Category:Atmega 16U2 firmware
Atmega 16U2 is a general purpose, small, low cost microcontroller from Atmel that has a built-in USB transceiver. It is used as a USB-to-serial converter on Rumba and other RepRap boards so these boards can interface to the world via USB.
In these 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.