Choosing an Arduino to buy can be confusing, especially if you are considering buying an Uno. Online sellers can omit important information, sell outdated or inappropriately priced boards, and some can be downright deceptive. I hope to give information in this article about navigating the process of choosing where to buy your board.

Step 1: Genuine Arduino, Clone, or Derivative

There are several categories of Arduino boards you can buy:

Genuine Arduino brand boards
Counterfeit boards
Clone boards
Derivative boards

Genuine and counterfeit boards

Genuine Arduino brand boards are made by a company in partnership with the owner of the Arduino trademark in a particular country.

For USA buyers, the most common sellers of Arduino may be adafruit.com or sparkfun.com. Boards are also available through brick-and-mortar stores such as Micro Center.

Genuine Arduino boards are the standard by which clone or derivative boards are based, and are the boards for which the standard IDE software is designed to work with out-of-the-box.

Genuine Arduino boards look exactly as shown on the Arduino website, include board color, logo quality and shape, component placement, and component colors, in particular the color of the polyfuse.

Here is an article on the arduino.cc website giving information about counterfeit boards:

http://blog.arduino.cc/2013/07/10/send-in-the-clones/

A counterfeit board violates copyrights and trademarks and is made by a producer who wishes to be deceptive. There is little reason for a manufacturer to make a counterfeit of an open source hardware design, because makers are permitted to make exact copies as long as they don't violate trademarks, but for some reason it is common. I recommend taking a little extra time in your buying process to make sure you are not buying a counterfeit. If the reason you are attracted to a web site that offers counterfeits is the price, or if you are looking at what appears to be a genuine Arduino board but it has a reduced price compared to Adafruit, SparkFun, or the other official sellers, you can save yourself some money and simply buy a clone or derivative instead, and those are acceptable to the Arduino trademark owners.

If you are buying a genuine Arduino board you will be spending $20 to $35 USD on it, or you'll be buying a counterfeit and not realize it. So, you should just buy genuine from a reputable vendor and not try to buy genuine from a discounter.

Clone and derivative boards

A clone is a board that uses the same layout and components a genuine board is made from. It is an exact copy. Since the design, bootloader or firmware, and associated software such as the IDE are all open source, there is nothing wrong with making a clone, and buying them is not detrimental to the Arduino project. The silk screen of the printed circuit board will not have the Arduino markings such as logo and the Arduino name, and they normally cost less. As long as they don't violate trademarks, they are okay.

A derivative board is one that may have a similar layout and components, and that may be compatible with the Arduino IDE, but there are differences in the design that make the board cost less to manufacture, or that offer additional or fewer features compared to the genuine Arduino boards. Derivative boards often cost less, unless the board has additional features not offered in a genuine Arduino board.

Examples of additional features are additional power supply or power regulation, reverse polarity protection, switchable logic level, logic level tolerance, conversion, or protection, custom form factors, additional or reduced circuitry. Derivatives are beneficial to the founding project, because new features sometimes make their way into next generations of genuine Arduinos. And derivative makers and supporters contribute to code and documentation. Just as with clones, if a derivative doesn't violate trademarks, they are okay.

What is genuine?

The below text about the Arduino companies splitting up is now old news, because the companies have reunited. There is now one Arduino company. The remaining text in this "step" is retained for historical purposes.

Old news:

One of the 5 founders of Arduino, Gianluca Martino, has severed his relationship from the others. There is a rift in the founding team, ongoing legal disputes, and now there are two separate companies using the Arduino name. Both the original arduino.cc and the newer arduino.org websites have some of the same distributors listed.

Massimo Banzi said in a blog on arduino.cc they have stopped receiving royalties for the Italian-made Arduinos, and those are the Arduinos made by Gianluca Martino's company that operates arduino.org.

http://makezine.com/2015/03/19/massimo-banzi-fighting-for-arduino/

http://blog.arduino.cc/2015/03/20/dear-arduino-community/

http://www.arduino.org/blog/1-the-new-blog/first-round-won

These problems are being resolved for arduino.cc via new manufacturing partnerships. The Genuino brand was created by arduino.cc because of this rift in the Arduino team. Unos are made under the Genuino brand for China and other Asian markets via a partnership with SeeedStudio. Arduino Uno is now made in the USA as of July 2015 via a partnership with Adafruit.

http://makezine.com/2015/06/20/ardunio-announces-manufacturing-partnership-seeedstudio/

http://makezine.com/2015/05/26/first-arduino-made-american-soil/

The dispute and split of the companies is unfortunate. Some people are choosing sides, and are strong supporters of one company or the other. Some people are supporting both companies, or are simply choosing boards and associated software based on suitability to the project they are building. Some are choosing boards from the company with strongest online support, or most helpful forum community.

Step 2: Deception or Differences in Uno

So, this all comes down to what is your definition of Uno, and what is important to you.

ATmega328P with any serial adapter

If you consider an Uno to be an ATmega328P-based board with any built-in USB to serial adapter and a 115200 baud serial bootloader, that would include the many Unos offered on eBay that have CH340G USB chips instead of the ATmega16U2. Many of these boards are offered and are sold as and screen printed as Uno R3 or Rev 3, which is inaccurate, since the Rev 3 was essentially an upgrade from ATmega8U2 to ATmega16U2. There is little reason to call an Uno board a "Rev 3" or "R3" unless it has an ATmega16U2. Boards without the ATmega16U2 are an Arduino Duemilanove derivative burned with an Optiboot bootloader.

