System Features
EPM-15 Reference Manual
25
ACPI Power Management
The EPM-15 supports the Advanced Configuration and Power Interface (ACPI) “S3 Sleeping
State,” also known as “suspend to RAM” mode. Wakeup is accomplished by grounding pin 39 to
pin 40 on connector J8 or via pushbutton (or relay attached to the pushbutton interface). Power
consumption in standby mode is under 1 watt. Wakeup typically occurs in 1 to 6 seconds.
Standby mode functionality has been tested under Windows XP and Windows XP Embedded.
Also see the Power Management Control Block Diagram on page 4.
T
HE
S3
S
LEEPING
S
TATE
The ACPI Specification defines the S3 sleeping state as a low wake latency sleeping state where
all system context is lost except system memory. CPU, cache, and chipset context are lost in this
state. The hardware maintains memory context and restores some CPU configuration context.
Control starts from the processor’s reset vector after the wake event.
Since the state of the operating system and all applications (including open documents) is
sustained in main memory, the system can resume work exactly where it left off. The contents of
main memory when the computer wakes from standby are the same as when it was put into
standby.
S
ETUP
To set up the EPM-15 to use ACPI power management:
1.
Verify that the CMOS Setup ACPI 1.0 setting is set to Enabled. This is the default
setting.
2.
If you plan to use a pushbutton or relay for wakeup, remove the jumper from jumper
block V4[7-8]. Removing this jumper enables the ACPI pushbutton interface.
3.
If you plan to use a pushbutton or relay for wakeup, attach the switch contacts to pins 3
and 4 of connector J2 on the CBR-5010 utility board. Pin 3 is ground, and pin 4 is the
pushbutton input. (If you are not using CBR-5010, the pushbutton input is pin 40 of
connector J8 on the EPM-15 motherboard.)
4.
Install the most current drivers for all system devices. If a driver is not installed correctly,
an exclamation point will appear before the device name in Device Manager. Incorrectly
installed or older drivers may prevent the system from entering standby mode.
E
NTERING
S
TANDBY
M
ODE
Standby mode can be entered through the operating system (by configuring the standby settings
in Power Options Properties) or programmatically, through a function call or the execution of a
shutdown utility. The Microsoft Windows utility DUMPPO.EXE can be used to set up and fine
tune ACPI power states.
