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Anyone Have stability issues with Arduino Uno Q?

SensoredHacker0 — Thu, 07 May 2026 12:16:08 GMT

So im at my PC typing away. The Uno Q ran my code on the first try on the first day i got it, a couple days ago.
made some more tests, for 2 days everything was working great. Then, without warning, did not move it, or touch it, it stopped.
ok fine I guess. Then I tried to upload new test code. it compiles, and claims to have been uploaded. but the code doesnt work.

The hardware which was attached, when it failed:
a Max33041E shield, and the Ethernet R3 shield. these had been working for a couple days straight.

Not like the code is buggy, but like it doesn't even init the serial print lines.
bash my head on the wall for a while.
Press Reset. nothing. Un plug it, wait, re insert usb power.
$dmesg shows it, loading without issue.

Pull the shields off, load blink. same thing, it compiles, and claims to upload, but the code never runs.

I haven't reinstalled the boot-loader, by the time I thought to try that, I'd already gone to bed.
But I've never had such random problems before. Ive got arduino running in projects that have run for 6 years straight not problem.

besides reloading the bootloader and one have some ideas?

Are there stability issues with the Arduino Uno Q I should know about?

Perhaps the most frustrating thing was that the LED matrix was making little hearts and arduino logos the whole time.
meanwhile blink wont run.

RE: Anyone Have stability issues with Arduino Uno Q?

BigG — Sat, 09 May 2026 20:55:11 GMT

This video (from 8 mins) might help explain what's going on... suspect your issues are related to this new "LLEXT" feature

https://docs.zephyrproject.org/latest/services/llext/index.html

www.youtube.com/watch

RE: Anyone Have stability issues with Arduino Uno Q?

SensoredHacker0 — Sat, 09 May 2026 14:26:05 GMT

Weird, because for everyone I know IRL, these things typically just work.

RE: Anyone Have stability issues with Arduino Uno Q?

embeddedguy — Sat, 09 May 2026 02:48:10 GMT

From your problem description, I can just imagine that it is just typical Arduino thing. Most people have experienced this..

RE: Anyone Have stability issues with Arduino Uno Q?

SensoredHacker0 — Fri, 08 May 2026 23:32:59 GMT

Welp, I re-flashed the linux image, but the arduino bits are still doing the same thing. it says the code uploaded but doesnt run it.
so then IDK i messed with it ALOT.

My conclusion:
The Uno Q, despite appearing to be functional in the traditional arduino toolchain is not actually, compatible with it, and subject to breaking if you try to to use it the same way.

Saying it another way, The integration of Arduino Uno Q is not complete. the code examples for everything are not going to work right, and the IDE is not going to tell you.

so then I got on the shell. and wrote code from there, it worked, but, no serial.

so then more digging:
you can to this to build and compile in the same step, which was a function of the build command prior to Arduino's acquisition.
Evidently, just pressing build doesn't save and compile you code as it once did.
$ arduino-cli compile --upload -p /dev/ttyACM0 --fqbn arduino:zephyr:unoq .

Here is a corrected blink.ino for the Uno Q.

#include <Arduino_RouterBridge.h>

void setup() {
Bridge.begin();
Monitor.begin();
pinMode(LED_BUILTIN, OUTPUT);
Monitor.println("BOOT");
}

void loop() {
Monitor.println("Off");
digitalWrite(LED_BUILTIN, HIGH);
delay(400);

Monitor.println("On");
digitalWrite(LED_BUILTIN, LOW);
delay(400);
}

https://forum.arduino.cc/t/arduino-uno-q-via-ide-no-serial-monitor-output/1411255/21?page=2

https://docs.arduino.cc/tutorials/uno-q/user-manual/

"Note: Serial still works over UART"

I'd say thats a lie, but it was working for the first few days, which is very confusing.
Its like someone came in an broke all the macros. I can write my own, now that I have a better idea why they are broken.
I just wish we werent pretending they we're broken. would have saved me several hours, and much frustration.
For real, why would we mess with the serial library??? you know how much stuff that breaks??

$tio /dev/ttyACM0 -b 9600

herdeedur.

RE: Anyone Have stability issues with Arduino Uno Q?

SensoredHacker0 — Fri, 08 May 2026 21:29:59 GMT

When ever Opta first came out, my employer wanted desperately to switch. but all the devices you might want to interface with were locked out. I wrote to Arduino and they said they were concerned about licensing, which amounted to a locked down open platform. as I understand it, that has improved over time, but still, we couldn't adopt it. if anyone is going to transition, to some other system, that system either needs support for other devices, or needs to have devices that offer the missing functionality. Arduino Opta had neither.

RE: Anyone Have stability issues with Arduino Uno Q?

SensoredHacker0 — Fri, 08 May 2026 19:31:16 GMT

yeah the first thing I did was grab an arduino Mega, and keep on working on my project. but for 4 hours, I thought to myself this board is brand new, I literally havent touched, it, was working, and now it doesn't work. The expensive dev board arent what I slap into projects. If I have to buy a dev kit, to experiment on, Im not going to think ooh a 70$ arduino. Ill just pick up a 3$ Uno clone, and see where its lacking. If im putting an expensive devboard in something, I've already built the prototype. So Arduino is probably missing out on a lot of entry level development. I could buy an Uno Q, but now I have some random fail as the first thing Im going to think of. versus this 15 year old arduino MEGA that has never failed even once.

