USB Host Stack

Overview
Universal Serial Bus (USB) Host Stack, including Application Programming Interfaces (APIs) and services that enable software and device manufacturers to incorporate standard USB Host connectivity in their embedded devices.
USB Host: The USB host platform is where the USB host controller is installed and where the client software/device driver runs. The USB Host Controller is the interface between the host and the USB peripherals. The host is responsible for detecting the insertion and removal of USB devices, managing the control and data flow between the host and the devices, providing power to attached devices, and more.

Spec
The USB Specification allows for the connection of a maximum of 127 peripheral devices (including hubs) to the system, either on the same port or on different ports. USB also supports Plug and Play installation and hot swapping. The USB 1.1 standard supports both isochronous and asynchronous data transfers and has dual speed data transfer: 1.5 Mb/s for low-speed USB devices and 12 Mb/s for full-speed USB devices (much faster than the original serial port). Cables connecting the device to the PC can be up to five meters (16.4 feet) long. USB includes built-in power distribution for low power devices and can provide limited power (up to 500 mA of current) to devices attached on the bus. The USB 2.0 standard supports a signaling rate of 480 Mb/s, known as "high-speed", which is 40 times faster than the USB 1.1 full-speed transfer rate. USB 2.0 is fully forward- and backward-compatible with USB 1.1 and uses existing cables and connectors. USB 2.0 supports connections with PC peripherals that provide expanded functionality and require wider bandwidth. In addition, it can handle a larger number of peripherals simultaneously. USB 2.0 enhances the user’s experience of many applications, including interactive gaming, broadband Internet access, desktop and Web publishing, Internet services and conferencing.

Implementation
USB Host Stack Implementation
USB VersionProcessorUSB ControllerClass Drivers
USB1.1MIPS
X86
POWERPC
 OHCI
UHCI
SL811		Key Board, Mouse,
Hub, Printer,
Mass Storage Devices (Flash disks, hard disk)
Digital Camera,Modem,
Host to Host Adapter,
USB to Ethernet
USB2.0X86
PowerPC
Toshiba		EHCI
(NEC/VIATech)		Keyboard, Mouse,
Hub, Printer,
Mass Storage Devices

Resources
  • USB Host Stack, including Application Programming Interfaces (APIs) and services that enable software and device manufacturers to incorporate standard USB Host connectivity in their embedded devices.
  • USB Host Stack–Learn about: Application Programming Interfaces ...
  • Architecture of USB Host Stack
  • Driver for USB Controller–FAQ USB-IF
  • Information, tools, and links to material about the Universal Serial Bus-brought to you by Jan Axelson book


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