Datasheet

BLE GATT

GATT, which standards for the

Generic ATTribute Profile

, governs data organization and data

exchanges between connected devices. One device (the peripheral) acts as a GATT Server,

which stores data in

Attribute

records, and the second device in the connection (the central)

acts as a GATT Client, requesting data from the server whenever necessary.

The following commands can be used to create custom GATT services and characteristics on

the BLEFriend, which are used to store and exchange data.

Please note that any characteristics that you define here will automatically be saved to non-

volatile FLASH config memory on the device and re-initialised the next time the device starts.

GATT Limitations

The commands below have the following limitations due to SRAM and resource availability,

which should be kept in mind when creating or working with customer GATT services and

characteristics.

These values apply to firmware 0.7.0 and higher:

Maximum number of services: 10

Maximum number of characteristics: 30

Maximum buffer size for each characteristic: 32 bytes

Maximum number of CCCDs: 16

If you want to clear any previous config value, enter the 'AT+FACTORYRESET' command

before working on a new peripheral configuration.

AT+GATTCLEAR

Clears any custom GATT services and characteristics that have been defined on the device.

Codebase Revision: 0.3.0

Parameters: None

You need to perform a system reset via 'ATZ' before most of the commands below

will take effect!