USB Host Controller Registers
14-26
Table 14–20. HC Root Hub A Register (HcRhDescriptorA) (Continued)
Bit
Reset
Value
Type
Description
Value
Name
10
DT
Device type
This bit is always 0, which indicates that the USB host
controller implemented is not a compound device.
R
0
9
NPS
No power switching
R/W
1
0
Indicates that VBUS power switching is supported and
is either per-port or all-port switched per the power
switching mode field.
1
Indicates that VBUS power switching is not supported
and that power is available to all downstream ports
when the USB host controller is powered.
Because OMAP5910 does not provide connections
from the USB host controller to control external VBUS
switching, this bit defaults to 1.
8
PSM
Power switching mode
R/W
0
0
Indicates that all ports are powered at the same time.
1
Indicates that individual port power switching is
supported.
Because OMAP5910 does not provide signals from the
USB host controller to control external VBUS switching,
this bit defaults to 0.
7–0
NDP
Number of downstream ports
This register defaults to 3 to indicate three downstream
ports.
The USB signal multiplexing mode and OMAP5910
top-level pin multiplexing features may place the
OMAP5910 device in a mode where 0, 1, 2, or 3 of the
USB host controller downstream ports are actually
usable. This register reports three regardless of USB
signal multiplexing mode and OMAP5910 top-level pin
multiplexing mode.
See Section 14.5, USB Pin Multiplexing, for information
on USB signal multiplexing.
R
0x03