CMI8787 Datasheet, PDF (7/28 Pages) C-Media Electronics – High Performance PCI Audio Processor

C-Media High Performance PCI Audi o Processor
Oxygen^TM HD CMI8787 Datasheet v0.5
1.2 General Description
The CMI8787 is a high quality PCI 32-bit multi-channel audio processor that can be
built into home audio electronics or personal computers to provide high fidelity sound
playback and processing. It supports up to 12 output channels and 8 input channels. The
12 output channels are composed of 3 playback DMA’s, which are multi-channel DMA
(32 bits, 8 channels, 192k), S/PDIF DMA (32 bits, 2 channels, 192k), and front panel
DMA (16 bits, 2 channels, 48k). The 8 input channels are spread across 3 recording
DMA’s (32 bits, 192k) - recording A, B, and C DMA’s. The architecture of recording is
a unique point of CMI8787 that enables very flexible recording options for the user. The
details of the recording mode selection will be explained in the later sections.
The CMI8787 is compatible with all the popular codecs, from I²S codecs with over
120dB quality to the usual AC97 codecs. This ability gives customers the flexibility to
design their products exactly the way they want them. The I²S, AC-Link, 2-wire master
bus, and SPI interfaces are used to transfer audio data and control data between the
CMI8787 and codecs. To facilitate the connection with existing home audio electronics,
the CMI8787 has incorporated the S/PDIF transmitter and receiver with 192k sampling
rate.
An EEPROM interface is built for the CMI8787 in connection with the EEPROM to
store and retrieve the non-evaporable data for customer applications, such as board
configuration, sub- vendor and sub-system IDs of the PCI configuration, or any dynamic
data that customers want to restore at the next power-on.
The CMI8787 has an independent 2-wire slave bus to communicate with the micro
control unit (MCU). This interface is used as a medium for the system driver and the
MCU to exchange data. One of the applications of the 2-wire slave bus is to transmit the
control data from the remote controller to the system driver. The MPU-401 MIDI UART
is also integrated in the CMI8787.
There are six GPI phone jack detect pins in CMI8787, which can be used to distinguish
if a cable is plugged in the phone jack. The re are 9 GPIO pins on the chip, however
some of them are shared with other functions. The C-Media’s unique device sensing
technology is implemented in CMI8787, which can indicate whether a speaker or a
headphone is plugged in the jack. Then according to this information, the system driver
can decide to turn on the C-Media’s X-ear 3D audio technology if appropriate.
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