Arduino/Arduino_-_MakeUseOf.com.pdf.txt

By Brad Kendall
http://www.bradkendall.ca/

Published August 2013

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Table Of Contents                              

1. Intro to the Arduino                                       

2. What Can You Do With an Arduino? 

3. What Is Inside an Arduino?                             

4. What You Will Need For This Guide                    

5. Electrical Component Overview                        

5.1 What is a Breadboard? 

5.2 What is an LED? 

5.3 What is a Photo Resistor? 

5.4 What is a Tactile Switch? 

5.5 What is a Piezo Speaker? 

5.6 What is a Resistor? 

5.7 What are Jumper Wires? 

6. Programming Overview                                   

6.1 Variables 

6.2 Functions 

6.3 Logic Overview 

== - The Equals operator 

&& - The AND operator 

|| - The OR operator 

! - The NOT operator 

Using Multiple Expressions 

7. Setting Up Your Arduino                               

7.1 Installing the Arduino IDE on Windows 

Step 1: Download the Arduino software 

Step 2: Install the software 

7.2 Installing the Arduino IDE on Mac OS X 

Step 1: Download the Arduino software 

Step 2: Install the software 

7.3 Installing the Arduino IDE on Ubuntu/ Linux 

7.4 Running the Arduino Software 

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GETTING STARTED WITH ARDUINO 
8. Starter Projects                                                     

8.1 Communicating Between Your Arduino and Your PC 

Reading from the Serial Port 

8.2 Building a Calculator 

8.3 Turning on an LED 

8.4 Making Your LED Blink 

8.5 Making Multiple LEDs Blink 

8.6 Pushbuttons with a Pull-up Resistor 

8.7 Turning on an LED with a Pushbutton 

8.8 Control an LED’s Brightness 

8.9 Observing Light with your Arduino 

8.10 Making Music with your Arduino 

9. Where to go From Here                                 

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GETTING STARTED WITH ARDUINO1. Intro to the Arduino                                      

Arduino is an open-source electronics prototyping platform based on flexible, easy-to use hardware and software. It’s 
intended for artists, designers, hobbyists, and anyone interested in creating interactive objects or environments.

Arduino can sense the environment by receiving input from a variety of sensors and can affect its surroundings by 
controlling lights, motors, and other actuators. The microcontroller on the board is programmed using the Arduino 
programming language and the Arduino Development Environment. Arduino projects can be stand-alone, or they can 
communicate with software running on a computer.

There are plenty of other microcontrollers available. So you may be asking, why choose the Arduino? Arduino really 
simplifies the process of building projects on a microcontroller making it a great platform for amateurs. You can easily 
start working on one with no previous electronics experience.

That is what this guide is about.

In addition to Arduino’s simplicity, it is also inexpensive, cross-platform and open source. The Arduino is based on 
Atmel’s ATMEGA8 and ATMEGA168 microcontrollers. The plans for the modules are published under a Creative Com-
mons license, so experienced hobbyists and professionals can make their own version of the Arduino, extending it and 
improving it.

Believe it or not, even relatively inexperienced users can build a version of the Arduino module on a breadboard in 
order to understand how it works and save a little bit of money.

2. What Can You Do With an Arduino?

There is a lot you can do with an Arduino. An Arduino can basically do anything by interfacing sensors with a com-
puter. This would allow you to take any sensor and have any action applied with the readings. For example (in one of 
our projects) we will read the level of light in a room and adjust an LED’s brightness to react based on that input. This 
of course is a simple example of what you can do with an Arduino. A more complicated example would be to read from 
multiple sensors and use that data to affect other outputs. Think of the possibility of wiring your house with all sorts 
of different sensors (photocells, oxygen sensors, thermometers) and having it adjust your blinds, air conditioner and 
furnace and make your house a more comfortable place.

Hackers have used Arduinos to create some amazing electronics projects. Things like:

•	 Robots

•	 Breathalyzers

•	 Remote	controlled	cars

•	

3d	printers

•	 Video	games

•	 Home	automation	systems

And much more. Read about more great examples of Arduino projects.

3. What Is Inside an Arduino?                            

Although there are many different types of Arduino boards available, this manual focuses on the Arduino Uno. This is 
the most popular Arduino board around. So what makes this thing tick? Here are the specifications:

•	 Processor:	16	Mhz	ATmega328

•	 Flash	memory:	32	KB

•	 Ram:	2kb

•	 Operating	Voltage:	5V

•	

Input	Voltage:	7-12	V

•	 Number	of	analog	inputs:	6

•	 Number	of	digital	I/O:	14	(6	of	them	pwm)

The specs may seem meager compared to your desktop computer, but remember that the Arduino is an embedded 
device. We have a lot less to process than your desktop.

