Language: EN


What is Arduino? What model to buy?

What is Arduino?

Arduino is a programmable board with digital and analog inputs and outputs, whose low cost makes it ideal for getting started in automation or for small domestic projects in electronics and robotics. This means that we have a small “automaton,” capable of receiving information from the environment (sensors) and performing actions (actuators, motors…), according to a program that we introduce with a computer, and that can be executed autonomously.

For you to get an idea, until shortly before the appearance of Arduino, commercial/industrial automatons with a similar capacity cost several hundred euros. These types of automatons are used to interact with and control all kinds of systems, from installations in buildings (air conditioning, pumping), industrial installations, vehicles, robots… any physical system that needs to be controlled electronically.

Arduino is flexible, and reliable. So, why have we said in domestic projects? Why not in commercial or industrial applications? It is something that may tempt you at some point, in fact, we know that people create commercial products based on Arduino. However, if one day you have to control (for example) the air conditioning of a 4000m2 sports center, where only the refrigerator costs €250,000, it will seem reckless to install a €15 controller. You will prefer to install a general automaton that costs €500 to €1,000, which offers you a certificate and a guarantee for your peace of mind, and to protect your signature (although everyone has their own professional criteria).

However, everything you have learned about electronics, automation, programming, and telecommunications, you can apply directly and easily in case you have to use a more expensive automaton, so Arduino is an excellent platform for practice and learning. It will also bring you hours and hours of fun in your robotics and electronics projects for less than the cost of a night out, which is always very good.

To start with Arduino, logically, the first thing is to buy one. That’s why we are going to see the different available models.

What model of Arduino to buy?

There are many Arduino models available, which can be a bit confusing for new users. When choosing, it is normal that we look at the number of inputs and outputs, especially the analog ones since they are the ones that usually restrict our project. In the following table, you can see the most common Arduino models, with their most important characteristics, and a reference price when buying them on eBay or AliExpress from Chinese international sellers. You have a complete list of the different models and revisions at

Uno r31666132kb7.5€
Mega r35416144256kb12.5€
Mini 051468132kb2.5€


It is most common that to start you use an Arduino UNO r3. This is the most standard model and is the board you will usually use. For certain large projects, which require handling a significant number of motors or servo motors (robots, CNC machines, 3D printers), it may be necessary to switch to a model with a greater number of outputs, especially analog ones. In that case, it is normal to use an Arduino MEGA r3.

On the other hand, the Mini 05 model is for advanced users. It is a board of just 2.5€ and a really small size, designed for final applications, that is, when you are going to leave the board permanently connected (and therefore you are going to “lose” it). It comes without connection terminals, they must be soldered, and to program it, a USB FTDI adapter is required, which costs 3.5€. At the expert levels, this is practically the only board model you will use given that, if you require a large number of inputs or outputs, it is more economical to form a network of 3 or 4 mini boards, and you get a capacity superior to a MEGA.

Therefore, final recommendation. Buy an Arduino UNO, which will be your standard development board. When you are advanced, buy one or two Arduino Minis, along with the programmer. And only for specific projects where the UNO is too small, and if you don’t want to complicate your life by making networks of Arduino Minis, or if you need to use the additional serial ports, you can use a MEGA.

In the next tutorial, we will see how to install the Arduino development environment, to start development.

Update 10/02/2014: Several of you have asked me where to get those prices. Simply search on eBay or AliExpress, choosing the option “search from international sellers” and sorting the list of items by “lowest price + shipping”.

Update 24/04/2015: The appearance of the USB/TTL CH340G serial converter has caused the price of the boards to drop a lot compared to this post, so the prices have become outdated. Currently, the price of the Arduino UNO R3 is 2.80€, that of the Arduino MEGA 7.5€, and that of the Arduino Nano V3.0 1.95€. With these prices, the Arduino Nano V3.0 becomes my favorite board, surpassing the Arduino Mini Pro v2.0.