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Interface #0

Interface #1

PCM2904

PCM2906

SLES042C – JUNE 2002 – REVISED NOVEMBER 2007

Interface #0 is the control interface. Alternative setting #0 is the only possible setting for interface #0. Alternative

setting #0 describes the standard audio control interface. The audio control interface is constructed by a terminal.

The PCM2904/2906 has the following five terminals.

• Input terminal (IT #1) for isochronous-out stream

• Output terminal (OT #2) for audio analog output

• Feature unit (FU #3) for DAC digital attenuator

• Input terminal (IT #4) for audio analog input

• Output terminal (OT #5) for isochronous-in stream

Input terminal #1 is defined as a USB stream (terminal type 0x0101). Input terminal #1 can accept 2-channel

audio streams consisting of left and right channels. Output terminal #2 is defined as a speaker (terminal type

0x0301). Input terminal #4 is defined as a microphone (terminal type 0x0201). Output terminal #5 is defined as a

USB stream (terminal type 0x0101). Output terminal #5 can generate 2-channel audio streams consisting of left

and right channels. Feature unit #3 supports the following sound control features.

• Volume control

• Mute control

The built-in digital volume controller can be manipulated by an audio-class-specific request from 0 dB to –64 dB

in steps of 1 dB. Each channel can be set for different values. The master volume control is not supported. A

request to the master volume is stalled and ignored. The built-in digital mute controller can be manipulated by

audio-class-specific request. A master mute control request is acceptable. A request to an individual channel is

stalled and ignored.

Interface #1 is the audio streaming data-out interface. Interface #1 has the following seven alternative settings.

Alternative setting #0 is the zero-bandwidth setting. All other alternative settings are operational settings.

ALTERNATIVE

SAMPLING RATE

DATA FORMAT

TRANSFER MODE

SETTING

(kHz)

00

Zero bandwidth

01

16 bit

Stereo

2s complement (PCM)

Adaptive

32, 44.1, 48

02

16 bit

Mono

2s complement (PCM)

Adaptive

32, 44.1, 48

03

8 bit

Stereo

2s complement (PCM)

Adaptive

32, 44.1, 48

04

8 bit

Mono

2s complement (PCM)

Adaptive

32, 44.1, 48

05

8 bit

Stereo

Offset binary (PCM8)

Adaptive

32, 44.1, 48

06

8 bit

Mono

Offset binary (PCM8)

Adaptive

32, 44.1, 48

Copyright © 2002–2007, Texas Instruments Incorporated

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Product Folder Link(s): PCM2904 PCM2906