For other uses, see Arduino (disambiguation).

Arduino Uno SMD R3
Type Single-board microcontroller
Operating system None
CPU Atmel AVR (8-bit),
ARM Cortex-M0+ (32-bit),
ARM Cortex-M3 (32-bit),
Intel Quark (x86) (32-bit)
Memory SRAM
Storage Flash, EEPROM
Graphics None

Arduino is an open-source project that created microcontroller-based kits for building digital devices and interactive objects that can sense and control physical devices.[1]


Arduino is an open source hardware and software project first introduced in 2005 based on 8-bit Atmel AVR, aiming to provide an accessible way for novices and professionals to create devices that interact with their environment using sensors and actuators. Common examples of such devices intended for beginner hobbyists include simple robots, thermostats, and motion detectors.

The project is based on microcontroller board designs, which use inputs and outputs in the same way an ordinary computer does. Inputs capture information from the user or the environment while outputs do something with the information that has been captured. An input could be digital or analog, and could come form the environment or a user. Outputs can control and turn on and off devices such as motors or other computers. These systems provide sets of digital and analog input/output (I/O) pins that can interface to various expansion boards (termed shields) and other circuits. The boards feature serial communication interfaces, including Universal Serial Bus (USB) on some models, for loading programs from personal computers. For programming the microcontrollers, the Arduino project provides an integrated development environment (IDE) based on a programming language named Processing, which also supports the languages C and C++. The Arduino language is very similar to C, but provides several libraries for ease of use.

Arduino comes in a variety of different boards. Arduino boards are available commercially in pre-assembled form, or as do-it-yourself kits. The hardware design specifications are openly available, allowing the Arduino boards to be produced by anyone. In mid-2011, it was estimated that over 300,000 official Arduinos had been commercially produced,[2] and in 2013 that 700,000 official boards were in users' hands.[3]


An early Arduino board[4] with an RS-232 serial interface (upper left) and an Atmel ATmega8 microcontroller chip (black, lower right); the 14 digital I/O pins are at the top, the 6 analog input pins at the lower right, and the power connector at the lower left.

An Arduino board consists of an Atmel 8-, 16- or 32-bit AVR microcontroller (although since 2015 other makers' microcontrollers have been used) with complementary components that facilitate programming and incorporation into other circuits. An important aspect of the Arduino is its standard connectors, which let users connect the CPU board to a variety of interchangeable add-on modules termed shields. Some shields communicate with the Arduino board directly over various pins, but many shields are individually addressable via an I²C serial bus—so many shields can be stacked and used in parallel. Before 2015, Official Arduinos had used the Atmel megaAVR series of chips, specifically the ATmega8, ATmega168, ATmega328, ATmega1280, and ATmega2560. In 2015, units by other producers were added. A handful of other processors have also been used by Arduino compatible devices. Most boards include a 5 V linear regulator and a 16 MHz crystal oscillator (or ceramic resonator in some variants), although some designs such as the LilyPad run at 8 MHz and dispense with the onboard voltage regulator due to specific form-factor restrictions. An Arduino's microcontroller is also pre-programmed with a boot loader that simplifies uploading of programs to the on-chip flash memory, compared with other devices that typically need an external chip programmer. This makes using an Arduino more straightforward by allowing the use of an ordinary computer as the programmer. Currently, optiboot bootloader is the default bootloader installed on Arduino UNO.[5]

At a conceptual level, when using the Arduino integrated development environment, all boards are programmed over a serial connection. Its implementation varies with the hardware version. Some serial Arduino boards contain a level shifter circuit to convert between RS-232 logic levels and transistor–transistor logic (TTL) level signals. Current Arduino boards are programmed via Universal Serial Bus (USB), implemented using USB-to-serial adapter chips such as the FTDI FT232. Some boards, such as later-model Uno boards, substitute the FTDI chip with a separate AVR chip containing USB-to-serial firmware, which is reprogrammable via its own ICSP header. Other variants, such as the Arduino Mini and the unofficial Boarduino, use a detachable USB-to-serial adapter board or cable, Bluetooth or other methods, when used with traditional microcontroller tools instead of the Arduino IDE, standard AVR in-system programming (ISP) programming is used.

