Programming Arduino Getting Started with Sketches

• 
Chapter 9
: LCD Displays
In this chapter, you program with the LCD Shield library to
make a simple USB message board example.
• 
Chapter 10
: Arduino Ethernet Programming
You learn how to make the Arduino
behave like a web server as you get a little background on HyperText Markup Language
(HTML) and the HyperText Transfer Protocol (HTTP).
• 
Chapter 11
: C++ and Libraries
You go beyond C, looking at adding object-orientation
and writing your own Arduino libraries.
Resources
This book is supported by an accompanying website:
www.arduinobook.com
There you will find all the source code used in this book as well as other resources, such
as errata.

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1
This Is Arduino
Arduino is
a microcontroller platform that has captured the imagination of electronics
enthusiasts. Its ease of use and open source nature make it a great choice for anyone
wanting to build electronic projects.
Ultimately, it allows you to connect electronics through its pins so that it can control
things—for instance, turn lights or motors on and off or sense things such as light and
temperature. This is why Arduino is sometimes given the description 
physical computing.
Because Arduinos can be connected to your computer by a universal serial bus (USB)
lead, this also means that you can use the Arduino as an interface board to control those
same electronics from your computer.
This chapter is an introduction to the Arduino, including the history and background of
the Arduino, as well as an overview of the hardware.
Microcontrollers
The heart of your Arduino is a microcontroller. Pretty much everything else on the board
is concerned with providing the board with power and allowing it to communicate with
your desktop computer.
A microcontroller really is a little computer on a chip. It has everything and more than
the first home computers had. It has a processor, a kilobyte or two of random access
memory (RAM) for holding data, a few kilobytes of erasable programmable read-only
memory (EPROM) or flash memory for holding your programs and it has input and output
pins. These input/output (I/O) pins link the microcontroller to the rest of your electronics.
Inputs can read both digital (is the switch on or off?) and analog (what is the voltage at
a pin?). This opens up the opportunity of connecting many different types of sensor for
light, temperature, sound, and more.
Outputs can also be analog or digital. So, you can set a pin to be on or off (0 volts or 5
volts) and this can turn light-emitting diodes (LEDs) on and off directly, or you can use
the output to control higher power devices such as motors. They can also provide an
analog output voltage. That is, you can set the output of a pin to some particular voltage,
allowing you to control the speed of a motor or the brightness of a light, rather than simply
turning it on or off.
The microcontroller on an Arduino board is the 28-pin chip fitted into a socket at the
center of the board. This single chip contains the memory processor and all the electronics
for the input/output pins. It is manufactured by the company Atmel, which is one of the
major microcontroller manufacturers. Each of the microcontroller manufacturers actually

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produces dozens of different microcontrollers grouped into different families. The
microcontrollers are not all created for the benefit of electronics hobbyists like us. We are
a small part of this vast market. These devices are really intended for embedding into
consumer products, including cars, washing machines, DVD players, children’s toys, and
even air fresheners.
The great thing about the Arduino is that it reduces this bewildering array of choices by
standardizing on one microcontroller and sticking with it. (Well, as we see later, this
statement is not quite true, but it’s close enough.)
This means that when you are embarking on a new project, you do not first need to
weigh all the pros and cons of the various flavors of microcontroller.