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Re: [avr-chat] Strange problem with ATMega32A-PU

From: Royce Pereira
Subject: Re: [avr-chat] Strange problem with ATMega32A-PU
Date: Thu, 28 Apr 2011 20:31:46 +0530

Hi all,

Thanks for your replies.

I got the new chips, but they too showed the same symptoms, So I guess
the original chips were good.

With divide by 8 issue, I was not able to find any suggestion in the
data sheet that the clock is divided by 8. There is also no fuse that
determines this (in both M32L & M32A)

The watchdog is also not enabled at reset ( See below)

I finally disabled the Timer2 (my system tick) interrupt, & put a
while(1) ; after the LCD welcome message (The 'while(1);' does cause a
reset, so WD is not started by default).

Now I get the welcome message.

I've compared the interrupt vectors, Timer regisaters etc... no clue
yet. I'll tinker around a bit more...

-- Royce.

On Thu, Apr 28, 2011 at 7:19 PM, Gjermund Stensrud
<address@hidden> wrote:
> Another thing that has changed with newer versions of the AVR chips is the
> Watchdog, it was disabled on reset before. On newer devices it needs to be
> disabled in the beginning of your program. That is if you have a long
> initiation phase.
> I'm not sure about this particular chip, but on the ATmeaga1284p-PU I had
> this problem.
> But I agree, the clock divider fuse is more likely to be the problem.
> - Gjermund
> On Thu, Apr 28, 2011 at 2:37 PM, Graham Davies <address@hidden>
> wrote:
>> Royce Pereira wrote:
>>> Searched the ATMega32A-PU data sheet. No 'CDIV' found.
>> OK, but Dave did write "I seem to recall ...", so he's just pointing you
>> in a direction, not giving you text to search for in the data sheet.  Look
>> in Section 8, System Clock and Clock Options.  You will find that indeed the
>> ATmega32(L/A) parts are shipped with the clock divided by 8, just as Dave
>> said.
>>> Atmels migration from M32 to M32A document says nothing about any fuse
>>> etc.
>> That's because there's no change here.  Maybe Dave wasn't suggesting that
>> there's a change, but rather that there's more to bringing up an ATmega than
>> loading the program.  Perhaps you should compare the fuse settings for the
>> parts that work and the new parts, that don't.
>>> I am suspecting a case of bad ICs.  I'm awaiting delivery
>>> of a couple of M32A's from another source. Will try
>>> those & update the list.
>> I think that would be great.  I hate it when the OP does not post the
>> outcome.
>> Graham.
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