An official Arduino Uno R2 with descriptions of the I/O locations

The Arduino board exposes most of the microcontroller's I/O pins for use by other circuits. The Diecimila,[lower-alpha 1] Duemilanove,[lower-alpha 2] and current Uno[lower-alpha 3] provide 14 digital I/O pins, six of which can produce pulse-width modulated signals, and six analog inputs, which can also be used as six digital I/O pins. These pins are on the top of the board, via female 0.1-inch (2.54 mm) headers. Several plug-in application shields are also commercially available. The Arduino Nano, and Arduino-compatible Bare Bones Board[6] and Boarduino[7] boards may provide male header pins on the underside of the board that can plug into solderless breadboards.

Many Arduino-compatible and Arduino-derived boards exist. Some are functionally equivalent to an Arduino and can be used interchangeably. Many enhance the basic Arduino by adding output drivers, often for use in school-level education, to simplify making buggies and small robots. Others are electrically equivalent but change the form factor, sometimes retaining compatibility with shields, sometimes not. Some variants use different processors, of varying compatibility.

Official boards

The original Arduino hardware was produced by the Italian company Smart Projects.[8] Some Arduino-branded boards have been designed by the American companies SparkFun Electronics and Adafruit Industries.[9] As of 2016, there has been 17 versions of the Arduino hardware had been commercially produced.


  1. ^ Arduino RS232 official webpage;
  2. ^ Arduino Diecimila official webpage;
  3. ^ Arduino Duemilanove official webpage;
  4. ^ Arduino Uno official webpage;
  5. ^ Differences between Official Arduino Uno, R2, R3 boards; Starting Electronics.
  6. ^ Arduino Uno SMD official webpage;
  7. ^ Arduino Leonardo official webpage;
  8. ^ Arduino Pro official webpage;
  9. ^ Arduino Mega official webpage;
  10. ^ Arduino Nano official webpage;
  11. ^ Arduino LilyPad official webpage;
  12. ^ Arduino Robot official webpage;
  13. ^ Arduino Esplora official webpage;
  14. ^ Arduino Ethernet official webpage;
  15. ^ Arduino Yun official webpage;
  16. ^ Arduino Due official webpage;


Arduino and Arduino-compatible boards use printed circuit expansion boards called shields, which plug into the normally supplied Arduino pin headers. Shields can provide motor controls for 3D printing and other applications, Global Positioning System (GPS), Ethernet, liquid crystal display (LCD), or breadboarding (prototyping). Several shields can also be made do it yourself (DIY).[10][11][12]



Arduino Software IDE

Screenshot of the Arduino IDE showing the Blink simple beginner program
Developer(s) Arduino Software
Stable release
1.6.13 / 22 November 2016 (2016-11-22)[13]
Written in Java, C and C++
Operating system Microsoft Windows, OS X, Linux
Platform IA-32, x86-64, ARM
Type Integrated development environment
License LGPL or GPL license

Arduino IDE

The Arduino project provides the Arduino integrated development environment (IDE), which is a cross-platform application written in the programming language Java. It originated from the IDE for the languages Processing and Wiring. It was created for people with no profound knowledge of electronics. It includes a code editor with features such as syntax highlighting, brace matching, cutting/pasting text, searching/replacing text and automatic indentation, and provides simple one-click mechanism to compile and upload programs to an Arduino board. It also contains a message area, a text console, a toolbar with buttons for common functions and a series of menus.

A program written with the IDE for Arduino is called a "sketch".[14] Sketches are saved on the development computer as files with the file extension .ino. Arduino Software (IDE) prior to 1.0 saved sketches with the extension .pde.

The Arduino IDE supports the languages C and C++ using special rules to organize code. The Arduino IDE supplies a software library called Wiring from the Wiring project, which provides many common input and output procedures. A typical Arduino C/C++ sketch consist of two functions that are compiled and linked with a program stub main() into an executable cyclic executive program:

After compiling and linking with the GNU toolchain, also included with the IDE distribution, the Arduino IDE employs the program avrdude to convert the executable code into a text file in hexadecimal coding that is loaded into the Arduino board by a loader program in the board's firmware.

Other IDE

Arduino programs may be written in any programming language with a compiler that produces binary machine code. Atmel provides a development environment for their microcontrollers, AVR Studio and the newer Atmel Studio, which can be used for programming Arduino.[15][16]

Arduino can be controlled using C/C++ interpreter Ch without the binary code. [17]

Sample programs

The bare minimum code[18] to start a sketch program consists of two functions setup()[19] and loop().[20]

void setup() {
  // Put your setup code here, to run once at startup (power-up or reset). 
  // This executes before loop().

void loop() {
  // Put your main code here, to run repeatedly.

