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Re: Fw: [avr-gcc-list] placing a variable in flash

From: Sean Casey
Subject: Re: Fw: [avr-gcc-list] placing a variable in flash
Date: Mon, 22 Nov 2004 12:25:09 -0800
User-agent: Mutt/1.3.28i

I wish I could find all the beginner stuff like this in one place.
There should be an O'Reilly book!

E. Weddington <address@hidden> said...
> Royce & Sharal Pereira wrote:
> >
> >================================================
> > 
> >
> >>Wouldn't the variable be better off stored in the EEPROM and not in
> >>Flash (Program Memory)?
> >>   
> >>
> >-------------------------------------------------------------------------
> >Is there some advantage of that as compared to storing it in flash?
> >Anyways, is it at all possible to fix a variable at a predetermined 
> >location
> >in flash ?
> >
> > 
> >
> Here are just two advantages:
> 1.  Endurance.
> For example, the mega128 data sheet specifies that the Flash has 10,000 
> read/write cycles. It specifies the EEPROM has 100,000 read/write cycles.
> 2. Ease of use.
> Reading and writing the EEPROM is easy especially for small values, 
> because each byte can be erased. While reading Flash is easy, it is more 
> complicated to write to Flash because you have to erase and write a 
> block of data at a time, which means you need to flush the contents of a 
> Flash block to a RAM buffer, erase the block and write the block with 
> the new contents.
> The EEPROM is *designed* to hold values that must persist between power 
> cycles. The Flash was designed to hold your program, not data.

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