Arduino UNO R3

Weight: Help
38 g

Arduino reference version - will serve you for a long time!

Product is retired

Replaced by: Arduino UNO R3 Clone ATMega328P + Mega16U2

Tags: arduino, uno, R3, BJ2155

Arduino UNO is a new model of Arduino. It's compatible with the previous one, but contains a few improvements in comparision to Duemilanove.

  • New USB chip simplifying the installation in Windows (look here)
  • The USB chip can be reprogrammed, creating new possibilities of utilizing Arduino. For example, the board can appear as keyboard when connected to PC
  • Bootloader is smaller, so you have additional 1.5 kB of Flash memory for your sketches
  • An additional 3.3V voltage regulator with output maximum current of 150 mA will enhance the performance of devices powered from it (Duemilanove provides only 50 mA and approaching this limit may cause instability of USB connecion)
  • Arduino Uno is packed in a box, where you will find also some stickers - with Arduino logo, DIY etc.

UNO R3 - reference version

Arduino Team announced that Arduino UNO R3 (R3 stands for Revision 3) is reference model.
What it means?
Arduino is a live project, constantly evolving. Both the hardware and the software (the IDE itself as well as Arduino library) was changing in the past time. When R3 and IDE v. 1.0 were released, the Arduino team announced that since then Arduino and the IDE will be further developed, but the UNO R3 and IDE version 1.0 will be reference for future releases.

For an ordinary user, it doesn't matter much, but in case you want to, for example, conduct a workshop which will be periodically repeated, or you to use Arduino in your school, then basing on R3 and version 1.0 should keep everything up-to-date for a long time.

Changes in R3

The differences between Arduino UNO R3 and UNO R2 are:

  • In each row of pins there is two more now. In "digital section" there are two pin header sockets: 10 and 8 pins, instead of 2 x 8. In "analog section" there are now 8 and 6 pins instead of 2 x 6.
  • ATmega8U chip responsible for USB communication were replaced by ATmega16U (16 kB of flash memory instead of 8) - this involves only advanced users, who want to change the type of hardware, as which Arduino appears, when connected to PC (e.g. keyboard instead of serial port)

Adding new pins causes some confusion. In digital pins row there are now two separate I2C (or TWI, according to Atmel's documentation) bus signals - SDA and SCL. These aren't additional signals - in Arduino UNO R2 SDA and SCL are available at A5 and A4. In R3 they are also there, so the new pins are merged with old ones.

In analog section among new pins there is IOREF signal informing, at which voltage levels the board works. This allows shields to adapt to Arduino's voltage level. The second pin is not yet connected. It's reserved for future use.

What is this for?

SDA and SCL are available at the same pins in Arduino UNO and Mega, IOREF is 5V in every case, so what are the new pins for? Things may change when new Arduino models, Due and Leonardo, will be introduced. These models may not have SDA and SCL at A4 and A5 and operate at supply voltage 3.3V.

Thanks to the new pins, shields using I2C and designed to use SDA and SCL at the new pins will also work with UNO R3 as well as future Arduino versions. IOREF in turn will allow a single shield to work with both UNO R3 and future versions employing 3.3V logic.

Simply speaking - UNO R3 ensures you will be able to use new shields for a long time.

New pins in UNO R3

What is Arduino?

Arduino is a developer board based on ATmega328 microcontroller. It has 32 kB of Flash memory (0.5 kB occupied by the bootloader), 2 kB of RAM and 1 kB of EEPROM.

The power of Arduino is plenty of inputs and outputs. You get:

  • 14 pins serving either as inputs or outputs. 6 among them can work in PWM mode, which means you are able to vary output power (works perfectly as LED diode brightness regulator)
  • 6 analog inputs (for measuring voltage values) working with voltages up to 5V (this can be changed by applying other voltage at AREF pin). Measuring resolution - 1024.

Some of them can also perform other tasks allowed by Arduino software:

  • serial communication (RS)
  • I2C protocol
  • external interrupts

Electronic circuits for beginners

If you want to learn how to build electronic circuits, Arduino is great as the initial choice. Jeżeli chcesz się nauczyć tego jak budować układy elektroniczne, Arduino jest świetnym pierwszym wyborem. In order to simplify your first steps, we prepared Starter Kit for Arduino, an unique all in one set, containing Arduino itself and additional parts to get youu started into the world of electronics. On our Starter Kit blog there are also some example circuits with detailed step by step instructions, guiding you through the world of electronics and microcontrollers.

Physical computing

Arduino is one of devices representing a new trend called physical computing. The development of microcontrollers, and, first of all, expansion of open source software provided new tools wide range of people. By this way many projects were created, combining electronics, software and multimedia. In other words - it's new approach to possibilities given to us by digital technologies.

Drivers installation on Windows

After connecting Arduino to computer Windows will attempt to install a driver, but it won't succeed. Then you have to open Device Manager, find serial ports and for the one called 'Arduino UNO' choose driver update. Arduino IDE folder (which you have to download first) contains ArduinoUNO.inf file, defining the serial port.

Detailed instruction is on Arduino wiki.


Arduino board sold currently work seamlessly with Linux without a need to update firmware.