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Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors—USB 1.1 Device
Controller
Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
Developer’s Manual
August 2006
278
Order Number: 306262-004US
8.0
USB 1.1 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
Universal Serial Bus Device Controller (UDC) of the Intel
®
IXP45X and Intel
®
IXP46X
Product Line of Network Processors 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 the following Web
site:
.
Both this, USB-device interface and the USB-host interface can be used at the same
time. (For more information on the USB-host interface, see
8.1
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