I have 2 types of Pro-Micro(as shown here), both 5v, micro-usb, which worked as expected, until, accidentally were flashed as 3.3v using the Arduino IDE.

At first I thought that the fact it stoped working right after, has nothing to do with that error, but since again, did the same mistake, I understand that this is no coincidence.

After doing so, boards seemed to be powered on ( leds are ON ), but are not found under port in the Arduino IDE.

Are they really can be destroyed by such an error ?


Holding RST and GND pins after re-connecting USB, showed it on port menu. needed another such holding, prior to upload.

All good now.


I had the same issue with a promicro wired in to a button box, before i found out that you need to upload a sketch....I know...I`m a noob, I was trying to rename my button boxes board to a Sparkfun board but I think i had 3.3v 8mhz selected instead of 5v 16mhz, as a result my board was not detected under comm ports and gave a driver error, given that...with my board at least there is only an 8 second delay in which you have to select the correct comm device and then upload a sketch, I shortened the process by opening IDE and selecting the board type and left IDE with a black sketch, of coarse this does not allow the board to be detected as a usb device but it fixes the comm port issue, instead of using a fiddly wire jumper i just used a small screw driver to jump the gnd and reset contacts and quickly selected the boards comm port in IDE then upload with out a delay, by the time IDE actually recognizes a device you actually have closer to 3-4 seconds to react....but its doable.

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