I want to build a simple Bluetooth Low Energy-based application using a custom profile. The adopted profiles / services / characteristics / descriptors use 16-bit UUIDs as seen on the official site.
The 16-bit UUIDs are shortcuts for a corresponding 128-bit UUID and is translated as
128-bit UUID = 16-bit Attribute UUID * 2^96 + Bluetooth_Base_UUID
with Bluetooth_Base_UUID
being 00000000-0000-1000-8000-00805F9B34FB
. (Source: Bluetooth Core Specification Vol 3 Part F Section 3.2.1)
Since I am using a custom profile, I'm wondering what UUIDs I am allowed to use.
- Which range of 128-bit UUIDs can be used to describe vendor defined attributes in Bluetooth Low Energy?
All of the 16-bit and 32-bit UUIDs above the base UUID that you show above are reserved for items in the spec (or future specs). So vendor apps are free to use any 128-bit UUID less than the base UUID. There is no reserved space for vendors to use 16-bit or 32-bit UUIDs.
You can register 16-bit UUIDs with the Bluetooth SIG:
https://www.bluetooth.org/en-us/Pages/LoginRestrictedAll/16-bit-UUIDs-member.aspx
This is useful if you need to save the bytes (for space, energy or other performance reasons).
My interpretation of the Bluetooth spec is that you can use any 128-bit UUID outside of Bluetooth UUID Base "range", freely:
xxxxxxxx-0000-1000-8000-00805F9B34FB
I've put range in quotation marks, because the spec's 16-bit to 128-bit conversion formula that you quoted, suggests that the left-most bytes are the most significant (big endian!). Note, that if you treat the UUID as a 128-bit integer, the Bluetooth UUID Base "range" is not a continuous range of values.
You may not use 16-bit or 32-bit UUIDs unless they are assigned to you by registering.
Using a short UUID that was not registered will result in incompatibilities with your device and future standards and or other device's registered numbers. Bluetooth qualification will require valid numbers.
When not registering, generate your own valid 128-bit UUIDs:
- Use a tool such as
- https://www.uuidgenerator.net
uuidgen
or guidgen.exe
command line tools
- Understand the UUID format https://en.wikipedia.org/wiki/Universally_unique_identifier
- The Version 4 variant uses random numbers and you can create your own base UUID by replacing the leading 8 hex characters to 0.
Here is FAQ\Talk about BLE UUID
http://www.cypress.com/forum/psoc-4-ble/how-can-i-get-uuid-services-and-characteristics