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.

Building a Yún-powered weather station

The Arduino Yún – designed in collaboration with Dog Hunter – is based on Atmel’s popular ATMega32u4 microcontroller (MCU) and also features the Atheros AR9331, an SoC running Linino, a customized version of OpenWRT. The Yún is somewhat unique in the Arduino lineup, as it boasts a lightweight Linux distribution to complement the traditional microcontroller (MCU) interface.

The Atmel-powered Yún – which hit the streets late last year – has been used in a wide variety of Maker projects that we’ve recently covered on Bits & Pieces, including an electricity monitor, mesh extender platform, Foursquare soap bubble machine, a Gmail (alert) lamp, water heater regulator and Evil Alarm System.

Today, we’re going to be taking a look at how Marc-Olivier Schwartz built a cloud-connected weather station with the Yún. Aside from the Atmel-based board, key hardware specs include:

• DHT11 (or DHT22) sensor and 4.7K resistor (for humidity)
• 
BMP085 sensor on a simple breakout board/Adafruit BMP180 sensor board (for pressure and temperature)
• Photocell with a 10K Ohm resistor (light level)
• Breadboard + assorted male-male jumper wires

On the software side, Schwartz used the Arduino IDE, Temboo, DHT library, the BMP085/BMP180 library, unified sensor library and a Google Docs account for the collected data to be analyzed and stored.

“The hardware connections for this project are actually quite simple: we have to connect the DHT11 sensor and then the part responsible for the light level measurement with the photocell. First, connect the Arduino Yun +5V pin to the red rail on the breadboard and the ground pin to the blue rail,” Schwartz explained in a detailed Adafruit tutorial.

“Then, connect pin number 1 of the DHT11 sensor to the red rail on the breadboard and pin number 4 the blue rail. Also connect pin number 2 to pin number 8 of the Arduino Yún. To finish up with the DHT11 sensor, connect the 4.7k Ohm between pin number 1 and 2 of the sensor.”

Next up is the photocell.

“First place the cell in series with the 10k Ohm resistor on the breadboard. Then, connect the other end of the photocell to the red rail on the breadboard and the other end of the resistor to the ground. Finally, connect the common pin to the Arduino Yún’s analog pin A0,” Schwartz continued.

“For the BMP085 or BMP180 sensor, connect the VIN pin to the +5V, GND to Ground, SCL to Arduino Yún pin number 3 and SDA pin to Arduino Yún pin number 2.”

According to Schwartz, multiple Yún boards can be used in various parts of a single residence.

“You can also customize the email alert part: you can build more complex alerts based on the measured data, or set the project to email you the sensor data at a regular time interval,” he added.

Interested in learning more? You can check out Schwartz’s full Adafruit tutorial here.

Playing RFID Pic-Tap-Toe

The Boston firm of Allen & Gerritsen recently acquired the Philadelphia-based Nieman, expanding the total number of company staff to a formidable 200. As Erik Oster of AgencySpy notes, it was obviously going to be quite a challenge for the two corporations to get to know each other.

Ultimately, the folks at Allen & Gerritsen decided on a rather unconventional approach, choosing to eschew the traditional email and profile picture exchange. Instead, they kicked off a friendly cross-office game of Tic-Tac-Toe. However, rather than using simple Xs and Os, Allen & Gerritsen created a platform based on 9 radio frequency identification (RFID) readers, a Wi-Fi enabled (Atmel-powered) Arduino Yún (ATmega32u4) and Instagram to put a new spin on the traditional game.

So, how is the game of Pic-Tap-Toe played?

Each office takes turns by placing a game piece on sections of a custom game board consisting of RFID readers and an Arduino. Instead of Xs and Os, Instagram photostreams appear on one of the 9 corresponding screens in each office. Screens are updated in real-time in both locations – acting as a social digital connection point for all employees.

Interested in learning more about Pic-Tap-Toe? You can check out the game’s official page here.

Arduino’s Yún (ATmega32u4) controls this SmartBoiler

The Arduino Yún – designed in collaboration with Dog Hunter – is based on Atmel’s popular ATMega32u4 microcontroller (MCU) and also features the Atheros AR9331, an SoC running Linino, a customized version of OpenWRT. The Yún is somewhat unique in the Arduino lineup, as it boasts a lightweight Linux distribution to complement the traditional microcontroller (MCU) interface.

