MKRNB1500, yellow led glowing


I have a small problem with my MKRNB1500. I have a sketch that just reads input from one pin, and then send status to a webpage. So really basic for that board.

The problem is that everything works for about 10-12 hours, and around that time the yellow led on the board starts glowing, or slowly pulsing, and the board don't respond to input changes. I need to pull the power to the board and start all over. The board is powerered through the USB port with a 2A powersupply.

What does this glowing/pulsing light mean? Since everything locks up and it takes so long time for it to happen, it is hard for me to troubleshoot, but I guess the led is trying to give me a hint?

I have no experience with any of the MKR boards (!!)

Boards with native USB have the glowing / pulsing as an indication that the boot loader is active. Double tapping the reset button should also show this. You can also simulate it by opening and closing the serial port with a baudrate of 1200 baud (e.g. using serial monitor).

However, the boot loader will only stay active for a few seconds so it does not quite make sense that it's the boot loader.

Please show your sketch. Any serial print / println statements in there?

Note that your topic has been moved to a more suitable location on the forum. Installation and Troubleshooting is not for problems with (nor for advise on) your project :wink: See About the Installation & Troubleshooting category.

Thank you for the reply.

I put it in the troubleshooting category because the problem is not related to any NB IOT communication that is specific for this board. And since the sketch is working for 10-12 hours.

Glowing/pulsing yellow light should be common for any Arduino board and the chance of getting help is bigger in a general category. If it had been a specific problem with sending/receiving NB IOT this category would have been perfect.

And as you said, active bootloader is one time when the light is glowing, common for all boards with USB. But are there any other circumstances when that can happen, since the sketch is working for many hours? That is the question =)

I can post the sketch later when I'm back from work.

Thank you for your help.

My feel is that you have a better chance in the dedicated MKRNB1500 section. You can move it yourself to wherever you want. Open the topic, click the black pencil next to the topic title, select a better category and click the green button with the tick. Just don't put it in the Installation and Troubleshooting section :slight_smile:

As said, not familiar with the board; and I haven't managed to get my Leonardos, Micros and ProMicros invoking the bootloader from code :wink:

One additional question; is the board running stand alone or connected to a PC for monitoring / logging purposes.

It is using a USB adapter for power, not connected to a PC. Don't know if that would help me, since the sketch is working fine until it doesn't =) So don't know what kind of output that could be useful to find the problem.

Guess I found the problem =/ It seems that it is the useage of the watchdog, Adafruit_SleepyDog, that is the problem. Just thought I would run the test program for that watchdog, and it gives the same behaviour immediately.

So in my real sketch something goes wrong after some hours and the watchdog tries to do it's thing. But it don't work.

I know i searched a long time to find a watchdog function until I found this one, that I thought worked. But how can I find one that works?

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Any chance that your sketch uses Serial output? I asked before :wink:

Yes, I use serial output, but I don't have any equipment so I can get the output when it is not connected to a PC, since I use the USB on the board for power. Guess I need som serial to USB converter and connect to some pins?

And to my earlier findings where I thought I had found the problem, I think I was wrong. Doesn't seem to help to remove the watchdog code.

And also what is strange, now the board changes ports. When I connect it is one port, and then when I start to compile and download the sketch I get error message that the port is not available. And then I check and see that the board have a new port number. Si I don't know what is happening with this board.

If your board can be used as a HID (I think it can but I'm not sure) and you print via USB, it might be the cause of the problem. From my experience with the 32U4, you can bring a 32U4 to a near grinding halt by printing after a terminal program did connect and later was closed / USB cable removed. Same might apply to the MKRNB1500.

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