Description
The 8bits mega AVR with USB interface devices are factory configured with a USB bootloader located in the on-chip flash boot section of the controller.
This USB bootloader allows to perform In-System Programming from an USB host controller without removing the part from the system or without a pre-programmed application, and without any external programming interface.
This document describes the USB bootloader functionalities as well as the serial protocol to efficiently perform operations on the on chip Flash memories (Flash and EEPROM).

FEATUREs
• USB Protocol
   – Based on the USB DFU class
   – Autobaud (8/16 MHz crystal)
• In-System Programming
   – Read/Write Flash and EEPROM on-chip memories
   – Read Device ID
   – Full chip Erase
   – Start application command
• In-Application Programming
   – Software Entry-points for on-chip flash drivers