Reprograming the Mega16U2

Using Arduino IDE 1.x
1

I need to try reprogramming the firmware for the Usb chip on my Arduino, if that doesn't work I am going to try to change it, need the smd practice. Then it will need programming.
Will a TinyISP work for hardware?
In Windows will Avrdude work thru the Arduino IDE like for a 328, or do I need WinAVR also.
I found the latest firmware, but it is a Hex file (I think). Looks like a bunch of garbage numbers, had to open and then cut and paste,
no download provided. I'll keep trying to find the right file.
I have about $5 in repairing this board including the Mega16U2, so I don't want to spend more than necessary, but everyone needs an ICSP programmer, right?
Any info or links to such problems would be greatly appreciated.
Thanks
TomJ

Edit,
If I pulled the Atmega16U2 completely out of the board could I hook up the RX, TX, Grnd, Power, and reset pins from my FTDI friend to program the 328, just like a breadboard setup or Boarduino?
Just wonderin'.
Thanks again
TomJ

2

This is what I found so far (on a Mac - on Windows the paths will be a bit different):

I have a Uno Rev 3, so the Atmega16U2 has a 6-pin ISP breakout plug-thing on it. So that's a start.

I plugged my USBtinyISP into this header, and tried this:

avrdude -c usbtiny -v -p m328p

Got this response:

avrdude: Device signature = 0x1e9489
avrdude: Expected signature for ATMEGA328P is 1E 95 0F

So, wrong signature, which I expected. So I needed to find the chip code for the signature 0x1e 0x94 0x89. That was not in my avrdude.conf file. You can test by trying this:

avrdude -c usbtiny -v -p m16u2

I got:

avrdude: AVR Part "m16u2" not found.

A bit of a Google search, and I turned up this patch:

http://www.nmj.sumomo.ne.jp/suz-avr/USB162/avrdude-5.8-confu2.patch

Who knows if it is the right one?

However inside that file was this:

+#------------------------------------------------------------
+# ATMEGA16U2
+#------------------------------------------------------------
+
+part
+    id               = "m16u2";
+    desc             = "ATMEGA16U2";
+    has_jtag         = no;
+    has_debugwire    = yes;
+    signature        = 0x1e 0x94 0x89;

(Note: that isn't the complete file - you have to download it).

Looks like the right signature, and the right part number.

I found my avrdude.conf file here:

/usr/local/CrossPack-AVR-20100115/etc/avrdude.conf

Changing to the directory /usr/local/CrossPack-AVR-20100115/etc/ I tried to patch it, as follows:

cp avrdude.conf avrdude.conf.orig  # make backup!!!
patch < avrdude-5.8-confu2.patch  # patch file

That gave this:

can't find file to patch at input line 4
Perhaps you should have used the -p or --strip option?
The text leading up to this was:
--------------------------
|diff -ru avrdude-5.8/avrdude.conf.in avrdude-5.8-wk/avrdude.conf.in
|--- avrdude-5.8/avrdude.conf.in	2010-12-06 13:47:47.000000000 +0900
|+++ avrdude-5.8-wk/avrdude.conf.in	2010-12-06 13:49:52.000000000 +0900
--------------------------
File to patch:

I replied: avrdude.conf

Got this:

File to patch: avrdude.conf
patching file avrdude.conf
Hunk #1 succeeded at 12785 (offset -383 lines).

Tried to read the chip again:

avrdude -c usbtiny -v -p m16u2

Got:

Reading | ################################################## | 100% 0.01s

avrdude: Device signature = 0x1e9489
avrdude: safemode: lfuse reads as EF
avrdude: safemode: hfuse reads as D9
avrdude: safemode: efuse reads as F4

avrdude: safemode: lfuse reads as EF
avrdude: safemode: hfuse reads as D9
avrdude: safemode: efuse reads as F4
avrdude: safemode: Fuses OK

avrdude done.  Thank you.

So far so good. It recognized the chip and gave me the fuses.

Now to read the existing flash:

avrdude -c usbtiny -p m16u2 -U flash:r:usb_chip.hex:i

Success! ...

avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.01s

avrdude: Device signature = 0x1e9489
avrdude: reading flash memory:

Reading | ################################################## | 100% 30.30s

avrdude: writing output file "usb_chip.hex"

avrdude: safemode: Fuses OK

avrdude done.  Thank you.

Convert to machine-readable:

avr-objdump -j .sec1 -d -m avr3 usb_chip.hex > usb_chip.asm

Edit that:

usb_chip.hex:     file format ihex


Disassembly of section .sec1:

00000000 <.sec1>:
       0:	90 c0       	rjmp	.+288    	;  0x122
       2:	00 00       	nop
       4:	a9 c0       	rjmp	.+338    	;  0x158
       6:	00 00       	nop
       8:	a7 c0       	rjmp	.+334    	;  0x158
...
     122:	11 24       	eor	r1, r1
     124:	1f be       	out	0x3f, r1	; 63
     126:	cf ef       	ldi	r28, 0xFF	; 255
     128:	d2 e0       	ldi	r29, 0x02	; 2
     12a:	de bf       	out	0x3e, r29	; 62
... blah blah

And further down after a lot of FFs:

    3000:	4b c0       	rjmp	.+150    	;  0x3098
    3002:	00 00       	nop
    3004:	64 c0       	rjmp	.+200    	;  0x30ce
    3006:	00 00       	nop
    3008:	62 c0       	rjmp	.+196    	;  0x30ce
...
    3098:	11 24       	eor	r1, r1
    309a:	1f be       	out	0x3f, r1	; 63
    309c:	cf ef       	ldi	r28, 0xFF	; 255
    309e:	d2 e0       	ldi	r29, 0x02	; 2
    30a0:	de bf       	out	0x3e, r29	; 62
    30a2:	cd bf       	out	0x3d, r28	; 61
    30a4:	11 e0       	ldi	r17, 0x01	; 1
    30a6:	a0 e0       	ldi	r26, 0x00	; 0

Looks like something. And is that a bootloader at the bottom? Who knows?

Now if you have a replacement .hex file (eg. firmware.hex in my example), you should be able to flash it like this:

avrdude -c usbtiny -p m16u2 -U flash:w:firmware.hex

The new firmware file should look something like this inside:

:2000000090C00000A9C00000A7C00000A5C00000A3C00000A1C000009FC000009DC00000DB
:200020009BC0000099C0000097C0000048C400000CC4000091C000008FC000008DC00000EC
:200040008BC0000089C0000087C0000085C0000083C0000081C000007FC0000002C10000FA
:200060007BC0000079C0000077C0000075C0000073C0000071C000006FC000006DC00000E0

Don't blame me if this goes wrong, but this is a pointer to the direction you might take.

3

(deleted)

avrdudepatch.zip (1.82 KB)