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Table Of Contents
Zynq-7000 AP SoC Technical Reference Manual www.xilinx.com 398
UG585 (v1.11) September 27, 2016
Chapter 15: USB Host, Device, and OTG Controller
Queue Head (QH). Each dTD can point to another dTD (using next dTD pointer) or terminate the
linked list by setting its (T) bit = 1.
The controller maintains a local, working copy of the dQH that it overlays with the one or more dTDs
as the transaction request is processed. After each dTD transfer is complete, the dTD overlay is
written back to the system memory with transfer results (status). While a transfer is in progress, the
overlay area of the dQH in controller memory is used as a staging area for the dTDs.
15.1.7 Implementation Summary
There are EHCI enhancements to support the embedded Transaction Translator and hardware
assistance features to support OTG. Here is a summary of special features, enhancements, deviations
and unsupported features.
EHCI Enhancements and Deviations, section 15.11 EHCI Implementation.
Hardware Assistance Features for OTG, section 15.14.1 Hardware Assistance Features.
Embedded Transaction Translator (no separate companion controller hardware), section
15.11.2 Embedded Transaction Translator.
The AHB interface is a master-only and used by the DMA controller (no PCI registers).
The ULPI Carkit feature is not supported.
15.1.8 Documentation
Scope of TRM
The Zynq-7000 Technical Reference Manual (TRM) describes hardware functionality and
register-level software programming for Host controller mode drivers (HCD) and Device controller
mode drivers (DCD). Guidance for the upper software layers, including device classes and
applications, are beyond the scope of the TRM.
X-Ref Target - Figure 15-5
Figure 15-5: USB Controller Link-list Concept
UG585_c15_34_030713
QH
First TD
Completed TD’s TD’s Queued and Ready
Current
TD
Last TD
T = 1
Read
TD
Write
Result