ble uuid

### Bluetooth Low Energy (BLE) UUID Usage and Definition UUIDs (Universally Unique Identifiers) play a critical role in the functionality of BLE devices by uniquely identifying services, characteristics, and descriptors within the protocol stack. A UUID is typically represented as a 128-bit number but often shortened into 16-bit or 32-bit variants when possible to save space on resource-constrained devices. #### Standard vs Custom UUIDs The Bluetooth Special Interest Group (SIG) maintains a list of standard UUIDs that represent common profiles, services, and characteristics. These predefined UUIDs simplify interoperability between different BLE-enabled devices. For example, the Heart Rate Service has an assigned 16-bit UUID `0x180D` corresponding to its full 128-bit representation defined by the SIG[^1]. Developers may also define custom UUIDs for proprietary applications not covered under existing standards. #### Structure of UUIDs A complete UUID consists of five sections separated by hyphens (-), following this format: `xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx`, where M indicates version information while N specifies variant details. In practice though, many BLE implementations utilize shorter forms such as: ```csharp // Example C# code showing how you might declare these values. ushort heartRateServiceUuid = 0x180D; ushort deviceInformationServiceUuid = 0x180A; ``` When defining your own service or characteristic outside official specifications, ensure uniqueness through random generation tools unless explicitly basing off known patterns from other vendors' products. #### Practical Application Scenario Consider developing firmware targeting Nordic Semiconductor's nRF5 SDK using SEGGER J-Link debugger hardware alongside their desktop application suite including Programmer tool mentioned earlier [^3]. Here’s what setting up basic communication could look like programmatically: ```cpp #include "ble.h" #include "nrf_sdm.h" void ble_uuid_init(void){ uint32_t err_code; // Initialize base UUID structure based upon company identifier prefix allocation rules set forth by bluetooth sig guidelines. ble_uuid128_t app_base_uuid = {YOUR_COMPANY_BASE_UUID}; err_code = sd_ble_uuid_vs_add(&app_base_uuid, &custom_service.uuid_type); APP_ERROR_CHECK(err_code); } int main(){ ble_event_t evt; ble_stack_init(); gap_params_init(); gatt_init(); ble_uuid_init(); advertising_start(); while(true){ if(nrf_sdh_soc_evt_get(&evt)){ ble_dispatch(&evt); } } } ``` This snippet demonstrates initializing user-defined UUID types before starting advertisements so peers scanning nearby know available capabilities offered via those endpoints once connected successfully according established procedures outlined previously regarding attribute exchange mechanisms facilitated primarily thanks att/gatt layers introduced initially here too!