Hardware Reference
In-Depth Information
Conclusion
The projects in this chapter have covered a number of ideas that are central to all
networked data communication. First, remember that data communication is based on
a layered series of agreements, starting with the physical layer; then the electrical, the
logical, the data layers; and finally, the application layer. Keep these layers in mind as
you design and troubleshoot your projects, and you'll find it's easier to isolate problems.
Second, remember that serial data can be sent either as
ASCII or as raw binary values, and which you choose to
use depends both on the capabilities and limitations of all
the connected devices. It might not be wise to send raw
binary data, for example, if the modems or the software
environments you program in are optimized for ASCII data
transfer.
Fourth, consider the flow of data, and look for ways to
ensure a smooth flow with as little overflowing of buffers
or waiting for data as possible. A simple call-and-response
approach can make data flow much smoother.
Finally, get to know the modems and other devices that
link the objects at the end of your connection. Understand
their addressing schemes and any command protocols
they use so that you can factor their strengths and limita-
tions into your planning, and eliminate those parts that
make your life more difficult. Whether you're connecting
two objects or two hundred, these same principles will
apply.
X
Third, when you think about your project, think about the
messages that need to be exchanged, and come up with
a data protocol that adequately describes all the informa-
tion you need to send. This is your data packet. You might
want to add header bytes, separators, or tail bytes to make
reading the sequence easier.
The Jitterbox by Gabriel barcia-Colombo
The JitterBox is an interactive video Jukebox created from a vintage 1940s radio restored to working condition. It features a tiny video-
projected dancer who shakes and shimmies to the music. The viewer can tune the radio and the dancer will move in time with the tunes. The
JitterBox uses serial communication from an embedded potentiometer tuner—which is connected to an Arduino microcontroller—in order to
select from a range of vintage 1940s songs. These songs are linked to video clips and played back out of a digital projector.
The dancer trapped in the JitterBox is Ryan Myers.
