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I happened to short-circuit my Arduino by mistake. It was powered by USB on my Windows 7. The OS was so smart to pop-up warning about USB power surge and shut it down immediately. Arduino survived.

I fixed the circuit and connected it back. Arduino was powered again, but it was not recognized as COM port anymore. There was no unknown device in Device manager. I tried different USB connector on the same computer and it was found and it worked. But the other USB was out.

I restarted the computer and connected the Arduino back to the broken connector. The drivers were automatically reinstalled (I don't know why) and it worked again.

Is it possible to re-enable Arduino on the same USB connector without restart? I'd like to understand what happened on the computer side.

  • Windows wouldn't have reacted fast enough to shut it down itself. The hardware driving the USB port will have overcurrent protection built in and would have shut down the port and notified the OS of this occurrence. It might be possible to avoid having to restart the PC by disabling and re-enabling the USB system from the Windows Device Manager but since your keyboard and mouse probably are USB devices this might be tricky. – Wossname Nov 18 '16 at 13:27
  • But that said, shorting out the USB host controller can cause damage to your motherboard. If you are worried this might happen again, I'd suggest you run your arduino from a powered USB hub instead of directly from the PC, that way it won't risk maging the motherboard. – Wossname Nov 18 '16 at 13:56
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Most likely, your motherboard detected a over-current situation, and disabled power to that port. Since it has to way to know if the cause of the over-current has been fixed, it will continue to disable the port (since the only way to know would be to turn the power back on, and doing that to many times might cause permanent damage).

I wouldn't expect there to be a way to force your MoBo to reset the port, as this is an unlikely event. You should be glad the MoBo prevented any damage.

Using a different port sounds like an okay solution.

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    I happened to do it again (shame on me), I noticed Win7 produced a background popup asking if that buggy device is disconnected with option to turn it on again. After that, another device such as mouse can be connected to it, but not Arduino until reset. So I guess it is a Windows feature. – Jan Turoň Nov 19 '16 at 0:01

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