Using a C-Media multichannel USB DAC

Bertrand Petit elrond at phoe.frmug.org
Thu Oct 10 03:14:09 UTC 2013


	Here on my desktop lies a new cheap multichannel brand-less USB DAC. I
suppose it is based on a C-Media CM6206 chip. [1] From what I read in the
datasheet [2] signals must properly be routed using HID requests before
anything goes out of the connectors. How could this be done? My use case is to
use four channels consisting of independent stereo signals. One pair is to be
routed either to a jack or the S/PDIF output while the second pair is to be
routed to a headphone.

	When plugged-in snd_uaudio recognises this device only a as stereo
one:

ugen1.2: <vendor 0x0d8c> at usbus1
uaudio0: <vendor 0x0d8c USB Sound Device, class 0/0, rev 1.10/0.10, addr 2> on usbus1
uaudio0: Play: 48000 Hz, 2 ch, 16-bit S-LE PCM format
uaudio0: Record: 48000 Hz, 2 ch, 16-bit S-LE PCM format
uaudio0: No midi sequencer
pcm1: <USB audio> on uaudio0
uhid0: <vendor 0x0d8c USB Sound Device, class 0/0, rev 1.10/0.10, addr 2> on usbus1

I've not yet managed to understand how the 8 channels of the device can be
exposed to userland. Could this be done? How? If it helps I've attached the
output produced by lsusb on this device.


[1] <URL:http://www.daqarta.com/dw_ggnn.htm>
[2] <URL:http://www.steila.com/USB4IO/CMedia/CM6206+datasheet+1.7.pdf>

-- 
%!PS -- Bertrand Petit
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-------------- next part --------------

