Ogg+RTEMS on GameBoy Advance was Re: RTEMS device driver andinterrupt

[Lou Woods]

>>Pretty easy design if anyone is interested.

Very interested.  How easy is it?  I am still very green.  You have to
design and fab a pcb, right?  How hard would it be to interface with the
bus system on the GBA?  How would you get around the hardware
limitations of the GBA sound chip? 


Lou Woods
Computer Engineer
OAR Corporation
(256) 722-9985
Lou.Woods at OARCorp.com
www.OARCorp.com


-----Original Message-----
From: Glenn West [mailto:gwest at nano-storage.com] 
Sent: Monday, April 15, 2002 8:49 PM
To: rtems-users at oarcorp.com
Subject: Re: Ogg+RTEMS on GameBoy Advance was Re: RTEMS device driver
andinterrupt


Thinking out of the box.

Take a off-the-shelf MP3 decoder. (Quite a few nice ones
with small die/package, combine it with a SD Slot (Very small), a 64K
SRAM, and a small cheap fpga.

You can either play thru the existing sound, or better put
the codec local, have high quality. Also could have extra
rom images in the SD card.

Now you can stream the audio, and do nice
images at the same time. (Might even be able
to display some nice personal photos as well
on the LcD.)

Pretty easy design if anyone is interested.


At 04:17 AM 4/13/2002, you wrote:


>Craig Graham wrote:
> >
> > On Friday 12 April 2002 8:28 pm, you wrote:
> > > Mike Panetta wrote:
> > > > On Fri, 2002-04-12 at 11:32, Joel Sherrill wrote:
> > > > > Mike Panetta wrote:
> > > > > > Thinking GBA are we?  An ogg player for the GBA might be 
> > > > > > pretty
> neat.
> > > > > > Esp if it had some sort of visualization like winamp or 
> > > > > > whatnot.
> > > > >
> > > > > Busted.  So the big question now..
> > > > >
> > > > >   Is this a feasible project from a HW perspective?
> > > > >
> > > > > The GBA has 16 Mhz ARM, 32K+256K RAM, <= 256Mb flash, and as 
> > > > > best I can tell 8 bit stereo.  I know the sound won't please 
> > > > > an audiophile but is this doable given the HW limitations.
> > > >
> > > > I think we would need to have your previous question answered 
> > > > first, before we could make any educated guesses on that.  I 
> > > > myself do not
> know
> > > > much about the ogg format to guess :).  As for ram, I bet it 
> > > > would not be too hard to add some external ram where the flash 
> > > > would normally be. You would just need some sort of burst 
> > > > counter and address demux in an external CPLD I think.  The only

> > > > thing I can think of that would
> prevent
> > > > it would be if the GBA disalowed writes to the ROM address 
> > > > space.  The burst counter and demux would be needed to interface

> > > > flash anyways if I read the schematics right on the pages I 
> > > > looked at, so its not much added effort.  I do know about the 
> > > > RAM space that the GBA cartrage has, but it would only allow you

> > > > to add an additional 64K of ram IIRC, which would not be 
> > > > significant (or would it?  I guess we would need to know buffer 
> > > > size requirements to figure that one out).
> > >
> > > I would prefer to be able to stick to off-the-shelf flash 
> > > cartridges for the GBA.  So even preprocessing files to a "game 
> > > boy audio" format on the host side would be OK by me if it made 
> > > processing easier on the GBA side and did not explode the size of 
> > > the files.
> >
> > I don't think you'll manage to play ogg files on GBA.
> >
> > Reasoning:
> > It took almost the entire processing power of a Playstation1's R3000
> core to
> > play an MP3. MP3 & Ogg have roughly the same processing requirment. 
> > The PS1's R3000 was clocked at 30MHz, which is a fair bit faster 
> > than a
> 16MHz
> > ARM. QED, it won't work.
>
>:(  Well that sounds like we are going to have to look at 
>"preprocessing" files on the host side and only giving the GBA 
>something lighter.  I guess
>the next step in the "feasibility study" is to see how the size of an
>Ogg or MP3 file compares to the raw bit stream required to drive the
>sound chip on the GBA.
>
> > Of course, if you prove me wrong I'm first in the first in the queue

> > to
> stick
> > it on my GBA ;)
>
>:)
>
> > Craig.
> > --
> > Craig Graham <craig at data-uncertain.co.uk>
> > Technology is like a war fought with symbols, words and gestures
> > - all you have to lose is everything, so trust no-one...
>
>--
>Joel Sherrill, Ph.D.             Director of Research & Development
>joel at OARcorp.com                 On-Line Applications Research
>Ask me about RTEMS: a free RTOS  Huntsville AL 35805
>Support Available                (256) 722-9985