A20 User Manual (Revision 1.2) Copyright © 2013 Allwinner Technology Co., Ltd. All Rights Reserved. Page 677 / 812
Register Name: PORTSC
Default Value: 0x00002000(w/PPC set to
one);0x00003000(w/PPC set to a zero)
one. Software must appropriately time the Resume and set
this bit to a zero when the appropriate amount of time has
elapsed. Writing a zero (from one) causes the port to return
high-speed mode (forcing the bus below the port into a
high-speed idle). This bit will remain a one until the port has
switched to high-speed idle. The host controller must complete
this transition within 2 milliseconds of software setting this bit
to a zero.
This field is zero if Port Power is zero.
OCC
Over-current Change
Default = 0. This bit gets set to a one when there is a change
to Over-current Active. Software clears this bit by writing a one
to this bit position.
OCA
Over-current Active
0 = This port does not have an over-current condition. 1 = This
port currently has an over-current condition. This bit will
automatically transition from a one to a zero when the over
current condition is removed.
The default value of this bit is ‘0’.
PEDC
Port Enable/Disable Change
Default = 0. 1 = Port enabled/disabled status has changed. 0 =
No change.
For the root hub, this bit gets set to a one only when a port is
disabled due to the appropriate conditions existing at the
EOF2 point (See Chapter 11 of the USB Specification for the
definition of a Port Error). Software clears this bit by writing a 1
to it.
This field is zero if Port Power is zero.
PED
Port Enabled/Disabled
1=Enable, 0=Disable. Ports can only be enabled by the host
controller as a part of the reset and enable. Software cannot
enable a port by writing a one to this field. The host controller
will only set this bit to a one when the reset sequence
determines that the attached device is a high-speed device.
Ports can be disabled by either a fault condition(disconnect
event or other fault condition) or by host software. Note that
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