This is a Funduino, a shield-like board designed to hold an Arduino Nano-type board.
Now unrelated to the issues I’m having with an (older and as yet unused) Arduino Nano not wanting to connect or upload, until recently that one Nano was the only board I had of that form factor. I’ve now got a few of the new Arduino Nano R4 boards. Other than the fact that when compiling on my Raspberry Pi400, which takes waaaaay longer than if I’m building for the usual Atmel chips, the Nano R4 seems to work well, and has LOTS more code and data space.
So my question is:
Has anybody tried using the Nano R4 with a Funduino? The pinouts of the old Nano and the Nano R4 appear to match each other, and that of the Funduino’s socket.
IMO you can't use Nano R4 with an old Nano shield, and even if the pinouts look "similar" I wouldn't put an R4 in a shield designed for older boards.
If you try to force insert the card:
Best-case scenario: The computer doesn't recognize the card or the code doesn't work (I hope it's your case).
Worst-case scenario: overheating of the Renesas chip, and goodbye to your ~$18-20 card.
I don't know of any Funduino-link boards for Nano R4, so I'm sorry but my advice is to keep that board to be used with a classic Nano, and use the Nano R4 without this board (e.g. use a breadboard for testing. It's less elegant but it's the only way to be 100% sure you don't short circuit while you wait for adapters specifically for the R4 series). And buy a UNO R4 for future projects if you need its form factor.
I don't have any Nano R4 yet, but as they don't have much in common (different CPU, different pins usage, different memory, etc) my opinion is like saying both a Toyota and a Dodge have a combustion engine, four wheels and both run with gas, but can't be used the same way because the engine is different, the size is different, the car behavior is totally different, so you can't install the same gearbox on both.
Jokes aside, I know the Nano Classic Operates at 5V and its input/output pins tolerate and exchange 5V signals, while even if Nano R4 can be powered at 5V, the Renesas microcontroller operates internally at 3.3V.
The problem may arise because expansion boards could connect pins directly to the 5V line, and if you connect something that sends a 5V signal to a Nano R4 pin, you risk burning out the processor, since the R4 isn't "5V tolerant" on all pins in the same way as the older version.
This is what I can understand, not having a nano R4. Obviously, the choice and the risk are on your side, just check how that board connects the various pins and handles the power. But you said you can't seem to communicate so it looks you're in the previous "best case". And for this project, if I were you, I would switch to a UNO R4, leaving the Funduino for the Nano Classics.
I hope someone else here, having Nano R4 experience and that specific board, could help you much more than this.
I only was wondering because I have a plain vanilla Arduino Nano (version 3.3 it says, but not 3.3v) which I cannot get to program, either with my Raspberry Pi 400 or my Windows laptop, both using the earlier-than-version-2 IDE. (1.8.19?) More on that issue is on this forum under the subject line Cannot program Nano v3.3 from Windows 11 system. And I have a little project for Arduino Days 2026 (11 days from now) that could use a dozen of those GPIO pins at the same time. I suppose as a backup, I can use a proto breadboard, wires, and header pins to get to my home-brew breakout boards.
