[En-Nut-Discussion] AT91SAM7X-EK TFTP Bootloader

[Harald Kipp]

Jason Bourne wrote:

> I did this question already but I am still have some doubs.

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> Is the latest release candidate Version 4.8.0 includes the bootloader for the AT91SAM7X-Ek development board? If so, how can I use it? 

Unfortunately not.


> I need to implement the booloader but I am still do not how to program into the internal ROM. If that is not the way, could someone explain me where it is located the bootloader 

This is a bit more complicated than usual. The routine for programming
the Flash cannot run in Flash, but must run in RAM. For this you need a
special linker script, which specifies a RAM function. See
arch/arm/ldscripts/at91_httprom.ld
If you look to
arch/arm/dev/at91_efc.c
you will notice, that the Flash programmer function At91EfcCmd has the
attribute RAMFUNC. The runtime initialization will copy the .data
segment to RAM before calling main. Thus, if the .ramfunc is part of the
.data segment, it will be copied as well.

That's the tricky part about flashing. Beside that, it depends on how
much flash space is available for the bootloader. To keep it small you
should avoid any reference to newlib.

Harald