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Topic: Uno all of a sudden no longer recognized by computer. (Read 488 times) previous topic - next topic


Note:  This is NOT a new arduino.  I have been using it for months, and when plugged into power, the code on the board still runs.

I can not get my computer to recognize my Uno in order to upload new code. I am running OSX Lion, and as far as I can tell, nothing has changed since the last time I uploaded code a few weeks ago. 

The problem is simple: the board is not recognized.  When I go to tools>serial port> the usual usb options are not listed.  I tried downloading the arduino ide on my wife's mac and the same thing happened, no usb option. 

The only thing that could have possibly changed is that I did run the arduino off of a diy solar charger kit several times, and I suppose it is possible that may have done some sort of damage, though there are no physical signs or other indications.  As I said, the board is running the current code fine. 

Any help would be greatly appreciated.


As I said, the board is running the current code fine. 

That only requires that the 328P chip to be functional and the board has power. To upload new code requires the on board USB serial converter chip to be functional, and that is apparently what isn't working on your board.



Is there a way to test if that is the case, or to fix/replace that component, or am I stuck buying a new board?

Nick Gammon

Run the loop-back test (see sticky).

Also you can always program it via the ICSP header if you have damaged the USB chip.


Run the loop-back test (see sticky).

I am trying to do this, but am stuck at step 7. "Connect the terminal application to the serial port for your board.  The baud rate is irrelevant."  How do I connect the terminal to the serial port when the computer already doesn't recognize the serial port?

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