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Have you looked at this page? Has lots of info on it.
http://www.reinerziegler.de/GBA/gba.htm#How%20does%20the
Anyway, my understanding is that the high 8 bits of the address coming out of the GBA are always valid, since they are not multiplexed. So you can have counters on the whole 24 bits if you want, or just have counters for 16 bits and read the other 8 bits from the address lines on every access, either should work.
Perhaps you could give us some more detail on what exactly you are trying to do? And you might want to look at the DS as well, it has a lot more power & features, and still has the GBA cart interface.
-David R
http://www.reinerziegler.de/GBA/gba.htm#How%20does%20the
Anyway, my understanding is that the high 8 bits of the address coming out of the GBA are always valid, since they are not multiplexed. So you can have counters on the whole 24 bits if you want, or just have counters for 16 bits and read the other 8 bits from the address lines on every access, either should work.
Perhaps you could give us some more detail on what exactly you are trying to do? And you might want to look at the DS as well, it has a lot more power & features, and still has the GBA cart interface.
-David R
On Sat, Sep 6, 2008 at 9:51 AM, dreamflighter78 <simnav@...> wrote:
Hi to everybody,
I'm new here but I'm studying how to "bend" GBA to use it for
something different from gaming. I'm trying to understand how
sequential memory access works: I readed that firstly a non sequential
access is needed, lower 16 bits of address are put on AD0-AD15 and
latched into a counter keeping /CS low while higher 8 bits of address
are direcly put on A16-A23 then when /RD goes low, data out from flash
and it is latched by GBA on /RD rising edge. The doubt is what happens
in sequential access: /CS should remain low when /RD goes high, this
will increment by one the counter containing the 16 bit lower part of
address but what happens if previous readed address in non sequential
way is for example 0x00ffff ? New address will be 0x000000 !? What's
the mistake ? Pheraps counter have to latch and count all 24 bits ?
Thank you.
Regards,
Simone Navari.
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