Source to UNO USB to Serial Chip

Where could I find the source code to the USB to Serial chip on the UNO?

The board has a nice ICSP header just begging to be used. I would like to enhance the functionality but I don’t want to break anything either.

I would like to be able to do some of the things that the Leonardo can do. Having two separate chips can have it’s advantages. In the old days it was call distributed processing.

Is anyone else doing anything like this?

On a Mac it's:


On other OS's it's probably in a similar directory tree starting with 'hardware'.


Great, I found it in \arduino-1.0.1\hardware\arduino\firmwares\arduino-usbserial

I will look it over.

I assume I can use the tools but not the IDE to edit and build this. The makefile should help.

Has anyone else attempted to enhance the functionality?

Depends one what you mean by enhance. Others have created alternative firmware applications (like HID support).

That is the sort of think I was thinking of. To ADD HID support without losing the existing functionality.