FireLink USB
82C862
912-2000-030
Revision 1.0
Page 17
®
Individual Power Switching is the mode in which the power to the USB ports can be controlled individually by using the Port
Status registers for each port, or can also be controlled globally depending on the value in the PowerControlMask register.
When strapping into this mode, the PowerControlMask registers will be set. All four signals, PWRON1#, PWRON2#,
PWRON3#, and PWRON4# will be used to turn on the respective USB ports power and will be independently controlled.
When supporting this mode the following registers are of significance:
Register
Field
Value or Function
HcRhDescriptorA
NoPowerSwitching
MEMOFST 49h[1]
0: Ports are power switched
HcRhDescriptorA
PowerSwitchingMode
MEMOFST 49h[0]
1: Each port is powered individually. This mode allows
the port to be either global or individual controlled
depending on value in PortPowerControlMask.
HcRhDescriptorB
PortPowerControlMask
MEMOFST 4Eh[2:1]
This register determines if the ports power is controlled
individually by the Port Status register, or globally by the
Root Hub Status register.
0=port uses global Set/ClearGlobalPower
1=port uses per-port Set/ClearPortPower
HcRhStatus
ClearGlobalPower (write)
MEMOFST 50h[0]
This bit is written to ‘1’ to turn off power to ports whose
PortPowerControlMask=0.
HcRhStatus
SetGlobalPower (write)
MEMOFST 52h[0]
This bit is written to ‘1’ to turn on power to ports whose
PortPowerControlMask=0.
HcRhPort1Status
HcRhPort2Status
PortPowerStatus (read)
MEMOFST 55h[0] port 1
MEMOFST 59h[0] port 2
0=port power is off
1=port power is on
If per-port switching is enabled for this port, then only
Set/ClearPortPower affect this bit. If global mode is
enabled, then Set/ClearGlobalPower control this bit.
HcRhPort1Status
HcRhPort2Status
SetPortPower (write)
MEMOFST 55h[0] port 1
MEMOFST 59h[0] port 2
1: sets PortPowerStatus
Only valid if port is enabled for per-port switching.
HcRhPort1Status
HcRhPort2Status
ClearPortPower (write)
MEMOFST 55h[1] port 1
MEMOFST 59h[1] port 2
1: clear PortPowerStatus
Only valid if port is enabled for per-port switching.
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