Although the Atmel-powered Yún hit the streets just a few short months ago, the board has already been used in a wide variety of Maker projects that we’ve recently covered on Bits & Pieces, including an electricity monitor, mesh extender platform, Foursquare soap bubble machine and the Gmail (alert) lamp. And today we’ll be taking a closer look at how George Koulouris used the Atmel-powered Yún to regulate his water heater.

“I have two small problems in my house. An ever-increasing electricity consumption bill and a girlfriend [who] likes to take hot baths at unpredictable times during the day,” Koulouris wrote in a recent blog post re-published on the official Arduino site. “Until recently, we left our water heater switched on, 24/7. But then we took a look at our electricity counter readings. Needless to say, we switched it off immediately! An old water heater can indeed make the electricity counter wheel spin fast, very fast.”

As such, says Koulouris, he started switching it on and off whenever the two needed to take a bath. However, the duo weren’t always at home and the water took almost an hour to heat. Enter the SmartBoiler, a device housed in a small box and placed on top of the main electricity board.

“A mechanical arm extends out of the box. Its bottom end is clipped to the heater’s switch whereas its top end is attached to a motor in the SmartBoiler,” Koulouris explained. “The box contains a motor and an Arduino Yún. The latter checks, at regular time intervals, a .txt file on a web-server to see whether me (or my girlfriend!) have turned on the heater. If yes, it launches the motor and the switch is turned on.”

Although Koulouris originally created the SmartBoiler to regulate his water heater, he does note that the project can be used as a basis to control any mechanical switch.

“Simply dimension the box correctly and you can control everything via the Internet. Your lights, your main electricity switch… The possibilities are limitless!”

Interested in learning more? You can download the laser cutter files here, the code on Github and the dimensions of the mechanical parts on Thingiverse, while the user interface (UI) can be viewed here.

Building a localization beacon with Arduino

A team participating in a recent hackathon hosted by Hub Singapore managed to develop an Arduino-powered indoor localization platform in just 24 (CodeXtreme) hours.

Ted, who submitted the project to the official Arduino blog, explained that the Batman-inspired platform converts existing speakers located inside shopping malls into an indoor localization beacon.

“This allows malls to track the location density without adding extensive infrastructure since it uses embedded inaudible sound signatures in music that shops play in the malls,” Ted wrote in an email sent to Arduino. “In short, instead of tracking Joker, we use Arduino (with WiFI Shield & MP3 Shield) and Android Uno (Atmel ATmega328) to track people (customer) inside a mall.”

Ted’s team is now working on fine-tuning the code with the recently launched Atmel-powered (ATmega32u4) Arduino Yún. As previously discussed on Bits & Pieces, the Yún – designed in collaboration with Dog Hunter – is based on Atmel’s popular ATMega32u4 microcontroller (MCU) and also features the Atheros AR9331, an SoC running Linino, a customized version of OpenWRT. The Yún is somewhat unique in the Arduino lineup, as it boasts a lightweight Linux distribution to complement the traditional microcontroller (MCU) interface.

Arduino Yún powers this Foursquare soap bubble machine

Earlier this month, Bits & Pieces took a closer look at Stefano Guglielmetti’s Yún-powered Gmail (alert) lamp that is programmed to ping him in real-time about incoming emails labelled “important.”

And today we’re going to get up close and personal with a Foursquare soap bubble machine built around the versatile Atmel-based Yún.

“When you check in to our balcony with foursquare, a soap bubble machine starts filling the air with bursting bubbles. The first prototype uses Arduino connected to an XBee Wifly to control the soap bubble machine and a Rat Pack server that handles the Foursquare API,” Sven Kräuter explained in a guest post published on the official Arduino blog.

“Quite complex and actually and as you might have guessed the Yún helped reducing both the software and the hardware complexity drastically. Adding it to the project made it possible to cut off a lot of fat. Actually it now only consists of the Yun connected to the soap bubble machine.”

According to Kräuter, what’s true for the hardware is also true for the software.

“Reduced complexity is achieved by processing the response of the Foursquare API on Linino as opposed to letting the Ruby server take care of it,” he continued.

“And although there’s much debate when it comes to JSON processing with regular expressions in general, I just used grep and a matching regexp to extract the information from Foursquare’s JSON response. The parts marked green are the only ones necessary after adding the Yun to the setup.”

