Hi All,

I was being a dumbass the other day, trying to put Darran's USB HID keyboard firmware onto my Arduino Uno using FLIP for windows. The firmware seemed to be working with some demo sketches, but I had to go back and forth between DFU and normal mode, swapping the USB serial & keyboard HID firmware with each change in sketch. Instead of loading the USBkeyboard.hex to the flash buffer, I loaded it to the EEPROM by accident. Ever since, Arduino IDE won't recognize my Uno, listing a bunch of serial, java errors. Any help anyone can provide would be greatly appreciated. Can I somehow get things back to the way they're supposed to be? My Arduino is the SMD version.

Thanks all!


If you have a dedicated avr programmer (highly recommended and quite cheap: usbtiny, see my signature as well…), you can just re-flash the firmware, which is in the arduino folder and named ‘UNO-dfu_and_usbserial_combined.hex’.

This shouldn’t take more than a few minutes - with the right tools.

Thanks for the reply Madworm!

Do you know if there’s a difference between using the ISP you mention versus using FLIP? The reason I’m wondering is that I’ve tried to burn the USB-Serial firmware, but my Uno still isn’t recognized. If the ISP has some advantage in that regard I will look into these.

Thanks again!


I only mentioned the ISP as I was under the impression that uploading using FLIP + bootloader was non-functional.

The main advantage of an ISP is that is usually works, as long as the chip itself is not damaged.