Bus /dev/usb Device /dev/ugen1.2: ID 0d8c:0102 C-Media Electronics, Inc. CM106 Like Sound Device
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               1.10
  bDeviceClass            0 (Defined at Interface level)
  bDeviceSubClass         0 
  bDeviceProtocol         0 
  bMaxPacketSize0         8
  idVendor           0x0d8c C-Media Electronics, Inc.
  idProduct          0x0102 CM106 Like Sound Device
  bcdDevice            0.10
  iManufacturer           0 
  iProduct                2 USB Sound Device        
  iSerial                 0 
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength          534
    bNumInterfaces          4
    bConfigurationValue     1
    iConfiguration          0 
    bmAttributes         0x80
      (Bus Powered)
    MaxPower              500mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           0
      bInterfaceClass         1 Audio
      bInterfaceSubClass      1 Control Device
      bInterfaceProtocol      0 
      iInterface              0 
      AudioControl Interface Descriptor:
        bLength                10
        bDescriptorType        36
        bDescriptorSubtype      1 (HEADER)
        bcdADC               1.00
        wTotalLength          200
        bInCollection           2
        baInterfaceNr( 0)       1
        baInterfaceNr( 1)       2
      AudioControl Interface Descriptor:
        bLength                12
        bDescriptorType        36
        bDescriptorSubtype      2 (INPUT_TERMINAL)
        bTerminalID             1
        wTerminalType      0x0101 USB Streaming
        bAssocTerminal          0
        bNrChannels             8
        wChannelConfig     0x063f
          Left Front (L)
          Right Front (R)
          Center Front (C)
          Low Freqency Enhancement (LFE)
          Left Surround (LS)
          Right Surround (RS)
          Side Left (SL)
          Side Right (SR)
        iChannelNames           0 
        iTerminal               0 
      AudioControl Interface Descriptor:
        bLength                12
        bDescriptorType        36
        bDescriptorSubtype      2 (INPUT_TERMINAL)
        bTerminalID             4
        wTerminalType      0x0201 Microphone
        bAssocTerminal          0
        bNrChannels             2
        wChannelConfig     0x0003
          Left Front (L)
          Right Front (R)
        iChannelNames           0 
        iTerminal               0 
      AudioControl Interface Descriptor:
        bLength                10
        bDescriptorType        36
        bDescriptorSubtype      6 (FEATURE_UNIT)
        bUnitID                 8
        bSourceID               4
        bControlSize            1
        bmaControls( 0)      0x01
          Mute
        bmaControls( 1)      0x02
          Volume
        bmaControls( 2)      0x02
          Volume
        iFeature                0 
      AudioControl Interface Descriptor:
        bLength                10
        bDescriptorType        36
        bDescriptorSubtype      6 (FEATURE_UNIT)
        bUnitID                 9
        bSourceID               4
        bControlSize            1
        bmaControls( 0)      0x01
          Mute
        bmaControls( 1)      0x02
          Volume
        bmaControls( 2)      0x02
          Volume
        iFeature                0 
      AudioControl Interface Descriptor:
        bLength                25
        bDescriptorType        36
        bDescriptorSubtype      4 (MIXER_UNIT)
        bUnitID                12
        bNrInPins               3
        baSourceID( 0)          1
        baSourceID( 1)          9
        baSourceID( 2)         11
        bNrChannels             8
        wChannelConfig     0x063f
          Left Front (L)
          Right Front (R)
          Center Front (C)
          Low Freqency Enhancement (LFE)
          Left Surround (LS)
          Right Surround (RS)
          Side Left (SL)
          Side Right (SR)
        iChannelNames           0 
        bmControls         0x00
        bmControls         0x00
        bmControls         0x00
        iMixer                  0 
        junk at descriptor end: 00 00 00 00 00 00 00 00 00
      AudioControl Interface Descriptor:
        bLength                16
        bDescriptorType        36
        bDescriptorSubtype      6 (FEATURE_UNIT)
        bUnitID                13
        bSourceID              12
        bControlSize            1
        bmaControls( 0)      0x01
          Mute
        bmaControls( 1)      0x02
          Volume
        bmaControls( 2)      0x02
          Volume
        bmaControls( 3)      0x02
          Volume
        bmaControls( 4)      0x02
          Volume
        bmaControls( 5)      0x02
          Volume
        bmaControls( 6)      0x02
          Volume
        bmaControls( 7)      0x02
          Volume
        bmaControls( 8)      0x02
          Volume
        iFeature                0 
      AudioControl Interface Descriptor:
        bLength                 9
        bDescriptorType        36
        bDescriptorSubtype      3 (OUTPUT_TERMINAL)
        bTerminalID             3
        wTerminalType      0x0301 Speaker
        bAssocTerminal          0
        bSourceID              13
        iTerminal               0 
      AudioControl Interface Descriptor:
        bLength                13
        bDescriptorType        36
        bDescriptorSubtype      4 (MIXER_UNIT)
        bUnitID                17
        bNrInPins               2
        baSourceID( 0)          9
        baSourceID( 1)         11
        bNrChannels             2
        wChannelConfig     0x0003
          Left Front (L)
          Right Front (R)
        iChannelNames           0 
        bmControls         0x00
        iMixer                  0 
      AudioControl Interface Descriptor:
        bLength                 9
