Interface #2

Interface #3

End-Points

PCM2903B

Interface #2 is the audio streaming data-in interface. Interface #2 has the 19 alternative settings described in

Table 6. Alternative setting #0 is the zero-bandwidth setting. All other alternative settings are operational settings.

Table 6. Interface #2 Alternative Settings

ALTERNATIVE

TRANSFER

SAMPLING RATE

SETTING

DATA FORMAT

MODE

(kHz)

00

Zero bandwidth

01

16-bit

Stereo

Twos complement (PCM)

Asynchronous

48

02

16-bit

Mono

Twos complement (PCM)

Asynchronous

48

03

16-bit

Stereo

Twos complement (PCM)

Asynchronous

44.1

04

16-bit

Mono

Twos complement (PCM)

Asynchronous

44.1

05

16-bit

Stereo

Twos complement (PCM)

Asynchronous

32

06

16-bit

Mono

Twos complement (PCM)

Asynchronous

32

07

16-bit

Stereo

Twos complement (PCM)

Asynchronous

22.05

08

16-bit

Mono

Twos complement (PCM)

Asynchronous

22.05

09

16-bit

Stereo

Twos complement (PCM)

Asynchronous

16

0A

16-bit

Mono

Twos complement (PCM)

Asynchronous

16

0B

8-bit

Stereo

Twos complement (PCM)

Asynchronous

16

0C

8-bit

Mono

Twos complement (PCM)

Asynchronous

16

0D

8-bit

Stereo

Twos complement (PCM)

Asynchronous

8

0E

8-bit

Mono

Twos complement (PCM)

Asynchronous

8

0F

16-bit

Stereo

Twos complement (PCM)

Synchronous

11.025

10

16-bit

Mono

Twos complement (PCM)

Synchronous

11.025

11

8-bit

Stereo

Twos complement (PCM)

Synchronous

11.025

12

8-bit

Mono

Twos complement (PCM)

Synchronous

11.025

Interface #3 is the interrupt data-in interface. Alternative setting #0 is the only possible setting for interface #3.

Interface #3 consists of the HID consumer control device and reports the status of these three key parameters:

• Mute (0xE209)

• Volume up (0xE909)

• Volume down (0xEA09)

The PCM2903B has the following four end-points:

• Control end-point (EP #0)

• Isochronous-out audio data stream end-point (EP #2)

• Isochronous-in audio data stream end-point (EP #4)

• HID end-point (EP #5)

The control end-point is a default end-point. The control end-point is used to control all functions of the

PCM2903B by the standard USB request and an USB audio class specific request from the host. The

isochronous-out audio data stream end-point is an audio sink end-point, which receives the PCM audio data. The

isochronous-out audio data stream end-point accepts the adaptive transfer mode. The isochronous-in audio data

stream end-point is an audio source end-point that transmits the PCM audio data. The isochronous-in audio data

stream end-point uses asynchronous transfer mode. The HID end-point is an interrupt-in end-point. HID

end-point reports HID0, HID1, and HID2 pin status every 32 ms.

The human interface device (HID) pins are defined as consumer control devices. The HID function is designed

as an independent end-point from both isochronous-in and -out end-points. Therefore, the result obtained from

the HID operation depends on the host software. Typically, the HID function is used as the primary audio-out

device.

Copyright © 2008, Texas Instruments Incorporated

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