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RE: [avr-libc-dev] Atmega2560

From: Darcy Watkins
Subject: RE: [avr-libc-dev] Atmega2560
Date: Mon, 14 Nov 2005 09:31:20 -0800

Hi David and Uwe,

A while back I did some experiments using an ATmega2561 in an old Kanda
STK300 (after cutting a few traces specific to the ATmega103).

I found that my simple program flashing LEDs, some from a background loop
using delay macros, and others from a timer interrupt, would work after
programming the flash using the AVRISP.  But when the unit would be powered
down and then back up, the program misbehaved.

Like you, I compiled for ATmega128 and then used very careful code to avoid
generating incompatible machine code.  I avoided passing parameters to
functions.  I overrode the initialized data copy and zerofill startup code
and explicitly initialized my static variables during startup.  I made sure
that nothing inadvertently block copies into the expanded register I/O space
(which is what the default startup code for the ATmega128 would do unless
you change the memory addresses).

I haven't pursued it much since and wasn't going to press the matter until I
try the same type of program in assembler.

The symptoms appeared like something was preventing (or messing up) my
initialization of the ATmega timers and the output pins assigned to them.  I
mention this because, perhaps you are experiencing the same type of problem
in relation to initializing your USART.

I don't have a JTAG mkII so I haven't been able to effectively debug the



Darcy L. Watkins             email: address@hidden
Senior Software Developer++  phone: (604) 455-2000
TASC Systems, Inc.           fax:   (604) 888-2712
9415 - 202 Street,           web:   http://www.tascsystems.com
Langley B.C. Canada V1M 4B5

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