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RE: [avr-gcc-list] boot vector address for ATMega32 in datasheet correc

From: Uccelli Danilo
Subject: RE: [avr-gcc-list] boot vector address for ATMega32 in datasheet correct ?
Date: Thu, 18 Dec 2003 10:34:47 +0100

> -----Original Message-----
> From: Ewout Boks [mailto:address@hidden
> Sent: Thursday, December 18, 2003 9:46 AM
> To: address@hidden
> Subject: [avr-gcc-list] boot vector address for ATMega32 in datasheet
> correct ?
> Hello all,
> I converted the AVR230 DES bootloader application to be used with GCC 
> and want to load it into my target, an ATMega32. I need to know (of 
> course) what location I should feed into the linker script to 
> place the 
> bootloader.
> In the datasheet , the application flash is said to end at 0x37ff and 
> the reset vector is said to start at 0x3800 with BOOTZ set to 0 0 .
> I do not understand this, as the ATMega32 has 32K of flash 
> and address 
> 0x37ff is exactly at 16K, ie halfway the application flash of 
> the ATMega32.
> I would expect the bootloader section to start at something 
> like 0x7800 .
> Could someone please shed some light on this ?
> Thanks,
> Ewout Boks


It is depending if you speak about words or bytes, 32K Bytes = 16K words, in
the AVRStudio 4 the address are displayed as word but in the AVR-GCC
makefile the linker parameters have to be expressed as Byte address.

My experience of boot loader is from ATmega64 (64K Bytes), and I used the
following makefile informations: 

        ORG = 0xF000
        LDFLAGS = -Wl,-Map=$(TARGET).map,--cref, --section-start

I hope this help you to understand.

Danilo Uccelli

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