In my opinion, if you are interested in one of these boards, you should just buy a CH340G or FTDI Nano 3.0, which is essentially the same thing in a smaller package. It is less expensive, and can be put directly on a breadboard or embedded in a project. You can burn the Optiboot bootloader on it yourself and call it an Uno.

If you are shopping for an Uno with an ATmega328P and any serial adapter, you should be happy if somebody burns an Optiboot bootloader on a Duemilanove or derivative, and puts the name Uno on it.

ATmega328P with ATmega16U2 as a serial adapter

If you consider an Uno Rev 3 to be an ATmega328P-based board with an ATmega16U2, including additional capabilities, such as able to interface with your computer as a keyboard, mouse, etc., then one of these derivatives described above with a CH340G or FTDI chip would not be correctly described as an Uno Rev 3, and you need to beware. An Uno Rev 3 that has an ATmega16U2 could be considered to be a 2-in-1 Arduino, since the ATmega16U2 is not a great deal different from the processor chip on the Leonardo or Pro Micro, the ATmega32U4. The ATmega16U2 is attached to the ATmega328P via a serial connection and there is potential for both to be programmed and interact with each other to give you more capacity or capability compared to a Duemilanove or similar classic Arduino board.

Microcenter.com has what I consider to be good clones, and they do have the ATmega16U2. The brand is Inland. They have stores in the US and sell online. My experience was from walking in a store and buying. I have also bought from eBay seller axeprice, and he lists both ATmega16U2 and CH340G UNO's separately, and he was responsive to eBay message communication. My order from axeprice arrived in the US in 8 days. I can't guarantee your experience buying from these sellers will be as good as mine, I am simply sharing info.

Going into the jungle

If you're shopping on eBay or Amazon or other open marketplace, Uno boards are very commonly offered for sale where a photo shows plainly a square SMD USB chip AND the description or title specifically says ATmega16U2 or ATmega8U2, but what you actually get is a board with a CH340G or other chip that is not programmable and that does not look like the photo in the ad. If you care, you must ask very specific questions to the seller and judge for yourself how trustworthy and responsive the seller is before you buy.

There are cases where somebody gets an Uno, and they can't upload to it. Some makers put an older bootloader on it and sell it as an Uno. It may actually have nice and pretty silk image with the name Uno or Uno R3 on it. But because of the older bootloader, which occupies more memory and operates at a different baud rate, the board is actually a Duemilanove. It's ok to go with an inexpensive board, but just be aware you may need to do some tinkering or troubleshooting to get going.

http://forum.arduino.cc/index.php?topic=332638.0

Step 3: How Many to Buy

In online forums, I have noticed a fairly large number of postings from people asking for help fixing their one-and-only Arduino. In some cases, re-burning the bootloader fixes some issues. Users can also swap chips from one Arduino to another, to troubleshoot or see if the problem they are experiencing follows the moved chip or stays with the main board. Often, the solutions to problems are much easier if you have another Arduino.

I think it is a really good idea to have more than one Arduino. If budget is a concern, having two clones is probably better than having one and only one genuine Arduino. Or you can buy one genuine and a clone.

Things beginners may not be aware of:

You can program an Arduino to be an ISP programmer, and then program another Arduino with it, to re-burn the bootloader or to load a sketch without using a bootloader.
You can program an Arduino to be a serial adapter, and then use it to program one of the Arduino boards that do not have built-in serial adapters, such as the Pro Mini and some of the LilyPads. But it's really just easier and quite affordable to buy a separate serial adapter.

Step 4: To SMD, or Not to SMD...

As seen in this picture, the Uno may come with a large plug-in DIP chip, or a surface mount soldered-on little chip. Both have the same functionality.

Let cost, beauty of design, and your intended use of the Uno be your guide. The ATmega328P is hardy, so it is likely you would smoke a regulator or capacitor before you smoked the ATmega328P. But, if you have a need, it is possible to unplug the old chip and plug in a new one if you have the DIP version. A more likely need to unplug and replace the chip is to use the Uno board as supporting circuitry for programming stand-alone chips. If you think you may be interested in that, you may favor the DIP.

You can use your other Arduino as an ISP programmer to burn the bootloader or other programs onto the blank new chips you insert.

If you are interested in shrinking your final version of the project and permanently embedding Arduino functionality into it, you could just buy a very inexpensive Nano or Pro Mini instead of working with discrete components. Those miniature-sized boards have the SMD chip and supporting circuitry such as regulator and crystal. So, you may not need to get into the building your own Arduino from parts, unless the intention is to have fun with it and learn those particulars.

For derivatives, consider the SparkFun "RedBoard - Programmed with Arduino" and Adafruit "METRO 328." They are Uno-like boards with SMD ATmega328P. They have FDTI USB chips, not ATmega16U2 like the genuine Uno. Don't let that worry you, unless you know you will want to do something advanced which requires an Uno with ATmega16U2 USB chip.

Introduction: Buying Guide for Arduino Uno

Step 1: Genuine Arduino, Clone, or Derivative

Step 2: Deception or Differences in Uno

Step 3: How Many to Buy

Step 4: To SMD, or Not to SMD...