Game Boy Advance Architecture: One Chip to Rule Them All by Rodrigo Copetti

Author:Rodrigo Copetti [Copetti, Rodrigo]
Language: eng
Format: epub
Tags: Nonfiction, Computers, Advanced Computing, Engineering, Computer Architecture, Application Software, Computer Graphics, Computer Science
ISBN: 9798201628505
Amazon: B0B6SSRGPC
Goodreads: 62908908
Published: 2019-08-28T14:30:00+00:00

6 Audio

The GBA features a 2-channel sample player which works in combination with the legacy Game Boy sound system.

6.1 Functionality

Here is a breakdown of each audio component using Sonic Advance 2 as an example:

6.1.1 PCM

Figure 6.1: PCM-only channels. Video available in the website edition.

The new sound system can now play PCM samples, it provides two channels called Direct Sound where it receives samples using a FIFO queue (implemented as a 16-byte buffer).

Samples are 8-bit and signed (encoded in values from -128 to 127). The default sampling rate is 32 kHz, although this depends on each game: since a higher rate means a larger size and more CPU cycles, not every game will spend the same amount of resources to feed the audio chip.

DMA is essential to avoid clogging CPU cycles. Timers are also available to keep in-sync with the queue.

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