We'll see I guess. Maybe a firmware update patches it.
A linux server I built in college 20 years ago is still running.
The only folks who are going to accept linux as a fault are new linux users.
On paper the Uno Q sounds amazing.

RE: Anyone Have stability issues with Arduino Uno Q?

SensoredHacker0 — Fri, 08 May 2026 19:12:37 GMT

Much appreciated. Ill check this out.

RE: Anyone Have stability issues with Arduino Uno Q?

kmikemoo — Thu, 07 May 2026 19:10:30 GMT

A bit aside, but I see the Opta in the same category of "not ready for prime time". I have one. It's too quirky. It's not what I consider "Arduino" - which, to me, infers stable and well supported (both by the company and the community).

RE: Anyone Have stability issues with Arduino Uno Q?

BigG — Thu, 07 May 2026 16:34:40 GMT

Ah right, I did not know that. Agree, many of the old libraries will simply do not work. It's a case of rethinking our old ways when doing things with Zephyr. Info is there. It needs understanding. That's tricky without tutorials.

docs.zephyrproject.org/.../README.html

RE: Anyone Have stability issues with Arduino Uno Q?

ralphjy — Thu, 07 May 2026 16:14:34 GMT

If you are using the Q, the default is using Zephyr - both in AppLab and the standalone Arduino IDE. Creates problems with legacy hardware because some (many?) third party libraries are not updated. I ran into problems with the Arducam libraries. Right now the only option is to port it yourself (a handful of class definition changes). Hope the manufacturers will update their libraries to Zephyr soon.

The standalone IDE does work with the Q, but I wouldn't recommend it. Not sure what the real use case is. I tried it because it is more familiar to me and I hoped to reuse code, but I don't think that Arduino is really going to support using software external to AppLab for the Q. Have not investigated if it is possible to remove AppLab to get back the system resources.

RE: Anyone Have stability issues with Arduino Uno Q?

ralphjy — Thu, 07 May 2026 15:58:49 GMT

I agree with your comments, but just to clarify what I meant - the Q has much more complexity and many more points of failure, both in hardware and software. I do think the current implementation is faulty and hopefully that will be fixed in time.

You're smart to wait for things to settle down, I expect many of the issues to be resolved in the next couple of quarters. And the media interface should be available soon.

RE: Anyone Have stability issues with Arduino Uno Q?

BigG — Thu, 07 May 2026 15:33:22 GMT

I think by default you still use MBed. You need to manually switch to the Zephyr option. Personally, having persevered with getting to know Zephyr RTOS, I find it really good.

RE: Anyone Have stability issues with Arduino Uno Q?

shabaz — Thu, 07 May 2026 15:30:03 GMT

I hope they hurry up. That's a long time to be unsure if things will be stable and if the API or subtle behavior will change.

Sad to say that it appears right now for an amount of networking capability, one might want to simply walk away and consider non-Arduino boards, unless they pull their socks up.

RE: Anyone Have stability issues with Arduino Uno Q?

BigG — Thu, 07 May 2026 15:05:07 GMT

Arduino has switched to using Zephyr RTOS: https://github.com/arduino/ArduinoCore-zephyr

Still a long way to go to get to version 1 - they're at version 0.55.

My guess is that it'll go version 1 once the next Zephyr LTS version is released next year.

RE: Anyone Have stability issues with Arduino Uno Q?

shabaz — Thu, 07 May 2026 15:00:17 GMT

I'm glad you guys are investigating the Q and working through the issues. It will help everyone.

However, got to strongly disagree with this:

The Q can't really be expected to be compared reliability/stability wise with previous Arduinos. With the new hybird MPU/MCU structure it is going to have a lot more issues than the MCU only boards.

That may be the current reality with Q, but is in no way normal. I believe it means that the Arduino people have either (a) treated their creation like a Linux server or desktop PC device, or (b) is simply buggy in their implementation. Either way it's a showstopper as far as I can see. It's frustrating, I would love to use the Q but not if it cannot be power-cycled with confidence.

This is not the first device containing a microprocessor and microcontroller, and it needs to start up consistently every single time. I'd be especially concerned if the cause is (a) because then that means there's a complete misunderstanding by them about how people use any typical SBC or any Arduino board for that matter.

RE: Anyone Have stability issues with Arduino Uno Q?

ralphjy — Thu, 07 May 2026 14:14:51 GMT

The Q can't really be expected to be compared reliability/stability wise with previous Arduinos. With the new hybird MPU/MCU structure it is going to have a lot more issues than the MCU only boards. I have found that I encountered different sets of issues depending on the hardware and software configuration and development environment. You really haven't indicated how you are set up (PC USB host, headless, standalone), how you are powered, and what your development setup is.

