CM6571 Datasheet, PDF (26/63 Pages) C-Media Electronics – USB 2.0 full speed-compliant

CM6571
USB Audio Sound Chip
standard as ISO out audio data endpoint descriptor (ep 1)
Offset
Field
Size Value (Hex)
Description
0
bLength
1
09
Descriptor length
1
bDescriptorType
1
05
Endpoint Descriptor
2
bEndpointAddress 1
1
IN Endpoint, Endpoint number 1
3
bmAttributes
1
0D
ISO Endpoint, synchronous
4
wMaxPacketSize
2
0188 Maximum packet size: 392 bytes
6
bInterval
1
01
1ms
7
bRefresh
1
00
Reset to 0
8
bSynchAddress
1
00
No synchronization pipe
class-specific as ISO out audio data endpoint descriptor (ep 1)
Offset
Field
Size Value (Hex)
Description
0
bLength
1
07
Descriptor length
1
bDescriptorType
1
25
CS_ENDPOINT descriptor type
2
bDescriptorSubtype 1
01
EP_GENERAL descriptor subtype
3
bmAttributes
1
01
Sampling Frequency control
4
bLockDelayUnits
1
00
Reset to 0
5
wLockDelay
2
0000 No synchronization pipe
standard as interface descriptor (interface 2, alternate 0)
Offset
Field
Size Value (Hex)
Description
0
bLength
1
09
Descriptor length
1
bDescriptorType
1
04
Interface Descriptor
2
bInterfaceNumber 1
02
Interface number: 02
3
bAlternateSetting 1
00
Alternate interface
4
bNumEndpoints
1
00
Number of endpoint used by this interface
5
bInterfaceClass
1
01
Audio Interface Class
6
bInterfaceSubClass 1
02
Subclass code
7
bInterfaceProtocol 1
00
Protocol code
8
iInterface
1
00
Index of string descriptor describing this interface
standard as interface descriptor (interface 2, alternate 1)
Offset
Field
Size Value (Hex)
Description
0
bLength
1
09
Descriptor length
1
bDescriptorType
1
04
Interface Descriptor
2
bInterfaceNumber 1
02
Interface number: 02
3
bAlternateSetting 1
01
Alternate interface
4
bNumEndpoints
1
01
Number of endpoint used by this interface
5
bInterfaceClass
1
01
Audio Interface Class
6
bInterfaceSubClass 1
02
Subclass code
7
bInterfaceProtocol 1
00
Protocol code
8
iInterface
1
00
Index of string descriptor describing this interface
class-specific as general interface descriptor (interface 2, alternate 1)
Offset
Field
Size Value (Hex)
Description
0
bLength
1
07
Descriptor length
1
bDescriptorType
1
24
CS_INTERFACE descriptor type
2
bDescriptorSubtype 1
01
AS_GENERAL descriptor subtype
3
bTerminalLink
1
04
Link to Output USB Stream
4
bDelay
1
01
Sync delay: 1ms
5
wFormatTag
2
0001 PCM 16-bits format
Revised: Nov. 2012
Page 26 / 63
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