Which Arduino board is right for you?

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Picking an Arduino is as easy as Uno, Due, Tre! 

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Thinking about starting a project? See which Arduino board is right for the job.

Arduino Uno

This popular board — based on the ATmega328 MCU — features 14 digital input/output pins (of which 6 can be used as PWM outputs), 6 analog inputs, a 16 MHz ceramic resonator, USB connection, power jack, an ICSP header and a reset button.

The Uno does not use the FTDI USB-to-serial driver chip. Instead, it features the ATmega16U2 (ATmega8U2 up to version R2) programmed as a USB-to-serial converter.

In addition, Revision 3 of the Uno offers the following new features:

• 
1.0 pinout: added SDA and SCL pins that are near to the AREF pin and two other new pins placed near to the RESET pin, the IOREF that allow the shields to adapt to the voltage provided from the board. Note: The second is not a connected pin.
• 
Stronger RESET circuit.
• ATmega16U2 replace the 8U2.

Arduino Leonardo

The Arduino Leonardo is built around the versatile ATmega32U4. This board offers 20 digital input/output pins (of which 7 can be used as PWM outputs and 12 as analog inputs), a 16 MHz crystal oscillator, microUSB connection, power jack, an ICSP header and a reset button.

The Leonardo contains everything needed to support the microcontroller; simply connect it to a computer with a USB cable or power it with a AC-to-DC adapter or battery to get started. Plus, the ATmega32U4 offers built-in USB communication, eliminating the need for a secondary processor. This allows it to appear as a mouse and keyboard, in addition to being recognized as a virtual (CDC) serial / COM port.

Arduino Due

The Arduino Due is an MCU board based on the Atmel | SMART SAM3X8E ARM Cortex-M3 CPU.

As the first Arduino built on a 32-bit ARM core microcontroller, Due boasts 54 digital input/output pins (of which 12 can be used as PWM outputs), 12 analog inputs, 4 UARTs (hardware serial ports), an 84 MHz clock, USB OTG capable connection, 2 DAC (digital to analog), 2 TWI, a power jack, an SPI header, a JTAG header, a reset button and an erase button.

Unlike other Arduino boards, the Due runs at 3.3V. The maximum voltage that the I/O pins can tolerate is 3.3V. Providing higher voltages, like 5V to an I/O pin, could damage the board.

Arduino Yún

The Arduino Yún features an ATmega32U4, along with an Atheros AR9331 that supports a Linux distribution based on OpenWRT known as Linino.

The Yún has built-in Ethernet and Wi-Fi support, a USB-A port, a microSD card slot, 20 digital input/output pins (of which 7 can be used as PWM outputs and 12 as analog inputs), a 16 MHz crystal oscillator, microUSB connection, an ICSP header and 3 reset buttons. The Yún is also capable of communicating with the Linux distribution onboard, offering a powerful networked computer with the ease of Arduino.

In addition to Linux commands like cURL, Makers and engineers can write their own shell and python scripts for robust interactions. The Yún is similar to the Leonardo in that the ATmega32U4 offers USB communication, eliminating the need for a secondary processor. This enables the Yún to appear as a mouse and keyboard, in addition to being recognized as a virtual (CDC) serial?COM port.

Arduino Micro

Developed in conjunction with Adafruit, the Arduino Micro is powered by ATmega32U4.

The board is equipped 20 digital input/output pins (of which 7 can be used as PWM outputs and 12 as analog inputs), a 16 MHz crystal oscillator, microUSB connection, a ICSP header and a reset button. The Micro includes everything needed to support the microcontroller; simply connect it to a computer with a microUSB cable to get started. The Micro even has a form factor that lets the device be easily placed on a breadboard.

Arduino Robot

The Arduino Robot is the very first official Arduino on wheels. The robot is equipped with two processors — one for each of its two boards.

The motor board drives the motors, while the control board is tasked with reading sensors and determining how to operate. Each of the ATmega32u4 based units are fully-programmable using the Arduino IDE. More specifically, configuring the robot is similar to the process with the Arduino Leonardo, as both MCUs offer built-in USB communication, effectively eliminating the need for a secondary processor. This enables the Robot to appear to a connected computer as a virtual (CDC) serial?COM port.