Another wonderful feature of the Arduino is the ability to use what are called “Shields”. Although we will not be cov-
ering shields in this manual, an Arduino shield will give you crazy functionality like you wouldn’t believe. Check out 
this list of some really cool Arduino shields to take your projects to the next level.

4. What You Will Need For This Guide                   

Below you will find a shopping list of the components we will use for this manual. All these components should come 
in under $50.00 USD. This should be enough to give you a good understanding of basic electronics and have enough 
components to build some pretty cool projects.

•	

•	

•	

•	

•	

•	

•	

•	

•	

•	

•	

1x	Arduino	Uno	Microcontroller

1	x	USB	A-B	Cable	(same	as	your	printer	takes)

1x	Breadboard

2	x	LEDs

1	x	Photo	Resistor

1	x	Tactile	Switch

1	x	Piezo	Speaker

1	x	10	k-Ohm	Resistors

1	x	2	k-Ohm	Resistors

2	x	1	K-Ohm	Resistors

1	x	Jumper	Wire	Kit

5. Electrical Component Overview                       

5.1 What is a Breadboard?
Breadboards are blocks of plastic with holes into which wires can be inserted. The holes are connected electrically, so 
that wires stuck in the connected holes are also connected electrically.

The connected holes are arranged in rows, in groups of five, so that up to five parts can be quickly connected just by 
plugging their leads into connected holes in the breadboard. When you want to rearrange a circuit, just pull the wire or 
part out of the hole, and move it or replace it. The breadboard I recommended also includes power and ground lanes 
on each side for easy power management.

5.2 What is an LED?
An LED, short for Light Emitting Diode, is a semiconductor light source. LEDs are typically used as visual indicators. 
For instance, your new Arduino microcontroller has an LED on pin 13 that we frequently use to indicate an action or 
event.

5.3 What is a Photo Resistor?
A photo resistor allows us to measure light by decreasing its resistance when it detects an increase of light intensity.

5.4 What is a Tactile Switch?
A tactile switch is an electric switch that controls the flow of electricity. When pressed, the switch completes the circuit. 
Basically, it is a button.

5.5 What is a Piezo Speaker?
A piezo speaker is a single frequency beeper that converts an electrical signal into a tone. This will allow your Arduino 
to sing to you.

5.6 What is a Resistor?
A resistor is an electrical component that limits or regulates the flow of electricity.

5.7 What are Jumper Wires?
Jumper wires are short wires that are used for prototyping circuits. These are what you will use to connect the various 
components electrically to your Arduino.

6. Programming Overview                                  

If you’re not too familiar with programming, this guide should get you used to some of the fundamentals. If you’d like to 
learn more about Arduino-specific functions, http://www.arduino.cc/en/Reference/HomePage is an excellent resource.

6.1 Variables
A variable is defined as a quantity that can assume any of a set of values. In the Arduino programming language, vari-
ables have types associated with them, which provide the set of valid values the variable can hold. Some languages 
are not strict and allow a variable to hold nearly anything, but that is out of the scope of this manual.

For example, a variable with type ‘int’ can only hold integer values like 1 or 12, and not 12.5 or “cats”. Unfortunately, 
no variable is capable of holding a cat, something the programming world is quite upset about.

Variables are an excellent resource, as they improve code readability and reuse, and are extremely convenient for use 
as temporary storage.

Before using a variable, you must declare it. This merely lets the Arduino compiler know what data type your variable 
will hold.

An example of a variable declaration is as follows:

int itemCount;
In this case, the variable will be of type int, and therefore will only accept integers.

Here are a few example assignments and operations.

itemCount = 4; itemCount = itemCount + 8; // itemCount now holds the value 12. itemCount = 
“10”; // This will not compile. 
6.2 Functions
A function is essentially a group of instructions that perform a specific task. There are many built-in functions, such as 
digitalWrite() or tone(). In those cases, you don’t necessarily have to see the code, but can still reap the benefits. You 
can also specify your own functions.

The general form of a function is:

[return type] [function name] ({arguments}) { [ Code to execute ] } 
Note that functions can return data, as illustrated by the function having a return type.

In many cases, there is no data to return, and in that case, the keyword ‘void’ would be used.

The function name is a user-friendly ‘handle’ to reference later (digitalWrite would be the function name for the digi-
talWrite function).

A function can accept zero or more arguments. Each argument must be of the form [datatype] [identifier]. For exam-
ple, if we called a function foo as such:

foo(10);
The function header for foo would have to look like:

void foo(int number) { } 
In the function, code can reference ‘number’ to retrieve the passed value. Outside of the function, ‘number’ would be 
undefined.

