The instructions on the Arduino DFU update page are pretty vague when it comes to updating to the latest firmware using the Atmel Flip utility. Here’s what I did to get my Uno 8U2 firmware updated using Windows XP:
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Install Flip from the Atmel webpage. If you don’t already have a JRE, you probably want the 20 megabyte package that includes one.
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Download the 8U2 firmware. That’s the “Arduino-usbserial-uno.hex” file. The “UNO-dfu_and_usbserial_combined.hex” is the Arduino Uno bootloader firmware for the 328p. If you try installing the 328p firmware onto the 8U2 in Flip, you’ll get an error dialog:
class com.atmel.flipGui.FileMenuHandler Address is out of range. -
I ended up cutting & pasting the hex file contents into a text editor because I couldn’t figure out how to download a single file from github, and I didn’t want the whole 200 megabyte wad.
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Hook up wires and touch them to the right spots on the Uno at the right time as described in this Arduino forum post by pluggy.
Update: Pluggy’s image has disappeared. Here it is:
I found it at www.ardumania.es/reflashear-el-8u2/.You’ll know you did it right when Windows detects a new device. It took me a few tries to keep the first wire steady enough when touching the second wire. Make sure you’re going to the right pads - you could short out your Uno if you touch the wrong place!
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After Windows detects the new device, you don’t have to hold the wires in place any more. Move them to the side so you don’t accidentally short out something.
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When the Windows device installer comes up, select “have disk” and install the Atmel USB driver. By default the Atmel USB driver is installed in C:\Program Files\Atmel\Flip 3.4.2\usb\atmel_usb_dfu.inf
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Notice that the driver is AT90USB82, not ATmega8U2
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Although it tells you that you have to reboot XP when you install the driver, I didn’t bother.
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Start Flip from the Program menu
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File->Load HEX file->Arduino-usbserial-uno.hex
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Device->Select->AT90USB82
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Settings->Communication->USB and press Open
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At this point, you should be ready to program. Press the “Run” button on the main screen.
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Programming is quick, taking about 4 seconds. After it’s done, remove the two wires you put in earlier, then unplug the USB cord and reinsert it.
Once you’ve done that, your Uno should be out of DFU mode and back into normal mode.
You can go to My Computer->Manage->Device Manager->Ports (COM & LPT), right-click on “Arduino UNO” and select “Properties”. Under the Details tab, Firmware Revision should now be 00.01.
Update: Someone mentioned they couldn’t find the atmel_usb_dfu.inf file. Looks like there’s a copy here.