SAA7780 データシートの表示（PDF） - Philips Electronics
部品番号
コンポーネント説明
メーカー
SAA7780 Datasheet PDF : 70 Pages
| |||
Philips Semiconductors
Product Specification
ThunderBird Q3D PCI Audio
Accelerator
SAA7780
Systems that provide DDMA or have the ISA bridge on the primary PCI bus are able to perform SoundBlaster emulation
enabling the operation of legacy DOS based games. The SAA7780 chip provides two 8237 style DMA channels to
perform legacy DMA cycles on selected systems. The same two 8237 channels provide Distributed DMA support as
well. PC/PCI is also supported to provide legacy DMA support on chipsets that support said protocol.
DirectSound acceleration, both for 2D and 3D audio along with wavetable sample fetching, is accomplished using the
SAA7780 chip PCI 2.1 bus master. This bus master provides the means for the SAA7780 chip to accelerate
DirectSound audio streams as well as fetch wavetable samples for the 64 voice wavetable synthesis and effects
algorithms. Wavetable sample fetching is always retrieved from system memory saving the cost of an external
wavetable ROM. Downloadable sample sets, with software, are also supported using the bus master hardware.
Additionally, the SAA7780 chip follows the AC97 Architecture to provide high quality audio by the use of a separate
codec. Serial DACs, as well as an AC97 CODEC can be selected to provide audio into the analog world. A serial DAC
is used in case the system designer wishes to use an inexpensive playback converter and does not require a record
function. A codec and a DAC can be used if multi-channel audio is required.
The SAA7780 chip supports additional interfaces to sustain both required and optional features. These interfaces
include a standard 4-axis/4 button joystick, external MIDI port, an SRAM interface for external DSP code or enhanced
reverb, and a 16650 UART for an external modem.
The ActiMedia DSP runs the audio algorithms for wavetable synthesis, FM synthesis, special effects such as reverb
and chorus, along with sample rate conversion and data management. The imbedded DSP core and its peripherals are
managed solely by the DSP and require no intervention from the host. The DSP can pass messages to and from each
domain to provide a host software interface into the DSP domain.
Structural and Functional Overview
The SAA7780 contains components to implement the sound generation with accessories to add value to a gaming type
environment. In short, there are three basic types of blocks to implement all of the advanced features present in this
chip. The three types of blocks are PCI domain, DSP domain and mailbox. The PCI domain type of blocks refer to the
blocks that connect only to the internal and external PCI interfaces. The DSP domain blocks connected only to the DSP
code or data busses. The mailbox type interfaces between both worlds providing both functional and test operations
between the two domains. The following sections will give more details on the function and operation of each block.
PCI Interface, Configuration and Interrupt Serializer
The SAA7780 chip PCI interface is composed of master and slave state machines, an address/data/byte enable
datapath, a bus arbiter for the two on chip masters, control logic for the master and slave internal busses, an interrupt
serializer, and the standard PCI configuration register header.
The standard PCI configuration header is also supported. Since the SAA7780 is a multi-function device, there are three
PCI configuration spaces allocated for each function. The three functions are the audio device, the joystick and the
16650 UART. The purpose of the multiple configuration headers is to ensure PCI compliance and enable the operating
system to select the correct software driver for each individual device. The Serial CFG Port is used to shift in subvendor
specific data for each of the PCI configuration headers. The Serial CFG port is an industry standard I2CTM format. The
configuration headers are included in the PCI interface to reduce inter-block routing. All other PCI configuration space
registers are included in the blocks that utilize these registers.
16650 UART
In order to support an external hardware modem chip set, a 16650 UART is included in the SAA7780 chip. The 16650
UART excludes the need for an additional ISA based UART thereby reducing system costs. The 16650 UART resides
in I/O space and is re-mappable.
1999 Sep 30
11
Share Link: 