For example, a laptop computer or a phone would be
the host device. The Bluetooth host would be integrated with the operating
system on the laptop or the phone.
The Bluetooth radio module or controller usually is a hardware module
like a PC card (see Figure 1.3) that plugs into a target device. More and
more devices have the Bluetooth controller built into the device. The
upper stack interfaces to the Bluetooth radio module via the HCI. The
Bluetooth radio module usually interfaces with the host system via one of
the standard input/output (I/O) mechanisms, such as the universal asynchronous
receiver-transmitter (UART) and universal serial bus (USB).
Although the Bluetooth host and the Bluetooth controller classifications
apply to most devices, the two are integrated in some devices??”headsets,
for example??”and HCI is not used. The various blocks shown in Figure 1.3
are part of the Bluetooth protocol stack, which is discussed next.
Applications
L2CAP
Link Manager
Audio
SDP
Data
Baseband
RF
Control
RFCOMM Bluetooth Host ??“ (usually
this is the software running on the
host machine and is part of the
system software)
??“ (usually this is
the hardware module or
radio module which plugs into
a USB, PCMCIA, UART, etc.)
Bluetooth Controller
HCI Interface
Figure 1.3 Bluetooth host and device classification.
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