Arduino Esplora

The Arduino Esplora is an ATmega32u4 powered microcontroller board derived from the Arduino Leonardo. It’s designed for Makers and DIY hobbyists who want to get up and running with Arduino without having to learn about the electronics first.

The Esplora features onboard sound and light outputs, along with several input sensors, including a joystick, slider, temperature sensor, accelerometer, microphone and a light sensor. It also has the potential to expand its capabilities with two Tinkerkit input and output connectors, along with a socket for a color TFT LCD screen.

Arduino Mega (2560)

The Arduino Mega features an ATmega2560 at its heart.

It is packed with 54 digital input/output pins (of which 15 can be used as PWM outputs), 16 analog inputs, 4 UARTs (hardware serial ports), a 16 MHz crystal oscillator, USB connection, a power jack, an ICSP header and a reset button. Simply connect it to a computer with a USB cable or power it with a AC-to-DC adapter or battery to get started. The Mega is compatible with most shields designed for the Arduino Duemilanove or Diecimila.

Arduino Mini

Originally based on the ATmega168, and now equipped with the ATmega328, the Arduino Mini is intended for use on breadboards and projects where space is at a premium.

The board is loaded with 14 digital input/output pins (of which 6 can be used as PWM outputs), 8 analog inputs and a 16 MHz crystal oscillator. It can be programmed with the USB Serial adapter, the other USB, or the RS232 to TTL serial adapter.

Arduino LilyPad

The LilyPad Arduino is designed specifically for wearables and e-textiles. It can be sewn to fabric and similarly mounted power supplies, sensors and actuators with conductive thread.

The board is based on the ATmega168V (the low-power version of the ATmega168) or the ATmega328V. The LilyPad Arduino was designed and developed by Leah Buechley and SparkFun Electronics. Readers may also want to check out the LilyPad Simple, LilyPad USB and the LilyPad SimpleSnap.

Arduino Nano

The Arduino Nano is a tiny, complete and breadboard-friendly board based on the ATmega328 (Arduino Nano 3.x) or ATmega168 (Arduino Nano 2.x).

The Nano has more or less the same functionality of the Arduino Duemilanove, but in a different package. It lacks only a DC power jack and works with a Mini-B USB cable instead of a standard one. The board is designed and produced by Gravitech.

Arduino Pro Mini

Powered by an ATmega328, the Arduino Pro Mini is equipped with 14 digital input/output pins (of which 6 can be used as PWM outputs), 8 analog inputs, an on-board resonator, a reset button and some holes for mounting pin headers.

A 6-pin header can be connected to an FTDI cable or Sparkfun breakout board to provide USB power and communication to the board. Note: See also Arduino Pro.

Arduino Fio

The Arduino Fio (V3) is a microcontroller board based on Atmel’s ATmega32U4. It has 14 digital input/output pins (of which 6 can be used as PWM outputs), 8 analog inputs, an on-board resonator, a reset button and holes for mounting pin headers. It also offers connections for a lithium polymer battery and includes a charge circuit over USB. An XBee socket is available on the bottom of the board.

The Arduino Fio is intended for wireless applications. The user can upload sketches with an a FTDI cable or Sparkfun breakout board. Additionally, by using a modified USB-to-XBee adaptor such as XBee Explorer USB, the user can upload sketches wirelessly. The board comes without pre-mounted headers, facilitating the use of various types of connectors or direct soldering of wires. The Arduino Fio was designed by Shigeru Kobayashi and SparkFun Electronics.

Arduino Zero

Last year, the tandem of Atmel and Arduino debuted the Zero development board – a simple, elegant and powerful 32-bit extension of the platform. The Arduino Zero board packs an Atmel | SMART SAM D21 MCU, which features an ARM Cortex M0+ core. Additional key hardware specs include 256KB of Flash, 32KB SRAM in a TQFP package and compatibility with 3.3V shields that conform to the Arduino R3 layout.

