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Arduino Uno R3

The Arduino Uno R3 is a microcontroller board based on a removable, dual-inline-package (DIP) ATmega328 AVR microcontroller. It has 20 digital input/output pins (of which 6 can be used as PWM outputs and 6 can be used as analog inputs). Programs can be loaded on to it from the easy-to-use Arduino computer program. The Arduino has an extensive support community, which makes it a very easy way to get started working with embedded electronics. The R3 is the third, and latest, revision of the Arduino Uno.

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Arduino Uno R3, bottom view.

Overview

The Arduino Uno is a microcontroller board based on the ATmega328. It has 20 digital input/output pins (of which 6 can be used as PWM outputs and 6 can be used as analog inputs), a 16 MHz resonator, a USB connection, a power jack, an in-circuit system programming (ICSP) header, and a reset button. It 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.

The Uno differs from all preceding boards in that it does not use the FTDI USB-to-serial driver chip. Instead, it features the Atmega16U2 programmed as a USB-to-serial converter. This auxiliary microcontroller has its own USB bootloader, which allows advanced users to reprogram it.

The Arduino has a large support community and an extensive set of support libraries and hardware add-on “shields” (e.g. you can easily make your Arduino wireless with our Wixel shield), making it a great introductory platform for embedded electronics. Note that we also offer an Arduino starter kit and the Arduino Inventor’s Kit, both of which include an Arduino Uno along with an assortment of components (e.g. breadboard, sensors, jumper wires, and LEDs) that make it possible to create a number of fun introductory projects.

This is the 3rd revision of the Uno (R3), which has a number of changes:

The USB controller chip changed from ATmega8U2 (8K flash) to ATmega16U2 (16K flash). This does not increase the flash or RAM available to sketches.
Three new pins were added, all of which are duplicates of previous pins. The I2C pins (A4, A5) have been also been brought out on the side of the board near AREF. There is a IOREF pin next to the reset pin, which is a duplicate of the 5V pin.
The reset button is now next to the USB connector, making it more accessible when a shield is used.

More information about the Arduino Uno R3 is available on Arduino’s website.

Comparison table for the Arduino Uno, Baby Orangutan B-328, Orangutan SV-328, and Orangutan SVP-1284.

Summary

Microcontroller: ATmega328
Operating voltage: 5 V
Input voltage (recommended): 7-12 V
Digital I/O pins: 20 (of which 6 provide PWM output)
Analog input pins: 6*
DC current per I/O pin: 40 mA
DC current for 3.3V pin: 50 mA
Flash memory: 32 KB (ATmega328) of which 0.5 KB used by bootloader
SRAM: 2 KB (ATmega328)
EEPROM: 1 KB (ATmega328)
Clock speed: 16 MHz

*The Arduino Uno has 20 total available I/O lines; all of them can function as digital I/O lines, and six of them can be used as analog inputs.

Warning: We recommend not connecting the Arduino to USB while it is powered through VIN. See this forum post for more information.

Choosing the Right Controller

The table to the right compares the Arduino Uno to Orangutan robot controllers, which are based on the same AVR architecture and feature integrated motor drivers and additional hardware suitable for robotics applications. We also offer the Basic Stamp, which offers a lot of support and educational materials for beginners, and the much higher performance mbed development board, which is based on a 96 MHz 32-bit ARM Cortex M3. See their product pages for more information.