I too bought some Arduino Uno R3 from a reputable distributor and got the Arduino.org boards. When those were plugged in, they were not recognized and a serial port was not assigned.
I could have just downloaded the software from Arduino.org, but I do not want to have to install two serial port drivers.
Shows how to reprogram the Usb chip.
Flip must be downloaded from:
But the process was not easy. I got missing dll errors, the boards were not recognized as Arduinos. Finally, I happened onto a procedure that worked. Here it is:
Steps 1…6 are a one time setup
- download and install flip 3.4.7 with java
- go to C:\Program Files\Atmel\Flip 3.4.7\usb\x86 and rename libusb0_x86.dll into libusb0.dll
- copy libusb0.dll to C:\Windows\System32
- plug in the arduino and with the board horizontally so arduino uno can be read, short the two vertical pins on the left of the 6 pin header next to the reset button
- go to the control panel and go to computer management->device manager->Other Devices.
- Right click on ATmega16U2 DFU → Update Driver Software → Browse My Computer → select C:\Program Files\Atmel\Flip 3.4.7\ and subfolders
Steps 7…13 are to be repeated for each arduino.org to be changed to arduino.cc
7 ) Open Flip, click on the first icon on the task bar (the chip), select AtMega16U2
8 ) click on File->Load Hex File → C:\Program Files\Arduino\hardware\arduino\avr\firmwares\atmegaxxu2\arduino-usbserial,
9 ) select Arduino-usbserial-atmega16u2-Uno-Rev3.hex
10) click the second icon (the USB cable), then on Usb (Ctrl+U), then on Open
11) On the Operations Flow block, click on Run (if an error programming the 16U2 is shown, exit flip and launch it again)
12) On the ATmega16U2 block, uncheck “Reset” and click “Start Application” or unplug and plug the arduino.org, it will be detected as an arduino.cc
13) Wait for a serial port to be assigned to this arduino, then unplug it
14) plug the next device and short the dfu pins
13) exit Fip, relaunch it for the next device, sometimes I can jump to step 10 without relaunching Flip
At the end of this procedure, the arduino.org boards with VID 2A03 and PID 0043 Rev_001 will be shown as arduino.cc boards with VID 2341 and PID 0043 Rev_001