Most Arduino boards contain an LED and a load resistor connected between pin 13 and ground which is a convenient feature for many tests.[21]

A typical program for a beginning Arduino programmer blinks a light-emitting diode (LED) on and off. This program is usually loaded in the Arduino board by the manufacturer. In the Arduino environment, a user might write such a program as shown:[21]

Power LED and Integrated LED on Arduino Compatible Board
Power LED (red) and integrated LED on Line 13 (green) on Arduino compatible board, made in China
#define LED_PIN 13                  // Pin number attached to LED.

void setup() {
    pinMode(LED_PIN, OUTPUT);       // Configure pin 13 to be a digital output.

void loop() {
    digitalWrite(LED_PIN, HIGH);    // Turn on the LED.
    delay(1000);                    // Wait 1 second (1000 milliseconds).
    digitalWrite(LED_PIN, LOW);     // Turn off the LED.
    delay(1000);                    // Wait 1 second.


Arduino-compatible R3 UNO board made in China with no Arduino logo, but with identical markings, including "Made in Italy" text

Arduino is open-source hardware. The hardware reference designs are distributed under a Creative Commons Attribution Share-Alike 2.5 license and are available on the Arduino website. Layout and production files for some versions of the hardware are also available. The source code for the IDE is released under the GNU General Public License, version 2.[22] Nevertheless an official Bill of Materials of Arduino boards has never been released by the staff of Arduino.

Although the hardware and software designs are freely available under copyleft licenses, the developers have requested that the name "Arduino" be exclusive to the official product and not be used for derived works without permission. The official policy document on use of the Arduino name emphasizes that the project is open to incorporating work by others into the official product.[23] Several Arduino-compatible products commercially released have avoided the Arduino name by using -duino name variants.[24]



Colombian student Hernando Barragán created the development platform Wiring as his Master's thesis project in 2004 at the Interaction Design Institute Ivrea (IDII) in Ivrea, Italy. Massimo Banzi and Casey Reas (known for his work on Processing) were supervisors for his thesis. The goal was to create low cost, simple tools for non-engineers to create digital projects. The Wiring platform consisted of a hardware PCB with an ATmega168 microcontroller, an IDE based on Processing and library functions to easily program the microcontroller.[34]

In 2005, Massimo Banzi, with David Mellis (then an IDII student) and David Cuartielles, added support for the cheaper ATmega8 microcontroller to Wiring. But instead of continuing the work on Wiring, they forked (or copied) the Wiring source code and started running it as a separate project, called Arduino.[34]

The Arduino's initial core team consisted of Massimo Banzi, David Cuartielles, Tom Igoe, Gianluca Martino, and David Mellis.[35]

The name Arduino comes from a bar in Ivrea, where some of the founders of the project used to meet. The bar was named after Arduin of Ivrea, who was the margrave of the March of Ivrea and King of Italy from 1002 to 1014.[36]

Following the completion of the Wiring platform, its lighter, lower cost versions[37] were created and made available to the open-source community. Associated researchers, including David Cuartielles, promoted the idea.[35]


The Arduino project received an honorary mention in the Digital Communities category at the 2006 Prix Ars Electronica.[38]

Trademark dispute

In early 2008, the five cofounders of the Arduino project created a company, Arduino LLC,[39] to hold the trademarks associated with Arduino. The manufacture and sale of the boards was to be done by external companies, and Arduino LLC would get a royalty from them. The founding bylaws of Arduino LLC specified that each of the five founders transfer ownership of the Arduino brand to the newly formed company.

At the end of 2008, Gianluca Martino's company, Smart Projects, along with Microsoft, registered the Arduino trademark in Italy and kept this a secret from the other cofounders for about two years. This was revealed when the Arduino company tried to register the trademark in other areas of the world (they originally registered only in the US), and discovered that it was already registered in Italy. Negotiations with Gianluca and his firm to bring the trademark under control of the original Arduino company failed. In 2014, Smart Projects began refusing to pay royalties. They then appointed a new CEO, Mr. Musto, who renamed the company to Arduino SRL and created a website named, copying the graphics and layout of the original This resulted in a rift in the Arduino development team. All Arduino boards are still available to consumers so the implications of this are uncertain.[40][41][42]

In May 2015, "Genuino" was created around the world as another trademark, held by Arduino LLC, and is currently being used as Arduino LLC's brand name outside of the US.[43]

Joining of the two Arduinos

At the World Maker Faire in New York on October 1, 2016, Arduino LLC co-founder Massimo Banzi and Arduino SRL CEO Federico Musto announced that the 2 Arduino companies will join and become one.[44]

