Adaptation of Peter Dannegger's AVR bootloader for Linux
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This is an adaptation of Peter Dannegger's fine AVR Bootloader (Fastboot) for Linux and WinAVR.

New in Build #22

The entire configuration has been moved into Makefile. You don't need to go into another file anymore to adapt the bootloader to your configuration.

Quick Start (Linux)

Edit the marked section at the beginning of the Makefile. There are comments with every topic which should be enough to get you started. Note that the CPU frequency is now defined in Makefile, not in fastload.h as with the original, as well as the MCU type. So don't change anything in the other files even if the comments say so.

Then add the file which you named in Makefile into the current directory. See the Makefile for instructions on how to get at it. (It is needed to create atmel_def.mak.)

Edit the section after that to reflect your transmitter and receiver pins. Make sure none of the include files is selected.

After this is done, simply run make. This creates the output files bootload.elf and bootload.hex (ELF and IHEX format), ready for programming into the AVR's flash.

Quick Start (WinAVR/AVR Studio)

If you're on Windows, consider using the original sources and AVR Assembler. For now, I'll assume you have a some reason not to do so.

Unpack, edit Makefile and add the file as described above for Linux.

Create a new project using AVR Studio. Give it the name 'bootload' (ignoring for now that there is no bootload.c file) and use the fastboot/ directory as project directory. Other AVR Studio options as usual.

In Project->Configuration Options, check the box "Use External Makefile". Press the '...' button to the right and select the Makefile in the above project subdirectory.

Now you can build the bootloader.


See here for the original software (German).

This bootloader speaks a protocol of its own, see Bootloaderprotokoll.txt and thus needs its own PC download software. You can use Boregards FBoot-Linux on Linux and OS X or UpdateLoader (German) on Windows.

Supported devices

There's a list of supported devices in the Makefile, but you shouldn't trust it too much. If your MCU is not in the list, just try nonetheless ;)

There surely are many devices out there running fastboot, but only the following ones were reported back to be working with this version of the software:

  • atmega168
  • atmega32
  • atmega324a
  • atmega328p
  • atmega48
  • atmega8
  • atmega88
  • atmega8515
  • attiny13a
  • attiny2313
  • attiny25
  • attiny84 (use fastboot for attiny85)
  • attiny85

If you succeed in using this version on another device, please open a pull request / issue.


You don't need to be very adventurous to try with other devices, but some familiarity with the tools and with AVRs in general won't hurt and may be needed. Be prepared for some problems to show up. If they do and you have access to a Windows machine to assemble the original, have a look at the Makefile section about the target 'cmp'. It will allow you to compare the original with the Linux version, displaying in more detail where something went wrong.

The directory structure may seem unintuitive. It is a result of the build process: most of the original sources were auto-converted by a script, the goal being to use as few edits as possible in order to ease keeping track with future changes to the original. Readability was definitely not the very first concern during the make of this port - staying as close to the original as possible was the primary intention.


The bootloader 'fastboot' is written by Peter Dannegger.

The Linux adaptation was done by H. C. Zimmerer

Some small tweaks were made by J. Deitmerg (mowfask).


'fastboot' was released under the GPL, so all the derivative work you see here is licensed under the GPL as well (see LICENSE file)