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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: Sat, 30 Apr 2011 14:26:44 +0530

Hi, all,

Well I discovered a solder bridge from a MCU pin to ground.

Probably that was hanging my MCU ? Strange, the 'L' version chip did not hang.

After removing the bridge, the board works with any chip (32/L/A).

Perhaps, this means that the 'L' version chips are more resilient
towards pin current overloads/shorts (only the 'A' chips hung).


On Fri, Apr 29, 2011 at 11:52 AM, Royce Pereira <address@hidden> wrote:
> Thanks, Graham,
> If you're asking "Have you set the CKSEL fuse bits correctly to your
> required frequency ?", Yes I have !
> This is the first check I do if something is fishy - the H & L fuse bytes.
> Usually with wrong CKSEL fuses, only stuff that is timing dependent
> (LCD / USART etc) doesn't work. Rest of the stuff (like a beep when I
> press a key, Relays etc) function, though the timing is out.
> Same with the OSCAL byte, if you forget to initialise it.
> Anyways this is stuff common to both M32L & M32A, & my project (its an
> old project, programmed into many M32L's) works fine in an M32L or
> M16L.
> But this time, like I've said it works only when I disable my
> interrupts, (besides the interrupt / tick dependent stuff).
> I get a stable welcome message on my LCD etc., which was earlier dead
> or displaying garbage.
> The mystery remains.
> --Royce.
> On Thu, Apr 28, 2011 at 11:33 PM, Graham Davies <address@hidden> wrote:
>> Royce Pereira wrote:
>>> With divide by 8 issue, I was not able to
>>> find any suggestion in the data sheet that
>>> the clock is divided by 8 ...
>> Let me assume that you have the latest data sheet, which is Atmel document
>> 8155C-AVR-02/11.  If not, download it.  Now go to page 26 and read the
>> paragraph at the bottom.  Also take a look at Section 8.7 on page 30.
>> It does rather sound as if the fuses affect the actual frequency of the RC
>> oscillator, but it is much more likely that they simply set the division
>> ratio.
>> In any case, it should be clear that the default fuse settings will give you
>> 8 MHz divided by 8 equals 1 MHz.  The suggestion is that you see if this is
>> the source of your problems.
>> Graham.
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