The Arduino Zero boasts flexible peripherals along with Atmel’s Embedded Debugger (EDBG) – facilitating a full debug interface on the SAMD21 without the need for supplemental hardware. Beyond that, EDBG supports a virtual COM port that can be used for device programming and traditional Arduino bootloader functionality. This highly-anticipated board will be available for purchase from the Arduino Store in the U.S. on Monday June 15th.

Arduino AtHeart

The Arduino AtHeart program was specifically launched for Makers and companies with products based on the open-source board that would like to be clearly identified as supporters of the versatile platform. The program is available for any device that includes a processor that is currently supported by the Arduino IDE, including the following Atmel MCUs:

• ATMega328 clocked at 8 or 16 MHz
• ATMega1280 clocked at 16 MHz
• ATMega2560 clocked at 16 MHz
• ATMega32U4 clocked at 16MHz
• Atmel | SMART SAM3X

Participants in the program include startups like:

EarthMake – ArLCD

The touchscreen ArLCD combines the ezLCD SmartLCD GPU with the Arduino Uno.

Bare Conductive Touch Board

The ATmega32U4 based Touch Board can turn nearly any material or surface into a sensor by connecting it to one of its 12 electrodes, using conductive paint or anything conductive.

Blend Micro

The RedBearLab integrated dev platform “blends” the powers of Arduino with Bluetooth 4.0 Low Energy into a single board. It is targeted for Makers looking to develop low-power IoT projects in a quick, easy and efficient manner. The MCU is driven by an ATmega32U4 and a Nordic nRF8001 BLE chip.

littleBits Arduino Module

The fan-favorite Arduino module, which happens to also be based on an ATmega32U4, lets users easily write programs in the Arduino IDE to read sensors and control lights and motors within the littleBits system.

Smart Citizen Kit

An Arduino-compatible motherboard with sensors that measure air composition (CO and NO2), temperature, light intensity, sound levels, and humidity. Once configured, the Smart Citizen Kit is capable of streaming data collected by the sensors over Wi-Fi.

WifiDuino for the Internet of Things

Powered by Atmel’s versatile ATmega32U4 microcontroller (MCU), the open source WiFiDuino is a chip-sized development board that packs a 28×64 OLED display.

“We designed WifiDuino based on our belief in the future of the Internet of Things (IoT) when everything is connected. We will be living in a world when every object can communicate with each other using WiFi,” a WiFiDuino rep explained in a recent Indiegogo post.

“With WifiDuino, you no longer need to worry about getting a WiFi shield. [We] have done the hard part for you. It’s great for people who are tired of buying WiFi shields every time you want the board to be connected.”

Aside from Atmel’s ATmega32U4 MCU, key WiFIDuino specs and features include:

• Supports Arduino IDE (Leonardo)
• STA, AP, ADHOC network modes
• Connects directly with smartphone
• 20 digit I/O
• 12 Analog I/O
• UART, I2C, SPI
• 5v power and I/O pin level

Interested in learning more? You can check out the project’s Indiegogo page here.

Silverlink clone resurrects pre-USB calculators

The Silverlink of yore connected TI calculators without USB ports to PCs, facilitating the easy transfer of files, screenshots and operating systems.

As KermMartian of Cemetech notes, Silverlink was first introduced about 15 years ago, so it doesn’t comes as much of a surprise that a number of units are starting to show their age by failing over time.

“We anticipate that the rest will gradually lose their firmwares (with no way of repairing them) in the next decade or two,” writes KermMartian.

“To fill this gap, ideas for a community-coded Silverlink clone have been kicking around for several years. Tim ‘geekboy1011’ Keller has taken the initiative in creating Silverlink clone software for the Arduino Leonardo (Atmel ATmega32U4) microcontroller development board.”

Keller kicked off his clone project by leveraging KermMartian’s Arduino to TI calculator linking routines, which he ported from Arduino “C” to bare-AVR C. He then deduced the relevant file transfer protocols using USB sniffing, the TI Link Protocol & File Format Guide and checking against the TILP repository.

“Tim is using the LUFA library for AVRs to handle USB; the flexibility of the library lets his Silverlink clone appear to be an original Silverlink to the host computer, and thus requires no new drivers,” KermMartian explains.

