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Arduino By Example

Chapter 1. Getting Started with Arduino

Hello there! If you are reading this book right now, it means that you've taken your first step to make fascinating projects using Arduinos. This chapter will teach you how to set up an Arduino and write your first Arduino code.

You'll be in good hands whilst you learn some of the basics aspects of coding using the Arduino platform; this will allow you to build almost anything including robots, home automation systems, touch interfaces, sensory systems, and so on. Firstly, you will learn how to install the powerful Arduino software, then set that up, followed by hooking up your Arduino board and, after making sure that everything is fine and well, you will write your first code! Once you are comfortable with that, we will modify the code to make it do something more, which is often what Arduino coders do. We do not just create completely new programs; often we build on what has been done before, to make it better and more suited to our objectives. The contents of this chapter are divided into the following topics:

Prerequisites
Setting up
Hello World
Summary

Connecting the Arduino

It is time to hook up the Arduino board. Plug in the respective USB terminals to the USB cable and the tiny LEDs on the Arduino should begin to flash.

Arduino UNO plugged in

If the LEDs didn't turn on, ensure that the USB port on your computer is functioning and make sure the cable isn't faulty. If it still does not light up, there is something wrong with your board and you should get it checked.

Windows

The computer will begin to install the drivers for the Arduino by itself. If it does not succeed, do the following:

Open Device Manager.
Click on Ports (COM & LPT).
Right-click on Unknown Device and select Properties.
Click on Install Driver and choose browse files on the computer.
Choose the drivers folder in the previously installed Arduino folder.

The computer should say that your Arduino UNO (USB) has been successfully installed on COM port (xx). Here xx refers to a single or double digit number. If this message didn't pop up, go back to the Device Manager and check if it has been installed under COM ports.

Arduino UNO COM port

Remember the (COMxx) port that the Arduino UNO was installed on.

Mac OS X

If you are using Mac OS, a dialog box will tell you that a new network interface has been detected. Click Network Preferences and select Apply. Even though the Arduino board may show up as Not Configured, it should be working perfectly.

Linux

You are ready to go.

The serial ports for Mac OS and Linux will be obtained once the Arduino software has been launched.

The Arduino IDE

The Arduino software, commonly referred to as the Arduino IDE (Integrated Development Environment), is something that you will become really familiar with as you progress through this book. The IDE for Windows, Mac OS, and Linux is almost identical. Now let's look at some of the highlights of this software.

Arduino IDE

This is the window that you will see when you first start up the IDE. The tick/check mark verifies that your code's syntax is correct. The arrow pointing right is the button that uploads the code to the board and checks if the code has been changed since the last upload or verification. The magnifying glass is the Serial Monitor. This is used to input text or output debugging statements or sensor values.

Examples of Arduino

All Arduino programmers start by using one of these examples. Even after mastering Arduino, you will still return here to find examples to use.

Arduino tools

The screenshot shows the tools that are available in the Arduino IDE. The Board option opens up all the different boards that the software supports.

LED blink

That wasn't too bad but it isn't cool enough. This little section will enlighten you, literally.

Open up a new sketch.

Go to File | Examples | 01. Basics | Blink.

Blink example

Before we upload the code, we need to make sure of one more thing. Remember the LED that we spoke about in the prerequisites? Let's learn a bit about it before plugging it in, as shown in the following image:

LED basics

We will make use of it now. Plug in the LED such that the longer leg goes into pin 13 and the shorter leg goes into the GND pin, as in the following:

LED blink setup (Fritzing)

Note

This diagram is made using software called Fritzing. This software will be used in future projects to make it cleaner to see and easier to understand as compared to a photograph with all the wires running around. Fritzing is open source software which you can learn more about at www.fritzing.org.

Arduino LED setup

Upload the code. Your LED will start blinking, as shown in the following image.

A lit up LED

Isn't it just fascinating? You just programmed your first hardware. There's no stopping you now. Before advancing to the next chapter, let's see what the code does and what happens when you change it.

This is the blink example code that you just used:

/*
Blink
Turns on an LED on for one second, then off for one second, repeatedly.
  
