--- In Larry Schuler <> wrote:
>
> Hi,
> I've just gotten a ts-7250 and I'm trying to learn about embedded
> programming using the O'Reilly "Programming Embedded Systems"
Book. In
> the book the authors actually use a Viper-lite board, but it's
very
> similar to the TS-7250.
>
> Anyway, I've written a simple C program to flash the LED's, but
I'm
> having some confusion with how it gets loaded on the board,
specifically
> with what is going on with the memory.
>
> I compile the program using gcc fine, then run the linker with a
linker
> script following the procedure in the book. I started off trying
to use
> E000_0000 as the base of the RAM address as referenced in the ts-
7250
> manual, but redboot would complain when I tried to load the
resulting
> program that there was no memory at that address??
>
> Then I realized that redboot prints the RAM location as 0x0-
0x02000000
> when it starts up, so I tried 0 in the linker script, but that
didn't
> work either.
>
> Finally, I tried to use the command "load -v -b %{FREEMEMLO} -m
xmodem"
> and that loaded the program stating the following:
> Address offset =
> 0x40053000
> Entry point: 0x00053100, address range:
> 0x00053000-0x0005318c
> xyzModem - CRC mode, 11(SOH)/0(STX)/0(CAN) packets, 2 retries
>
> I then changed the linker script to use 53000 as the base of the
RAM and
> it works fine, but I'm not sure I understand why it works.
>
> Where does 40053000 come from as the address offset? There is
nothing
> mentioned of a 0x4000000 in the ts-7250 manual.
>
> And what does the ts-7250 manual mean by the definition of:
> 0x0001_0000 - 0x0000_FFFF SDRAM region ???
>
> Thanks for any teachings,
> --larry
>
redboot as it's name suggests is a boot loader . you should not be
trying to load a useland prog with it. Maybe you did not explain too
well what is happening.
look in the files section of the forum (menu top left), there are
plenty of example progs including IIRC one to flash the leds. That
may be of more help than working from a book that covers something
else and try to adapt it to a system to which you are completely new.
HTH
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