You need to find out what flash chips are in the cart, and info about
the custom ASIC in the cart as well.

Usually, you need to access a specific set of addresses to put the cart
into read/write mode. Once that is done, you then can use the
programming sequence for the flash chip. Usually, if there are two
flash chips, they will be interleaved with one doing the top 8-bits and
the other doing the bottom 8-bits. Which means that to program them
successfully, you have to put both chips into write mode.

Most likely, the MBV2 software already supports the flash chip, just
not the ASIC. To find out what you need for that, you will probably
need to disassemble the f2a code that the USB cable uploads to the GBA,
since that's the bit of code that will actually be doing the writing.

dennis

On May 2, 2004, at 2:38 PM, Mike Reid wrote:

> hi john,
>
>> Ironically though, most of the info you can extract from it is about
>> the
>> f2a usb cable, not about the flashing process itself.
>>
> yep, i took a closer look and i would have to agree, there is nothing
> that reveals the flashing process. i'm pretty sure i don't have any
> idea
> how to reverse engineer that, so this might not be possible.
>
> on the other hand, i seem to recall reading somewhere that actually
> writing to flash memory is the same across all carts, so it might be
> that the firmware just does the timing of the serial writes as opposed
> to
> the if2a code, which just dumps the data down the usb cable in
> manageably-
> sized chunks. the code for the timing of flash/serial writes should
> already be accomplished in Jeff's mbv2 code. and since the protocol is
> exposed
> in the if2a code, it might be possible after all.
>
>> A PC file-server for the GBA, whether through serial or USB
>> (provided you have the code to drive the USB cable) can't
>> be that hard to write from scratch ?
>>
> probably not too hard, but why would i want to duplicate work? in
> my estimation, adapting the if2a code to write to a serial interface
> would be easier than writing file-serving code from scratch. (assuming
> the above speculation is true and that it's possible)
>
>> I'de be very interested to hear about what you are doing. For myself,
>> I'd like to try driving the USB cable from a PC program to communicate
>> with the GBA (file-serving and more) so I'm always keen on following
>> what others have done in this domain.
>>
> i'm using the gba as an experimental platform for operating system
> development. so my first project is a from-scratch kernel, with
> pre-emptive multi-threading, a dynamic linker/loader, and other
> "standard" features of modern operating systems.
>
> obviously i can't do memory protection, or virtual memory, but that's
> okay. its actually part of why i am doing this on the gba rather than
> the
> PC--it simplifies things greatly.
>
> if you want to discuss this more, i suppose we should take this off the
> list, as its probably somewhat off-topic.
>
> -mike
>
>
>
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