Hardware Reference
In-Depth Information
Project 3
Wireless Monski Pong
Monski Pong is fun, but it would be more
fun if Monski didn't have to be tethered to
the computer through a USB cable. This
project breaks the wired connection
between the microcontroller and the
personal computer, and introduces a few
new networking concepts: the
modem
and the
address
.
NOTE:
The first digital modems converted data signals to audio
to send them across a telephone connection. They modulated the
data on the audio connection, and demodulated the audio back
into data. Now increasingly rare, their descendants are every-
where, from set-top boxes that modulate and demodulate between
a cable TV signal and Internet connection, to the sonar modems
that convert data into ultrasonic pings used in marine research.
Bluetooth
is a multilayered communications protocol,
designed to replace wired connections for a number of
applications. As such, it's divided into a group of possible
application protocols called
profiles
. The simplest
Bluetooth devices are serial devices, like the module used
in this project. These implement the Bluetooth
Serial
Port Profile
(SPP)
. Other Bluetooth devices implement
other protocols. Wireless headsets implement the audio
Headset Profile
. Wireless mice and keyboards implement
the
Human Interface Device (HID) Profile
. Because there
are a number of possible profiles a Bluetooth device might
support, there is also a
Service Discovery Protocol
, by
which radios exchange information about what they can
do. Because the protocol is standardized, you get to skip
over most of the details of making and maintaining the
connection, letting you concentrate on exchanging data.
It's a bit like how RS-232 and USB made it possible for
you to ignore most of the electrical details necessary to
connect your microcontroller to your personal computer,
which let you focus on sending bytes in the last project.
MATERIALS
» 1 completed Monski Pong project
» 1 9V battery and snap connector
» Female power plug, 2.1mm ID, 5.5mm OD
» 1 bluetooth Mate module
» 1 project box
NOTE:
If your computer doesn't have built-in Bluetooth, you'll
need a Bluetooth adapter. Most computer retailers carry USB-to-
Bluetooth adapters.
Add the Bluetooth module to the Monski pong breadboard,
as shown in Figure 2-16. Connect the module's ground
and VCC to the breadboard ground and +5V, respectively.
Connect Arduino's TX to the module's RX, and vice versa,
Connect the battery, and the module will start up.
Bluetooth: A Multilayer Network Protocol
The new piece of hardware in this project is the Bluetooth
module. This module has two interfaces: two of its pins,
marked RX and TX, are an asynchronous serial port that
can communicate with a microcontroller. It also has a
radio that communicates using the Bluetooth communica-
tions protocol. It acts as a
modem
, translating between
the Bluetooth and regular asynchronous serial protocols.
Pairing Your Computer with the
Bluetooth Module
To make a wireless connection from your computer to the
module, you have to pair them. To do this, open your com-
puter's Bluetooth control panel to browse for new devices.
