[dorkbotpdx-blabber] rg matrix backpack mind-wipe

[Matt Waddell]

Dear Dorkbot,

Has anyone here tried reprogramming the led matrix backpacks from 
sparkfun?  Are there any particular hoops that need jumping-through?

I'm trying my hand at it, with little success, using a parallel (bsd 
style) reprogramming cable <http://www.bsdhome.com/avrdude/>, and 
avrdude.  I've triple checked the cable, and from all I can tell, it 
seems to be constructed correctly--minor deviation is that I use 470 ohm 
resistors on RESET, MISO, MOSI, and SCK, instead of 1k...

The power source I've been using has been provided by the 5v out of an 
Arduino--hooked up to the vcc and gnd SPI pins of the backpack.  The 
programmer is hooked up to the 10 pin icsp header.

When I attempt to upload my code, avrdude apparently isn't able to 
detect the processor:

me at machine$ avrdude -vvvv -c bsd -E novcc,noreset -p m8 -P /dev/parport0 
-e -U flash:w:somefirmware.hex

...
avrdude: Calibrating delay loop... calibrated to 449 cycles per us
...
bitbang_cmd(): [ AC 53 00 00 ] [ FF FF FF FF ]
avrdude: AVR device not responding
avrdude: initialization failed, rc=-1
          Double check connections and try again, or use -F to override
          this check.

I can see that the backback is being reset by avrdude, but otherwise 
have no other indication of what's going on...

Anyway, having never attempted to directly flash AVR devices before, I'm 
sort of at a loss as to where to begin debugging this problem :-( Should 
I just break down and get a real programmer, or stick to my guns and try 
and make this rig work?

Has anyone tried this, or perhaps have some words of encouragement?

Thanks,
_matt