Arduino By Example: Design and build fantastic projects and devices using the Arduino platform

Well, you can't jump onto a horse without putting on a saddle first, can you? This section will cover what components you need to start coding on an Arduino. These can be purchased from your favorite electrical hobby store or simply ordered online.

This topic involves downloading the Arduino software, installing the drivers, hooking up the Arduino, and understanding the IDE menus.

Downloading and installing the software

Arduino is open source-oriented. This means all the software is free to use non-commercially. Go to http://arduino.cc/en/Main/Software and download the latest version for your specific operating system. If you are using a Mac, make sure you choose the right Java version; similarly on Linux, download the 32-or 64-bit version according to your computer.

Arduino download page

Windows

Once you have downloaded the setup file, run it. If it asks for administrator privileges, allow it. Install it in its default location (C:\Program Files\Arduino or C:\Program Files (x86)\Arduino). Create a new folder in this location and rename it My Codes or something where you can conveniently store all your programs.

Mac OS X

Once the ZIP file has finished downloading, double-click to expand it. Copy the Arduino application to the Applications folder. You won't have to install additional drivers to make the Arduino work since we will be using only the Arduino UNO and MEGA throughout the book. You're all set.

If you didn't get anything to work, go to https://www.arduino.cc/en/guide/macOSX.

Linux (Ubuntu 12.04 and above)

Once you have downloaded the latest version of Arduino from the preceding link, install the compiler and the library packages using the following command:

sudo apt-get update && sudo apt-get install arduino arduino-core

If you are using a different version of Linux, this official Arduino walkthrough at http://playground.arduino.cc/Learning/Linux will help you out.

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:

1. Open Device Manager.

2. Click on Ports (COM & LPT).

3. Right-click on Unknown Device and select Properties.

4. Click on Install Driver and choose browse files on the computer.

5. 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.

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.

The easiest way to start working with Arduinos begins here. You'll learn how to output print statements. The Arduino uses a Serial Monitor for displaying information such as print statements, sensor data, and the like. This is a very powerful tool for debugging long codes. Now for your first code!

Writing a simple print statement

Open up the Arduino IDE and copy the following code into a new sketch:

void setup() {
Serial.begin(9600);
Serial.println("Hello World!");
}

void loop() {
}

Open Tools | Board and choose Arduino UNO, as shown in the following screenshot:

Open Tools | Port and choose the appropriate port (remember the previous COM xx number? select that), as shown in the following screenshot. For Mac and Linux users, once you have connected the Arduino board, going to Tools | Serial Port will give you a list of ports. The Arduino is typically something like /dev/tty.usbmodem12345 where 12345 will be different.

Selecting the Port

Finally, hit the Upload button. If everything is fine, the LEDs on the Arduino should start flickering as the code is uploaded to the Arduino. The code will then have uploaded to the Arduino.

To see what you have accomplished, click on the Serial Monitor button on the right side and switch the baud rate on the Serial Monitor window to 9600.

You should see your message Hello World! waiting for you there.

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)

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.

You have now completed the basic introduction to the world of Arduino. In short, you have successfully set up your Arduino and have written your first code. You also learned how to modify the existing code to create something new, making it more suitable for your specific needs. This methodology will be applied repeatedly while programming, because almost all the code available is open source and it saves time and energy.

In the next chapter, we will look into sensors and displays. You will build a digital ruler that you can use to measure short distances. It will consist of an ultrasound sensor to compute distance and a small LCD screen to display it. Additionally, we will look at safely powering the Arduino board using a battery so that you are not dependent on your computer for USB power every time.