Digi NS9750 - Manual (Page 779)

w w w . d i g i e m b e d d e d . c o m 7 5 5
U S B C o n t r o l l e r M o d u l e
HcRhDescriptorB register
Address: 9010 104C
The HcRhDescriptorB register is the second of two registers describing the
characteristics of the root hub. These fields are written during initialization to
correspond with the system implementation. Reset values are implementation-
specific.
Register bit assignment
Bits Access Mnemonic Reset Description
D31:16 R/W PPCM IS PortPowerControlMask
Each bit indicates whether a port is affected by a global
control command when PowerSwitchingMode (see
"HcRhDescriptorA register" on page 753) is set.
When set, the port’s power state is affected only by per-
port power control (Set/ClearPortPower).
When cleared, the port is controlled by the global power
switch (Set/ClearGlobalPower).
If the device is configured to global switching mode
(PowerSwitchingMode=0), this field is not valid.
Bit 0: Reserved
Bit 1: Ganged-power mask on port #1
Bit 2: Ganged-power mask on port #2
...
Bit 15: Ganged-power mask on port #15
Table 442: HcRhDesdcriptorB register
13 12 11 10 9 8 7 6 5 4 3 2 1 0 15 14
31 29 28 27 26 25 24 23 22 21 20 19 18 17 16 30
PortPowerControlMask (PPCM)
DeviceRemovable (DR)