Say we want to write a function to multiply two numbers, for whatever reason. This function would look like:

int multiply(int num1, int num2) { int result; result = num1 * num2; return result; } 
Note that this could simply look like:

int multiply(int num1, int num2) { return num1 * num2; }
It’s usually a good idea to be liberal with the use of spaces, as it makes for much easier debugging. To each their own, 
however.

6.3 Logic Overview

You’ll often find yourself wanting to execute certain code under certain conditions. This will give you a quick overview 
of the logical operators you have to work with.

First up, with the exception of the NOT operator, each logical operation takes two operands.

== - The Equals operator
This operator ensures that both operands are equal to one another. To test whether or not the operands are not equal 
to one another, use the != (not-equals) operator.

Example:

4 == 4 (true) 4 == 5 (false) 4 != 5 (true) 
&& - The AND operator
The AND operator is quite similar to the equals operator, except it does not evaluate to true when both operands are 
false.

For example: (true && true) evaluates to true, while (true && false) and (false && false) both evaluate to false.

|| - The OR operator
The OR operator will evaluate to true so long as at least one of the two operands is true.

The only time OR will evaluate to false is if both the operands are false.

! - The NOT operator
This simply flips the truthiness of the operand specified. !false == true.

Using Multiple Expressions
Sometimes you’d like to have more than one test. Fortunately, since (as above), something like (false == true) will 
evaluate to false, nesting statements in brackets works, and the statements in brackets will be evaluated first.

For example:

if (( a != b) && (b > 12))
a != b and b > 12 will have to be evaluated first, as their outcome determines whether the entire logical expression is 
true.

The past two sections should have given you enough basic knowledge to get started with our projects below. If it all 
seems a little complicated, don’t worry. It will make a lot more sense when we apply it in a practical sense.

7. Setting Up Your Arduino                              

Before we can start on our projects, we first need to get your Arduino talking to your computer. We need to do this so 
you can compile and send code for your Arduino to execute.

7.1 Installing the Arduino IDE on Windows
Step 1: Download the Arduino software
Go to http://arduino.cc/en/Main/Software and download the Arduino Software for your Windows.

Step 2: Install the software
Install the Drivers:

•	 Plug	in	your	board	and	wait	for	Windows	to	begin	its	driver	installation	process.	After	a	few	mo-

ments,	the	process	will	fail,	despite	its	best	efforts.

•	 Click	on	the	Start	Menu,	and	open	up	the	Control	Panel.

•	 While	in	the	Control	Panel,	navigate	to	System	and	Security.	Next,	click	on	System.	Once	the	

System	window	is	up,	open	the	Device	Manager.

•	

Look	under	Ports	(COM	&	LPT).	You	should	see	an	open	port	named	“Arduino	UNO	(COMxx)”.

•	 Right	click	on	the	“Arduino	UNO	(COMxx)”	port	and	choose	the	“Update	Driver	Software”	option.

•	 Next,	choose	the	“Browse	my	computer	for	Driver	software”	option.

•	 Finally,	navigate	to	and	select	the	Uno’s	driver	file,	named	“ArduinoUNO.inf”,	located	in	the	“Driv-

ers”	folder	of	the	Arduino	Software	download.

•	 Windows	will	finish	up	the	driver	installation	from	there.

7.2 Installing the Arduino IDE on Mac OS X
Step 1: Download the Arduino software
Go to http://arduino.cc/en/Main/Software and download the Arduino Software for your Mac OS X.

Step 2: Install the software
The disk image (.dmg) should mount automatically. If it doesn’t, double-click it. It should look like the following image.

Copy the Arduino application into the Applications folder (or elsewhere on your computer). Since you’re using an Ar-
duino Uno, you don’t have any drivers to install.

7.3 Installing the Arduino IDE on Ubuntu/ Linux
Install gcc-avr and avr-libc from the Terminal. 

sudo apt-get install gcc-avr avr-libc

If you don’t have openjdk-6-jre already, install and configure that too:

sudo apt-get install openjdk-6-jre sudo update-alternatives --config java 

Select the correct JRE if you have more than one installed.

Go to http://arduino.cc/en/Main/Software/ and download the Arduino Software for Linux. You can untar and run it with 
the following command:

tar xzvf arduino-x.x.x-linux64.tgz cd arduino-1.0.1 ./arduino 

7.4 Running the Arduino Software
Now that our software is installed and our Arduino is setup, let’s verify everything is working. The easiest way to do 
this is by using the “Blink” sample application.

1.	 Open	the	Arduino	Software	by	Double-clicking	the	Arduino	Application	(./arduino	on	Linux).

2.	 Make	sure	the	board	is	still	connected	to	your	computer.

3.	 Open	the	LED	blink	example	sketch:	File	>	Examples	>	1.Basics	>	Blink.	You	should	see	the	

code	for	the	application	open	and	it	should	look	like	this:

 
 
 
4.	 You’ll	need	to	select	the	entry	in	the	Tools	>	Board	menu	that	corresponds	to	your	Arduino.	Se-

lect	the	Arduino	Uno	Option.

