Arduino nano KiCad symbols

Question

Can anyone explain me the difference between the symbols for Arduino nano in KiCad? Is there any important difference at all? All of them seem to have all basic pins.

Answer 1

In short, there aren't any substantial differences. But it makes sense to use the one that actually matches what you have.

My KICAD symbols are out of date, so I downloaded and unpacked the current archive for MCU Module symbols. These things are defined in text files, so doing this allows you to employ the usual diff tools to them, if you break the parts of interest out into separate files, which is what I did to produce the below images.

Index Entries

Besides the name, they're different in what datasheet they refer to:

Definitions

In the below, on the left you'll see in dark blue background that both the Nano v2.x and v3.x are actually defined in the same file. So, they are in fact sharing a definition; so, no differences there at all. The original Nano boards varied in that some had ATMega168P and some had ATMega328P. These are practically but not quite the same chip. The significant difference is sizes of the various memories. And they had different bootloaders. Nothing that would make their symbols or footprints significantly different.

On the right is the Nano-Every, which is a fairly different beast from the older Nanos in that it's an ATMega4809, one of the new-series AVR parts, and different significant ways greater than just memory sizes. But, it was designed to have the same layout as the prior Nano boards. They even went so far as to make classes and objects to try to "emulate" the more traditional style GPIO ports of the Nano for Nano Every users.

As you can see there's really no differences besides the names of the pins and a few changes in drawn locations between the v2/v3 symbol on left and the "Every" symbol on the right. Some of the pin names are different, but it's the pin numbers that matter when mating it to a footprint in Kicad, and those are the same between the two.

For whatever reason pin number 29 changed from W (in 2/3) to N (in "Every"), which according to their documentation is a change from power input to not connected. I suppose this might make a difference between whether or not you need to add a PWR_FLAG symbol somewhere in your design to satisfy electrical rules check (ERC). In the "Every", for whatever reason when they (slightly) rearranged the pins locations in the symbol, they stuck pin number 29 right on top of pin 4. So, if you're having a hard time seeing pin 29, that (and the light gray text) are why.