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Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
August 2006
Developer’s Manual
Order Number: 306262--, Revision: 004US
391
USB 2.0 Host Controller—Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
The Asynchronous list is a simple circular list of queue heads as shown in
(This figure is identical to
; it is duplicated here for convenience.)
The ASYNCLISTADDR register is simply pointer to the next queue head. This
implements a pure round-robin service for all queue heads linked into the
asynchronous list.
9.13.3
Isochronous (High-Speed) Transfer Descriptor (iTD)
The format of an isochronous transfer descriptor is illustrated in
Transaction Descriptor (iTD)” on page 392
. This structure is used only for high-speed
isochronous endpoints. All other transfer types should use queue structures.
Isochronous TDs must be aligned on a 32-byte boundary.
Figure 46.
Asynchronous Schedule Organization
B4020-01
Operational Registers
Bulk Control Queue Heads
H
ASYNCLISTADDR