Mass Storage Device Class


  • Only uses standard interface descriptors
    • for Bulk Only Transport, BOT
    • for Control/Bulk/Interrupt Transport, CBI


  • for BOT
    • Mass Storage Reset
    • Get Max LUN
      • Devices that do not support multiple LUNs may STALL this command.
      • LUN: Logic Unit Numbers (0~15)
      • If the device supports four LUNs then the LUNs would be numbered from 0 to 3 and the return value would be 3.
  • for CBI
    • Accept Device-Specific Command (ADSC)

Composition of BOT

Command/Data/Status Protocol
command transport, data transport, status transport

CBW: Command Block Wrapper
CSW: Command Status Wrapper

CBW -> Data -> CSW

  • USB Floppy Interface, UFI
    • occupies CBWCB, the last field of CBW

Suggested Readings

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