Bridge - Arduino Sketches: Tools and Techniques for Programming Wizardry - page 362

■ FileSystem.rmdir()
■ FileSystem.remove()
■ YunServer.begin()
■ YunClient.connected()
■ YunClient.stop()
The hardware needed to use these functions includes:
■ Arduino Yún
■ 1 x Breadboard
■ 1 x LDR
■ 1 x 10 kΩ resistor
■ Wires
You can i nd the code download for this chapter at http://www.wiley.com/
go/arduinosketches on the Download Code tab. The code is in the Chapter 23
folder and the i lename is Chapter23.ino .
Introducing Bridge Library
There is often confusion as to the name of a microcontroller. A microcontroller
(as the name implies) controls, whereas a microprocessor processes data. This
becomes apparent for the Arduino Yún, where both are present.
In December 2002, Linksys released its WRT54G residential wireless router.
It was a small device with two antennae behind a blue-and-black cover. Behind
were four Ethernet LAN ports and an uplink port. It was an easy way to add
high-speed Wi-Fi to a home network and was used by a large number of people,
including myself. My WRT54G increased my wireless range at home and allowed
me higher speeds than what my Internet modem provided. (The WRT54G
provided Wi-Fi-G instead of the aging Wi-Fi-B.) It was also a device destined
to be tinkered with.
These devices were based on a 125-MHz MIPS microprocessor with surpris-
ingly good characteristics. With 16 MB of RAM and 4 MB of l ash memory, it was
more than capable of running a complete Linux distribution which shipped with
the device. The Linux distribution was delivered under the GPL license, and as
such, Linksys had to make the source code available on its site. This sparked a
group of people to look at that code, and to modify it, allowing more and more
features to be added. Within the space of a few months, a consumer-level router
had functions reserved for top-of-the-line industry-level routers. Although most
routers simply allowed home devices to connect, this new software allowed for
advanced frequency scanning programs, trafi c shaping, i rewall, scheduling,
and mesh networking, to name but a few. All that the user had to do was to