This example code is in the public domain.
*/

//Pin 13 has an LED connected on most Arduino boards.
//give it a name:
int led = 13;

//the setup routine runs once when you press reset:
void setup() {
// initialize the digital pin as an output.
pinMode(led, OUTPUT);
}

//the loop routine runs over and over again forever:
void loop() {
  digitalWrite(led, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(1000);               // wait for a second
  digitalWrite(led, LOW);    // turn the LED off by making the voltage LOW
  delay(1000);               // wait for a second
}

We have three major sections in this code. This format will be used for most of the projects in the book.

int led = 13;

This line simply stores the numerical PIN value onto a variable called led.

void setup() {
// initialize the digital pin as an output.
pinMode(led, OUTPUT);
}

This is the setup function. Here is where you tell the Arduino what is connected on each used pin. In this case, we tell the Arduino that there is an output device (LED) on pin 13.

void loop() {
digitalWrite(led, HIGH);   // turn the LED on (HIGH is the voltage level)
delay(1000);               // wait for a second
digitalWrite(led, LOW);    // turn the LED off by making the voltage LOW
delay(1000);               // wait for a second
}

This is the loop function. It tells the Arduino to keep repeating whatever is inside it in a sequence. The digitalWrite command is like a switch that can be turned ON (HIGH) or OFF (LOW). The delay(1000) function simply makes the Arduino wait for a second before heading to the next line.

If you wanted to add another LED, you'd need some additional tools and some changes to the code. This is the setup that you want to create.

Connecting two LEDs to an Arduino

If this is your first time using a breadboard, take some time to make sure all the connections are in the right place. The colors of the wires don't matter. However, GND is denoted using a black wire and VCC/5V/PWR is denoted with a red wire. The two resistors, each connected in series (acting like a connecting wire itself) with the LEDs, limit the current flowing to the LEDs, making sure they don't blow up.

As before, create a new sketch and paste in the following code:

/*
Double Blink
Turns on and off two LEDs alternatively for one second each repeatedly.

This example code is in the public domain.
*/

int led1 = 12;
int led2 = 13;

void setup() {
// initialize the digital pins as an output.
pinMode(led1, OUTPUT);
pinMode(led2, OUTPUT);

// turn off LEDs before loop begins
digitalWrite(led1, LOW);   // turn the LED off (LOW is the voltage level)
digitalWrite(led2, LOW);   // turn the LED off (LOW is the voltage level)
}

//the loop routine runs over and over again forever:
void loop() {
digitalWrite(led1, HIGH);   // turn the LED on (HIGH is the voltage level)
digitalWrite(led2, LOW);    // turn the LED off (LOW is the voltage level)
delay(1000);                // wait for a second
digitalWrite(led1, LOW);    // turn the LED off (LOW is the voltage level)
digitalWrite(led2, HIGH);   // turn the LED on (HIGH is the voltage level)
delay(1000);                // wait for a second
}

Once again, make sure the connections are made properly, especially the positive LEDs (the longer one to OUTPUT PIN) and the negative (the shorter to the GND) terminals. Save the code as DoubleBlink.ino. Now, if you make any changes to it, you can always retrieve the backup.

Upload the code. 3… 2… 1… And there you have it, an alternating LED blink cycle created purely with the Arduino. You can try changing the delay to see its effects.

For the sake of completeness, I would like to mention that you could take this mini-project further by using a battery to power the system and decorate your desk/room/house. More on how to power the Arduino will be covered in subsequent chapters.

What you will learn

Understand and utilize the capabilities of the Arduino Integrate sensors to gather environmental data and display this information in meaningful ways Add modules such as Bluetooth and WiFi that allow the Arduino to communicate and send data between devices Create simple servers to allow communication to occur Build automated projects including robots while learning complex algorithms to mimic biological locomotion Implement error handling to make programs easier to debug and look more professional Integrate powerful programming tools and software such as Python and Processing to broaden the scope of what the Arduino can achieve Practice and learn basic programming etiquette

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