Universal Serial Bus Host Interface; Overview; Signals - Intel PXA27 Series Design Manual

Universal Serial Bus Host Interface

This chapter describes guidelines for:
•
Interfacing the Universal Serial Bus (USB) host controller of the Intel
Family (PXA27x processor) to a USB host cable connector
•
Attaching USB client devices to the USB host controller of the PXA27x processor
20.1

Overview

The Universal Serial Bus (USB) is a bus cable that supports serial-data exchange between a host
computer and a variety of simultaneously accessible peripherals. The attached peripherals share
USB bandwidth through a host-scheduled, token-based protocol. Peripherals are attached,
configured, used, and detached, while the host and other peripherals continue operation.
Familiarity with the Universal Serial Bus Specification, Revision 1.1
are necessary to fully understand the material contained in this section.
20.2

Signals

See Table 20-1
Table 20-1. USB Host Controller Interface Signals Summary
Signal Name
USBHPWR<3:1> Input
USBH_P<3:1>
USBH_N<3:1>
USBHPEN<3:1>
1. To access the latest revision of the Universal Serial Bus Specification Revision 1.1, use the Internet site at: http://www.usb.org/.
2. Refer to Open Host Controller Interface Specification for USB, Release 1.0a,loc cit.
®
Intel PXA27x Processor Family Design Guide
for description of the four USB Host controller signals.
Direction
Signal indicates an over-current fault condition on the USB power supply
Bidirectional Data positive differential signal (USB D+)
Bidirectional Data negative differential signal (USB D-)
Signal controls an external power switching device that supplies power to
Output
USB peripherals
®
PXA27x Processor
1
and the OHCI specification
Description
20
2
II:20-1