RE: pc-ble-driver-py is assigning one service / characteristics uuid_type=3

Vidar Berg — Mon, 15 Aug 2022 12:31:56 GMT

Hello,

The BLE_UUID_TYPE_VENDOR_BEGIN (0x2) marks the start index for the vendor UUID storage in the Softdevice, and it will get incremented every time you register a new one through the BLEUUIDBase() -> sd_ble_uuid_vs_add() function. In other words, a 'type' value above 0x2 is really a reference to a particular base uuid in the Softdevice's UUID buffer.

From the Softdevice API documentation:

Add a Vendor Specific base UUID.

This call enables the application to add a Vendor Specific base UUID to the BLE stack's table, for later use with all other modules and APIs. This then allows the application to use the shorter, 24-bit ble_uuid_t format when dealing with both 16-bit and 128-bit UUIDs without having to check for lengths and having split code paths. This is accomplished by extending the grouping mechanism that the Bluetooth SIG standard base UUID uses for all other 128-bit UUIDs. The type field in the ble_uuid_t structure is an index (relative to BLE_UUID_TYPE_VENDOR_BEGIN) to the table populated by multiple calls to this function, and the UUID field in the same structure contains the 2 bytes at indexes 12 and 13. The number of possible 128-bit UUIDs available to the application is therefore the number of Vendor Specific UUIDs added with the help of this function times 65536, although restricted to modifying bytes 12 and 13 for each of the entries in the supplied array.

Hope this helps!

Best regards,

Vidar

RE: pc-ble-driver-py is assigning one service / characteristics uuid_type=3

Kaja — Fri, 12 Aug 2022 13:40:04 GMT

Hi,

our key support on this topic is out of office on vacation, they will be back next week, and will get back to you then!

Best regards,
Kaja