Hardware Reference
In-Depth Information
Connections allow for a much richer, layered data model. They also have the potential
to use much less power than broadcast mode because they can extend the delay between
connection events further out, or push large chunks of data out only when new values
are available, rather than having to continually advertise the full payload at a specific
rate without knowing who is listening or how often. Not only that, but the fact that both
peers know when the connection events are going to take place in the future allows the
radio to be turned off for longer, potentially saving battery power when compared to
broadcasting.
Finally, these topologies can be mixed freely in a wider BLE network, as shown in
Figure 1-5
. A BR/EDR/LE-capable device can bridge together BLE and BR/EDR con‐
nections, and the number of combinations and participants on the network is con‐
strained only by the limitations of the radios and protocol stacks of each device taking
part in it.
Figure 1-5. Mixed topology
More advanced dual-mode and single-mode devices are starting to appear, devices that
are able to combine multiple roles concurrently. This allows them to participate in sev‐
eral connections at a time, while also using advertising to broadcast data.
Protocols versus Profiles
From its inception, the Bluetooth specification introduced a clear separation between
the distinct concepts of
protocols
and
profiles
:
