Message Stream

Fast Pair requires an additional channel for a persistent connection with the Providers to support Fast Pair extensions. When the Provider connects to a supported Seeker, the Seeker will attempt to connect the message stream.

Supported Implementation

Fast Pair supports two kinds of message stream implementations:

RFCOMM

Use fixed UUID as the endpoint df21fe2c-2515-4fdb-8886-f12c4d67927c

L2CAP

Use GATT PSM Characteristic to obtain the PSM value for L2CAP connection.

Message Format

Once connected, messages can be exchanged in the following format:

Octet Data Type Description Mandatory?
0 uint8 Message group Mandatory
1 uint8 Message code Mandatory
2 - 3 uint16 Additional data length Mandatory
4 - n Additional data Optional

The additional data length and additional data fields should be big endian.