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Intel
®
IXP42X product line and IXC1100 control plane processors—Universal Serial Bus (USB)
v1.1 Device Controller
Intel
®
IXP42X Product Line of Network Processors and IXC1100 Control Plane Processor
DM September 2006
468 Order Number: 252480-006US
18.0 Universal Serial Bus (USB) v1.1 Device Controller
This chapter describes the Universal Serial Bus (USB) protocol and its implementation-
specific options for device controllers. These options include:
• Endpoint number, type, and function
• Interrupts to the Intel XScale
®
Processor
• A transmit/receive FIFO interface
A working knowledge of the USB standard is vital to effective use of this chapter. The
Intel
®
IXP42X Product Line of Network Processors and IXC1100 Control Plane
Processor’s Universal Serial Bus Device Controller (UDC) is USB-compliant and supports
all standard device requests issued by the host. UDC operation summaries and quick
reference tables are provided.
Refer to the Universal Serial Bus Specification, revision 1.1, for a full description of the
USB protocol. The Universal Serial Bus Specification is available at http://www.usb.org.
18.1 USB Overview
The UDC supports 16 endpoints and can operate half-duplex at a rate of 12 Mbps (as a
slave only, not as a host or hub controller). The UDC supports four device
configurations. Configurations 1, 2, and 3 each support two interfaces. This allows the
host to accommodate dynamic changes in the physical bus topology. A configuration is
a specific combination of USB resources available on the device. An interface is a
related set of endpoints that present a device feature or function to the host.
The UDC transmits serial information that contains layers of communication protocols.
Fields are the most basic protocol. UDC fields include:
Fields are combined to produce packets.
A packet’s function determines the combination and number of fields that make up the
packet. Packet types include:
• Sync • Packet identifier (PID) • Address
• Endpoint • Frame number • Data
• Cyclic Redundancy Check (CRC)
• Token • Start of frame
• Data • Handshake