Hcrhdescriptora register, Table 441: hcrhdescriptora register – Digi NS9750 User Manual
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U S B C o n t r o l l e r M o d u l e
HcRhDescriptorA register
Address: 9010 1048
The HcRhDescriptorA register is the first of two registers describing the
characteristics of the root hub. The root hub is the logical hub built into a USB host.
Reset values are implementation-specific.
Register bit assignment
Bits
Access
Mnemonic
Reset
Description
D31:24
R/W
POTPGT
IS
PowerOnToPowerGoodTime
Specifies the length of time the host controller driver has
to wait before accessing a powered-on port of the root hub.
The unit of time is 2 ms. The duration is calculated as
POTPGT*2 ms
.
D23:13
N/A
Reserved
N/A
N/A
D12
R/W
NOCP
IS
NoOverCurrentProtection
Describes how the overcurrent status for the root hub ports
is reported. When the NOCP bit is cleared, the
OverCurrentProtectionMode field (D11 in this register)
specifies global or per-port reporting:
0
Overcurrent status is reported collectively for all
downstream ports.
1
No overcurrent protection supported.
Table 441: HcRhDescriptorA register
NDP
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
POTPGT
Reserved
Reserved
NOCP OCPM
DT
PSM
NPS