User Guide • PC3-ALLEGRO • CompactPCI
®
PlusIO CPU Board • Intel® i7-3xxx Processor
Reset
The PC3-ALLEGRO is provided with several supervisor circuits to monitor supply rails like the CPU core
voltage, 1.5V, 3.3V or 5V. This circuitry is responsible also to generate a clean power-on reset signal.
To force a manual board reset, the PC3-ALLEGRO offers a small tactile switch within the front panel.
This push-button is indent mounted and requires a tool, e.g. a pen to be pressed, preventing from
being inadvertently activated.
The ejector within the front panel contains a micro switch that is used to generate a power button
event. This is done by pushing the red button of the ejector until the handle unlocks without ejecting
the board. Immediately after that push up the ejector back to its original position (the red button
jumps up as well). Animated GIF: www.ekf.com/c/ccpu/img/reset_400.gif
NOTE: To prevent the board to cause a power button override, the handle should be closed
immediately after unlocking the front panel handle. A power button override is triggered by opening
the front panel handle for at least 4 seconds, which results in bringing the board to power state S5.
In case of entering this state, unlock and lock the front panel handle a 2
nd
time to reenter normal
power state S0 again. See also section 'PG (Power Good) LED' to see how the PC3-ALLEGRO indicates
the different power states.
WARNING: The PC3-ALLEGRO will enter the power state S5 if the front panel handle is not closed
properly when the system powers up. An open handle is signalled by a yellow blinking ‘PG LED’.
The manual reset push-button and the power button functionality of the front panel handle could be
passivated by BIOS settings.
An alternative (and recommended) way to generate a system reset is to activate the signal PRST#
located on
CompactPCI
connector J2 pin C17. Pulling this signal to GND will have the same effect as
to push the tactile reset switch.
The healthy state of the PC3-ALLEGRO is indicated by the LED PG (Power Good) located in the front
panel. This bicoloured LED signals different states of the board (see section below). As soon as this
LED begins to lite green, all power voltages are within their specifications and the reset signal has
been deasserted.
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