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3.3 Defining Characteristics

3.3.1 <characteristic> : Characteristic Definition element

The XML element is used to define define a characteristic, it's UUID and internal ID used in

applications.

The attributes are described in more detail in the table below.

Attribute Description

uuid

Universally Unique IDentifier. The UUID uniquely identifies a characteristic.

Options:

0000 to 16-bit UUIDs are reserved for the characteristics standardized by the FFFF:

Bluetooth

and must not be used for vendor specific implementations.

SIG

00000000-0000-0000-0000-000000000000 to FFFFFFFF-FFFF-FFFF-FFFF-FFFFFFFFFFFF:

128-bit UUIDs are reserved for vendor specific implementations.

The ID is used to identify a characteristic. The ID can be used in the application code (BGScript)

to manage the characteristic instead of using its handle number.

When the project is compiled with the compiler a text file called for BLE BGBuild attributes.txt

and for BT121 is generated. This file contains the s and corresponding handle constants id

values (dec).

The value of an ID can be any UTF-8 string. Every characteristic must use a unique ID.

Examples: A standardized characteristic with UUID 2a00 (corresponding to device name):

Bluetooth SIG

Example: A vendor specific characteristic with UUID e7add780-b042-4876-aae1-112855353cc1 and ID

xgatt_data: