Category:Atmega 16U2 firmware
Atmega 16U2 is a general purpose USB-to-serial converter, that among other live on Rumba and other RepRap boards.
The Atmega 16U2's purpose is to mediate the communication between the PC and the main board microcontroller e.g. ATmega644P, ATmega1284P - and Atmega2560.
A possible substitute could be FTDI chips, but these can not be reprogrammed.