No USB connection



I began test on M2 since 1 month it was ok until last monday. I use Ardiuno on Visual Studio 2017. Since monday I can’t have USB connection. On Windows system, I can’t see Ardiuno Programming Port.
I checked USB cable and it is ok and tested the USB connection on an other computer and it was the same thing.
Do you think if device is stuck or damned ?
Thanks a lot


Try clearing your M2 and go from there. Somehow you locked up your M2. It is highly unlikely the hardware is damaged unless you hooked up something wrong.


And by clearing he means “plug it into the USB port, hold down the Erase button for about 2 seconds, release the erase button, unplug USB, wait a second or two, plug it back in”. You should then have an erased M2 which will enumerate as a serial port once again (hopefully) but be completely blank so you’ll have to reprogram it.

As Rod said, hardware damage is unlikely. Software glitches can cause it to lock up before the USB code starts running and then it won’t show up as a USB port.


Hi Collin and Rod,

It’s ok my M2 can run now.
Thanks a lot



I have two M2 and recently one of them stopped being recognised from my computer.
I tried to clean it as advised but nothing new happened.

What I noticed is that when connected with usb to the computer the usb plug as well as the SD card slot gets really really hot compared to the sound M2. I tried to locate the components on the processor board from which the heat is spreading and it seams to be the main fuse F1 and the Mosfet Q1.

Do you have any idea of what’s happening?

Here is what I did before it stopped being recognised:

  • I wanted a high frequency PWM but I saw in the 12VIO library that it was capped at 1kHz
  • I changed the value to 100kHz in the library
  • I uploaded the new library and a sketch where I called a 10kHz PWM
  • I disconnected the USB and powered the M2 with 12V.
  • The PWM worked so I was happy, but when I reconnected the M2 to my laptop it couldn’t be recognised

Can this sw modification could have damaged my M2 in any way??

Thanks a lot,


(BTW not really related but I received this second M2 with a yellow dot of paint on the board)


Is either of your boards an early beta board? The early boards had a quirk where it was possible to short the power rail with the outputs. The newer boards can’t do that.


No I don’t think so, they are from mid '18.
All the fuses of the IO are ok…


Any other suggestion to understand where the issue is coming from?
It seems that the processor board is damaged, but is there a way to check if the interface board is also faulty?


Try powering the M2 while holding down the erase button.
This should erase your sketch, then reboot your M2 this may overcome your problem.
You may need to do this a couple of times to assure the sketch is erased as the processor may be very busy servicing PWM outputs,
The Library was capped at 1KHz because at higher PWM the processor would not respond reliably to USB inputs as the processor was too busy servicing PWM outputs.


Thanks. I tried to erase the sketch multiple times with no sucess.
Any other way to do it?
Next time I will definitly ask before doing a library modification…