3.2 BASIC OPERATIONS AND FUNCTIONS

void setup(); void loop ()

The basic structure of the Arduino programming language is fairly simple and runs in at least two functions:

preparation

void setup()

execution

void loop()

Setup function

should follow the declaration of any variables at the very beginning of the program

Setup function

first function to run in the program, is run only once, and is used to set pinMode or initialize serial communication

Loop function

follows next and includes the code to be executed continuously – reading inputs, triggering outputs, etc.

Loop function

the core of all Arduino programs and does the bulk of the work

Functions

A block of code that has a name and a block of statements that are executed when the function is called

Functions

Can be written to perform repetitive tasks and reduce clutter in a program

Curly braces

Define the beginning and end of function blocks and statement blocks such as the void loop() function and the for and if statements

Semicolon

Must be used to end a statement and separate elements of the program

Semicolon

Also used to separate elements in a for loop

Block comments

Used for large text descriptions of code or comments that help others understand parts of the program

Block comments

Begin with /\* and end with \*/ and can span multiple lines

Line comments

Begin with // and end with the next line of code.

Variables

A way of naming and storing a numerical value for later use by the program

Locally declared variable

Defined inside a function or as part of a for loop

Globally declared variable

Can be seen and used by every function and statement in a program

Globally declared variable

Declared at the beginning of the program, before the setup() function

byte

stores an 8-bit numerical value without decimal points. They have a range of 0- 255.

int

primary datatype for storage of numbers without decimal points and store a 16-bit value with a range of 32,767 to -32,768.

long

Extended size datatype for long integers, without decimal points, stored in a 32-bit value with a range of 2,147,483,647 to -2,147,483,648.

float

A datatype for floating-point numbers, or numbers that have a decimal point.

float

have greater resolution than integers and are stored as a 32-bit value with a range of 3.4028235E+38 to -3.4028235E+38.

Arithmetic

include addition, subtraction, multiplication, and division

Constants

few predefined values

true/false

Boolean constants that define logic levels.

high/low

Define pin levels as ___ or ___ and are used when reading or writing to digital pins

input/output

Constants used with the pinMode() function to define the mode of a digital pin as either ___ or ___

Flow control

Statements used to alter the flow of code

if

Test whether a certain condition has been reached, such as an analog value being above a certain number, and executes any statements inside the brackets if the statement is true

if else

Allows for ‘either-or’ decisions to be made

for

Used to repeat a block of statements enclosed in curly braces a specified number of times

while

Will loop continuously, and infinitely, until the expression inside the parenthesis becomes false

while

Something must change the tested variable, or the while loop will never exit

do while

A bottom driven loop that works in the same manner as the while loop, with the exception that the condition is tested at the end of the loop, so the do loop will always run at least once

pinMode

Used in void setup() to configure a specified pin to behave either as an INPUT or an OUTPUT

digitalRead

Reads the value from a specified digital pin with the result either HIGH or LOW

digitalWrite

Outputs either logic level HIGH or LOW at (turns on or off) a specified digital pin

analogRead

Reads the value from a specified analog pin with a 10-bit resolution

analogRead

Only works on the analog in pins (0-5). The resulting integer values range from 0 to 1023.

analogWrite

Writes a pseudo-analog value using hardware enabled pulse width modulation (PWM) to an output pin marked PWM.

pulse width modulation

aka PWM

analogWrite

The value can be specified as a variable or constant with a value from 0-255

delay

Pauses a program for the amount of time as specified in milliseconds, where 1000 equals 1 second

millis

Returns the number of milliseconds since the Arduino board began running the current program as an unsigned long value

Serial.begin

Opens serial port and sets the baud rate for serial data transmission

Serial.println

Prints data to the serial port, followed by an automatic carriage return and line feed