Arduino Uno R3 USB is not working I have a problem with my Arduino Uno board. It's not mounting in my Linux machine, but its power is on and the LED light is glowing. It was working before. After I tested buttons with an 12&nbsp;V external supply, I am facing this scenario.

I tried lsusb and I checked /dev/ ports. Also, I couldn't find `ttyACM. I tried with another Arduino board and it's working. I think the board is gone, and I need help to fix this problem.

I thought it was a bootloader problem, and I got a new ATmega328P chip board. It is getting power on and the LED is blinking, but the port is not mounted. I tried with lsusb and also ls /dev/ttyACM* with no result.
You could try to flash the firmware of the USB controller.

General steps for Arduino R3 are:


Put the Arduino in DFU mode (the R3 does not require soldering for that)
Flash the firmware using:

dfu-programmer atmega16u2 erase
dfu-programmer atmega16u2 flash Arduino-usbserial-atmega16u2-Uno-Rev3.hex
dfu-programmer atmega16u2 reset


The package "dfu-programmer" is most likely available for your distribution.


If you have to build it from source, because your DFU programmer does not know the ATmega16U2 yet, you will need to install libusb-dev (on Debian-based systems).

Useful links for that:


Resetting your Uno R3's default firmware
Updating the Atmega8U2 and 16U2 on an Uno or Mega2560 using DFU


A useful search term for that is Arduino R3 DFU-programmer.