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XBoot is an extensible, modular bootloader for the ATMEL XMEGA processor series. It is compatible with the AVR109 (butterfly) bootloader protocol with a few XMEGA specific extensions for access to the user and production signature rows. One of its main features is support for multiple serial busses. Many bootloaders only support RS232 for programming from a PC, but XBoot's modularity allows it to support the exact same set of commands over any hardware serial port. Currently, I²C support has been incorporated. This allows for easy in-system reconfiguration of XBoot equipped chips with little additional time investment. Also, XBoot includes support for I²C address autonegotiation for when multiple, identically configured processors sit on the same I²C bus.


  • Supports all ATMEL XMEGA series processors
  • AVR109 (AVR Butterfly) compatible protocol
  • RS232, RS485, and I²C communication
  • Highly reconfigurable
  • Supports I²C bus address autonegotiation