See also


  1. Diecimila means "ten thousands" in Italian
  2. Duemilanove means "two thousands nine" in Italian
  3. Uno means "one" in Italian


  1. "Arduino - Introduction".
  2. "How many Arduinos are "in the wild?" About 300,000". Adafruit Industries. May 15, 2011. Retrieved 2013-05-26.
  3. "Arduino FAQ – With David Cuartielles". Malmö University. April 5, 2013. Retrieved 2014-03-24.
  4. "Hardware Index". Arduino Project. Retrieved 2013-12-10.
  5. "Optiboot Bootloader for Arduino and Atmel AVR". Retrieved 2015-10-01.
  6. "Bare Bones Board".
  7. "Boarduino".
  8. "Redirect...".
  9. Schmidt, M. ["Arduino: A Quick Start Guide"], Pragmatic Bookshelf, January 22, 2011, Pg. 201
  10. "Arduino breadboard shield: $10 & 10 mins". todbot blog.
  11. "Arduino Shields for Prototyping".
  12. Jonathan Oxer. "Arduino Shield list". Retrieved 5 Nov 2013.
  13. "Arduino Software Release Notes". Arduino Project. Retrieved September 22, 2016.
  14. "Programming Arduino Getting Started with Sketches". McGraw-Hill. Nov 8, 2011. Retrieved 2013-03-28.
  15. "Using Atmel Studio for Arduino development". Retrieved 2013-01-18.
  16. "Using AVR Studio for Arduino development". Retrieved 2013-01-18.
  17. "Ch Arduino". Retrieved 2016-10-07.
  18. Tutorial: Bare Minimum code needed;
  19. Documenation for setup() function;
  20. Documenation for loop() function;
  21. "The arduino source code". The arduino source code.
  22. "Policy". Retrieved 2013-01-18.
  23. "Freeduino Open Designs". Retrieved 2008-03-03.
  24. "xoscillo – A software oscilloscope that acquires data using an arduino or a parallax (more platforms to come). – Google Project Hosting". Retrieved 2013-01-18.
  25. Pearce, Joshua M. 2012. "Building Research Equipment with Free, Open-Source Hardware". Science 337 (6100): 1303–1304. (open access)
  26. Kubínová, S. and Šlégr, J., 2015. ChemDuino: Adapting Arduino for Low-Cost Chemical Measurements in Lecture and Laboratory. Journal of Chemical Education, 92(10), pp.1751-1753.
  27. ArduinoPhone. (2013-07-17). Retrieved on 2013-08-04.
  28. DIY Cellphone, MIT
  29. Raspberry Pi Spy. Introducing the GertDuino Add-on Board for Raspberry Pi. Retrieved on 2014-11-09.
  30. Bas Wijnen, G. C. Anzalone and Joshua M. Pearce, Open-source mobile water quality testing platform. Journal of Water, Sanitation and Hygiene for Development, 4(3) pp. 532–537 (2014). doi:10.2166/washdev.2014.137 open access
  31. CNC V2.0. . Retrieved on 2016-02-24
  32. Arduino Robot – Motor Control. Retrieved on 2016-04-16
  33. 1 2 "Home". 2016-01-01. Retrieved 2016-03-06.
  34. 1 2 David Kushner (26 Oct 2011). "The Making of Arduino". IEEE Spectrum.
  35. Justin Lahart (27 November 2009). "Taking an Open-Source Approach to Hardware". The Wall Street Journal. Retrieved 7 September 2014.
  36. "Rhizome - Interview with Casey Reas and Ben Fry". 2009-09-23. Retrieved 2014-08-23.
  37. "Ars Electronica Archiv". Retrieved 2015-03-27.
  38. "Business Entity Summary for Arduino LLC". State of Massachusetts.
  39. Allan, Alasdair (6 March 2015). "Arduino Wars: Group Splits, Competing Products Revealed?". Maker Media, Inc. Retrieved 21 April 2015.
  40. Banzi, Massimo (19 March 2015). "Massimo Banzi: Fighting for Arduino". Maker Media, Inc. Retrieved 21 April 2015.
  41. Williams, Elliot (28 March 2015). "Arduino SRL to Distributors: "We're the Real Arduino"". Retrieved 21 April 2015.
  42. "Arduino Announces New Brand, Genuino, Manufacturing Partnership with Adafruit". Make:. 16 May 2015. Retrieved 17 May 2015.
  43. "Arduino Blog – Two Arduinos become one". Arduino Blog. Retrieved 2016-10-02.

Further reading

External links

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