5.	 Select	the	serial	device	of	the	Arduino	board	from	the	Tools	>	Serial	Port	menu.	On	Windows,	

This	is	likely	to	be	COM3	or	higher.	On	the	Mac	or	on	Linux,	this	should	be	something	with	‘/dev/
tty.usbmodem	‘	in	it.

6.	 Now,	simply	click	the	“Upload”	button	in	the	environment.	Wait	a	few	seconds	-	you	should	see	

the	RX	and	TX	LEDs	on	the	Arduino	flashing.	If	the	upload	is	successful,	the	message	“Done	up-
loading.”	will	appear	in	the	status	bar.

A few seconds after the upload finishes, you should see the pin 13 (L) LED on the board start to blink. If it does, con-
gratulations! You’ve got your Arduino up and running.

8. Starter Projects                                                    

Okay, now is when the real fun begins. Let’s get started.

8.1 Communicating Between Your Arduino and Your PC
Most of the communication you’ll be doing with the Arduino (for now) will be done via the Serial port (The USB cord). 
This is quite trivial to set up on the Arduino. Merely add the following line to your setup() method:

Serial.begin(9600);
9600 is the baud rate, something we will not get into here (it essentially means the number of signal changes made 
per second, and merely ensures that the PC and the Arduino are on the same page in regards to this). Whenever you 
would like to write something to the serial port, simply use the Serial.print or Serial.println function, as so:

Serial.print(“Hello world!”); 

Reading from the Serial Port
Note that you will have to read in a single character at a time via the serial port, which is rather unfortunate. If you take 
a peek at the sample code for our calculator application, specifically the waitForNum() method, you will see an exam-
ple of how to read in all characters entered, albeit in this case for a number.

8.2 Building a Calculator
To tie all of your new found programming knowledge together, we submit to you the following program that performs 
basic mathematical operations. We have clearly commented the code, so you should be able to understand each step. 
There is a download available for people who don’t like typing at: http://www.bradkendall.ca/arduino

Here we go!

/*
Example Arduino Calculator
Communication protocol: Send an ‘A’, ‘S’, ‘M’, or ‘D’ via serial, than two numbers. The arduino 
will reply with the result of the operation on the two numbers, (first number first). Note that 
the division will no doubt look strange - it is an integer division and therefore there will 
not be anything after the decimal point.
*/
void setup() {
Serial.begin(9600);
Serial.println(“Calculator initiated.”);
}
/* loop()
This code gets executed over, and over, and over, and over, and over, and over, and over, and 
over, and over, and over, and over, and over, and over, and over, and over, and over again.
Our loop pretty much starts the ‘waiting for input’ stage, where we wait for the user to input 
a character (the mathematical operation), then two operands.
After we output the result, we let the loop get hit again, and joy is had by all!
*/
void loop() {
char operation;
int number1;
int number2; // hehe, Number 2. 
int result; // Hold the result of the operation.
boolean success;
// Indicates whether the operation 
// was successful (we knew what to 
// do - nothing bad was inputted)
success = true; 
// Go ahead and set success to true ; 
// The only time we will be updating 
// this variable now is to set it to 
// false if we’ve encountered a 
// problem.

Serial.println(“Pick an operation: ‘A’dd, ‘S’ubtract, ‘M’ultiply, or ‘D’ivide (Simply input the 
first letter in quotes.)”);
// We have to wait for the user to send something
// here; the easiest way to do so is to simply loop
// and waitfor Serial.available() to be true.
while(Serial.available() == 0) {
; // ; indicates an empty statement. Or a sea
// monster in Nethack. God those suck.
}
// This loop will continue executing while Serial.
// available() == 0. Thus, it will be stuck here until 
// the serial has a character waiting.
operation = Serial.read();
// We have to do the same thing to get the two
// operands (numbers).
// I have factored this code into a function so that 
// I do not have to rewrite it twice. See if you can 
// determine why I would not be able to use it (at 
// least intuitively) to get the operation.
Serial.println(“Okay, now please enter the two numbers, one at a time!”);
number1 = waitForNum();
Serial.print(“Read: “);
Serial.println(number1);
number2 = waitForNum();
Serial.print(“Read: “);
Serial.println(number2);
// Now we have read in all the data we need. It is
// time to calculate the result. We will have to
// determine what operation the user specified, and
// perform the calculation from there.
Serial.print(“Operation: “);
if(operation == ‘A’)
{
// This checks to see if the user sent along the
// character ‘A’, specifying an add.
Serial.println(“ADD (Look, a kitty!)”);
result = number1 + number2;
} else if(operation == ‘S’)
{
// Note that the above condition will only be
// tested for if operation is not equal to ‘A’ -
// hence the else.
// This code executes if the operation is ‘S’ for
// subtract.
Serial.println(“Subtract”);
result = number1 - number2;
} else if(operation == ‘M’)
{
// In this case, we will be multiplying.
Serial.println(“Multiply”);
result = number1 * number2;
} else if(operation == ‘D’)
{
// Here we will be dividing.
Serial.println(“Divide”);
result = number1 / number2;
} else{
// This code will be used if the character
// specified doesn’t match anything - in other
// words, the user did not send A, S, D, or M,
// and we don’t know what to do.
// Hence, set ‘success’ to false
success = false;