“Since it appears to be a regular Silverlink to computer-side software, Tim’s clone works with both TI-Connect and TiLP, the two popular software options for linking TI calculators and computers.”

Interested in learning more about Tim’s initiative? Additional information is available on the Cemetech forums here.

Universal Proto-Shield connects your Arduino boards

Created by Max & Duane Galactic Enterprises, the Universal Screw-Block Proto-Shield System for Arduino is designed to securely connect various Atmel-based Arduino boards to the outside world.

Supported boards currently include the Uno, Due, Leonardo and Mega.

“The great thing about Arduino boards is that they are so easy to interface to the outside world – to monitor the state of sensors and to control actuators and make things happen. As part of this, you often need to add a few components or circuits of your own, and the best way to do this is by means of a prototyping (proto) shield,” a company rep explained in a recent Kickstarter post.

“Unfortunately, most proto-shields don’t make it particularly easy to actually connect wires to and from the outside world. The Universal Screw-Block Proto-Shield System for Arduino (and chipKIT counterparts) addresses this issue by means of its easy-to-use screw-block terminals.”

Indeed, the platform features two boards as shown below. More specifically, the Master Board on the left works with Arduino Uno and Leonardo, with the Due and Mega requiring the Expansion Board on the right.

“If you are anything like us, you will have a number of Arduino-based projects on the go at the same time. Depending on your mood, you might start working on one, then swap over to another, and swap back again later. The real hassle comes when you have to unplug lots of external sensors and actuators and other devices,” the rep added.

“This is where the Universal Screw-Block Proto-Shield System for Arduino is worth its weight in gold. If you create each project on its own Proto-Shield, then you can use a single Arduino – all you have to do is quickly and easily swap your Proto-Shields in and out… [In addition], the Universal Screw-Block Proto-Shield System for Arduino allows I2C-based Uno shields to work with the other types of Arduino.”

Interested in learning more? You can check out the project’s official Kickstarter page here.

energyShield jolts your Arduino projects

NightShade Electronics has debuted a rechargeable battery shield for Atmel-powered Uno (ATmega328) and Leonardo (ATmega32u4) Arduino boards.

More specifically, the lithium-polymer battery features three primary functions: 
a circuit to boost the battery’s nominal voltage of 3.7V to 5V; a lithium-polymer battery charging circuit; and an on-board fuel gauge IC which facilitates the measurement of battery voltage, current and accumulated charge by means of a Two-Wire Interface (TWI/I2C).

Additional key specs include:

• 5V output (and 3.3V when attached to an Arduino)
• 500 mA output (final version expected to be higher)
• Integrated charging circuit
• Fuel-gauge IC – monitor voltage, current and charge via a two-wire interface (TWI/I2C)
• Fully functional Arduino library
• On/off switch
• Charges from standard Arduino power adapter (7.2-20V)
• Powers Arduino while charging

The energyShield currently offers a capacity of 1200 mAh, a nominal current sourcing of 500 mA and, at full charge, a maximum current sourcing of 825 mA.

“We are looking to improving the current rating of the board to allow the energyShield to power even more demanding projects. The reason for the varying current limitation on the energyShield has to do with the output voltage (5V) being stepped up from the battery voltage (3.7V nominal),” a NightShade rep explained in a recent Kickstarter post.

“Because the battery voltage is lower than the output voltage, the current from the battery is larger than the current drawn from the energyShield at 5V. Assuming that the power from the battery is equal to the power used at 5V, the battery current (100% efficient) can be illustrated as such: I(bat) = I(out) * 5V / V(bat).”

Interested in learning more? You can check out energyShield’s official Kickstarter page here.

Arduino tweets temperature updates

The HackShed crew was recently testing out various sensors when Steve thought it would be a fun idea to task an Atmel-based Arduino board with tweeting the current environmental status of the office.

The Arduino now records the current, minimum, maximum and temperature change as well as humidity – automatically updating its Twitter account every 15 minutes.

