USB Host Controller
1551
SPNU503C – March 2018
Copyright © 2018, Texas Instruments Incorporated
Universal Serial Bus (USB)
29.2.4.20 HC Root Hub B Register (HCRHDESCRIPTORB)
The HC root hub B register defines several aspects of the USB host controller root hub functionality.
Figure 29-20. HC Root Hub B Register (HCRHDESCRIPTORB) [address = FCF78B4Ch]
31
16
PPCM[15-0]
R/W-0
15
0
DR[15-0]
R/W-0
LEGEND: R/W = Read/Write; -
n
= value at reset
Table 29-22. HC Root Hub B Register (HCRHDESCRIPTORB) Bit Field Descriptions
Bit
Field
Value
Description
31-16
PPCM
0-FFFFh
Port power control mask
Each bit defines whether a corresponding downstream port has port power controlled by the
global power control. If set, per-port power control is implemented for the corresponding port. If
clear, global power control is implemented for the corresponding port.
PPCM bit 0 is reserved.
PPCM bit 1 is the port power control mask for downstream port 0.
PPCM bit 2 is the port power control mask for downstream port 1.
PPCM bits 3 through 15 are reserved.
15-0
DR
0-FFFFh
Device removable
Each bit defines whether a corresponding downstream port has a removable or non-removable
device. A cleared bit indicates the corresponding port may have a removable device attached. A
set bit indicates that the corresponding port has a non-removable device attached.
DR bit 0 is reserved..
DR bit 1 is the device removable bit for downstream port 0.
DR bit 2 is the device removable bit for downstream port 1.
DR bits 3 through 15 are reserved.