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Re: [avr-gcc-list] bootloader

From: Ben L. Titzer
Subject: Re: [avr-gcc-list] bootloader
Date: Thu, 14 Jul 2005 13:11:20 -0700


From within a bootloader (i.e. in-system reprogramming), erasing the flash page is only necessary once before writing it. Make sure you have the boot lock bits set correctly.


On Jul 14, 2005, at 12:36 PM, Torsten Mohr wrote:


browsing through the sources of avrdude, i found that erasing a
chip is repeated up to 5 times until the chips flash is erased.
So the erase command is not only performed ONCE, but up to
five times.

Is the same necessary or useful when from within a bootloader?

Programming bytes seems to be done only once, is that correct?
Does it make sense to repeat the programming of bytes (is that
even possible)?

Best regards,


the bootloader i write at the moment basically works, but i experience the
problem that erasing/programming sometimes fails when programming
with my own bootloader.

When programming via avrdude via the parallel port, all works fine.

So now i wonder if my strategy for erasing/programming is wrong.

1. In the documentation in avr-libc-usermanual-1.2.3 it says
boot_page_erase(page).  It should say boot_page_erase(address),
is that right?

2. I only call erase/program once and i verify the erase/program
directly after that.  Can this be a problem?

What else could be a problem when just using the supplied functions
in avr-libc-1.2.3?  Should it work exactly the same as with avr-dude
via parallel port?

Best regards,

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