}
// Now we should have our result. Time to send the
// user back something! (Then start over again! Joy!)
if(success)
{
// Note that print will not start a new
// line, and the next print statement will
// continue writing right
// where the previous one left off.
// Output the result.
Serial.print(“Result: “);
Serial.println(result);
} else
{
Serial.print(“Sorry, I don’t understand what you want me to do! (You inputted ‘”);
Serial.print(operation);
Serial.println(“’)”);
}
}
int waitForNum()
{
int ret;
while(Serial.available() == 0) { ;
}
// Why minus ‘0’? The value we’ll get from Serial.
// read() will be a character. What this means is
// that its numeric value will not necessarily
// reflect the number it represents. (Look at an
// ASCII table, the character ‘0’ actually has a
// decimal value of 48!)
// The take-away from this is that, since fortunately
// all the numbers are in sequence, you can simply
// subtract the decimal value of ‘0’ from
// whatever you read in, and you’ll be left with the
// number itself. ‘5’ - ‘0’ = 5 .
ret = Serial.read() - ‘0’;
// To handle numbers that span more than one
// character (like 124, which spans three), we must
// loop until there is no more input, and multiply
// each number we read by one (as 124 would come in
// like: 4 2 1
// And the number we build would be:
// (((1 * 10) + 2) * 10) + 4,
// or 124! The joys of the decimal numbering system!
// Note that the delays are merely to slow things
// down a bit - removing them would have the
// code execute too quickly to ‘notice’ more
// characters waiting to come in from Serial.
// A little strange, neh? Welcome to the joys of this
// type of thing. =]
delay(10);
while(Serial.available() != 0)
{
ret = ret * 10;
ret += Serial.read() - ‘0’;
delay(10);
}
return ret;
}

 
8.3 Turning on an LED

What You Need:

•	

•	

•	

1	–	LED

1	–	Resistor	–	1	KOhm	(brown,	black,	red)

4	–	Jumper	Wires

You will build a circuit by plugging the LED and resistor leads into small holes called sockets on the breadboard.

Let’s get started!

Hardware Setup:

•	 Step	1	-	Unplug	the	USB	cord	from	your	Arduino.

•	 Step	2	-	Plug	a	jumper	wire	from	the	5V	port	on	your	Arduino	into	the	positive	section	of	your	

breadboard’s	power	lane.

•	 Step	3	-	Plug	a	jumper	wire	from	the	GND	port	on	your	Arduino	into	the	negative	section	of	your	

breadboard’s	ground	lane.

•	 Step	4	-	Plug	the	LED’s	cathode	(the	short	lead)	into	the	I-2	socket	on	your	breadboard.

•	 Step	5	-	Plug	the	LED’s	anode	(the	long	lead)	into	the	I-4	socket	on	your	breadboard.

•	 Step	6	-	Plug	one	of	the	resistor’s	leads	into	the	H-4	socket	on	your	breadboard.

•	 Step	7	-	Plug	the	resistors	other	lead	into	the	H-9	socket	on	your	breadboard.

•	 Step	8	-	Connect	a	jumper	wire	from	your	breadboard’s	power	lane	to	the	J-9	socket	on	your	

breadboard.

•	 Step	9	-	Connect	a	jumper	wire	from	your	breadboard’s	ground	lane	to	the	J-2	socket	on	your	

breadboard.

•	 Step	10	-	Reconnect	the	USB	cable	to	your	Arduino.

Summary: Once power is applied to the circuit, the LED will turn on. This is about as simple as a circuit gets.

8.4 Making Your LED Blink
What You Need:

•	

•	

•	

1	–	LED

1	–	Resistor	–	1	K	Ohm	(brown,	black,	red)

4	–	Jumper	Wires

Hardware Setup:

•	 Step	1	-	Unplug	the	USB	cord	from	your	Arduino.

•	 Step	2	-	Plug	a	jumper	wire	from	the	Digital	IO	pin	8	into	the	I-12	socket	on	your	breadboard.

