原创 A quest to learn the Arduino (Part 2)

In my last column on the Arduino, we looked at the hardware platform itself. Now it's time to consider how we create programs for this little rascal.

There are several programming environments one can use with the Arduino. If you are a beginner, perhaps the best option is to use the official Arduino IDE (integrated development environment), which you can download for free from the Download page on the Arduino website. Have your Arduino board and USB cable near your computer, but don't plug them in just yet.

As you will see, there are Windows, Mac OS X, and Linux versions of this IDE available. Just follow the instructions on the Arduino website. When you do come to connect your Arduino to your computer, one of the first things you must do in the Arduino IDE is use the "Tools > Board" pull-down menu to select the type of Arduino platform you are using. For the purposes of these discussions we will assume an Arduino Uno, so this is the option you would select.

Introducing the Arduino programming language
The Arduino programming language is an implementation of the open-source electronics prototyping platform called Wiring, which itself is based on an open-source electronics prototyping platform called Processing. For our purposes here, however, the simplest way to think of this is that the Arduino programming language is a simplified version of the C and C++ programming languages.

If you are already familiar with C/C++, then you will also be familiar with the concept of the "main" function. The idea here is that a standard C/C++ program consists of one or more functions, and that one of these functions must have the name "main":

A standard C/C++ program is executed when the higher-level operating system hands control over to the "main" function in the program. The "main" function differs from other functions in two ways:
* It may not be called from within the program.
* Any parameters to "main," if they exist, are provided (passed-in) by the operating system.

A program written for the Arduino is called a "sketch." The main point to note here is that sketches do not contain a "main" function. Instead, every Arduino program includes two primary functions (along with any functions you add of your own) called "setup" and "loop":

Any code you write within the curly brackets associated with a function will be executed when that function is called. The "setup" function runs only one time when the Arduino is first powered-up or when it is reset. The "loop" function runs continuously after the "setup" function has finished performing its tasks.

As an aside, for the C/C++ purists amongst us, my understanding is that when we initiate a compilation, the IDE slips in a "main" function while we aren't looking. The thing to remember is that the creators of the Arduino are trying to keep things as simple as possible for beginners.

Learning the Arduino programming language
First of all, there are a bunch of useful tutorials and other resources available for free on the main Aduino.cc website. If you are an absolute newcomer to C/C++, then one book that I would personally recommend is Programming Arduino Getting Started with Sketches by Simon Monk, which is available for a very reasonable $10.99 from Amazon.

It's worth knowing that an Arduino board typically arrives with a default program called "Blink" preinstalled. As soon as you connect the Arduino to your host computer with the USB cable, this program will cause a LED on the board to start blinking. The first half of Simon's book introduces you to various aspects of the C/C++ programming language via changes you make to this "Blink" sketch. Later experiments in the second half of the book will require you to use some very basic components and tools, like a resistor, a switch, a couple of pieces of wire, and a multi-meter.

As you become more advanced, you will discover that there are all sorts of Arduino-specific resources available on the Internet to answer your questions. Also, a lot of general-purpose C/C++ resources are out there, such as this 'const' and 'static' keywords tutorial and this pointer tutorial.

Next, we'll look at some Arduino kits for beginners...

Arduino kits for beginners
There are a couple of very useful starter kits available should you wish to avail yourself of them. The first is the Arduino Uno Ultimate Starter Kit for $54.99 from Amazon, as illustrated below:

This kit includes an Arduino Uno R3 board and a USB cable to connect it to your host computer. It also includes a small breadboard and a bunch of wires and electronic components sufficient for you to perform loads of experiments. Also included is a 72 page, full-colour instruction manual that will walk you through various experiments. What the kit doesn't include is a power supply, but you can pick one up from Amazon for $5.98 (click here). And, while you are at it, you might as well go for the ultrasonic distance sensor for only $4.85 (click here).

Now, I cannot personally vouch for the above kit because I don't have one, but the fact that it has a 4.5 star rating from 242 customer reviews (at the time of this writing) says a lot. As always, I would suggest that you take a look at some of these reviews yourself to get a better feel for what's going on.

Another kit that I can personally recommend is The Arduino Starter Kit for $109.95 from Amazon.

This little beauty comes with a host of tasty "stuff," including a 170-page Arduino Projects Book that walks you through building things like a "Light Theremin," a "Motorized Pinwheel," and a "Love-O-Meter." As for the other kit, one thing that isn't included is a power supply, but you can pick one up from Amazon for $5.98 (click here).

Everything in this kit is very nicely packaged and presented. When you open the box, the first thing you see is the Arduino Projects Book, as illustrated below:

When you remove the book, you are presented with a "jigsaw puzzle" of small boxes as illustrated below:

Opening the boxes reveals all sorts of goodies, including a small liquid crystal display as illustrated below:

Now, if you are an experienced hobbyist or engineer, this kit may well be too simplistic for you. On the other hand, if you wish to introduce a younger person to the magic of microcontrollers, then this kit would be ideal. You start with really simple experiments like connecting a LED to an output pin and flashing it, and then you build up to more complicated projects in easy-to-understand steps. Also, everything is achieved by means of the breadboard; that is, no soldering is required.

Two more books
As you may recall, one reason for my wanting to learn that Arduino in the first place is that I sponsored a Kickstarter project for a fast and easy-to-use machine vision system called the Pixy, which can be connected directly to an Arduino. In the video shown on this project's Kickstarter webpage, we see the Pixy being used to control a small robot.

Based on this, I ordered a book called Make an Arduino-Controlled Robot by Michael Margolis:

Generally speaking, this book has reasonably favourable reviews. Also, a lot of the information seems as though it would be of use for robots other than the two kits featured in the book. This is fortunate, because the kits themselves receive less than favourable reviews. However, we will leave that discussion to my next column, at which point we will consider the whole robot issue in more detail.

Last but certainly not least (in the book department), I just took possession of another book called Arduino Workshop: A Hands-On Introduction with 65 Projects by John Boxall (a.k.a. Tronixstuff):

Truth to tell, I haven't even had the chance to open the cover of this little beauty yet. Suffice it to say, for the moment, that one reviewer on Amazon said:

I really think Arduino Workshop is under selling itself. It's not just a workshop manual but a tutorial on electronics, programming and Arduino, and a very good one at that... Over all this is an excellent resource and one that should be on the shopping list of everyone interested in creating their own Arduino toys and tools.

Reading Arduino Workshop is high on my list of things to do, and I plan on writing full-up reviews of both Make an Arduino-Controlled Robot and Arduino Workshop in the not-so-distant future.

But wait, there's more...
Eeeek! I almost forgot to mention that my chum Tobias Strauch just sent me a very interesting link to a 30-minute documentary about how the Arduino came to be (click here to see this video).

And just this morning, I heard from Paul Kassebaum PhD, Maker Community Relations, MathWorks. Paul informed me that MathWork's Simulink has a relatively new capability to generate code to run on the Arduino Uno, Mega, and Nano platforms, as well as other low-cost microcontrollers like the Raspberry Pi and Beagleboard.

Even better, they've built a website to introduce beginners and inspire amateurs to the cool stuff this capability enables: makerzone.mathworks.com (you can see a simple example meant to get one up and running from scratch on the Arduino Uno by clicking here). As a more complex example of the sophistication Simulink can bring to Arduino-based projects, they used the Arduino Mega 2560 to automate sumobots in a competition last April (click here).

Arduino-powered robots
As I mentioned earlier, my next blog will be about creating Arduino-powered robots. In the meantime, do you have any questions? Alternatively, are there any Arduino books, kits, or other resources that you would recommend? If so, please share them with the rest of us in the comments below.