1. Why USB called Universal Bus?
  2. What advantages does USB bring compared to traditional RS232 connection mode
  3. List down various speed that USB1.1 supports
    1. USB1.1 : FS (12MBits/s), LS(1.5MBits/s)
    1. USB2.0 : FS, HS(480Mb/s)
  4. How many ports does USB PHY has
    1. What is benefit of differential transmission using D+/D-
  5. USB is host controlled; explain what is meant by host controlled?
  6. USB uses tiered star topology; explain this architecture using diagram
  7. Benefits of tiered star topology compared to Daisy chain topology?
    1. Power to each device can be monitored and even switched off if an overcurrent condition occurs without disrupting other USB devices.
    1. Both high, full and low speed devices can be supported, with the hub filtering out high speed and full speed transactions so lower speed devices do not receive them.
  8. 127 devices can be connected to USB host, where does this limitation come from?
    1. How do we ensure more USB devices can be connected to same laptop
      1. Hint: Add another port/host
  9. List down various USB host controllers
    1. USB1.1
      1. UHCI
        1. More burden on S/w, allows for cheaper hardware
      1. OHCI
        1. More burden on H/w, makes for simpler software
    1. USB2.0
      1. EHCI
  10. USB uses a NRZI (Non return to zero invert) encoding scheme to send data with a sync field to synchronize the host and receiver clocks. Explain significance of Sync and NRZI concept.
  11. USB support plug’n’play, explain
  12. What is significance of USB drivers? What is their role in interfacing USB devices to the Host?
  13. List down various transfers USB supports.
  14. List down various components involved in a USB architecture
    1. Host
    1. Host Controller Interface
    1. USB Link
    1. USB Core
    1. USB function controller
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