        bDescriptorType        36
        bDescriptorSubtype      3 (OUTPUT_TERMINAL)
        bTerminalID            10
        wTerminalType      0x0101 USB Streaming
        bAssocTerminal          0
        bSourceID               7
        iTerminal               0 
      AudioControl Interface Descriptor:
        bLength                10
        bDescriptorType        36
        bDescriptorSubtype      5 (SELECTOR_UNIT)
        bUnitID                 7
        bNrInPins               4
        baSource( 0)            8
        baSource( 1)           15
        baSource( 2)           16
        baSource( 3)            2
        iSelector               0 
      AudioControl Interface Descriptor:
        bLength                12
        bDescriptorType        36
        bDescriptorSubtype      2 (INPUT_TERMINAL)
        bTerminalID             6
        wTerminalType      0x0603 Line Connector
        bAssocTerminal          0
        bNrChannels             2
        wChannelConfig     0x0003
          Left Front (L)
          Right Front (R)
        iChannelNames           0 
        iTerminal               0 
      AudioControl Interface Descriptor:
        bLength                10
        bDescriptorType        36
        bDescriptorSubtype      6 (FEATURE_UNIT)
        bUnitID                15
        bSourceID               6
        bControlSize            1
        bmaControls( 0)      0x01
          Mute
        bmaControls( 1)      0x02
          Volume
        bmaControls( 2)      0x02
          Volume
        iFeature                0 
      AudioControl Interface Descriptor:
        bLength                10
        bDescriptorType        36
        bDescriptorSubtype      6 (FEATURE_UNIT)
        bUnitID                11
        bSourceID               6
        bControlSize            1
        bmaControls( 0)      0x01
          Mute
        bmaControls( 1)      0x02
          Volume
        bmaControls( 2)      0x02
          Volume
        iFeature                0 
      AudioControl Interface Descriptor:
        bLength                12
        bDescriptorType        36
        bDescriptorSubtype      2 (INPUT_TERMINAL)
        bTerminalID             5
        wTerminalType      0x0605 SPDIF interface
        bAssocTerminal          0
        bNrChannels             2
        wChannelConfig     0x0003
          Left Front (L)
          Right Front (R)
        iChannelNames           0 
        iTerminal               0 
      AudioControl Interface Descriptor:
        bLength                10
        bDescriptorType        36
        bDescriptorSubtype      6 (FEATURE_UNIT)
        bUnitID                 2
        bSourceID              17
        bControlSize            1
        bmaControls( 0)      0x01
          Mute
        bmaControls( 1)      0x02
          Volume
        bmaControls( 2)      0x02
          Volume
        iFeature                0 
      AudioControl Interface Descriptor:
        bLength                10
        bDescriptorType        36
        bDescriptorSubtype      6 (FEATURE_UNIT)
        bUnitID                16
        bSourceID               5
        bControlSize            1
        bmaControls( 0)      0x01
          Mute
        bmaControls( 1)      0x00
        bmaControls( 2)      0x00
        iFeature                0 
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       0
      bNumEndpoints           0
      bInterfaceClass         1 Audio
      bInterfaceSubClass      2 Streaming
      bInterfaceProtocol      0 
      iInterface              0 
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       1
      bNumEndpoints           1
      bInterfaceClass         1 Audio
      bInterfaceSubClass      2 Streaming
      bInterfaceProtocol      0 
      iInterface              0 
      AudioStreaming Interface Descriptor:
        bLength                 7
        bDescriptorType        36
        bDescriptorSubtype      1 (AS_GENERAL)
        bTerminalLink           1
        bDelay                  1 frames
        wFormatTag              1 PCM
      AudioStreaming Interface Descriptor:
        bLength                14
        bDescriptorType        36
        bDescriptorSubtype      2 (FORMAT_TYPE)
        bFormatType             1 (FORMAT_TYPE_I)
        bNrChannels             8
        bSubframeSize           2
        bBitResolution         16
        bSamFreqType            2 Discrete
        tSamFreq[ 0]        44100
        tSamFreq[ 1]        48000
      Endpoint Descriptor:
        bLength                 9
        bDescriptorType         5
        bEndpointAddress     0x06  EP 6 OUT
        bmAttributes            9
          Transfer Type            Isochronous
          Synch Type               Adaptive
          Usage Type               Data
        wMaxPacketSize     0x0310  1x 784 bytes
        bInterval               1
        bRefresh                0
        bSynchAddress           0
        AudioControl Endpoint Descriptor:
          bLength                 7
          bDescriptorType        37
          bDescriptorSubtype      1 (EP_GENERAL)
          bmAttributes         0x01
            Sampling Frequency
          bLockDelayUnits         0 Undefined
          wLockDelay              0 Undefined
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       2
      bNumEndpoints           1
      bInterfaceClass         1 Audio
      bInterfaceSubClass      2 Streaming
      bInterfaceProtocol      0 
      iInterface              0 
      AudioStreaming Interface Descriptor:
        bLength                 7
        bDescriptorType        36
        bDescriptorSubtype      1 (AS_GENERAL)
        bTerminalLink           1
        bDelay                  1 frames
        wFormatTag              1 PCM
      AudioStreaming Interface Descriptor:
