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Arduino Uno - R3

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  • Arduino A000066 | Arduino Uno - R3 - Image 1 | Proto-PIC.co.uk
  • Arduino A000066 | Arduino Uno - R3 - Image 2 | Proto-PIC.co.uk
£18.65 (inc VAT) £15.54 (exc VAT)
41.0 Grams

72 In Stock For Immediate Despatch Further Quantities Ordered On Demand which are usually despatched within 3-5 working days

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 Product Description


The Arduino UNO has been retired by Arduino in Europe and is now called the Genuino UNO, read the reasons why here. 

If you would like to buy the Genuino UNO you can find it here

If you are looking to get started with arduino why not try our Arduino starter kit?

Please note: This listing is for the new REV 3 UNO,

The Arduino Uno is a microcontroller board based on the ATmega328 (datasheet). It has 14 digital input/output pins (of which 6 can be used as PWM outputs), 6 analog inputs, a 16 MHz crystal oscillator, a USB connection, a power jack, an 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 (Atmega8U2 up to version R2) programmed as a USB-to-serial converter.
Revision 2 of the Uno board has a resistor pulling the 8U2 HWB line to ground, making it easier to put into DFU mode.
Revision 3 of the board has 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. In future, shields will be compatible both with the board that use the AVR, which operate with 5V and with the Arduino Due that operate with 3.3V. The second one is a not connected pin, that is reserved for future purposes.
  • Stronger RESET circuit.
  • Atmega 16U2 replace the 8U2.

"Uno" means one in Italian and is named to mark the upcoming release of Arduino 1.0. The Uno and version 1.0 will be the reference versions of Arduino, moving forward. The Uno is the latest in a series of USB Arduino boards, and the reference model for the Arduino platform; for a comparison with previous versions, see the index of Arduino boards.


Microcontroller ATmega328
Operating Voltage 5V
Input Voltage (recommended) 7-12V
Input Voltage (limits) 6-20V
Digital I/O Pins 14 (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


Schematic & Reference Design

EAGLE files: Tools > Board menu (according to the microcontroller on your board). For details, see the reference and tutorials.


The ATmega328 on the Arduino Uno comes preburned with a bootloader that allows you to upload new code to it without the use of an external hardware programmer. It communicates using the original STK500 protocol (reference, C header files).


You can also bypass the bootloader and program the microcontroller through the ICSP (In-Circuit Serial Programming) header; see these instructions for details.


The ATmega16U2 (or 8U2 in the rev1 and rev2 boards) firmware source code is available . The ATmega16U2/8U2 is loaded with a DFU bootloader, which can be activated by:

  • On Rev1 boards: connecting the solder jumper on the back of the board (near the map of Italy) and then resetting the 8U2.
  • On Rev2 or later boards: there is a resistor that pulling the 8U2/16U2 HWB line to ground, making it easier to put into DFU mode.

You can then use Atmel's FLIP software (Windows) or the DFU programmer (Mac OS X and Linux) to load a new firmware. Or you can use the ISP header with an external programmer (overwriting the DFU bootloader). See this user-contributed tutorial for more information.


Automatic (Software) Reset

Rather than requiring a physical press of the reset button before an upload, the Arduino Uno is designed in a way that allows it to be reset by software running on a connected computer. One of the hardware flow control lines (DTR) of the ATmega8U2/16U2 is connected to the reset line of the ATmega328 via a 100 nanofarad capacitor. When this line is asserted (taken low), the reset line drops long enough to reset the chip. The Arduino software uses this capability to allow you to upload code by simply pressing the upload button in the Arduino environment. This means that the bootloader can have a shorter timeout, as the lowering of DTR can be well-coordinated with the start of the upload.


This setup has other implications. When the Uno is connected to either a computer running Mac OS X or Linux, it resets each time a connection is made to it from software (via USB). For the following half-second or so, the bootloader is running on the Uno. While it is programmed to ignore malformed data (i.e. anything besides an upload of new code), it will intercept the first few bytes of data sent to the board after a connection is opened. If a sketch running on the board receives one-time configuration or other data when it first starts, make sure that the software with which it communicates waits a second after opening the connection and before sending this data.


