NO:
W90P710 Programming Guide
VERSION:
2.1
PAGE:
72
The above information is the exclusive intellectual property of Winbond Electronics and shall not be disclosed,
distributed or reproduced without permission from Winbond.
Table No.: 1200-0003-07-A
•
Transfer Descriptor
Lists
•
Host Controller Communication Area (HCCA)
Note1 : All these data structures are located in system memory. The Host Controller will
access these memory blocks by DMA transfer. All Endpoint Descriptors, Transfer Descriptors,
HCCA, and transfer buffers must be set to non-cacheable region.
Note2 : Endpoint Descriptors and Transfer Descriptors must be aligned with 32 bytes address
boundary. Host Controller Communication Area must be aligned with 256 bytes address
boundary.
6.4.1 Endpoint Descriptor (ED) Lists
The OpenHCI
Host Controller
fulfills USB transfers by classifying Endpoints into four types of
Endpoint Descriptor
lists. The Control
ED
list is pointed by
HcControlHeadED
register, the Bulk
ED
list is pointed by
HcBulkHeadED
register, the Interrupt
ED
lists are pointed by InterruptTable of
HCCA
, and the Isochronous
ED
list is linked behind the last 1m interval Interrupt
ED
.
HCD
must
create and maintain an
ED
for each endpoint of a USB device.
For all transfer types, they have the same
Endpoint Descriptor
format. The common format is
listed below:
Figure 6-1 Endpoint Descriptor Format
3
2
1 1 1 1 1 1 1
0 0 0 0 0 0 0 0
1
6
6 5 4 3 2 1 0
7 6 5 4 3 2 1 0
Dword 0
—
MPS
F K S D
EN
FA
Dword 1
TD Queue Tail Pointer (TailP)
—
Dword 2
TD Queue Head Pointer (HeadP)
0 C H
Dword 3
Next Endpoint Descriptor (NextED)
—
The
Endpoint Descriptor
format of W90P710 USB
Host Controller
is compliant to OpenHCI
Specification 1.0a. In this document, you can find detail descriptions about each field in
Endpoint
Descriptor
.