According to Steve, the following hardware components can be used for the project:

• 

1x Atmel-based Arduino Uno/Leonardo Board (ATmega328/ATmega32u4)
• 1x Ethernet Shield
• 1x Mini-Breadboard
• 1x DHT11 Digital Temperature/Humidity Sensor / 5K Pull-Up Resistor

“I hooked up the data pin on the DHT11 to Pin 1 on the Ethernet Shield,” the HackShed crew member explained in a blog post describing the project.

“That is about it for connecting up the components, it is a really easy solution for monitoring temperature.”

In terms of software, Steve made use of the Arduino IDE, Adafruit’s DHT library and the Arduino Twitter library.

“We have the Arduino tweeting out updates every 15 minutes; this may be a bit much for some people so just alter the delay as needed,” he wrote.

 “We also added the Update # number to the beginning of the tweet as if you send the exact same tweet consecutively to Twitter it won’t be posted… and if the temperature doesn’t change often this may happen a lot.”

The HackShed’s Arduino is still tweeting away, with streaming updates available here. As Steve notes, it should be fairly simple for Makers to modify the code.

“There are a few handy functions such as getTempChange which will calculate the change in temperature; even with negative numbers, so passing in -10C and -5C will produce a 5C temperature change and passing in 10C and 2C will produce a -8C change,” he added.

Interested in learning more? You can check out the project’s official page, along with the relevant Arduino sketch here.

Transforming touch into sound

Bare Conductive has debuted the Touch Board, an Atmel powered platform (ATMega32u4 MCU) that allows Makers to more easily create interactive and responsive projects.

“Use the Touch Board to change the world around you by turning almost any material or surface into a sensor. Connect anything conductive to one of its 12 electrodes and trigger a sound via its onboard MP3 player, play a MIDI note or do anything else that you might do with an Arduino or Arduino-compatible device,” a Bare Conductive rep explained in a recent Kickstarter post.

“The Touch Board project began as a way for us to create interfaces with our Electric Paint, but it can do a whole lot more. You can also connect tin foil, copper, conductive thread, Squishy Circuits, and more straight to the board. The list is long, but with 12 electrodes, you’ll be able to [conduct] plenty of experiments.”

Key Touch Board features include:

• Distance sensing – You don’t need to touch your sensors to use them
• No programming required – Unless you want to
• Arduino-compatible – Easy to program and works with popular shields
• Works great with Electric Paint – Or any other conductive material
• MP3 Player / MIDI device – Make a symphony of sounds
• microSD card socket – Change the sounds just by changing the card
• Standard 3.5mm audio jack – Works with headphones and speakers
• Lithium Polymer (LiPo) – Stand alone projects that recharge via USB
• HID capable – Turn the Touch Board into a keyboard or mouse

As noted above, the core of the Touch Board is Atmel’s ATmega32U4 processor clocked at 16MHz and running at 5V – the same as the Arduino Leonardo. It also offers 32kB of flash program memory and 4kB of RAM, plenty for most programs Makers might want to write.

This is connected to the micro USB socket on the board, allowing Touch to appear a serial port (CDC) or  keyboard / mouse (HID).

Interested in learning more about the Atmel powered Touch Board? You can check out the project’s official campaign on Kickstarter here.

Getting started with the Atmel-powered Arduino Robot

The recently launched Arduino Robot – the first official Arduino on wheels – boasts two processors, one on each board. The Motor Board controls the motors, while the Control Board interacts with the sensors and decides how to operate. Both Arduino microcontroller boards are powered by Atmel’s ATmega32u4 and can be programmed using the Arduino IDE.

The Robot has many of its pins mapped to on-board sensors and actuators, so programming the ‘bot is similar to the process with the Arduino Leonardo. Both processors are equipped with integrated USB communication, eliminating the need for a secondary processor. This allows the Robot to appear to a connected computer as a virtual (CDC) serial / COM port.

In honor of Maker Faire Rome 2013, RS Components has posted an exclusive video tutorial (the first in a series of five) featuring Arduino co-founder Massimo Banzi introducing the Robot and exploring various characteristics of the new open-source hardware platform on wheels.