The Uno contains a trace that can be cut to disable the auto-reset. The pads on either side of the trace can be soldered together to re-enable it. It's labeled "RESET-EN". You may also be able to disable the auto-reset by connecting a 110 ohm resistor from 5V to the reset line; see this forum thread for details.


USB Overcurrent Protection

The Arduino Uno has a resettable polyfuse that protects your computer's USB ports from shorts and overcurrent. Although most computers provide their own internal protection, the fuse provides an extra layer of protection. If more than 500 mA is applied to the USB port, the fuse will automatically break the connection until the short or overload is removed.


Physical Characteristics

The maximum length and width of the Uno PCB are 2.7 and 2.1 inches respectively, with the USB connector and power jack extending beyond the former dimension. Four screw holes allow the board to be attached to a surface or case. Note that the distance between digital pins 7 and 8 is 160 mil (0.16"), not an even multiple of the 100 mil spacing of the other pins.

 Other Details

Brand and Part Number:
Arduino A000066 Arduino Uno - R3

 Product Reviews

Showing reviews 1-10 of 25 | Next

  1. Does what it says on the website/forum/hackspace and everywhere else!

    Posted by on

    If you've already used an arduino you won't need to read a review, if you haven't then buy one from proto-pic (great price and swift delivery) and get started.
    Simple to learn, extremely versatile and well supported on and offline.
    I've used them for interactive and tactile artworks, temporary installations, hardware hacking and general messing about. They're fun to use but can be a double edged sword of being dragged into playing with the possibilities rather than just making what you should be making!

  2. Great value controller

    Posted by on

    Arduinos are always smaller than I think they are and are great value, especially when you conside the large amount of documentation and help around the web.

  3. Amazing piece of kit!

    Posted by on

    Order ID #66634

    I am a beginner with AVRs however I found this one very easy to use. It has really enhanced my project i am working on.

    Also it was delivered very quickly and satisfactorily.

    Very pleased all round.

  4. Great general purpose controller

    Posted by on

    I bought this to connect to the WiFly shield in order that I might control the movement of my telescope wirelessly. The Arduino is cheap, easy to programme and connects to dozens of useful interfaces (shields) enabling the control or monitoring of almost anything you could think of. The programming environment, which uses a language like C, is easy to work with. Many shields including the WiFly come with a library of useful routines to allow the beginner to achieve some advanced results quite quickly. Two reservations here. Firstly the library documentation could be much more detailed. Secondly, although one can achieve advanced results quickly when given all these complex aids, it requires time to really understand what is going on. Thus if something suddenly doesn't work it might take a long time to locate the problem. Often this can happen only when the user's understanding catches up with the sophistication of the product.
    For any Arduino product there is always some good step-by-step instructions to get you started.
    Overall an excellent product.

  5. Good product

    Posted by on

    I bought this for my husband as part of his Christmas. I can't say that I know what it's for, but he's happy, so that's what matters!
    I do know that he is currently on a mission to do all sorts of electronic wizardry, and has been busy with something in the kitchen :) Maybe it's a robot to replace me.

  6. Great product for a low price

    Posted by on

    Arduino Uno is a useful board at a great price, product build is excellent and easy to get operational, just add power supply and USB cable to start working with the Arduino IDE.

    Delivery and communications from Proto-Pic were excellent.

  7. A new version, same great product.

    Posted by on

    It's been said below but the addition of the printed pin headers is really great and saves you fiddling with the torch in tighter spaces.

    I've been using these for a while and the UNO is a great product, it looks professional, and works like it too.

  8. Better than ever

    Posted by on

    I've been using Arduino's for years, and the latest addition of the markings on the pin-headers themselves is just an extra bonus. The Uno has always been a flexible and reliable piece of kit for me and has been part of many of my projects.
    The only downside is the slightly low-featured Arduino IDE.

  9. Arduino for Beginners

    Posted by on

    I am a programmer but have no Arduino or electronics experience. I can however follow a wire diagram. i was persuaded by a friend to buy an Arduino to help him code for a project.

    The service by proto-pic was exceptional. The order arrived a few days before i excpected.

    The Arduino is a brilliant piece of kit. Sadly i did something to screw the bootloader, this is apparently easy to fix according to my Arduino friend.

  10. Great Product, Great Service

    Posted by on

    Packaging superb, service superb.

Showing reviews 1-10 of 25 | Next

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