        bLength                14
        bDescriptorType        36
        bDescriptorSubtype      2 (FORMAT_TYPE)
        bFormatType             1 (FORMAT_TYPE_I)
        bNrChannels             2
        bSubframeSize           2
        bBitResolution         16
        bSamFreqType            2 Discrete
        tSamFreq[ 0]        44100
        tSamFreq[ 1]        48000
      Endpoint Descriptor:
        bLength                 9
        bDescriptorType         5
        bEndpointAddress     0x06  EP 6 OUT
        bmAttributes            9
          Transfer Type            Isochronous
          Synch Type               Adaptive
          Usage Type               Data
        wMaxPacketSize     0x00c4  1x 196 bytes
        bInterval               1
        bRefresh                0
        bSynchAddress           0
        AudioControl Endpoint Descriptor:
          bLength                 7
          bDescriptorType        37
          bDescriptorSubtype      1 (EP_GENERAL)
          bmAttributes         0x01
            Sampling Frequency
          bLockDelayUnits         0 Undefined
          wLockDelay              0 Undefined
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       3
      bNumEndpoints           1
      bInterfaceClass         1 Audio
      bInterfaceSubClass      2 Streaming
      bInterfaceProtocol      0 
      iInterface              0 
      AudioStreaming Interface Descriptor:
        bLength                 7
        bDescriptorType        36
        bDescriptorSubtype      1 (AS_GENERAL)
        bTerminalLink           1
        bDelay                  1 frames
        wFormatTag              1 PCM
      AudioStreaming Interface Descriptor:
        bLength                14
        bDescriptorType        36
        bDescriptorSubtype      2 (FORMAT_TYPE)
        bFormatType             1 (FORMAT_TYPE_I)
        bNrChannels             4
        bSubframeSize           2
        bBitResolution         16
        bSamFreqType            2 Discrete
        tSamFreq[ 0]        44100
        tSamFreq[ 1]        48000
      Endpoint Descriptor:
        bLength                 9
        bDescriptorType         5
        bEndpointAddress     0x06  EP 6 OUT
        bmAttributes            9
          Transfer Type            Isochronous
          Synch Type               Adaptive
          Usage Type               Data
        wMaxPacketSize     0x0188  1x 392 bytes
        bInterval               1
        bRefresh                0
        bSynchAddress           0
        AudioControl Endpoint Descriptor:
          bLength                 7
          bDescriptorType        37
          bDescriptorSubtype      1 (EP_GENERAL)
          bmAttributes         0x01
            Sampling Frequency
          bLockDelayUnits         0 Undefined
          wLockDelay              0 Undefined
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       4
      bNumEndpoints           1
      bInterfaceClass         1 Audio
      bInterfaceSubClass      2 Streaming
      bInterfaceProtocol      0 
      iInterface              0 
      AudioStreaming Interface Descriptor:
        bLength                 7
        bDescriptorType        36
        bDescriptorSubtype      1 (AS_GENERAL)
        bTerminalLink           1
        bDelay                  1 frames
        wFormatTag              1 PCM
      AudioStreaming Interface Descriptor:
        bLength                14
        bDescriptorType        36
        bDescriptorSubtype      2 (FORMAT_TYPE)
        bFormatType             1 (FORMAT_TYPE_I)
        bNrChannels             6
        bSubframeSize           2
        bBitResolution         16
        bSamFreqType            2 Discrete
        tSamFreq[ 0]        44100
        tSamFreq[ 1]        48000
      Endpoint Descriptor:
        bLength                 9
        bDescriptorType         5
        bEndpointAddress     0x06  EP 6 OUT
        bmAttributes            9
          Transfer Type            Isochronous
          Synch Type               Adaptive
          Usage Type               Data
        wMaxPacketSize     0x0248  1x 584 bytes
        bInterval               1
        bRefresh                0
        bSynchAddress           0
        AudioControl Endpoint Descriptor:
          bLength                 7
          bDescriptorType        37
          bDescriptorSubtype      1 (EP_GENERAL)
          bmAttributes         0x01
            Sampling Frequency
          bLockDelayUnits         0 Undefined
          wLockDelay              0 Undefined
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       5
      bNumEndpoints           1
      bInterfaceClass         1 Audio
      bInterfaceSubClass      2 Streaming
      bInterfaceProtocol      0 
      iInterface              0 
      AudioStreaming Interface Descriptor:
        bLength                 7
        bDescriptorType        36
        bDescriptorSubtype      1 (AS_GENERAL)
        bTerminalLink           1
        bDelay                  1 frames
        wFormatTag              1 PCM
      AudioStreaming Interface Descriptor:
        bLength                11
        bDescriptorType        36
        bDescriptorSubtype      2 (FORMAT_TYPE)
        bFormatType             1 (FORMAT_TYPE_I)
        bNrChannels             2
        bSubframeSize           2
        bBitResolution         16
        bSamFreqType            1 Discrete
        tSamFreq[ 0]        48000
      Endpoint Descriptor:
        bLength                 9
        bDescriptorType         5
        bEndpointAddress     0x06  EP 6 OUT
        bmAttributes            9
          Transfer Type            Isochronous
          Synch Type               Adaptive
          Usage Type               Data
        wMaxPacketSize     0x0188  1x 392 bytes
        bInterval               1
