How do I back up the firmware of the Atmega32U4?

[Spaceless]

I have a 68-key keyboard, the main control chip is Atmega32U4(Like GH60), the PCB is made up of a column of GH60 motherboard but its firmware does not belong to any popular open source firmware, but I want to modify his firmware but I am afraid it can't work. So I want to ask, how do I back up the firmware that has been written in the Atmega32U4 with its bootloader. It is best to back up via a USB connection. Thank you

[algernon]

You do the same thing as if you were flashing with avrdude, but replace the "-Uflash:w:hex:i" part of the commandline with "-Uflash:r:dump.hex:i". For example:

avrdude -v -v -C /etc/avrdude.conf -patmega32u4 -cavr109 -D -P /dev/ttyACM0 -b57600 -Uflash:r:dump.hex:i

As with flashing, you have to put the board into bootloader/programmable mode first.