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Hardware > Question on GBA cartridge pin usage

#11305 - Cerberus - Thu Oct 02, 2003 12:18 am

Hello all. I'm new to these forums, I've found this site through searching for gba hardware info. I'm a computer engineer involved with 2 others on a senior design project. It's chosen by the students what to do for their project, and the 'class' lasts 2 semesters.

Anyhow, enough background for now. :p

I'm curious as to whether or not a GBA cartridge utilizes all of the available data and address pins while connected. Are any idle at any time or does the gba necessitate the use of all of them at all times?

I ask this because our project is to attach small piece of hardware that would allow the gba to play mp3s. I understand this has been done before but as long as we come up with our own design it will be valid. We already have been researching DSPs, etc. Any help/info on this subject would be greatly appreciated. Thanks.

#11335 - torne - Thu Oct 02, 2003 8:39 pm

Whenever you are reading the cart, you use all address and data lines (24 total). You supply the top 16 bits of the address one cycle, then you can throw as many bottom-8-bits as you want at it the next cycles, getting 16 bits of data out each time.

gbatek or the Cowbite spec should explain the functions of the cart pins in much more detail. If you're intending to do MP3 playing using the GBA as a sound output device only (i.e. mp3 storage and decoding on a cart), then you should just be able to pretend to be a cart, set the wait state registers as low as possible, and pull data across from the decoder into a sound fifo with DMA..