Re: [ECOS] eb40a target submitted

[Tim Drury <tdrury at siliconmotorsports dot com>]

Another note that I forgot about:

The FLASH on the eb40a is Atmel AT49xxxx which Jani
graciously gave the source code to me.  The AT49 FLASH
is divided into two planes (smaller A and larger B).  Because
the drivers assume equal sized sectors I simply ignored the
A plane.  This is a large FLASH device and plane A is pretty
small - besides Angel is burned into it.

This has a side effect.  Assume the FLASH is mapped to
0x01000000.  Plane A goes up to 0x01010000 -1 bytes
so I told the driver that this section is unusable.  When you
load redboot_ROMRAM into 0x01100000 (the upper half
of flash), you cannot have it load a new version of redboot
on top of itself like you can with the EB40 and its more sane
FLASH.  This is because when the redboot_ROMRAM is
mapped down to 0x01000000 by setting the onboard jumper,
you cannot tell the redboot running in RAM to burn the new
redboot image file into 0x01000000 because the driver considers
that address unusable.

So if you want to load a new version of redboot_ROMRAM, you
have to first load up the RAM version of redboot via Angel,
then run the RAM version of redboot to load the ROMRAM
version of redboot.

Ah well.  Perhaps someone can figure out how to make the
AT49 FLASH work with its differing sector sizes.

-tim


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