Universally Unique Identifier (UUID)

A Universally Unique Identifier (UUID) is a globally unique 128-bit (16-byte) number that is used to identify profiles, services, and data types in a Generic Attribute (GATT) profile.

For efficiency, the Bluetooth® Low Energy (BLE) specification adds support for shortened 16-bit UUIDs. These shortened formats can only be used with Bluetooth SIG defined GATT profiles.

​

All UUIDs in BLE are 128-bits. In other words, a 16-bit SIG-approved UUID is actually just part of a 128-bit UUID. For example, the Client Configuration Descriptor UUID (2902) is actually 00002902-0000-1000-8000–00805f9b34fb.

Therefore, these shortened formats can only be used with UUIDs that are defined by the BLE specification.

Creating Custom UUIDs

Several tools/utilities are available for generating UUIDs. There are even web-based tools for UUID generation:

uuid-generator.png
​
  • A Version 1 UUID is a universally unique identifier that is generated using a timestamp and the MAC address of the computer (web server) on which it was generated.
  • A Version 4 UUID is a universally unique identifier that is generated using random numbers. The Version 4 UUIDs produced by this site were generated using a secure random number generator.

  Return to Top

© 2020 Microchip Technology, Inc.
Notice: ARM and Cortex are the registered trademarks of ARM Limited in the EU and other countries.
Information contained on this site regarding device applications and the like is provided only for your convenience and may be superseded by updates. It is your responsibility to ensure that your application meets with your specifications. MICROCHIP MAKES NO REPRESENTATIONS OR WARRANTIES OF ANY KIND WHETHER EXPRESS OR IMPLIED, WRITTEN OR ORAL, STATUTORY OR OTHERWISE, RELATED TO THE INFORMATION, INCLUDING BUT NOT LIMITED TO ITS CONDITION, QUALITY, PERFORMANCE, MERCHANTABILITY OR FITNESS FOR PURPOSE. Microchip disclaims all liability arising from this information and its use. Use of Microchip devices in life support and/or safety applications is entirely at the buyer's risk, and the buyer agrees to defend, indemnify and hold harmless Microchip from any and all damages, claims, suits, or expenses resulting from such use. No licenses are conveyed, implicitly or otherwise, under any Microchip intellectual property rights.