SAA7780 datasheet(13/70 Pages) PHILIPS

13 / 70 page

ThunderBird Q3D PCI Audio

SAA7780

Accelerator

Philips Semiconductors

Product Specification

1999 Sep 30

Pro mixer registers. These registers are used as a mailbox to the DSP data bus to deliver data to the SoundBlaster

Emulation code. The SAA7780 chip supports DMA to the Sound Blaster that legacy code requires. All data transmitted

over the SoundBlaster Registers is processed by the DSP to emulate the Sound Blaster Pro hardware.

OPL3 Registers and the FM Accelerator

The OPL3 register interface is a subset of the complete SoundBlaster register set. The OPL3 registers are separate to

point out that the FM legacy is supported at the register level. The OPL3 registers simply pass FM synthesis commands

to the SoundBlaster Emulation code and receive status from the same code.

Virtual Registers

The Virtual Registers interfaces the PCI bus and two substantial wavetable synthesis accelerators: the Sample Fetch

and Address Generation accelerators. The Virtual Registers is responsible for setting up the PCI interface for master

cycles data fetches and retrieving those fetches into a sample buffer. The Virtual Registers get commands from the

Address Generation accelerator and turns them into PCI master requests. Once the data has been retrieved, the Virtual

Sample Fetch Accelerator notifies the Virtual Registers that all is clear and that new data can be processed.

Address Generation Accelerator

The Address Generation accelerator is a preprocessing unit for the sample fetching mechanism inside the Virtual

Registers. The Address Generator will get a set of parameters from the DSP code on a per voice basis for either

DirectSound processing or wavetable synthesis. Once these voice parameters are set, the hardware is instructed to

translate the addresses and fetch the audio samples from system memory. The Address Generator is also capable of

looping with intervention from the DSP code. The DSP kills voices by instructing the Address Generator to stop fetching

data. Once the samples are fetched, they are stored in the Virtual Register’s input sample buffer for processing by the

Sample Fetch Accelerator.

Sample Fetch Accelerator

The Sample Fetch accelerator is used to process audio samples fetched by the Virtual Registers and deliver them to

the DSP code for further processing. This processing can include pitch shifting or rate conversion. The degree of pitch

shifting is under direction of DSP code indicating the Sample Fetch accelerator is programmable. The input samples

are taken from the Virtual Register’s input sample buffer and stored in DSP memory space.

MIDI Registers and UART

An MPU401 compatible UART is supplied to enable external MIDI devices to use the SAA7780 chip synthesizers as

well as its external device’s own synthesizer. The MIDI register interface is used to pass the MIDI command stream

from the host to the DSP firmware for parsing into synthesizer commands. The MPU401 UART always operates in

“dumb”mode. Both the PCI and DSP can access the MIDI UART directly. Data is presented from/to the MPU401

Registers in a mailbox fashion to the MPU401 UART.

Music DAC Interface

The music DAC interface allows for an inexpensive, high quality, playback of the final stereo mix or for providing the

unique QUAD feature when used in conjunction with the standard AC97 V1.03 CODEC. The interface is a standard

EIAJ format supporting many brands of inexpensive 16 bit DACs. The Music DAC interface is capable of playback

sample rates from 22.05 - 48.0 KHz.

SAA7780 датащи(PDF) 13 Page - NXP Semiconductors

SAA7780 датащи(HTML) 13 Page - NXP Semiconductors

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70

датащи скачать

ссылки URL