Kräuter also noted that he sees the Yún as a major milestone in making the rapidly evolving Internet of Things (IoT) available to a broader audience.

“The Yún will empower fellow makers and tinkerers, [allowing them] to spend less time debugging and more time inventing,” he added.

As previously discussed on Bits & Pieces, 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. The Yún is somewhat unique in the Arduino lineup, as it boasts a lightweight Linux distribution to complement the traditional microcontroller (MCU) interface.

Arduino’s Yún powers this Gmail (alert) lamp

The Atmel-powered Arduino Yún may have only begun shipping this week, but eager Makers like Stefano Guglielmetti have already begun using the board in various DIY projects. Specifically, Guglielmetti built a Gmail (alert) lamp programmed to ping him in real-time about incoming emails labelled “important.”

“I need to be alerted in real time when I receive some important emails. Not all the emails –  we provide customer care for many clients, with different SLAs, and I need to be alerted only for the most important ones,” Guglielmetti wrote in an official Arduino blog post. “Moreover, sometimes I look forward to receiving a [specific] email, [so] I need something flexible, eye catching, that doesn’t depend on my computer or my cellphone.”

According to Guglielmetti, the working principle behind the DIY project is really quite straightforward.

“On Gmail, I defined a new label, so I can quickly change the rules for the messages that will go under it, then I tell to Arduino Yún which label to watch for (via REST APIs… amazing) and that’s it,” he explained. “The lamp – actually only just an LED [for now] – turns on every time I get new messages under that label. It’s the bat-signal principle!”

In terms of the code, Guglielmetti says he leveraged a number of new features unique to the Yún.

“In a single day I learned how to use the Bridge library to get data from REST webservices, how to save and load data from the Linux filesystem, and how to run processes on the Linux side and get the STDOUT results,” Guglielmetti added. “Now I will build the actual lamp, improving both the hardware and software.”

Additional information about the Gmail lamp project can be found here.

As previously discussed on Bits & Pieces, 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. The Yún is somewhat unique in the Arduino lineup, as it boasts a lightweight Linux distribution to complement the traditional microcontroller (MCU) interface.

The Atmel-powered Arduino Yún can be snapped up for $69, or €52.

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.

Understanding the Arduino Yún’s Bridge

The Arduino Yún is based on Atmel’s ATMega32u4 microcontroller (MCU) and also features the Atheros AR9331, an SoC running Linino.

Earlier this week, Bits & Pieces took a closer look at the board’s hardware and today we’ll be getting up close and personal with the Arduino Yún’s Bridge, describing how it helps facilitate communication between the two processors.

According to Arduino’s Federico Vanzati, the Bridge comprises two distinct parts. The first, written in Python, runs on the GNU/Linux processor and is tasked with three primary functions: Executing programs on the GNU/Linux side, providing a shared storage space for data and receiving/relaying commands from the Internet – passing them directly to the Arduino.

Meanwhile, the other part of Bridge is the library that runs on the 32U4, allowing users to access the Linino parts of Bridge through their sketches.

“With the Bridge you can do some awesome things by communicating between the 32U4 and the AR9331 processors,” Federico explained. “Some examples could be commanding and controlling your sketch over the Internet from a remote location, accessing remote APIs to get data for your sketch to process, or executing programs or scripts too complex to write in an Arduino sketch.”

For example, says Federico, if someone at home wanted to know if their office or workspace was comfortable enough to work in, they can simply connect a LDR sensor and thermistor to the Yún on a wireless network.

“Your sketch can access the board’s shared storage to publish the readings every second to a webpage running on the AR9331. By accessing the URL http://arduino.local/data/get you can call up those readings, letting you know if it’s bright enough but not too hot to get to work on your next project. Your sketch could also store the sensor readings on a Google Drive spreadsheet or publish them on Facebook,” he added.

In addition, the Bridge eliminates the need to upload a new version of a sketch to change text on an LCD screen, as sketches can use the shared storage to read the text to display, changing it remotely from a browser using REST based calls. Meaning, if the text to be displayed is identified by the label “lcd_text,” accessing the URL http://arduino.local/data/put/lcd_text/Hello%20World will show “Hello World” on the LCD.

Interested in learning more about the Yún’s Bridge? You can check out Arduino’s official “hands-on” guide to the Bridge 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.