        bRefresh                0
        bSynchAddress           0
        AudioControl Endpoint Descriptor:
          bLength                 7
          bDescriptorType        37
          bDescriptorSubtype      1 (EP_GENERAL)
          bmAttributes         0x01
            Sampling Frequency
          bLockDelayUnits         0 Undefined
          wLockDelay              0 Undefined
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        2
      bAlternateSetting       0
      bNumEndpoints           0
      bInterfaceClass         1 Audio
      bInterfaceSubClass      2 Streaming
      bInterfaceProtocol      0 
      iInterface              0 
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        2
      bAlternateSetting       1
      bNumEndpoints           1
      bInterfaceClass         1 Audio
      bInterfaceSubClass      2 Streaming
      bInterfaceProtocol      0 
      iInterface              0 
      AudioStreaming Interface Descriptor:
        bLength                 7
        bDescriptorType        36
        bDescriptorSubtype      1 (AS_GENERAL)
        bTerminalLink          10
        bDelay                  1 frames
        wFormatTag              1 PCM
      AudioStreaming Interface Descriptor:
        bLength                14
        bDescriptorType        36
        bDescriptorSubtype      2 (FORMAT_TYPE)
        bFormatType             1 (FORMAT_TYPE_I)
        bNrChannels             2
        bSubframeSize           2
        bBitResolution         16
        bSamFreqType            2 Discrete
        tSamFreq[ 0]        44100
        tSamFreq[ 1]        48000
      Endpoint Descriptor:
        bLength                 9
        bDescriptorType         5
        bEndpointAddress     0x85  EP 5 IN
        bmAttributes            5
          Transfer Type            Isochronous
          Synch Type               Asynchronous
          Usage Type               Data
        wMaxPacketSize     0x00f0  1x 240 bytes
        bInterval               1
        bRefresh                0
        bSynchAddress           0
        AudioControl Endpoint Descriptor:
          bLength                 7
          bDescriptorType        37
          bDescriptorSubtype      1 (EP_GENERAL)
          bmAttributes         0x01
            Sampling Frequency
          bLockDelayUnits         0 Undefined
          wLockDelay              0 Undefined
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        3
      bAlternateSetting       0
      bNumEndpoints           1
      bInterfaceClass         3 Human Interface Device
      bInterfaceSubClass      0 No Subclass
      bInterfaceProtocol      0 None
      iInterface              0 
        HID Device Descriptor:
          bLength                 9
          bDescriptorType        33
          bcdHID               1.00
          bCountryCode            0 Not supported
          bNumDescriptors         1
          bDescriptorType        34 Report
          wDescriptorLength      50
          Report Descriptor: (length is 50)
            Item(Global): Usage Page, data= [ 0x0c ] 12
                            Consumer
            Item(Local ): Usage, data= [ 0x01 ] 1
                            Consumer Control
            Item(Main  ): Collection, data= [ 0x01 ] 1
                            Application
            Item(Global): Logical Minimum, data= [ 0x00 ] 0
            Item(Global): Logical Maximum, data= [ 0x01 ] 1
            Item(Local ): Usage, data= [ 0xe9 ] 233
                            Volume Increment
            Item(Local ): Usage, data= [ 0xea ] 234
                            Volume Decrement
            Item(Global): Report Size, data= [ 0x01 ] 1
            Item(Global): Report Count, data= [ 0x02 ] 2
            Item(Main  ): Input, data= [ 0x42 ] 66
                            Data Variable Absolute No_Wrap Linear
                            Preferred_State Null_State Non_Volatile Bitfield
            Item(Local ): Usage, data= [ 0xe2 ] 226
                            Mute
            Item(Local ): Usage, data= [ 0x00 ] 0
                            Unassigned
            Item(Main  ): Input, data= [ 0x06 ] 6
                            Data Variable Relative No_Wrap Linear
                            Preferred_State No_Null_Position Non_Volatile Bitfield
            Item(Local ): Usage, data= [ 0x00 ] 0
                            Unassigned
            Item(Global): Report Count, data= [ 0x04 ] 4
            Item(Main  ): Input, data= [ 0x02 ] 2
                            Data Variable Absolute No_Wrap Linear
                            Preferred_State No_Null_Position Non_Volatile Bitfield
            Item(Global): Logical Maximum, data= [ 0xff 0x00 ] 255
            Item(Local ): Usage, data= [ 0x00 ] 0
                            Unassigned
            Item(Global): Report Size, data= [ 0x08 ] 8
            Item(Global): Report Count, data= [ 0x02 ] 2
            Item(Main  ): Input, data= [ 0x02 ] 2
                            Data Variable Absolute No_Wrap Linear
                            Preferred_State No_Null_Position Non_Volatile Bitfield
            Item(Local ): Usage, data= [ 0x00 ] 0
                            Unassigned
            Item(Global): Report Count, data= [ 0x04 ] 4
            Item(Main  ): Output, data= [ 0x02 ] 2
                            Data Variable Absolute No_Wrap Linear
                            Preferred_State No_Null_Position Non_Volatile Bitfield
            Item(Main  ): End Collection, data=none
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            3
          Transfer Type            Interrupt
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0003  1x 3 bytes
        bInterval               1
Device Status:     0x0000
  (Bus Powered)


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