UM10503
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© NXP B.V. 2012. All rights reserved.
User manual
Rev. 1.3 — 6 July 2012
554 of 1269
NXP Semiconductors
UM10503
Chapter 23: LPC43xx USB0 Host/Device/OTG controller
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Software writes a ‘1’ to the port reset bit in the PORTSC1 register to reset the device.
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Software writes a ‘0’ to the port reset bit in the PORTSC1 register after 10 ms.
This step, which is necessary in a standard EHCI design, may be omitted with this
implementation. Should the EHCI host controller driver attempt to write a ‘0’ to the
port reset bit while a reset is in progress, the write will simply be ignored, and the reset
will continue until completion.
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[Port Change Interrupt] Port enable change occurs to notify the host controller that
the device is now operational, and at this point the port speed has been determined.
23.8.3.1.2
Port speed detection
After the port change interrupt indicates that a port is enabled, the EHCI stack should
determine the port speed. Unlike the EHCI implementation which will re-assign the port
owner for any device that does not connect at High-Speed, this host controller supports
direct-attach of non High-Speed devices. Therefore, the following differences are
important regarding port speed detection:
•
Port Owner is read-only and always reads 0.
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A 2-bit Port Speed indicator has been added to the PORTSC1register to provide the
current operating speed of the port to the host controller driver.
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A 1-bit High Speed indicator has been added to the PORTSC1register to indicate that
the port is in High-Speed vs. Full/Low Speed – This information is redundant with the
2-bit Port Speed indicator above.
23.9 Device data structures
This section defines the interface data structures used to communicate control, status,
and data between Device Controller Driver (DCD) Software and the device controller. The
data structure definitions in this chapter support a 32-bit memory buffer address space.
Remark:
The software must ensure that no interface data structure reachable by the
Device controller crosses a 4kB-page boundary.
The data structures defined in the chapter are (from the device controller’s perspective) a
mix of read-only and read/ writable fields. The DCD must preserve the read-only fields on
all data structure writes.