How do you change the program counter (PC)

How do you change the program counter (PC)

[Jason Park]

hi, I've got another simple question... but couldn't find an answer in the
archives.

I just compiled the ppcboot for the ep8260.. and placed the .bin version at
location 0xffc00000.

i have the planetcore bootloader that came with the ep8260 at location
0xfff00000.

now, i want to test and check whether the ppcboot loader will work properly
before i overwrite the planetcore bootloader code.  how can i change the PC
(which states 0xfff0 0100 when i type "info" at the BDI prompt)...

also, whats the main difference between the 3 files created by ppcboot.
(ELF, BIN, SREC)  besides size..  is there an advantage/disadvantage using
one over the other?  is it dependant on the debugger?

thanks,
Jason P.


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Re: How do you change the program counter (PC)

[Shen Rong]

> now, i want to test and check whether the ppcboot loader will work properly
> before i overwrite the planetcore bootloader code.  how can i change the PC
> (which states 0xfff0 0100 when i type "info" at the BDI prompt)...
go 0xffc00100
or
ti  0xffc00100


> also, whats the main difference between the 3 files created by ppcboot.
> (ELF, BIN, SREC)  besides size..  is there an advantage/disadvantage using
> one over the other?  is it dependant on the debugger?
ELF: portable binary format, which has program headers/sections and others
information. You can't excute the ELF file directly. It needs intepreter(or named
loader) to load it to proper memory address. BDI can do it. But remember not to
program it to flash for excuting directly.

BIN: pure binary format, which has nothing but cpu instrctions(and data). If you
want to program it to flash, it's the proper choise.

SREC: (I am not much sure) It seems an old format used mostly by motorola.
It's like BIN format, but has other information used for downloading. It seems
some bootloaders need SREC format for downloading.

Don't trust me. For ELF & SREC, you can download the specification if you do
have interesting, and for BIN file, you do can disassemble it if you really want
to know what's in it (of course, ELF format is the best choise for disassembling).

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Re: How do you change the program counter (PC)

[Jason Park]

> go 0xffc00100
> or
> ti  0xffc00100

starting address for flash is 0xff00 0000 where there is a hardware reset
word .  even when i type in "go 0xffc00100", it still jumps to the part in
the flash where the embedded planetcore bootloader is stored (0xfff00100).
so, i decided to delete the hardware reset word... and now BDI cant even
connect to the target, as i get this output:

*** TARGET: resetting target failed
# PPC: unexpected response from target
- TARGET: target will be restarted in 10 sec
- TARGET: processing user reset request
- BDI asserts HRESET
- Reset JTAG controller passed
- Bypass check: 0x55 => 0xAA
- Bypass check: 0x55 => 0xAA
- JTAG exists check passed
- Target PVR is 0x00810101
- COP status is 0x05
- Check running state failed
- TARGET: Target PVR is 0x00810101
*** TARGET: resetting target failed
# PPC: unexpected response from target
- TARGET: target will be restarted in 10 sec

and it goes on and on... having some major regrets about deleting that
hardware reset word...  now i cant even connect to the embedded board.


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Re: How do you change the program counter (PC)

[Shen Rong]

> starting address for flash is 0xff00 0000 where there is a hardware reset
> word .  even when i type in "go 0xffc00100", it still jumps to the part in
> the flash where the embedded planetcore bootloader is stored (0xfff00100).
You should make sure that your ppcboot is linked to another address (not
the 0xfff00000), where your new ppcboot is located(whether in RAM or FLASH).
Change TEXT_BASE in your board directory to what you want. Be sure your
CFG_MONITOR_BASE is set to TEXT_BASE or hard coded to the same address.

> so, i decided to delete the hardware reset word... and now BDI cant even
> connect to the target, as i get this output:
No!!! Contact your HW engineer to help you to reprogram the HRCW.
Or if you are luck, and if your board had a switch to control /RSTCONF, you
can let 8260 use the default setting, and use the BDI program the HRCW.

> and it goes on and on... having some major regrets about deleting that
> hardware reset word...  now i cant even connect to the embedded board.
Good luck!


Shenrong

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Re: How do you change the program counter (PC)

[Kenneth Johansson]

On Fri, 2003-01-24 at 04:02, Shen Rong wrote:
>
> SREC: (I am not much sure) It seems an old format used mostly by motorola.
> It's like BIN format, but has other information used for downloading. It seems
> some bootloaders need SREC format for downloading.
>

SREC is more or less the same as a BIN file but it has an address and
checksum so it would be much smaller if you want to put a byte at 0 and
one at 100000 and you can be sure that is is correctly transfered.

--
Kenneth Johansson
Ericsson AB                       Tel: +46 8 404 71 83
Tellusborgsvägen  94              Fax: +46 8 404 72 72
126 25 Stockholm                  ken@switchboard.ericsson.se


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RE: How do you change the program counter (PC)

[erik.teose]

> > SREC: (I am not much sure) It seems an old format used
> mostly by motorola.
> > It's like BIN format, but has other information used for
> downloading. It seems
> > some bootloaders need SREC format for downloading.
> >
>
> SREC is more or less the same as a BIN file but it has an address and
> checksum so it would be much smaller if you want to put a
> byte at 0 and
> one at 100000 and you can be sure that is is correctly transfered.

A big difference is that SREC is full ascii, which means lots of
bytes of overhead, which means longer transfer times if you're loading
via rs232.

Erik

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