Front Panel Control - Intel SE7525GP2 Technical Manual

Platform Management
The server board has two analog fan speed signals that are driven by pulse-width modulator
(PWM) circuits by the server board hardware. These signals can be driven to several levels
according to temperature measurements. Multiple bytes of a Sensor Initialization Table are used
to hold parameters that set the temperature thresholds and corresponding PWM duty cycles.
This SDR or table is loaded as part of the server board configuration.
The management controller firmware expects to find an LM30 temperature sensor on the front
panel board. Thus, the ambient temperature-based fan speed control capability is not enabled
by default for SE7320SP2 or SE7525GP2 as a server board-only product, but can be enabled
via a management controller configuration change.
5.3.3.1 Fan Kick-start
Some fans may not begin rotating unless started at high speed. To ensure that the fans start,
the server board hardware will start and run the fans at high speed for a brief interval following
system power up.
5.3.4

Front Panel Control

The mBMC provides the main 'front panel control' functions. These include control of the system
Power Button, Reset Button, Diagnostic Interrupt (Front Panel NMI) Button, System Identify
Button, System ID LED, Status/Fault LED, and Chassis Intrusion Switch. Front panel control
also includes the front panel lockout features.
5.3.4.1 Power Button
After de-bouncing the front panel Power Button signal, the mBMC routes the signal state directly
to the chipset Power Button signal input. If the chipset has been initialized by the BIOS, the
chipset responds to the assertion of the signal by requesting a power state change. It reacts to
the press of the switch, not the release of it.
The Power Button signal toggles the system power. The Power Button signal to the mBMC is
activated by a momentary contact switch on the front panel assembly. The mBMC de-bounces
the signal. After de-bouncing the signal, the mBMC routes it directly to the chipset via the Power
Button signal. The chipset responds to the assertion of the signal. It responds to the press of the
switch, not the release of it.
If the system is in Secure Mode or the Power Button is forced protected, then when the power
switch is pressed, a Platform Security Violation Attempt event message is generated and no
power control action is taken.
In the case of simultaneous button presses, the Power Button action takes priority over all other
buttons. For example, if the sleep button is depressed for one second and then the Power
Button is pressed and released, the system powers down. Due to the routing of the de-bounced
Power Button signal to the chipset, the power signal action overrides the action of the other
switch signals.
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Intel® Server Boards SE7320SP2 and SE7525GP2
Revision 4.0