•	 Step	3	-	Plug	one	of	the	resistor’s	leads	into	the	H-12	socket	on	your	breadboard.

•	 Step	4	-	Plug	the	resistor’s	other	lead	into	the	H-4	socket	on	your	breadboard.

•	 Step	5	-	Plug	the	LED’s	cathode	(the	short	lead)	into	the	I-2	socket	on	your	breadboard.

•	 Step	6	-	Plug	the	LED’s	anode	(the	long	lead)	into	the	I-4	socket	on	your	breadboard.

•	 Step	7	-	Connect	a	jumper	wire	from	your	breadboard’s	ground	lane	to	the	J-2	socket	on	your	

breadboard.	Ensure	that	the	ground	lane	is	still	grounded.

•	 Step	8	-	Reconnect	the	USB	cable	to	your	Arduino.

Software Setup:

Open up your Arduino Development Environment and create a new sketch (File	>	New).

Enter the following code into your sketch:

void setup() {
// initialize the digital pin as an output.
// Pin 8 is our output pin
pinMode(8, OUTPUT);
}
void loop() {
digitalWrite(8, HIGH); // set the LED on
delay(1000); // wait for a second
digitalWrite(8, LOW); // set the LED off
delay(1000); // wait for a second
} 

After you enter the code, press the upload button and your LED should start blinking.

Summary: The digitalWrite(8, HIGH); command sets the output pin 8 on the Arduino to 5V. The digitalWrite(8, LOW); 
command sets the output pin 8 on the Arduino to 0V. The delay(1000); command pauses execution on the Arduino for 
1000 ms or 1 second. Since this in the loop() function, the code is called over and over again. Pretty cool, huh?

8.5 Making Multiple LEDs Blink

What You Need:

•	

•	

•	

2	–	LEDs

2	–	Resistor	–	1	K	Ohm	(brown,	black,	red)

4	–	Jumper	Wires

Hardware Setup:

•	 Step	1	-	Unplug	the	USB	cord	from	your	Arduino.

•	 Step	2	-	Setup	the	project	board	the	same	as	in	Project	3.

•	 Step	3	-	Plug	a	jumper	wire	from	the	Digital	IO	pin	9	into	the	I-16	socket	on	your	breadboard.

•	 Step	4	-	Plug	one	of	the	resistor’s	leads	into	the	H-16	socket	on	your	breadboard.

•	 Step	5	-	Plug	the	resistor’s	other	lead	into	the	H-24	socket	on	your	breadboard.

•	 Step	6	-	Plug	the	LED’s	anode	(the	long	lead)	into	the	I-24	socket	on	your	breadboard.

•	 Step	7	-	Plug	the	LED’s	cathode	(the	short	lead)	into	the	I-26	socket	on	your	breadboard.

•	 Step	8	-	Connect	a	jumper	wire	from	your	breadboard’s	ground	lane	to	the	J-26	socket	on	your	

breadboard.	Ensure	that	the	ground	lane	is	still	grounded.

•	 Step	9	-	Reconnect	the	USB	cable	to	your	Arduino.

Software Setup:

Open up your Arduino Development Environment and create a new sketch (File	>	New).

Enter the following code into your sketch:

void setup() {
// initialize the digital pins as an output.
pinMode(8, OUTPUT);
pinMode(9, OUTPUT);
}
void loop() {
digitalWrite(8, HIGH); // set the LED on
digitalWrite(9, LOW); // set the LED on

delay(1000); // wait for a second
digitalWrite(8, LOW); // set the LED off
digitalWrite(9, HIGH); // set the LED on
delay(1000); // wait for a second
}
After you enter the code, press the upload button and both your LEDs should start blinking.

Summary: This project is exactly the same as the last project, except we have added an additional LED on output pin 
9 that turns off when the other LED is on. Can you think of any other ways to expand on this?

8.6 Pushbuttons with a Pull-up Resistor
What You Need:

•	

•	

•	

•	

1	–	Resistor	2	K	Ohm	(red-black-red)

1	–	Resistor	–	1	K	Ohm	(brown,	black,	red)

1	–	Tactile	Switch

5	–	Jumper	Wires

Hardware Setup:

•	 Step	1	-	Unplug	the	USB	cord	from	your	Arduino.

•	 Step	2	-	Connect	a	jumper	wire	from	your	breadboard’s	power	lane	to	the	C-3	socket	on	your	

breadboard.	Ensure	that	the	power	lane	is	still	connected.

•	 Step	3	-	Plug	one	of	the	2	K	Ω	resistor’s	leads	into	the	B-3	socket	on	your	breadboard.

•	 Step	4	-	Plug	the	2	K	Ω	resistor’s	other	lead	into	the	B-7	socket	on	your	breadboard.

