UDA1331H 데이터 시트보기 (PDF) - Philips Electronics

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UDA1331H

Universal Serial Bus (USB) Audio Playback Peripheral (APP)

Philips Electronics 

Philips Semiconductors

Universal Serial Bus (USB) Audio

Playback Peripheral (APP)

Preliminary specification

UDA1331H

handbook, full pagewidth

INPUT TERMINAL

IT

FEATURE UNIT

FU

OUTPUT TERMINAL

OT

MBK530

Fig.3 Audio function topology.

The programmable part can be retrieved from one of four

configuration maps located in the (E)PROM or from an

I2C-bus EEPROM. At start-up one of four configuration

maps can be selected depending on the logical

combination of GP3 and GP0. It is possible to overwrite

this configuration map with a configuration map loaded

from an I2C-bus EEPROM.

AUDIO DEVICE CLASS SPECIFIC DESCRIPTORS

The audio device class is partly specified with standard

descriptors and partly with specific audio device class

descriptors. The standard descriptors specify the number

and the type of the interface or endpoint. The UDA1331H

supports 7 different audio modes:

• 8-bit Pulse Code Modulation (PCM) mono or stereo

audio data

• 16-bit PCM mono or stereo audio data

• 24-bit PCM mono or stereo audio data

• Zero bandwidth mode.

Each mode is defined as an alternate setting of the audio

interface, selectable with the standard audio streaming

interface descriptor bAlternateSetting field.

The seven alternate settings are described in more detail

by the specific audio device class descriptors.

The UDA1331H supports the Input Terminal (IT), Output

Terminal (OT) and the Feature Unit (FU) descriptors.

The input and output terminals are not controllable via the

USB. The feature unit provides the basic manipulation of

the incoming logical channels.

The supported sound features are:

• Volume control

• Mute control

• Treble control

• Bass control

• Bass boost control.

Table 2 Audio bandwidth at each audio mode

AUDIO MODE

8-bit PCM; mono

8-bit PCM; stereo

16-bit PCM; mono

16-bit PCM; stereo

24-bit PCM; mono

24-bit PCM; stereo

wMaxPacketSize

56 (8⁄8 × 1 × 56)

112 (8⁄8 × 2 × 56)

112 (16⁄8 × 1 × 56)

224 (16⁄8 × 2 × 56)

168 (24⁄8 × 1 × 56)

336 (24⁄8 × 2 × 56)

The maximum number of audio data samples within a USB

packet arriving on the isochronous sink endpoint is

restricted by the buffer capacity of this isochronous

endpoint. The maximum buffer capacity is 336 bytes/ms.

For each alternate setting with audio, a maximum

bandwidth is claimed as indicated in the standard

isochronous audio data endpoint descriptor

wMaxPacketSize field. To allow a small overshoot in the

number of audio samples per packet, the top sample

frequency of 55 kHz is taken in the calculation of the

bandwidth for each alternate setting. For each alternate

setting, with its own isochronous audio data endpoint

descriptor, wMaxPacketSize field is then defined as

described in Table 2.

Although in a specific UDA1331H application no endpoint

control properties can be used upon the isochronous

adaptive sink endpoint, the descriptors are still necessary

to inform the host about the definition of this endpoint:

isochronous, adaptive, sink, continuous sampling

frequency (at input side of this endpoint) with lower bound

of 5 kHz and upper bound of 55 kHz.

The audio class specific descriptors can be requested with

the ‘Get descriptor: configuration request’, which returns

all the descriptors, except the device descriptor.

1998 Oct 06

10

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