OCPRF100 MP Server System Technical Product Specification

Revision 1.0

10.2.7.6Development and Test Reset

In development and board testing the PLD and microcontroller can be put into a reset state by asserting the PB_RST_L signal.

10.2.8Speaker

The front panel contains a speaker that is controlled by either the FPC or the I/O board. The speaker is energized if either source commands the speaker on. The speaker impedance is approximately 8 ohms.

The FPC commands the speaker on by setting the PLD’s SPEAKER_LATCH. This latch also can be read. The state of the I/O board’s speaker command cannot be read by the FPC.

During reset the SPEAKER_LATCH is set to deasserted (off, low).

10.2.9Fan Control

There are six fans which plug into the front panel board. Each fan is powered from the VCCFAN supply (see Section Dual Speed Fan Power, Dual Speed Fan Power). Each fan also has a tachometer out signal, which is fed into Input Latch #1, to be monitored by the FPC. If a fan is determined to have failed, the FAN_FAILED_L signal turns on the yellow fan failed LED on the front panel. Also, an LED near the fan that has failed is illuminated by the FPC (via Output Latch #1).

10.2.10 ICMB and COM2 Redirection

The ICMB/COM2 redirection circuitry provides a number of capabilities. These capabilities are dealt with individually in the following subsections.

10.2.10.1 Receive Auto Switching

Both the COM2 RXD (received) and the ICMB RXD signals are routed to the front panel and are continuously available, regardless of the state of any other control signals. In certain conditions it is desirable to monitor both signals and to switch to whichever signal goes active first into the FPC’s RXD input. This section covers such an auto-switch capability, implemented in the PLD.

The FP PLD supports auto-switching of the first-active incoming RXD signal into the incoming RXD signals. The auto-switch is enabled by deasserting both the FORCE_RXD_ICMB_LATCH and the FORCE_RXD_COM2_LATCH. When these are both deasserted by firmware, the PLD goes into auto-switch mode.

Upon RXD activity, the microcontroller can determine which RXD signal is routed to the micro- controller by reading the states of both FORCE bits within the PLD. Only the FORCE bit corresponding to the switched RXD (ICMB or COM2) signal becomes asserted. In no case will both FORCE bits become asserted.

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