Hardware Reference
In-Depth Information
Table 2-1. Avertising Packet Types
Advertising Packet Type
Connectable
Scannable
Directed
GAP Name
ADV_IND
Yes
Yes
No
Connectable Undirected Advertising
ADV_DIRECT_IND
Yes
No
Yes
Connectable Directed Advertising
ADV_NONCONN_IND
No
No
No
Non-connectable Undirected Advertising
ADV_SCAN_IND
No
Yes
No
Scannable Undirected Advertising
The advertising packet types are used by the upper layers and, more specifically, GAP
to differentiate between operating modes and to define procedures. Therefore,
“Modes
and Procedures” on page 37
makes extensive use of them at its core.
Connections
To establish a connection, a master first starts scanning to look for advertisers that are
currently accepting connection requests. The advertising packets can be filtered by
Bluetooth Address or based in the advertising data itself. When a suitable advertising
slave is detected, the master sends a connection request packet to the slave and, provided
the slave responds, establishes a connection. The connection request packet includes
the frequency hop increment, which determines the hopping sequence that both the
master and the slave will follow during the lifetime of the connection.
A
connection
is simply a sequence of data exchanges between the slave and the master
at predefined times. Shown in
Figure 2-5
, each exchange is called a
connection event
.
Figure 2-5. Connection events
The following three
connection parameters
are another set of key variables communi‐
cated by the master during the establishment of a connection:
