EPX-C414/Configuration
v1.0
www.winsystems.com
Page 46
7.11.4 JPATX Power Supply Selection
Layout and Pin Reference
The EPX-C414 supports either AT (standard power supply) or ATX-type power supplies.
WinSystems recommends using zero-load supplies. JPATX specifies the style of supply
connected to the single board computer (SBC). An AT power supply is a simple on/off
supply with no interaction with the single board computer. Most embedded systems
use this type of power supply, and it is the default setting.
ATX-type power supplies function with a “soft” on/off power button and a +5VSB
(standby). If an ATX compatible power supply is connected, set JPATX accordingly and
connect a power button (momentary contact) between pin 3 (power button) and pin 2
(ground) of ATXAUX. The +5VSB signal provides the standby voltage to the EPX-C414
but does not power any other features of the board. When the power button is pressed,
the EPX-C414 pulls PSON (Power Supply On) low and the power supply turns on all
voltages to the single board computer. When the power button is pressed again, the
BIOS signals the event so ACPI-compliant operating systems can be shutdown before
the power is turned off. In ATX mode, if the power button is held for 4 seconds, the
power supply is forced off, regardless of ACPI. Because this is software driven, it is
possible that a software lockup could prevent the power button from functioning
properly. For the BIOS to report the ATX supply to ACPI-compatible operating systems,
JPATX must be setup correctly.
Pins 2-4-6 define what happens after G3 (all power removed) and when no battery is
present.
Panel Power
Jumper Positions
AT Power
Jumper pins 2 and 4 together
When jumpered 2-4, the board powers up without pressing the power
button.
ATX Power
Jumper pins 4 and 6 together
With no battery installed:
When jumpered 4-6, the user must press the
power button to power up the board.
With battery installed:
After the board has been powered and the power
button pressed for the first time, the next action is controlled by the
CMOS setting labeled “Power Loss Mode.” There are three options:
•
Keep last state
•
Always on
•
Always off
□ □
1 3 5
□
2 4 6
□
□
