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3.20 HC Root Hub B Register (HCRHDESCRIPTORB)
The HC root hub B register (HCRHDESCRIPTORB) defines several aspects of the USB1.1 host controller
root hub functionality. HCRHDESCRIPTORB is shown in
Note:
The device does not provide connections from the USB1.1 host controller to pins to provide
external port power switching. Systems that implement port power switching must use other
mechanisms to control port power.
31
15
LEGEND: R/W = Read/Write; -n = value after reset
Table 21. HC Root Hub B Register (HCRHDESCRIPTORB) Field Descriptions
Bit
Field
Value
31-20
PPCM[15-4]
0
19
PPCM[3]
0
1
18
PPCM[2]
0
1
17
PPCM[1]
0
1
16
PPCM[0]
0
15-4
DR[15-4]
0
3
DR[3]
0
1
2
DR[2]
0
1
1
DR[1]
0
1
0
DR[0]
0
SPRUFM8 – June 2009
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Figure 21. HC Root Hub B Register (HCRHDESCRIPTORB)
PPCM[15-4]
R/W-0
DR[15-4]
R/W-0
Description
Port power control mask. PPCM[15] through PPCM[4] are reserved.
Port power control mask. PPCM[3] is the port power control mask for downstream port 3. Defines
whether downstream port 3 has port power controlled by the global power control. System software can
update these bits to simplify host controller driver and/or OTG driver coding.
Global power control is implemented for downstream port 3.
Per-port power control is implemented for downstream port 3.
Port power control mask. PPCM[2] is the port power control mask for downstream port 2. Defines
whether downstream port 2 has port power controlled by the global power control. System software can
update these bits to simplify host controller driver and/or OTG driver coding.
Global power control is implemented for downstream port 2.
Per-port power control is implemented for downstream port 2.
Port power control mask. PPCM[1] is the port power control mask for downstream port 1. Defines
whether downstream port 1 has port power controlled by the global power control. System software can
update these bits to simplify host controller driver and/or OTG driver coding.
Global power control is implemented for downstream port 1.
Per-port power control is implemented for downstream port 1.
Port power control mask. PPCM[0] is reserved.
Device removable. DR[15] through DR[4] are reserved.
Device removable. DR[3] is the device removable bit for downstream port 3. Defines whether
downstream port 3 has a removable or nonremovable device.
Downstream port 3 may have a removable device attached.
Downstream port 3 has a nonremovable device attached.
Device removable. DR[2] is the device removable bit for downstream port 2. Defines whether
downstream port 2 has a removable or nonremovable device.
Downstream port 2 may have a removable device attached.
Downstream port 2 has a nonremovable device attached.
Device removable. DR[1] is the device removable bit for downstream port 1. Defines whether
downstream port 1 has a removable or nonremovable device.
Downstream port 1 may have a removable device attached.
Downstream port 1 has a nonremovable device attached.
Device removable. DR[0] is reserved.
Figure 21
and described in
20
19
PPCM[3] PPCM[2] PPCM[1] PPCM[0]
R/W-0
R/W-0
4
3
DR[3]
DR[2]
R/W-0
R/W-0
Universal Serial Bus OHCI Host Controller
Registers
Table
21.
18
17
16
R/W-0
R/W-0
2
1
0
DR[1]
DR[0]
R/W-0
R/W-0
29
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