Rainbow Electronics W90N740 - Manual (Page 153)

W90N740
Publication Release Date: November 26, 2004
- 149 - Revision A4
Host Controller Root Hub Descriptor A Register (HcRhDescriptorA)
This register is only reset by a power-on reset. It is written during system initialization to configure the
Root Hub. This bit should not be written during normal operation.
Register Address R/W Description Reset Value
HcRhDescriptorA 0xFFF0.5048 R/W
Host Controller Root Hub Descriptor A
Register
0x0100.0002
Register: HcRhDescriptorA
Bits Reset R/W Description
7-0 02h R
NumberDownstreamPorts
HYDRA-4 supports two downstream ports.
8 0 R/W
PowerSwitchingMode
Global power switching mode implemented in HYDRA-2. This bit is only
valid when NoPowerSwitching is cleared. This bit should be written '0'.
0 = Global Switching
1 = Individual Switching
9 0 R/W
NoPowerSwitching
Global power switching implemented in HYDRA-2. This bit should be
written to support the external system port power switching implementation.
0 = Ports are power switched.
1 = Ports are always powered on.
10 0 R
DeviceType
HYDRA-4is not a compound device.
11 0 R/W
OverCurrentProtectionMode
Global over-current reporting implemented in HYDRA-2. This bit should be
written 0 and is only valid when NoOverCurrentProtection is cleared.
0 = Global Over-Current
1 = Individual Over-Current
12 0 R/W
NoOverCurrentProtection
Global over-current reporting implemented in HYDRA-2. This bit should be
written to support the external system port over-current implementation.
0 = Over-current status is reported
1 = Over-current status is not reported
23-13 0h - Reserved. Read/Write 0's
31-24 01h R/W
PowerOnToPowerGoodTime
This field value is represented as the number of 2 ms intervals, which
ensuring that the power switching is effective within 2 ms. Only bits [25:24]
are implemented as R/W. The remaining bits are read only as ‘0’. It is not
expected that these bits be written to anything other than 1h, but limited
adjustment is provided. This field should be written to support system
implementation. This field should always be written to a non-zero value.