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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.
of the Uno board has a resistor pulling the 8U2 HWB line to ground, making it easier to put into DFU mode.
of the board has the following new features:
"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.
|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|
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:
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.
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.
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.
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.
Showing reviews 1-10 of 14 | Next
Posted by Robyn Duckworth on 18th Feb 2014
Love the Arduino. I use these with children along with a version of Scratch. Clear numbering, easy to connect up and looks good as well.
Posted by Dave on 25th Jan 2014
Bought this to use with a music shield and it came 2 day later in a study plastic case to protect it in the post. Great service and price!
Arduino itself looks well made and I haven't found any problems with it yet! There is loads of stuff on the web, so programming isn't too hard to learn!
Posted by Jannetta Steyn on 22nd Jan 2014
I bought the Arduino to use in conjuction with a shield that I bought from BackyardBrains.com. I'm having great fun and have used this to show students how I can drive a stepper motor with nerve signals from my hand. Check my blog to see it working: http://jannetta.com/wordpress/stepper-motors-and-nerves/
Posted by Ed Tippelt on 22nd Nov 2013
Very pleased with the items I purchased and the speed of delivery. Also impressed with the range of components available.
Posted by David James on 1st Nov 2013
Although I have some programming experience (from 20 years ago) I had no experience of using a micro controller. But the Arduino online documentation and support community made it easy to get started. I only had to plug in power and USB and the Uno was ready to go. Before I knew it I was writing sketches and connecting up circuits on a breadboard. Great fun.
Posted by Anthony on 26th Dec 2012
What a fun self-contained product. Already made a beer fermentation controller and anti-boilover controller.
Posted by mrglennjones on 12th Dec 2012
i love this arduino, its perfect for my electronics projects! it came superbly packaged as usual and a fast delivery time. i strongly recommend ordering from proto-pic they have never let me down.
Posted by Jago Lee on 11th Oct 2012
Came well packaged and in working order!
Posted by Dave Boulton on 4th Sep 2012
Arrived the very next day and what a cracking product. I'm new to both Arduino and electronics so I'll no doubt be back for more bits and pieces (in fact, I already have been...)
Excellent service, a great range and great prices too.
Posted by John on 11th Jul 2012
I bought this and the Adafruit motor shield. Both arrived within a couple of days and have been working ever since. Great price & service.
Showing reviews 1-10 of 14 | Next