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Re: [avr-chat] avrdude : chip not responding

From: gouy yann
Subject: Re: [avr-chat] avrdude : chip not responding
Date: Fri, 2 Sep 2005 10:28:29 +0200 (CEST)

Hi all,
Hi Vince,

if you need to discuss your problem, just send me a private mail and I'll give
you my phone number.
It seems to me you're quite capable in electronics but, by "retour
d'expérience", I know simply speaking and describing your system to someone
else can greatly help finding your problem.

I consider my self lucky as my ATmega32 runs at the very first time with a 70cm
long cable.


--- Vincent Trouilliez <address@hidden> a écrit :

> Hi Joerg, Erik and Brian,
> Thanks for all the suggestions, 8AM here, a new day of debugging is
> about to start ! ;-)
> I looked at the SCK line and it seems that qavrdude clocks the chip at
> about 125KHz, so hopefully I won't need to use a 20cm cable ?!
> I mean, the parallel port is obviously BEHIND the computer case, so I
> need at the very least 75cm of cable so I can at least put the AVR board
> in front of the computer case.
> Anyway, yesterday I looked at the signals sent by avrdude withOUT the
> avr being connected at all (removed from its socket...), thanks to the
> -F option, and the shape of the signal on the MOSI line was truly
> disastrous, and I could as disastrous signals on the MISO line ! But
> avrdude isn't supposed to dirve the MISO line right ? It's 100%
> dedicated to the AVR chip, right ? So if I see ANYTHING on this line,
> then it has to be the MOSI and/or SCK lines that "pollute" the MISO
> line... right ? So I guess my cable and/ord board arer not very clean !
> Sadly I don't have any chemical product to clean teh soldering
> "residues"...
> I am getting tired of seeing crap signal, so I will unplug the cable,
> and look at the signal stragiht from the parport connector of the PC,
> using just two tiny bits of wires to help the scop's probe get in the
> pin holes. If the signal aren't perfectly/decently square at this
> point... :-/
> I am thinking of adding Schmitt trigger buffers, but I have only TTL
> (74LS), chips and at 125KHz, with no load or at a light (150Kohms)
> resistive load, the high-level is nearer 4V than 5V, so I am unsure if
> the AVR will reliably (if at all !) consider this as a valid signal !
> Worse case, it will damage the input ! :-/
> Must check the datasheet again...
> Anyway, 8:15AM, a new day of debugging is now about to start...
> Regards,
> --
> Vince
> _______________________________________________
> AVR-chat mailing list
> address@hidden
> http://lists.nongnu.org/mailman/listinfo/avr-chat


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