Cirrus Logic EP93xx User Manual

Page 475

DS785UM1

11-35

Universal Serial Bus Host Controller

EP93xx User’s Guide

(WRITE) SetPortPower: The HCD writes a “1” to set the
PortPowerStatus bit. Writing a “0” has no effect.

Note: This bit is always reads “1” if power switching is not supported.

LSDA:

(READ) LowSpeedDeviceAttached. This bit indicates the
speed of the device attached to this port. When set, a Low
Speed device is attached to this port. When clear, a Full
Speed device is attached to this port. This field is valid
only when the CurrentConnectStatus is set.
0 = full speed device attached
1 = low speed device attached

(WRITE) ClearPortPower. The HCD clears the
PortPowerStatus bit by writing a “1” to this bit. Writing a “0”
has no effect.

CSC:

ConnectStatusChange. This bit is set whenever a connect
or disconnect event occurs. The HCD writes a “1” to clear
this bit. Writing a “0” has no effect. If
CurrentConnectStatus is cleared when a SetPortReset,
SetPortEnable, or SetPortSuspend write occurs, this bit is
set to force the driver to re-evaluate the connection status
since these writes should not occur if the port is
disconnected.
0 = no change in CurrentConnectStatus
1 = change in CurrentConnectStatus

Note: If the DeviceRemovable.NDP bit is set, this bit is set only after a Root Hub reset to inform

the system that the device is attached.

PESC:

PortEnableStatusChange. This bit is set when hardware
events cause the PortEnableStatus bit to be cleared.
Changes from HCD writes do not set this bit. The HCD
writes a “1” to clear this bit. Writing a “0” has no effect.
0 = no change in PortEnableStatus
1 = change in PortEnableStatus

PSSC:

PortSuspendStatusChange. This bit is set when the full
resume sequence has been completed. This sequence
includes the 20 ms resume pulse, LS EOP, and 3 ms
re-synchronization delay. The HCD writes a “1” to clear
this bit. Writing a “0” has no effect. This bit is also cleared
when ResetStatusChange is set.
0 = resume is not completed
1 = resume completed