AK5374 Datasheet, PDF (37/51 Pages) Asahi Kasei Microsystems – 24-bit Stereo ADC with USB Interface

4.8 Operational Alternate Setting 7
4.8.1 Standard Audio Streaming Interface Descriptor
(Alt = 7: St, 24bit, 8k/11.025k/16k/22.05k /32k/44.1k/48k)
Offset
0
1
2
3
4
5
6
7
8
Field
bLength
bDescriptorType
bInterfaceNumber
bAlternateSetting
bNumEndpoints
bInterfaceClass
bInterfaceSubclass
bInterfaceProtocol
iInterface
Size Value
1 0x09
1 0x04
1 0x01
1 0x07
1 0x01
1 0x01
1 0x02
1 0x00
1 0x00
Description
Size of this descriptor in bytes
INTERFACE descriptor
Index of this interface
Index of this setting
Endpoint 1
AUDIO
AUDIO_STREAMING
Not used. Must be set to 0.
Null string
4.8.2 Class-specific Audio General Interface Descriptor
Offset
0
1
2
3
4
5
Field
bLength
bDescriptorType
bDescriptorSubtype
bTerminalLink
bDelay
wFormatTag
Size Value
1 0x07
1 0x24
1 0x01
1 0x02
1 0x01
2 0x0001
Description
Size of this descriptor in bytes
CS_INTERFACE descriptor
AS_GENERAL
Unit ID of terminal (Output Terminal ID)
Interface delay
PCM
4.8.3 Type I Format Type Descriptor
Offset
0
1
2
3
4
5
6
7
8
11
14
17
20
23
26
Field
bLength
bDescriptorType
bDescriptorSubtype
bFormatType
bNrChannels
bSubFrameSize
bBitResolution
bSamFreqType
tSamFreq[0]
tSamFreq[1]
tSamFreq[2]
tSamFreq[3]
tSamFreq[4]
tSamFreq[5]
tSamFreq[6]
Size Value
1 0x1D
1 0x24
Description
Size of this descriptor in bytes
CS_INTERFACE
1 0x02
FORMAT_TYPE
1 0x01
FORMAT_TYPE_I
1 0x02
1 0x03
1 0x18
1 0x07
Two channels
Three bytes per slot
24 bits
Seven frequencies
3 0x001F40 8000Hz
3 0x002B11 11025Hz
0x003E80 16000kHz
3 0x005622 22050Hz
0x007D00 32000Hz
3 0x00AC44 44100Hz
3 0x00BB80 48000Hz
4.8.4 Standard Endpoint Descriptor
Offset
0
1
2
3
4
6
7
8
Field
bLength
bDescriptorType
bEndpointAddress
bmAttributes
wMaxPacketSize
bInterval
bRefresh
bSynchAddress
Size Value
1 0x09
1 0x05
1 0x81
1 0x0D
2 0x0120
1 0x01
1 0x00
1 0x00
Description
Size of this descriptor in bytes
ENDPOINT descriptor
Endpoint 1, IN direction
Isochronous, synchronous, not shared
3byte*48sample*2ch=288 byte/frame
One packet every frame (Must be set to 1)
MS1197-E-00
- 37 -
[AK5374]
2010/05