Workstation 4 and 4 LX Field Service Guide
2-27
WS4 Technical Overview
Complex Programmable Logic Device (CPLD)
•
If the previous power management state was
NOPOWER
, the workstation
remains in the
NOPOWER
state and waits for user to press the power button.
•
If the previous power management state was
SUSPEND
, the workstation
transitions to the
NOPOWER
state and waits for user to press the power
button.
ON
Refer to Figure 2-15. To transition the workstation to the
ON
state from the
UNPLUGGED
or
NOPOWER
state, the CPLD simulates a power button press by
toggling the
ON_OFF_SW
input to the CPU.
The power management logic in the CPU monitors the
ON_OFF_SW
input and
sets
ONCTL#
low to enable the +3V regulator. The CPLD logically inverts
ONCTL#
to
ONCTL
which in turn enables
VCORE
for the processor, as well as
the
VCC5V
,
VCC12V,
and
VCC-12V
outputs.
When the workstation is
ON
and the operating system is running, the power
button driver (POWER.DLL) polls the CPLD every 150ms to detect further
transitions of the power button. If the power button is pressed and held for less
than four seconds, the workstation enters the
SUSPEND
state. If the power button
is pressed and held for greater than four seconds, the workstation enters the
NOPOWER
state.
SUSPEND
Refer to Figure 2-15. When the workstation is in the
ON
state and the user presses
and holds the power button for less than four seconds, the power button driver
places the unit in
SUSPEND,
and continues to monitor CPLD for subsequent
transitions of the power button.
In the
SUSPEND
state, all voltages remain active, but the LCD screen is blanked,
and any activity on the touchscreen, or from external devices such as a PS/2
mouse or keyboard are ignored.
To transition to the
ON
state, the power button is pressed and the CPLD toggles the
ON_OFF_SW
input to the CPU, the workstation exits the
SUSPEND
state and
enters the
ON
state.
