RM0082
HS_USB2.0 host
Doc ID 018672 Rev 1
455/844
Table 384.
HcRhDescriptorA register bit assignments
Bits
Name
Reset
Read/Write
Description
HCD
HC
[31:24]
POTP
GT
IS
R/W
R
PowerOnToPowerGoodTime
This byte specifies the duration HCD has to wait before
accessing a powered-on port of the Root Hub. It is
implementation-specific. The unit of time is 2 ms. The
duration is calculated as POTPGT * 2 ms.
[23:13]
Reserved
[12]
NOCP
IS
R/W
R
NoOverCurrentProtection
This bit describes how the overcurrent status for the Root
Hub ports are reported. When this bit is cleared, the
OverCurrentProtectionMode field specifies global or per-
port reporting.
0: Over-current status is reported collectively for all
downstream ports
1: No overcurrent protection supported
[11]
OCPM
IS
R/W
R
OverCurrentProtectionMode
This bit describes how the overcurrent status for the Root
Hub ports are reported. At reset, this fields should reflect
the same mode as PowerSwitchingMode. This field is
valid only if the NoOverCurrentProtection field is cleared.
0: over-current status is reported collectively for all
downstream ports
1: over-current status is reported on a per-port basis
[10]
DT
0b
R
R
DeviceType
This bit specifies that the Root Hub is not a compound
device. The Root Hub is not permitted to be a compound
device. This field should always read/write 0.
[09]
NPS
IS
R/W
R
NoPowerSwitching
These bits are used to specify whether power switching is
supported or port are always powered. It is
implementationspecific. When this bit is cleared, the
PowerSwitchingMode specifies global or per-port
switching.
0: Ports are power switched
1: Ports are always powered on when the HC is powered
on