Re: [openwince-list] Adding support for MPC82xx

[Jeff C. <jc...@li...>]

On 07/20/05 11:20, Marcel Telka wrote:
> On Tue, Jul 19, 2005 at 07:27:08AM -0700, kacham ashok wrote:
> 
>> I want to add the support for mpc8241 to jtag tools(
>>jtag-0.5.1). I have got BSDL file for mpc8241. what
>>are the steps needed for it.
> 
> 
> Please read mailing list archives. The steps were described there.
> 

What are the limits to what can be done with the PPC chips via the jtag
interface.

The powerpc chips are usually programmed with the BDM port. Can anything
really be done via the JTAG port? Has anyone been able to program
registers or setup SDRAM/SRAM or anything like that?

I'd like to try to do it; if I knew it was theoretically possible. If
one was able to sucessfully program the chip select registers on the
82xx processor, then you might be able to write firmware into ram and
execute it.

Then again, this seems more like some sort of unrealistic dream.

For instance, I wonder about what these commands would do on a ppc cpu:
peek          read a single word
poke          write a single word

Would that really write values into the memory space of the ppc cpu?

If so, and you could actually identify the 82xx chip, you could dump out
the cpu internal registers (probably at 0xFFF00000 or something like
that -- read the 82xx manuals). That would be real progress!

Then, if you were actually able to write a value into the cpu register
space you would be getting somewhere -- you might even be able to setup
the external chips on the cpu.

Goodluck,
Jeff