Arduino Uno Quick Start Manual page 37

Let s see how this works and dissect the program s source code piece by piece.
In the first two lines, we define two
word. refers to the number of the digital IO pin we re using, and
LED_PIN
defines the length of the blink period in milliseconds.
Every Arduino program needs a function named
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
returns nothing. setup
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
• 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,
char c1 = 'A';
char c2 = 65;
Note that you have to use single quotes for
• 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
two bytes of memory but stores numbers from 0 to 65,535.
• For bigger numbers, use
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,
and occupy eight bytes of memory.
unsigned int
setup , and its return value type is
doesn t expect any arguments, so we left the parameter
c1 and
long . It consumes four bytes of memory and stores
www.it-ebooks.info
Hello, World!
constants using the
setup , and ours starts in line
true or false
c2 have the same value:
char literals.
also consumes
unsigned int
double values are more accurate
17
const key-
PAUSE
void : it
.
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