Implementation detail

This chapter examines the implementation of the various components that make up lib_xua. It also examines the integration of dependencies and supporting libraries.

• Audio Hub and I²S
  • Port configuration (xcore master)
  • Changing audio sample frequency
• Endpoint 0: Management and control
  • Enumeration
  • Overriding standard requests
  • Class requests
    • Audio requests
    • Audio request: Set sample rate
    • Audio Request: Volume control
• Audio endpoints (Endpoint Buffer and Decoupler)
  • Endpoint Buffer
  • Decouple
  • Audio buffering scheme
  • Decoupler/Audio Hub interaction
  • Asynchronous feedback
  • USB rate control
• XMOS USB Device (XUD) library
• External clock recovery (Clock Gen)
• Digital mixer
  • Control
  • Host control
• S/PDIF transmit
  • Clocking
  • Usage
  • Output stream structure
• S/PDIF receive
  • Usage and integration
• MIDI
• PDM microphones
  • Hardware characteristics
  • Usage & integration
• Audio controls via Human Interface Device (HID)
• Device Firmware Upgrade (DFU) over USB
  • Enumerating as a WinUSB device on Windows
• Resource usage