Objective 7: Configure USB Devices

Universal Serial Bus (USB) is a type of interface used to connect various types of peripherals, ranging from keyboards and mice, to hard drives, scanners, digital cameras, and printers. The USB Objective covers the general architecture of USB, USB modules, and configuring USB devices .

USB Topology

USB devices are attached to a host in a tree through some number of hub devices. The lsusb command can be used to see how devices are physically attached to a Linux system.

# lsusb -t
Bus#  4
'-Dev#   1 Vendor 0x0000 Product 0x0000
Bus#  3
'-Dev#   1 Vendor 0x0000 Product 0x0000
  |-Dev#   2 Vendor 0x046d Product 0xc501
  '-Dev#   3 Vendor 0x0781 Product 0x0002
Bus#  2
'-Dev#   1 Vendor 0x0000 Product 0x0000
  |-Dev#   2 Vendor 0x0451 Product 0x2036
  | |-Dev#   5 Vendor 0x04b8 Product 0x0005
  | '-Dev#   6 Vendor 0x04b8 Product 0x0602
  '-Dev#   3 Vendor 0x0451 Product 0x2046
    '-Dev#   4 Vendor 0x056a Product 0x0011
Bus#  1
'-Dev#   1 Vendor 0x0000 Product 0x0000

USB Controllers

There are three types of USB host controllers :

  • Open Host Controller Interface (OHCI)

  • Universal Host Controller Interface (UHCI)

  • Enhanced Host Controller Interface (EHCI)

OHCI and UHCI controllers are both USB 1.1 controllers, which are capable of a maximum of 12 Mbps. EHCI controllers are USB 2.0 controllers, which are capable of a theoretical maximum of 480 Mbps. To get greater than USB 1.1 speeds, you must have a USB 2.0 controller, as well as USB 2.0 devices, hubs, and cables. A USB 2.0 device attached to a USB 1.1 ...

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