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Topic: Reconnecting USB does not work (external power / Arduino 101) (Read 410 times) previous topic - next topic



i have the following setup:
- Arduino 101, powered through the 5V pin (using a dc-dc converter)
- IDE v. 1.8.1, Intel Curie Boards v. 1.0.7, Windows 10

and observe the following behavior:
- if i turn the external power on, the arduino starts is sketch
- if i plug in the USB connector to my computer, and start the Serial Monitor, it is possible to send and receive data.
- closing and restarting the Serial Monitor also works, BUT

- after unplugging the USB from the computer, and then reconnecting it (arduino is still powered by external supply), it is not possible to establish a communication with the Serial Monitor again.
If i try to send something to the arduino, the SM gets stuck. (It terminates, if the arduino USB is disconnected.) The USB is always recognized as COM 3, changing USB ports has also no effect.

I would love to have a standalone arduino (powered by a battery), and be able to have acces to the arduino while it is operational using the USB interface when needed.

Any helpful ideas are appreciated.
Thank you and best regards,


Hi Franz,
unfortunately there is a bug on the x86 firmware which prevents the USB reconnection event to work reliably.
As a workaround, you can print your data on Serial1 which is exposed on pins 0-1 and read it using an FTDI-like USB-to-serial adapter.
This bug will be solved in one of the upcoming core releases

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