•	 Step	5	-	Plug	a	tactile	switch	so	the	pins	are	in	the	F-9,	F-7,	E-9	and	E-7	on	your	breadboard.

•	 Step	6	-	Plug	one	of	the	1K	Ω	resistor’s	leads	into	the	H-7	socket	on	your	breadboard.

•	 Step	7	-	Plug	the	1K	Ω	resistors’	other	lead	into	the	H-14	socket	on	your	breadboard.

•	 Step	8	-	Plug	a	jumper	wire	from	the	Digital	IO	pin	9	into	the	I-14	socket	on	your	breadboard.

•	 Step	9	-	Connect	a	jumper	wire	from	your	breadboard’s	ground	lane	to	the	H-9	socket	on	your	

breadboard.	Ensure	that	the	ground	lane	is	still	connected.

•	 Step	10	-	Reconnect	the	USB	cable	to	your	Arduino.

Software Setup:

Open up your Arduino Development Environment and create a new sketch (File	> New).

Enter the following code into your sketch:

void setup() {
// initialize the digital pin 9 as an input.
pinMode(9, INPUT);
// initialize the serial port.
Serial.begin(9600);
}
void loop() {
int buttonStatus = digitalRead(9);
if (buttonStatus == LOW) //The button is down
{
Serial.println(“The button is down”);
}
}

After you enter the code, press the upload button and open the Serial Monitor (Tools	>	Serial	Monitor). When you 
press the tactile switch, the serial monitor should print “The button is down”.

Summary: This project reads the digital input for 5v (HIGH). When the button is pressed, the voltage is set to 0v 
(LOW) and the Arduino executes the code in our if statement.

8.7 Turning on an LED with a Pushbutton

What You Need:

•	

•	

•	

•	

1	-	LED

1	–	Resistor	–	1	K	Ohm	(brown,	black,	red)

1	–	Tactile	Switch

4	–	Jumper	Wires

Hardware Setup:

•	 Step	1	-	Unplug	the	USB	cord	from	your	Arduino.

•	 Step	2	-	Plug	a	tactile	switch	so	the	pins	are	in	H-9,	H-11,	J-9	and	J-11	on	your	breadboard.

•	 Step	3	-	Plug	a	jumper	wire	from	the	GND	port	on	your	Arduino	into	the	negative	section	on	your	

breadboard’s	ground	lane.

•	 Step	4	-	Plug	the	LED’s	cathode	(the	short	lead)	into	the	I-2	socket	on	your	breadboard.

•	 Step	5	-	Plug	the	LED’s	anode	(the	long	lead)	into	the	I-4	socket	on	your	breadboard.

•	 Step	6	-	Plug	one	of	the	resistor’s	leads	into	the	H-4	socket	on	your	breadboard.

•	 Step	7	-	Plug	the	resistor’s	other	lead	into	the	H-9	socket	on	your	breadboard.

•	 Step	8	-	Connect	a	jumper	wire	from	your	breadboard’s	power	lane	to	the	G-11	socket	on	your	

breadboard.

•	 Step	9	-	Connect	a	jumper	wire	from	your	breadboard’s	ground	lane	to	the	J-2	socket	on	your	

breadboard.

•	 Step	10	-	Reconnect	the	USB	cable	to	your	Arduino.

8.8 Control an LED’s Brightness
What You Need:

•	

•	

•	

•	

1	–	Photo	Resistor

1	–	Resistor	–	2	K	Ohm	(red-black-red)

1	–	LED

5	–	Jumper	Wires

Hardware Setup:

•	 Step	1	-	Unplug	the	USB	cord	from	your	Arduino.

•	 Step	2	-	Plug	one	of	the	photo	resistor’s	leads	into	the	I-14	socket	on	your	breadboard.

•	 Step	3	-	Plug	the	photo	resistor’s	other	lead	into	the	I-15	socket	on	your	breadboard.

•	 Step	4	-	Plug	the	LED’s	cathode	(the	short	lead)	into	the	H-17	socket	on	your	breadboard.

•	 Step	5	-	Plug	the	LED’s	anode	(the	long	lead)	into	the	H-15	socket	on	your	breadboard.

•	 Step	6	-	Plug	one	of	the	resistor’s	lead	into	the	I-17	socket	on	your	breadboard.

•	 Step	7	-	Plug	the	resistor’s	other	lead	into	the	I-22	socket	on	your	breadboard.

•	 Step	8	-	Connect	a	jumper	wire	from	your	breadboard’s	power	lane	to	the	J-14	socket	on	your	

breadboard.	Ensure	that	the	power	lane	is	still	connected.

•	 Step	9	-	Connect	a	jumper	wire	from	your	breadboard’s	ground	lane	to	the	J-22	socket	on	your	

breadboard.	Ensure	that	the	ground	lane	is	still	connected.

