Yoga AD-100

The chip is from C-Media and appears to be the CM102A. You can download the Technical Brief or Data Sheet.

yoga-ad-100.jpg

I picked up a Yoga AD-100 Virtual 5.1 Channel USB Adapter from Jaycar. It’s a standard USB-Audio chip (0x0d8c/0x0001) running at 12Mbps with a stereo audio socket. It has a reasonably beefy ampliier on-chip, at maximum volume it can over-drive headphones easily, and put out a respectable volume from a pair of small un-powered speakers. A switch on the side triggers a shutdown of the output stage of the chip, leaving the USB interface and decoder running.

Using my power monitoring board, I measured the current draw of the AD-100. Plugged in to USB, but with the switch off it draws 12mA. With the switch on it jumps to 49mA, but that includes the blue LED. Plugging in a pair of amplified speakers has no effect of power use, while a pair of 8ohm 2 Watt unpowered speakers takes it to 55mA to 80mA, depending on what music is playing.

It appears the onboard 0.5 Watt amplifier is good enough for smaller speakers. For volumes above what it’s able to drive, a good amp will give much better sound than most amplified PC speakers.

C-Media blurb

CM102A/CM102S USB Audio Controller
Features

  • USB v2.0 full speed operatible.
  • Fully compliant with USB audio device class specification v2.0
  • USB bus powered 500mA operation with suspend mode support
  • Single 12MHz crystal input with on-chip PLL and embedded USB transceiver
  • USB audio function topology has 1 input terminal, 1 output terminal, and 1 feature unit
  • Alternate zero bandwidth setting for releasing bandwidth on USB bus during inactive operation
  • Isochronous transfer using adaptive synchronization with internal PLL
  • High performance 48KHz sampling rate for audio playback
  • Embedded high performance 16 bit audio DAC
  • Embedded class AB power amplifier for speaker driving and enable/disable control pin
  • Volume control input with simple external VR circuit
  • Embedded power on reset block
  • Single 5V external power supply with internal power regulation
  • 3.3V IO with 5V tolerance; 3.3V core logics design
  • Compatible with Win98 SE / Win ME / Win 2000 / Win XP, and Mac OS 9 / OS X without additional driver
  • 18 pin PDIP (CM102)or SOP (CM102S) package

Kernel messages

usb 3-1: new full speed USB device using ohci_hcd and address 4
usbaudio: device 4 audiocontrol interface 0 has 0 input and 1 output AudioStreaming interfaces
usbaudio: valid output sample rate 48000
usbaudio: device 4 interface 1 altsetting 1: format 0x80000010 sratelo 48000 sratehi 48000 attributes 0x00
usbaudio: registered dsp 14,3
usbaudio: registered mixer 14,0

lsusb -v

 Bus 003 Device 020: ID 0d8c:0001 C-Media Electronics, Inc. 
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          0x0001 
  bcdDevice            0.10
  iManufacturer           1 
  iProduct                2 
  iSerial                 0 
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength          110
    bNumInterfaces          2
    bConfigurationValue     1
    iConfiguration          0 
    bmAttributes         0x80
    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                 9
        bDescriptorType        36
        bDescriptorSubtype      1 (HEADER)
        bcdADC               1.00
        wTotalLength           40
        bInCollection           1
        baInterfaceNr( 0)       1
      AudioControl Interface Descriptor:
        bLength                12
        bDescriptorType        36
        bDescriptorSubtype      2 (INPUT_TERMINAL)
        bTerminalID             1
        wTerminalType      0x0101 USB Streaming
        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                13
        bSourceID               1
        bControlSize            1
        bmaControls( 0)      0x03
          Mute
          Volume
        bmaControls( 1)      0x00
        bmaControls( 2)      0x00
        iFeature                0 
      AudioControl Interface Descriptor:
        bLength                 9
        bDescriptorType        36
        bDescriptorSubtype      3 (OUTPUT_TERMINAL)
        bTerminalID             3
        wTerminalType      0x0301 Speaker
        bAssocTerminal          0
        bSourceID              13
        iTerminal               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                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     0x00c0  1x 192 bytes
        bInterval               1
        bRefresh                0
        bSynchAddress           0
        AudioControl Endpoint Descriptor:
          bLength                 7
          bDescriptorType        37
          bDescriptorSubtype      1 (EP_GENERAL)
          bmAttributes         0x00
          bLockDelayUnits         0 Undefined
          wLockDelay              0 Undefined
 
 
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