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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: Fri, 29 Apr 2011 11:52:45 +0530

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

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.


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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