Based on your description, I assume that you are using AppLab running on a USB host. How are you determining that it doesn't reach the serial print lines (that would be Monitor rather than Serial in AppLab)? Your Linux side appears to be running (assume you checked dmesg via ssh). If you are in AppLab I would guess that the RouterBridge is failing and may be hanging the MCU. The AppLab Blink example no longer runs only on the MCU.

I would recommend that you connect a USB to UART adapter (3.3V) between your PC and the MCU. You could also try one (1.8V) between the PC and the MPU. That would help with debug.

RE: Anyone Have stability issues with Arduino Uno Q?

shabaz — Thu, 07 May 2026 13:30:15 GMT

That's concerning. Q has so much potential, but it's currently let down because of (it feels to me) lack of focus by Arduino. If it's going to stop starting up correctly after some power cycles, then it just won't get used, people will switch to other control boards. They have to take this seriously and eliminate such flakiness from the software/OS build or hardware, this to me is a showstopper, otherwise no-one can trust using it. I bought a Q to try it out, but will wait till it's more mature (hopefully). Also, a few of the other Arduino boards have at least perceived problems, since Mbed is EOL very shortly, and I wonder how long till any replacement Arduino libraries will be reliable. Think Arduino needs to have better messaging at a minimum, so users are not in the dark.

RE: Anyone Have stability issues with Arduino Uno Q?

skruglewicz — Thu, 07 May 2026 12:31:11 GMT

Yes I have had similar problems myself. To get it working again, I ended up Flashing a New Image to the UNO Q: https://docs.arduino.cc/tutorials/uno-q/update-image/ To restore the board, follow the specific procedures detailed in the Download & Install CLI Tool section.

CRITICAL WARNING! Be aware that performing these instructions will entirely wipe the board. All saved files and configurations will be permanently destroyed.

It is essential to back up your work to an external location before proceeding with the flash. Remember that this is currently an experimental platform, not yet suitable for production-level development. As early adopters, we are essentially the "guinea pigs" navigating a developing technology from Arduino.

If that works let me know

RE: Arduino device unused I/O's...... what to do with them?

geralds — Mon, 04 May 2026 17:01:38 GMT

With a microcontroller, I program all unused pins as inputs (analog input is also possible, but this can interfere with the ADC) and terminate them either to ground (a hard connection to ground is usually possible, depending on the manufacturer; otherwise, a soft connection to ground is used) -> or to a pull-down resistor (around 1kΩ; this can sometimes introduce noise).
The datasheet usually provides the relevant information.

If the software doesn't address the pin, then it's generally not reacting to disturbances occurring on the "open" or terminated pin.
Also, here you can let open the pin, depending to the manufacturer.

Unless these are over voltages or, CAUTION - !!!!! negative voltages (<< -0.3V).

Arduino device unused I/O's...... what to do with them?

colporteur — Mon, 04 May 2026 16:40:39 GMT

What is the best practice for unused Arduino device I/O pins, connect them to ground or Vcc? If not connected on the PCB what if anything do you do with them in code?

My go to bathroom reading material is The Art of Electronics Paul Horowitz & Winfield Hill. I just read a section on routine design considerations. "No open inputs" is the suggestion. It was a discussion on CMOS design but the commentary got me to thinking about Arduino's.

I've never done anything with them. I assumed they were conditioned in the device.

For No Open Inputs planning, I wonder how the pro's in E14 handle it.

RE: Arduino device unused I/O's...... what to do with them?

vmate — Mon, 04 May 2026 16:45:57 GMT

You shouldn't need to do anything with it. They would default to the high-impedance INPUT state, but it shouldn't be an issue at all, since you're not actually reading them. If you're paranoid, set all of them to INPUT_PULLUP, which will activate an internal pullup resistor in the MCU to make sure they are always HIGH.

The 'no floating inputs' guideline is a good one to keep in mind, but it's mostly related to analog ICs and circuits. Microcontrollers will essentially shut down all the logic 'behind' an unused input pin, so they won't really affect anything at all.

How large is your "hidden" Arduino folder

BigG — Sun, 19 Apr 2026 12:08:31 GMT

I've been doing a different sort of spring cleaning this weekend.

As my disk drive is almost full, I ran the Linux disk usage analyser tool on my Home folder and revealed, unsurprisingly, that the .arduino15 folder was the main culprit (being the "brains" behind it all). This was due to the staging folder, which was well over 15GB!

It turns out that the contents of this literal "staging" folder is really just a type of cache should you want to reinstall stuff again. It appears there is no automated means of cleaning.

So, if you haven't touched yours what size has yours grown too - it's indicative of how extensive you use it (bragging rights, I suppose :-D).

What other tricks do you use to automate disk usage spring cleaning.

RE: How large is your "hidden" Arduino folder

DAB — Tue, 21 Apr 2026 19:18:57 GMT

Thanks for the heads up, I need to go check mine.

RE: How large is your "hidden" Arduino folder

BigG — Mon, 20 Apr 2026 19:33:08 GMT

Impressive and interesting that you use cleanmgr. I like your approach.

I did a quick search online for any LinuxOS options, and I discovered https://www.bleachbit.org/

It seems to be worth a try. Its also available for Windows, but not for Mac.