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Arduino’s Tom Igoe discusses getting started with microcontroller boards

Arduino microcontroller board

Years ago I purchased a book called “Physical Computing”. It’s a terrific tutorial on how to interface computer and microcontroller boards with the physical world through sensors and actuators. If you’re interested in a career in automation or robotics, or just love electronics as a hobby, this is a great time! There’s never been more hardware and software to choose from at a more affordable price. One of the providers of this equipment is a company called Arduino. They’ve been getting a lot of positive attention for their offerings, and I thought they’d be a good contact for writing about how to get started using microcontroller boards. When I contacted them I quickly heard back from a gentleman named Tom Igoe, who said he’d be happy to talk on the phone about it. It wasn’t until I began the phone conversation that I realized he was also co-author of my book “Physical Computing”. I should have recognized the name but it was a pleasant surprise that I hadn’t. Here are my questions to him based on my own curiosities.

Q. Your website states that Arduino is “intended for artists, designers, hobbyists, and anyone interested in creating interactive objects or environments”. Hobbyists would be obvious users, but what would be examples of artists and designers?

I teach at the Interactive Telecommunications Program at NYU and artists and designers would be about 90% of my audience. My involvement in Arduino began with a program I had here called “Physical Computing” which is all about getting students who are coming from non-technical disciplines and giving them hands-on experience with interactive technologies. We’ve been using things like the Basic Stamp, and other microcontroller boards that are out there, to do that but most of the stuff we’d been seeing was created by engineers with engineers in mind. What we tried to do with Arduino was take an approach that doesn’t make those same assumptions, and tries to make the technology accessible to non-technologists.

Climate Dress with Arduino LilyPad microcontroller The Climate Dress project by Danish company Diffus uses over a hundred micro-LEDs, a CO2 sensor, and an Arduino LilyPad microcontroller. It monitors ambient carbon dioxide and illuminates the LEDs according to the concentration.

Q. On your website you have a selection of main and auxiliary boards. What would be the main controller boards that someone would begin with?

Our main board is the Arduino Uno, which is an 8-bit controller. It’s got 20 I/O pins and it’s designed for people to very easily get sensor data in, or to send signals out to actuators. There’s a larger version called the Arduino Mega 2560 that has the same processor family except that it has 57 I/O pins, 4 hardware serial ports instead of 1, and a little bit more memory. There are some specialty boards like the LilyPad, which is designed for use in wearable applications, so it’s easy to sew into garments and use conductive thread as the wiring between components. The Ethernet board is designed for embedded network applications. The Mega ADK has USB host built in and it’s really great for connecting to Android cell phones and other USB devices. The auxiliary boards are called “Shields” and add functionality to the main boards. For example, the Wireless Shield allows you to attach a radio transceiver on board. We designed it originally with Digi’s Xbee transceivers in mind but it can be used with other things too. There’s a Motor Shield, which allows you to easily control stepper and servo motors. There’s a lot of 3rd party Shields as well. We tried to make the system as openly compatible as possible and that’s one of the reasons it’s all open-source, including the hardware design.

Q. What is meant by Shield?

A Shield is just a plug-in board. Rather than having to design and build the auxiliary circuitry yourself you can just plug a Shield right on top of the main board to get that functionality. The term came about because Arduino was one of the first regional kings of Italy and we figured that kings from that period had shields.

Q. You said that you don’t think of these as computer boards but as microcontroller boards. How would you draw the distinction between them?

When you call something a computer people have a very specific image in mind. They imagine something with a keyboard, a mouse, a screen, and can run an operating system. That’s not what this is, so calling it a microcontroller board sends a more specific message and opens up the discussion as to what one is and what you can do with it, and how computing goes further than computers. A large reason that we’ve done what we have was to get people to expand their imaginations about what computing is.

Q. But they are capable of performing mathematical computation?

Yes, technically they are computers. We may eventually make something that’s more like a typical computer board but for right now we’ve been making that distinction so that people think about them as something different than that.

Q. What types of signals are the Uno and Mega 2560 controller boards compatible with?

The boards are typically 5 volt although some are running at 3.3 volt as well. The inputs are just basic TTL digital with a number of analog inputs also. The Uno has 14 digital I/O pins and 6 analog inputs, and the Mega 2560 has 54 digital I/Os and 16 analog inputs. The analog inputs use a 0-5 volt or 0-3.3 volt range and have a built-in analog reference so you can change that.

Q. Can you describe the programming software that’s designed for these boards?

It’s basically just a wrapper around the AVR GCC compiler, so it’s all C code, and we’ve written IDE software for it to make it compatible with Windows, Mac, and Linux. A couple of factors played into it: We looked at what the technical limitations might be for non-technical people learning C. One of them is “pointers” and memory management. C code tends to be very terse and difficult to read for everyday people, so we tried to make our function names more descriptive of what they did. Secondly, we tried to shield the memory management from the user so they didn’t have to worry about it as much. We also tried to make the basic functions as simple as possible, so there’s a setup and a loop and that’s it. You can add functions, or expand to assembly-level code if you want, but as a beginner you shouldn’t need more than 2 or 3 lines of code to get started with an LED blinking on a pin. That simplicity has been very important to us. Our philosophy is what I call a “glass box enclosure”. The libraries aren’t compiled until you do the final upload to the processor, so you can look inside and change them if you want. They’re written in a way to be as readable and understandable as possible.

Q. How can you expand beyond the limitations of the board you’ve selected? For example, if you need more I/O.

I get this question with students a lot. You would expand the same way as with any other microcontroller board. I describe these methods in detail in chapter 14 of my book “Physical Computing”. You can use multiple switch inputs on a resistor ladder to generate a single analog input. You can also use shift registers or multiplexers. Or you can use additional microcontrollers and link them together using synchronous serial communication. We have instructions on our site on how to do that.

Q. Do you have any announcements on future projects that you’re working on?

We recently announced that we’re working on a 32-bit board that should come out late 2011 or early 2012. We’re also working on a cheaper version of our main board called Leonardo, which has native USB and will show up on your computer just like a mouse or keyboard. We announced a Wi-Fi Shield that will allow you to connect to Wi-Fi networks. There’s an educational robot that we’re working on for kids. There’s also about 15 other things that we’re working on that aren’t ready for announcement yet.

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