how to change the lenth of UUID

[jerly]

Hi: i use ble_app_uart project and want to change the UUID lenth(128 bit) to be 32 bit;but i change "nus_base_uuid" to be 4 byte and change "uuid128[16]" to be "uuid128[4]";but uuid is not be changed when i use lightblue read it;how should i do that uuid lenth can be changed to be 32 bit;

what i changed in the project as below,two parts:

   uint32_t ble_nus_init(ble_nus_t * p_nus, const ble_nus_init_t * p_nus_init)
{
    uint32_t        err_code;
    ble_uuid_t      ble_uuid;
    ble_uuid128_t   nus_base_uuid = {0x9E, 0xCA, 0xDC, 0x24, 0x0E, 0xE5, 0xA9, 0xE0,
                                     0x93, 0xF3, 0xA3, 0xB5, 0x00, 0x00, 0x40, 0x6E};


   typedef struct
{ 
    unsigned char uuid128[16];
} ble_uuid128_t;

[endnode]

Hi Jerly,

but isn't it so that BLE defines only either 128-bit (16B) or 16-bit (2B) UUIDs? I doubt you can set your custom length.

Cheers Jan

[jerly]

Hi jan:

thank you for your answer.i am sorry about that.i have thought the length was changed freely. and now if i want to set the length to be 16bit .how to do it.

[endnode]

I believe you want to create 128-bit UUID for your custom service/characteristics because 16-bit values are derived from standard BT SIG 128-bit UUID and should be used for standard services used by defined profiles. Have you read Nordic's documentation to the SDK here and "Creating Bluetooth low energy applications using nRF51822" Application Note from Nordic (nAN-36, v1.1, chapter 2.2.4)?

[jerly]

OK.thand you again.i will read that documentation.and hope i can be clear on that.