Fetching the code from the Atmega chip


My question is a bit deliciously weird. Some weeks ago I uploaded a sketch(code) into the Arduino’s micro-controller. Now I need the code but i cannot remember and find the file in my PC.

I know that was the last code I uploaded and it is in there.

Is there a way to take it out?


This is a good question. I would be interested in knowing the answer to this as well.

You can take it out but it's post compiled, ie unintelligible.

The closest you can get is the disassembled machine code, which looks like this:

    f2d4:	85 e1       	ldi	r24, 0x15	; 21
    f2d6:	92 ee       	ldi	r25, 0xE2	; 226
    f2d8:	60 e0       	ldi	r22, 0x00	; 0
    f2da:	0f 94 c2 f1 	call	0x3e384	;  0x3e384
    f2de:	c8 01       	movw	r24, r16
    f2e0:	aa 27       	eor	r26, r26
    f2e2:	bb 27       	eor	r27, r27
    f2e4:	0f 94 11 f2 	call	0x3e422	;  0x3e422
    f2e8:	bb 27       	eor	r27, r27
    f2ea:	a1 2f       	mov	r26, r17
    f2ec:	90 2f       	mov	r25, r16
    f2ee:	8f 2d       	mov	r24, r15
    f2f0:	0f 94 11 f2 	call	0x3e422	;  0x3e422
    f2f4:	8e 2d       	mov	r24, r14

Not particularly useful unless you are an assembler guru.

I would be doing a “find files” for files ending in .pde or .ino and see if you can find that file.

hi nick,

what kind of method is used to reach the machine code? i mean basically.

Assuming you are using the USBtinyISP programmer (if not, modify to suit):

avrdude -c usbtiny -p m328p -U flash:r:myfile.hex:i
avr-objdump -j .sec1 -d -m avr3 myfile.hex > myfile.asm

That reads in the flash memory to myfile.hex, and the second line disassembles it into myfile.asm.