Pro Micro "Unknown USB device"

Using Arduino IDE 1.x
1

Hi!

I have received a blue Pro Micro (32u4) and I can't get it to work.

When I plug it in via USB, it says that the USB device is not known. It also says that in the device manager (Windows 10).
I wanted to install the Pro Micro Driver from sparkfun, but when I try to do that via device manager it will not allow me to do that.

When I connect Reset to Ground (also 2x quickly), it disconnects from USB and reconnects, saying the same thing again.
It does not show up as a COM port in the device manager or in the Arduino IDE.

Thinking it may have a faulty bootloader I burned bootloaders for Arduino Leonardo and for the Sparkfun Pro Micro onto it using ISP and my Arduino Leonardo board. The bootloader burning works, but it does not fix the issue. It still shows up as an unknown USB device.

The USB-cable should be fine, since the same cable works with my Arduino Leonardo without any issues.

Is there anything I can do, or is the board broken?

Thank you in advance!
Benny

2

It does indeed sound like a driver issue.

Are you using USB 2.0 or 3.0 ports as USB 3.0 have been known to cause issues ?
Can I presume you have the IDE installed ?
Also which version ? (just for clarity)
Are you running your computer as Administrator or a form of restricted user ?
What security do you have on your computer as McAfee and Norton have had issues with the IDE ? (false positives)

Whilst a REAL pro micro should not need any additional drivers other than those with the IDE it is not uncommon for some Chinese vendors to say it is a pro micro when it is nothing close and in those cases other drivers may on rare occasions be needed.
A decent picture of both sides of the board may be useful for those cases.

3

Thank you for the answer!

I tried it both on my Laptop (USB 2.0 only) and on my PC, both on latest IDE 1.8.7.
On both PC's I am Administrator, the antivirus software is Avira.

The board is not a real Pro Micro from sparkfun, it is one of the cheap blue ones: https://www.amazon.de/gp/product/B01KMFRCN0/ref=oh_aui_detailpage_o00_s02?ie=UTF8&psc=1

4

That should be OK with the drivers from the IDE.
Might be worth turning AVIRA off to re-install the IDE JIC it caused any issues.

What version of windows BTW as some have reported different minor glitches with drivers / com ports under win 10

Do you even get the new hardware notification / sound when you plug it in ?
If you dont then it is more than possible its a board issue.

5

Problem found:
One of the resistors for the USB transmission directly next to the USB port was not conducting at all, it should have 22 Ohm. I did not have such a low resistor, so for testing I soldered a 500 Ohm parallel to it, and suddenly it shows up in the device manager as Sparkfun Pro Micro.

For some reason the blink sketch will stop working after a few blinks, the analogReadSerial sketch seems to work fine.

But for now I am happy that the little board finally works.

Thanks for helping!