Arduino-like boards might be moving on a bit with built-in Wi-Fi or Bluetooth and 32 bit processors running at 100s of Megahertz but I still say there’s a good, strong use-case for the original Arduino Uno design. It’s relatively cheap, well tested and quite beginner friendly. The most well-known Arduino is arguably the Arduino Uno. At its core it has an 8 bit Atmel ATMega328 with 32KB program space, 2KB RAM and a 16MHz clock speed. The Arduino Uno is slightly smaller than a deck of playing cards measuring approximately 69 x 53mm.
There is another board that uses the same chip and you might have guessed from the title that it’s called the Nano. As it uses the same chip it is almost functionally identical to the Uno but it’s much smaller at 18 x 45mm, that’s over 4 times smaller. So the question becomes which Arduino to use? I’d say there’s 3 main aspects to look at: price, convenience and safety.
Price
Officially the Arduino Uno and Arduino Nano are both €20, however being open source designs, both are available from 3rd party manufacturers (often referred to as clones) for much less than this. On average a 3rd party Arduino Uno can be purchased for £5 to £8. The Nano, however can be purchased in triple packs for about £10. Looking at this it might seem an obvious no-brainer to get the Nano, seeing as how you get essentially the same board for about 1/3 of the price but we still have further considerations.
Convenience
When designing an electronics project based around Arduino, especially when starting out the Arduino Uno is much more convenient. The larger size makes wiring easier and generally allows full use of a breadboard for making connections, the Arduino Nano generally comes with male header pins for connections, this makes it ideal for plugging into a breadboard, this can be good in some ways as it can make the project more portable with wires going from one part of the breadboard to another. When using an Uno you have wires running from the Uno to a breadboard which can be a pain to move about. However, the Nano does limit space on the breadboard for additional circuitry. One way around this is to solder some female headers on top of the Arduino Nano, similar to how the Uno is designed however this only really works when there’s a few connections or you can design a circuit to fit on top of the Nano. Due to its size and weight it will likely get pulled and thrown about once you connect enough wires to it.
Regarding convenience, the Arduino Uno was designed with add-ons in mind, as such there are many boards called shields which plug into the Uno to provide additional functionality such as providing extra power for driving motors or large numbers of LEDs. There doesn’t appear to be such an infrastructure to support the Nano or similar sized boards (there are some exceptions but not in the scope of this article).
Another point to consider is power. Both Arduinos can be powered from either 5V USB or 7-12V, however the Uno has a 2.1mm barrel jack which makes using 12V power supplies like those used for hard drives possible. The Nano meanwhile only has a USB connector, leaving 7-12V to the realm of battery power or additional circuitry to provide your own barrel jack (or if you’re feeling especially brave to could connect bare wires from a 12V DC adapter). This will likely reduce any space savings you get from the Nano.
One point to talk about when considering convenience is programming the boards. Most 3rd party Arduino Unos come with FTDI chips which are officially supported by the default Arduino IDE (programming application), however these chips are quite expensive and it would seem that most 3rd party Nanos opt for a cheaper chip, usually the CH340. This requires the downloading of additional drivers before you’ll be able to use your board. It’s not a big deal but it does provide a slight barrier to entry.
One final point to talk about when considering convenience is that the Arduino Nano actually provides slightly more digital and analog pins which makes it better for slightly more complex applications.
Safety
This isn’t so much personal safety but more about safety for the microcontroller boards and their peripherals. In my experience, it is a lot easier to damage an Arduino Nano through even temporary shorts and it makes sense that you’re trading size and the extra pins for a reduced level of circuit protection. For example in my recent spooky skull project I received 2 DFPlayer boards, one of which was damaged, causing a short somewhere that wasn’t apparent when simply looking. When plugged into the Arduino Uno this just caused the Uno’s polyfuse to trip, essentially safely disabling the board. When plugged into the Nano however the ATMega got very hot and very quickly started smoking. I quickly yanked out the power and disconnected the DFPlayer and was able to salvage the Nano for a while but it eventually died, about 2 weeks later, right when I needed to demo the project. You might ask why I connected it if it wasn’t working on the Uno? At the time I thought it was the Uno that was at fault, not the DFPlayer. That said I’ve definitely managed to do the same to a Nano that was 100% user error when I managed to short the board while power was applied. By contrast I don’t think I’ve managed to destroy an Uno thanks to the additional circuitry.
Another point to consider is that the layout of the board offers some protection on the Uno. The pins are on the edge of a much larger board, allowing for clearer labelling. Another point to consider is that to make shields safer to use, the Uno is laid out in a slightly non-symmetrical design. This means that the pins are laid out in groups, slightly reducing the likelihood of an incorrect connection.
Conclusion
I would say that if you can, you should almost always design your project on an Arduino Uno and once you’re happy that its stable and need to save space, shrink it down to the Nano. This allows you to benefit from the extra circuit protection of the Uno and the safety that the layout of the board physically provides while tinkering. This may prove impractical however if you really need the extra IO pins. You might think that being so much cheaper it might be worth skipping the Uno and just live with blown Nanos if you mess something up but I would argue this will end up being a false economy, better to try and keep them for future projects and occasional whoopsies than to rely on their cost to save you from faults.
As I hinted above there are some similar sized boards to the Nano that do have an add-on board infrastructure but those are beyond the scope of this article and I don’t have any experience with them but if you’re interested have a look at the Adafruit Feather line of boards. There are also a lot more Arduino-compatible boards out there than just the Uno and Nano, some as big as or bigger than the Uno and some comparable in size to the Nano or even smaller but again I focused on these two boards because I have experience with them and because they are so functionally similar.
I hope you found this board comparison interesting and now have a clearer idea as to which to choose for your project. Let me know in the Discord or Twitter if you’d like more articles like this. If you’d like to support continued content you might consider visiting the links below for some Arduino purchases. These are affiliate links and any purchase you make will provide a small fee support to this blog.