The patch contains unrelated changes to ser_posix.c/ser_win32.c
(different indentation level).  I won't commit these changes.
If anything needs to be changed in those files, please resubmit
that.

Also, what happens if someone e.g. starts terminal mode on
a fastboot device, and tries to use one of the byte-access
functions, or tries a -U flash:r:foo.hex:i (paged read of
entire flash)?

Finally, the page write algorithm has changed meanwhile, the
respective backend functions are now called once per page
rather than on the entire memory region.  Since I don't have
any fastboot-ready target around, I would appreciate if you
could adapt your patch to the new structure.  (I can do it
myself, but it will be a "blind flight".)

Ok, so I will update the patch with documentation changes in the next days. I also think about to change the name of the programmer from 'pedabl' to 'fastboot'. So please wait with the integration of the patch.

At http://www.mikrocontroller.net/topic/73196 and http://www.mikrocontroller.net/articles/AVR_Bootloader_FastBoot_von_Peter_Dannegger exists an implementation of a serial bootloader for a wide range of 8-bit Atmel devices.

The attached patch adds support to program this devices with avrdude over a serial line. It should work on linux and windows. I plan to implement the one-wire mode later.

A complete call for programming might look like:
avrdude -c pedabl -p m8 -P /dev/ttyUSB0 -b 57600 -U flash:w:main.hex -x "reset_cmd=\nR\n" -x "reset_baud=9600"

The last two extended options are optional and are used to automatically reset the device for programming.

The bootloader does not support uploading the program to the pc therefore the verify procedure has to be change in avrdude. To verify a program it has to be sent to the device again but this time the device checks it itself against the flash and returns a status code.