•	 Step	10	-	Reconnect	the	USB	cable	to	your	Arduino.

Summary: As you see, the resistance of the photo resistor decreases with more light. The lower the resistance, the 
brighter the LED. Combine this with the pull up resistor project (Chapter 8.6) and watch the opposite effect.

8.9 Observing Light with your Arduino
What You Need:

•	

1	–	Photo	Resistor

•	

•	

1	–	Resistor	–	10	K	Ohm	(brown-black-orange)

5	–	Jumper	Wires

Hardware Setup:

•	 Step	1	-	Unplug	the	USB	cord	from	your	Arduino.

•	 Step	2	-	Plug	one	of	the	photo	resistor’s	leads	into	the	F-16	socket	on	your	breadboard.

•	 Step	3	-	Plug	the	photo	resistor’s	other	lead	into	the	F-15	socket	on	your	breadboard.

•	 Step	4	-	Plug	one	of	the	resistor’s	leads	into	the	I-15	socket	on	your	breadboard.

•	 Step	5	-	Plug	the	resistor’s	other	lead	into	the	I-10	socket	on	your	breadboard.

•	 Step	6	-	Connect	a	jumper	wire	from	your	breadboard’s	power	lane	to	the	G-16	socket	on	your	

breadboard.	Ensure	that	the	power	lane	is	still	connected.

•	 Step	7	-	Connect	a	jumper	wire	from	your	breadboard’s	ground	lane	to	the	J-10	socket	on	your	

breadboard.	Ensure	that	the	ground	lane	is	still	connected.

•	 Step	8	-	Plug	a	jumper	wire	from	the	Analog	IO	pin	0	into	the	G-15	socket	on	your	breadboard

•	 Step	9	-	Reconnect	the	USB	cable	to	your	Arduino.

Software Setup:

Open up your Arduino Development Environment and create a new sketch (File	>	New).

Enter the following code into your sketch:

int lightPin = 0; //define a pin for Photo resistor
void setup()
{
Serial.begin(9600); //Begin serial communication
}
void loop()
{
//Write the value of the photo resistor to the serial //monitor.
int lightValue = analogRead(lightPin);
Serial.println(lightValue);
delay(1000); //pause for 1000 ms or 1 second.
}

After you enter the code, press the upload button and open the Serial Monitor (Tools	>	Serial	Monitor). The console 
should give a light reading in the form of an integer. When you reduce the amount of light, the number will be lower.

Summary: This project is the same as the previous project, except we are reading the values from your Arduino 
instead of outputting to an LED. The resistance of the photo resistor decreases with more light. You could use logic to 
reverse this effect!

8.10 Making Music with your Arduino
What You Need:

•	

•	

1	–	Piezo	Speaker

3	–	Jumper	Wires

Hardware Setup:

•	 Step	1	-	Unplug	the	USB	cord	from	your	Arduino.

•	 Step	2	-	Plug	the	positive	lead	of	your	piezo	speaker	into	the	E-15	socket	on	your	breadboard.

•	 Step	3	-	Plug	the	negative	lead	of	your	piezo	speaker	into	the	F-15	socket	on	your	breadboard.

•	 Step	4	-	Plug	a	jumper	wire	from	the	Digital	IO	pin	8	into	the	A-15	socket	on	your	breadboard.

•	 Step	5	-	Connect	a	jumper	wire	from	your	breadboard’s	ground	lane	to	the	J-15	socket	on	your	

breadboard.	Ensure	that	the	ground	lane	is	still	connected.

•	 Step	6	-	Reconnect	the	USB	cable	to	your	Arduino.

Easy, right?

Software Setup:

This project is included in the Examples Section. No typing on this one! Open up your Arduino Development Environ-
ment .Open the toneMelody Example Sketch (File	>	Examples	>	Digital	>	toneMelody).

After you enter the code, press the upload button and your piezo speaker will start making noise. You can modify the 
sound by modifying the melody[] and noteDurations[] arrays.

Summary: This project produces sound out of the piezo speaker.

9. Where to go From Here                                

As you can see, the Arduino is an easy way to get into electronics and software. Hopefully you have seen that it is 
easy to build simple electronic projects with it. I hope you have realized that your projects don’t have to stay simple. 
You can build way more complex projects on top of these simple ones. Here are some of my favorite projects that 
would be a great next step:

•	 Create	Christmas	light	ornaments

•	 Arduino	Traffic	light	controller

•	 Arduino	Shields	to	superpower	your	project

•	 Make	your	own	Arduino

•	 Build	your	own	pong	game	with	an	Arduino

•	 Connect	your	Arduino	to	the	internet

•	 Create	a	home	automation	system	with	your	Arduino

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