Programming Arduino Getting Started with Sketches

Development Boards
We have established that the microcontroller is really just a chip. A chip will not just work
on its own without some supporting electronics to provide it with a regulated and accurate
supply of electricity (microcontrollers are fussy about this) as well as a means of
communicating with the computer that is going to program the microcontroller.
This is where development boards come in. An Arduino board is really a
microcontroller development board that happens to be an independent open source
hardware design. This means that the design files for the printed circuit board (PCB) and
the schematic diagrams are all publicly available, and everyone is free to use the designs
to make and sell his or her own Arduino boards.
All the microcontroller manufacturers—including Atmel, which makes the ATmega328
microcontroller used in an Arduino board—also provide their own development boards
and programming software. Although they are usually fairly inexpensive, these tend to be
aimed at professional electronics engineers rather than hobbyists. This means that such
boards and software are arguably harder to use and require a greater learning investment
before you can get anything useful out of them.
A Tour of an Arduino Board
Figure 1-1
 shows an Arduino board. Let’s take a quick tour of the various components on
the board.

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Figure 1-1
An Arduino Uno board
Power Supply
Referring to 
Figure 1-1
, directly below the USB connector is the 5-volt (5V) voltage
regulator. This regulates whatever voltage (between 7V and 12V) is supplied from the
power socket into a constant 5V.
The 5V voltage regulator chip is actually quite big for a surface mount component. This
is so that it can dissipate the heat required to regulate the voltage at a reasonably high
current. This is useful when driving external electronics.