“These videos from the makers of Arduino give a simple, step-by-step guide to using and developing projects with the Robot,” Glenn Jarrett, Global Head of Product Marketing, RS Components, told EDN. “The informative yet light-hearted content will appeal equally to existing Arduino enthusiasts and to anyone dipping their toes into the world of computer programming for the first time.”

As previously discussed on Bits & Pieces, every element of the Robot platform – hardware, software and documentation – is freely available and open-source. Meaning, users can learn exactly how the device is put together, while exploiting its design as a starting point to create and mod various configurations.

Additional key specs? The ATmega32u4 has 32 KB (with 4 KB used for the bootloader), along with 2.5 KB of SRAM and 1 KB of EEPROM (which can be read and written with the EEPROM library). Meanwhile, the Control Board is fitted with an extra 512 Kbit EEPROM that can be accessed via I2C. There is also an external SD card reader attached to the GTFT screen accessible by the Control Board’s processor for additional storage.

The Robot can be powered via a USB connection or with 4 AA batteries and features an on-board battery charger that requires 9V external power generated by an AC-to-DC adapter (wall-wart). The adapter can be connected by plugging a 2.1mm center-positive plug into the Motor Board’s power jack, although the charger will not operate if powered by USB (the Control Board is powered by the power supply on the Motor Board).

As noted above, the Robot can be programmed with Arduino software, while the ATmega32U4 processors on the Arduino Robot arrive pre-burned with a bootloader that allows users to upload new code without an external hardware programmer via the AVR109 protocol. Of course, users can also bypass the bootloader and program the microcontroller through the ICSP (In-Circuit Serial Programming) header.

Interested? Additional details can be found on Arduino’s official Robot page.

Orders kick off for Arduino’s Yún

The Atmel-powered Arduino Yún can now be snapped up for $69, or €52. The  Yún – designed in collaboration with Dog Hunter – is based on Atmel’s ATMega32u4 microcontroller (MCU) and also features the Atheros AR9331, an SoC running Linino, a customized version of OpenWRT. As previously discussed on Bits & Pieces, the Yún is somewhat unique in the Arduino lineup, as it boasts a lightweight Linux distribution to complement the traditional microcontroller (MCU) interface.

The Yún also features WiFi and Ethernet connections, enabling the board to communicate with networks out of the box. In addition, the Yún’s Linux and Arduino processors link through the Bridge library, allowing Arduino sketches to send commands to the command line interface of Linux.

“The Arduino Yún has the same footprint as an Arduino Uno but combines an ATmega32U4 microcontroller (the same as the Leonardo) and a Linux system based on the Atheros AR9331 chipset,” Arduino’s Federico Vanzati explained. “Additionally, there are built-in Ethernet and WiFi capabilities. The combination of the classic Arduino programming experience and advanced internet capabilities afforded by a Linux system make the Yún a powerful tool for communicating with the internet of things (IoT).”

According to Vanzati, the Yún’s layout keeps the I/O pins the same as the Leonardo and is therefore compatible with the most shields designed for Arduino.

“With the Yún’s auto-discovery system, your computer can recognize boards connected to the same network. This enables you to upload sketches wirelessly to the Yún,” he continued. “You can still upload sketches to the Yún through the micro-USB connector just as you would with the Leonardo.”

On the connectivity side, the Yún is equipped with two separate network interfaces, a 10/100 Mbit/s Fast Ethernet port and a IEEE 802.11 b/g/n standard compliant 2.4GHz WiFi interface, supporting WEP, WPA and WPA2 encryption. As expected, the WiFi interface can also operate as an access point (AP). In AP mode any WiFi enabled device can connect directly to the network created on the Yún. While a Yún in this mode can’t connect to the internet, it could act as a hub for a group of WiFi enabled sensors.

Alongside the new board, Arduino has rolled out IDE 1.5.4  with a number of general bug fixes and new features, including:

• Board recognition – The IDE recognizes the type of board Makers and engineers are working with every time an Arduino is connected.
• Memory – When a sketch is uploaded, the IDE displays just how much memory is being used.
• Copy Error button: Users can more easily copy and paste errors to share in various forums.

