Arduino uno User Manual

Let’s see how this works and dissect the program’s source code piece by piece.
In the first two lines, we define two unsigned int constants using the const key-
word. LED_PIN refers to the number of the digital IO pin we’re using, and PAUSE
defines the length of the blink period in milliseconds.
Every Arduino program needs a function named setup , and ours starts in line
4. A function definition always adheres to the following scheme:
<return value type> <function name> '(' <list of parameters> ')'
In our case the function’s name is setup , and its return value type is void : it
returns nothing. setup doesn’t expect any arguments, so we left the parameter
list empty. Before we continue with the dissection of our program, you should
learn more about the Arduino’s data types.
Arduino Data Types
Every piece of data you store in an Arduino program needs a type. Depending
on your needs, you can choose from the following:
• boolean values take up one byte of memory and can be true or false .
• char variables take up one byte of memory and store numbers from -128
to 127. These numbers usually represent characters encoded in ASCII;
that is, in the following example, c1 and c2 have the same value:
char c1 = 'A';
char c2 = 65;
Note that you have to use single quotes for char literals.
• byte variables use one byte and store values from 0 to 255.
• An int variable needs two bytes of memory; you can use it to store numbers
from -32,768 to 32,767. Its unsigned equivalent unsigned int also consumes
two bytes of memory but stores numbers from 0 to 65,535.
• For bigger numbers, use long . It consumes four bytes of memory and stores
values from -2,147,483,648 to 2,147,483,647. The unsigned variant
unsigned long also needs four bytes but ranges from 0 to 4,294,967,295.
• float and double are the same at the moment on most Arduino boards, and
you can use these types for storing floating-point numbers. Both use four
bytes of memory and are able to store values from -3.4028235E+38 to
3.4028235E+38. On the Arduino Due, double values are more accurate
and occupy eight bytes of memory.
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Arduino uno Specifications

General

Form factor	Arduino
Certification	RoHS, FC, CE
Processor model	-
Processor frequency	- MHz
Microcontroller model	ATmega328
Microcontroller frequency	16 MHz
DC input voltage	7-12 V
Operating voltage	5 V
DC current per I/O pin	40 mA
Flash memory	0.032 MB
Maximum internal memory	- GB
SRAM (Static Random Access Memory)	2 KB
EEPROM (Electrically Erasable Programmable Read-Only Memory)	1 KB
Wi-Fi	No
Number of analog I/O pins	6
Number of digital I/O pins	14

Weight and Dimensions

Board dimensions	53.4 x 68.6 mm