Hardware Reference
In-Depth Information
Server Control
All of the relay methods covered can also be used to control a server running software, such as a media player. Indeed,
this is usually preferable, because it limits the number of places where a problem can occur and is often employed
where most media is stored digitally on a hard disk.
When the server is providing the media to external locations, everything should be configured as a client/server.
This provides a more distinct separation than before, where the music being played was controlled by the remote
amplifier but the speaker volume was controlled locally. Adopting a full client/server approach has many benefits,
not least because it unifies the system. Here, every message (such as “pause track” or “increase volume”) is sent by
the client using whatever protocol (X10 or Bluetooth) is suitable. The server then listens to all of these messages and
translates them into the correct Linux commands. The effect of these commands can then be heard wherever its
outputs are connected. Furthermore, when a full-scale PC is available for server processing, more complex protocols
can be used.
A Web Interface
A traditional LAMP (Linux, Apache, MySQL, PHP/Perl) installation provides a good means of controlling your house
by the most ubiquitous interface of modern times—the web browser. Almost every device, including game consoles,
mobile phones, and in-wall touchscreens, have a web browser of some description built in.
Building or hacking your own touchscreen is no longer a problem either. You can start with the current range
of notebooks and subnotebooks that include a touchscreen (such as the Eee PC T91) or retrofit one to an old laptop
(such as the Acer Aspire or Dell Inspiron Mini). These kits comprise a touchscreen membrane that is attached
externally to the monitor screen and a USB plug that causes the screen to act like an external mouse.
These machines are small and powerful enough to fit anywhere, including on your refrigerator, but you can
reduce the footprint further by using an old phone (such as the Nokia 7710) and mounting it yourself.
The software is, naturally, Linux. Several slimmed-down distributions provide a browser as its only software,
such as Webconverger. These are live systems that can form a compact flash and are known as
kiosk systems
.
With zero installation and very short boot times, these are very good for occasional house terminals.
SMS
SMS is the short-message system available to all mobile phones as part of the standard infrastructure. It can be
utilized by the smart home in two ways. The first is to connect a mobile phone to the Linux machine and interface to
it using Gnokii, SMS Server Tools, or some similar software. This software now provides support for many phones,
although originally it was only for Nokia phones. Gnokii provides two-way communication for SMS messages,
allowing your PC to read and interpret them or send out reminders or status updates.
N
Use a prepaid phone if possible when the majority of the communication is outbound, lest a software bug
or cracker cause a lot of sent messages and a very large phone bill. This isn't always the best choice for inbound
communication, however, as some operators (in Northern American, notably) charge for inbound SMS on prepaid
phones as well!
Note
A second method is to subscribe to an SMS service provider, such as mBlox, which will provide you with a phone
number, login credentials, and an API; this allows two-way communication with any machine as if it were a mobile
phone. You should check with the service provider whether it's possible to limit the amount spent on the account in
case of problems.
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