Nano 33 BLE Sense Rev2 died?

Hi everyone,

I bought a Nano 33 BLE Sense Rev2 board for ML tasks. I tested it with the default examples from the TensorFlowLite library and it worked fine so I decided to do a sound recognition model using Edge Impulse. Everything was fine until I was recording data with the microphone and it suddenly stopped sending data to Edge Impulse (a Timeout error appeared) so I checked the board and everything looked fine (lights were on and the board wasn't hot) then I stopped every process and unplugged the board. But when plugged in again no LEDs were flashing and my laptop (Ubuntu 22) didn't recognize the board anymore. I've checked the voltage in the USB loader and it reads 5V but no lights flash. I tried to use other USB cables and other computers (windows and Linux) and nothing happened. I've realized that if I leave the board unplugged for a long time and then plug it in the red/orange LED blinks for 2 seconds but then turns off forever.

What could have happened? Is there any solution other than buying another board?

Thank you so much guys!

I'm not familiar with your board. As your board is a 3.3V board, I would check the 3.3V pin. If there is no voltage (or relatively low voltage) the voltage regulation circuit is broken; no idea why that would happen unless you created a short. If you have 3.3V available, check below.

  1. Does windows device manager give any reaction when you connect the board?
    • If yes, any errors.
  2. Does Linux lsusb see the board when you connect it?
    • If yes, check the output of dmesg after connecting the board.

If the answer to (1) and.or (2) is no, it's either the cable, a bad contact somewhere or the processor (providing the USB functionality).

Additional info.

If the BLE sense is anything like other boards with native USB, does is react on double-tapping the reset button? That should invoke the boot loader.

Due to a bug in your sketch (I do not know), the sketch might be touching on memory that is used by the functionality that performs board detection and reaction of a software reset issued by the IDE.

The 3.3V pin also reads the correct voltage. The laptop does not detect the board, neither the device manager nor lsusb read anything. I have tried other cables and nothing changes. I've visually inspected all the connections and everything looks fine and it stopped working before I touched it so I couldn't break anything I guess. It was resting on a plastic surface while working so I'm also ruling out static discharge. I wonder if I overloaded it but it was just recording sound....

Unfortunately the reset button doesn't work either. I double tap and push it for a while and nothing happens :frowning:

Due to a bug in your sketch (I do not know), the sketch might be touching on memory that is used by the functionality that performs board detection and reaction of a software reset issued by the IDE

When stopped working I just was recording sound and uploading it to Edge Impulse. Theoretically, no sketch was loaded in the board. I guess that Impulse Edge CLI was loaded on it but I guess that the CLI is properly designed to not to damage the boards. I hope... :confused:

  1. What about the double-tap reset?
    • Does the L-LED pulsate?
    • Does Windows device manager pick it up?
    • Does dmesg -w pick it up?

no :frowning: none of the three

If it does not react on tghe double-tap reset with a flashing LED, either (1) the boot loader is malfunctioning or (2) the board is dead.

For (1) you can try to "burn the bootloader" but I have no idea how to do that on the BLE Sense.

Note that this is based on my experience with 32U4 based boards, not with your board. Your board might not even have a boot loader but uses another mechanism; I really don't know.

Hopefully somebody else will come along who is more knowledgeable in this area.

but the green LED should turn on even if the boot loader is corrupted, doesn't it?

I really can't say. I have downloaded a schematic (link from https://docs.arduino.cc/hardware/nano-33-ble-sense-rev2/) but it states that it's the BLE Sense version, not Rev2). There are two LEDs (one yellow, one unknown) and a RGB LED. All of them are connected to GPIO pins of the processor. So I think that it depends on what the processor is doing with them whether it should be on or not. The unknown one is probably known as "the power LED".

I wonder if anything gets hot (using a clean, dry finger as a sensor of last resort - or an IR camera if you have one).

Good to know, I'll try to burn the bootloader. I hope it works... I'll let you know.

dry finger test didn't feel any hot part haha. Tomorrow I'll be able to use a IR to check it but it doesn't seem to be the problem. When it stopped working it wasn't hot either.

But you wouldn't have known that at the time - unless you were performing a similar audit then.

Well - these exposed boards like they are - perhaps there was an ESD event.
Hard to say.