Free AVR ATmega Xmega Bootloader - chip45boot2

chip45boot2 is a professional bootloader for Atmel AVR ATmega Xmega microcontrollers with Intel hex file support and automatic baudrate adjustment.

The bootloader automatically adjusts at start to the hosts baudrate, so that it is not necessary to recompile the bootloader to a particular MCU clock. There exist precompiled hexfiles for different controller types and probably different UARTs, which work independently from MCU clock.

PC Software

The chip45boot2 GUI is a comfortable PC/Windows application with a graphical user interface for the bootloader, which simplifies flash and eeprom programming over a COM port. Similar to the precompiled bootloader hexfiles, the chip45boot2 GUI can be downloaded below for free.

Linux Software

In case your desired AVR controller is not listed, write us an Email and we will provide a new hexfile as soon as possible. This service so free of charge for you!


chip45boot2 provides the following functionality

  • directly reads Intel hex files
  • automatic baud rate adjustment
  • XON/XOFF protocol
  • programs Flash and/or EEPROM
  • new: support of RS485 half-duplex communication!!!
  • commands for byte wise reading and writeing of SRAM memory
  • commands for byte wise reading and writeing of EEPROM memory
  • 2kbyte boot block (8k with ATxmega devices)
  • graphical Windows user interface chip45boot2 GUI for comfortable target programming from PC!
If you need a more sophisticated bootloader and easy to customize GUI (Visual C#) also check our chip45boot3 bootloader with fast binary protocol, strong checksum, firmware version check, verify and optional encryption.

Supported AVR Controller

Currently precompiled and ready to use hexfiles exist for the following controllers:

  • ATmega8, ATmega88, ATmega88P, ATmega8515, ATmega8535,
  • ATmega16, ATmega162, ATmega164P, ATmega168, ATmega168P,
  • ATmega32, ATmega324P, ATmega325, ATmega3250,
  • ATmega328P, ATmega3290P,
  • ATmega32U4,
  • ATmega64, ATmega640, ATmega645, ATmega644, ATmega644P
  • ATmega128, ATmega1280, ATmega1281, ATmega1284P
  • ATmega2560, ATmega2561
  • AT90CAN32, AT90CAN64, AT90CAN128
  • AT90PWM216, AT90PWM316
  • ATxmega64a1, ATxmega128A1, ATxmega128A1U
  • ATxmega64A3, 128A3, 128A3U, 192A3, 256A3 (including workaround for mask revision D)
  • ATxmega16A4, ATxmega16A3U, ATxmega32A4, ATxmega128A4U
  • ATxmega64D3, ATxmega128D3


Further informations are available in the Infosheet.


The precompiled hexfiles may be used for either commercial or non-commercial projects and products without limitations.

In case you want to extend the bootloader by own functions or make changes to it, you can buy the sourcecode (for Atmel Studio with AVR GNU Toolchain) in the shop.