The Arduino Yún can be ordered here. Additional information about the Yún’s hardware and key specs are available here, while a detailed explanation of the Yun’s bridge can be read here.

A closer look at the Atmel-powered Arduino Yún

The Arduino Yún – designed in collaboration with Dog Hunter – is based on Atmel’s ATMega32u4 microcontroller (MCU) and also features the Atheros AR9331, an SoC running Linino, a customized version of OpenWRT.

The new Atmel-powered board will be available on September 10, so today we’ll be taking a closer look at the Yún’s hardware. As previously discussed on Bits & Pieces, the Yún is somewhat unique in the Arduino lineup, as it boasts a lightweight Linux distribution to complement the traditional microcontroller (MCU) interface.

The Yún also features WiFi and Ethernet connections, enabling the board to communicate with networks out of the box. In addition, the Yún’s Linux and Arduino processors link through the Bridge library, allowing Arduino sketches to send commands to the command line interface of Linux.

“The Arduino Yún has the same footprint as an Arduino Uno but combines an ATmega32U4 microcontroller (the same as the Leonardo) and a Linux system based on the Atheros AR9331 chipset,” Arduino’s Federico Vanzati explained. “Additionally, there are built-in Ethernet and WiFi capabilities. The combination of the classic Arduino programming experience and advanced internet capabilities afforded by a Linux system make the Yún a powerful tool for communicating with the internet of things (IoT).”

According to Vanzati, the Yún’s layout keeps the I/O pins the same as the Leonardo and is therefore compatible with the most shields designed for Arduino.

“With the Yún’s auto-discovery system, your computer can recognize boards connected to the same network. This enables you to upload sketches wirelessly to the Yún,” he continued. “You can still upload sketches to the Yún through the micro-USB connector just as you would with the Leonardo.”

On the connectivity side, the Yún is equipped with two separate network interfaces, a 10/100 Mbit/s Fast Ethernet port and a IEEE 802.11 b/g/n standard compliant 2.4GHz WiFi interface, supporting WEP, WPA and WPA2 encryption. As expected, the WiFi interface can also operate as an access point (AP). In AP mode any WiFi enabled device can connect directly to the network created on the Yún. While a Yún in this mode can’t connect to the internet, it could act as a hub for a group of WiFi enabled sensors.

As Vanzati notes, interfacing Arduino with web services has historically been rather challenging due to memory restrictions.

“[However], the Yun’s Linux environment simplifies the means to access internet services by using many of the same tools you would use on your computer,” he said. “You can run several applications as complex as you need, without stressing the ATmega microcontroller.”

To help engineers and Makers develop applications that can connect to popular web services, Arduini has partnered with Temboo, a service that simplifies accessing hundreds of the web’s most popular APIs. In fact, a Temboo library is packaged with the Yún, making it easy to connect to a large variety of online tools.

Facilitating a seamless connection between the two processors is achieved via the Yún’s Bridge library, which connects the hardware serial port of the AR9331 to Serial1 on the 32U4 (digital pins 0 & 1).

“The serial port of the AR9331 exposes the Linux console (aka, the command line interface, or CLI) for communication with the 32U4,” Vanzati confirmed. “The console is a means for the Linux kernel and other processes to output messages to the user and receive input from the user. File and system management tools are installed by default. It’s also possible to install and run your own applications using Bridge.”

Of course, the ATmega32U4 can also be programmed from the AR9331 by uploading a sketch through the Yún’s WiFi interface. When connected to the same WiFi network as your computer, the board will appear under the “Port” menu of the Arduino IDE. The sketch will be transferred to the AR9331 and the Linux distribution will program the ATmega32U4 through the SPI bus, emulating an AVR ISP programmer.

Last, but certainly not least, the Yún can be powered through the micro-USB connector, the Vin pin, or the optional Power Over Ethernet (POE) module. When powering the board though the Vin pin, users must supply a regulated 5VDC, as there is no on-board regulator for higher voltages.

Additional information about the Atmel-powered Arduino Yún can be found on the board’s official page here.