0x9B,0x49,0xDD}} /**< Used vendor specific UUID. */
#define CHAR1_BASE_UUID                  {{0x66,0x9A,0x0C,0x20,0x00,0x08,0x06,0xBD,0xE4,0x11,0xD2,0x9B,0x20,0x64,0x95,0xA0}} /**< Used vendor specific UUID. */
#define CHAR2_BASE_UUID                  {{0x66,0x9A,0x0C,0x20,0x00,0x08,0xD8,0xBC,0xE4,0x11,0xD8,0xa2,0xD0,0x50,0x86,0xc4}}
#define CHAR3_BASE_UUID                  {{0xFB,0x34,0x9B,0x5F,0x80,0x00,0x00,0x80,0x00,0x10,0x01,0xE0,0xD0,0x4F,0xBD,0x90}}

#define BLE_UUID_NUS_SERVICE            0x9B70                      /**< The UUID of the Nordic UART Service. */
#define BLE_UUID_CHARACTERISTIC1        0x6420                      /**< The UUID of the Characteristic1. */
#define BLE_UUID_CHARACTERISTIC2        0x50d0                      /**< The UUID of the Characteristic2. */
#define BLE_UUID_CHARACTERISTIC3        0x4fd0                      /**< The UUID of the Characteristic3. */

Can you help me fix this? Thanks a lot!!

[Marjeris Romero]

Hi,

Do you have a requirement for different base UUIDs in your project? What is usually recommended is to use a 128-bit vendor specific UUID which will look something like this "4A98xxxx-1CC4-E7C1-C757-F1267DD021E8" as a “base UUID”. The four x’s represent a field where you will insert your own 16-bit IDs for your custom services and characteristics and use them just like a predefined UUID. You will have different customs UUID for each service and characteristic but only one "base UUID".

Take a look at our Service tutorial and also this Custom BLE service example if you want a step by step guide of how to make your own custom service including vendor specific UUIDs.

Best regards,

Marjeris

[Gaht]

Hi Msromero,
Thanks for your comment and sorry for my question lack information and that causes you misunderstood my question.

Instead of coding the BLE Peripheral, I must code the BLE Central to take data from it.
You can see the picture I post above that its Service has differents base UUID from Characteristics ( I use nRF Connect app in my Smartphone connect to the BLE Peripheral).

My question is why I can not scan the BLE Peripheral when I add some base UUIDs in the BLE Central? ( I use NRF52832 board, SDK15.2, s132, and the ble_app_uart_c example).

[Gaht]

I found the solution. In main.c, I changed the type 
NUS_SERVICE_UUID_TYPE = BLE_UUID_TYPE_VENDOR_BEGIN + the number of base UUID that I wanna add) 

And I can scan my BLE Peripheral.

For instance, I wanna add 3 UUID more. So I modified the the NUS_SERVICE_UUID_TYPE = BLE_UUID_TYPE_VENDOR_BEGIN +3;

But I am curious and have a question: Does the final base UUID that I add must belong to Service?
because when I add it first, It can not discover my characteristics. Is it relate to ble_db_discovery_evt_register() function?

Sorry for my English, it may be not clear :( 

[Marjeris Romero]

Hi,

I am so sorry but can you please explain a bit better what are you trying to do and what the problem is? I don't quite understand what you want to achieve right now.

We have a tutorial about Bluetooth central devices, which is unfortunately a little updated but may still be helpful for you, I recommend you take a look at it.

Best regards,

Marjeris