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Re: [avr-libc-dev] noinitdata section ?

From: Theodore A. Roth
Subject: Re: [avr-libc-dev] noinitdata section ?
Date: Tue, 27 Aug 2002 20:52:25 -0700 (PDT)

On Wed, 28 Aug 2002, daniel_laptop wrote:

:)I am talking about external device battery backed SRAM
:)(or nvram - www.simtek.com
:)- www.zmd.de   http://www.zmd.de/nvsram_overview.html  )
:)That can be programed once by itself and then normal runtime changes
:)and if flash MCU software upgrade still keep data.
:)eg counter of something since board installed.
:)(to many changes for normal eeprom).

Seems to me if you map the nvram into the external sram space (which you 
almost have to), then you would not have problem. The chip erase 
functionality is implemented internally in the avr's and shouldn't to my 

In the worst case, couldn't you mmap a latch byte into the external space
which disables the sram on a reset or powerdown and then gets renabled after
the standard initial? Maybe in the .init8 section? You might even be able to
disable latch in .init0. Of course, this would probably mean external 
circuitry, so it isn't as nice as a software solution.

I wonder if you could find some voodoo or incantantion to place in one of 
the .initN sections which would do want you want. Hmmm...

Ted Roth

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