SYSTEM OPERATION
4-2
600-2708 PCI Express Expansion System User’s Manual
Revision 1.0, June 2010
The top (or right) LED on the panel is "Expansion System Signal Detect". The LED is on when the
PCIe-425 detects a signal on Lanes 0-3 of the PCIe cable. The LED ON indicates normal operation. If
the LED is not on, there is something wrong with the cable or the expansion system is not operating
properly.
4.3.4
PCIe-425 Output Swing, De-Emphasis and Receive Equalization
The transceiver silicon used on the PCIe-425 has eight steps of programmable de-emphasis, four steps
of output swing and eight steps of receive equalization. The PCIe-425 has three DIP switches to adjust
these settings on the cable interface. The as-shipped-default DIP switch configuration is what Cyclone
Microsystems has determined is the best setting for Gen2 operation with both the 1m and 3m PCIe
cables shipped with Cyclone PCIe Expansion systems. Users should not change the DIP switch settings
unless they have the proper test equipment to verify their results. Users change de-emphasis, output
swing and receive equalization at their own peril. The default DIP switch configuration is shown below:
4.4
PCIe-451 LED INDICATORS
The PCIe-451 has eighteen LEDs to indicate PCIe link status. Each slot and the cable have two,
redundant, LED link status indicators. Nine surface mount LEDs, one for each slot and one for the cable
are arranged in a column near the PCIe cable connector, see Figure 5-2. The LEDs are labeled "J1"
through "J8" and "CABLE". At each slot, there is an LED located just off axis to the bottom side of an
installed board so as not to be obscured by components on the add-in card. The LEDs are labeled "J1"
through "J8". The second LED for cable link status is the top, yellow LED of the rear panel LED tower.
A slot linked at Gen2 rates will have its LEDs ON solid. A slot linked at Gen1 rates will indicate status
with BLINKING LEDs. Likewise, the CABLE LED should be ON indicating the link to the host is
Gen2 and will BLINK if a Gen1 link with the host has been established.
The bottom, green LED of the rear panel LED tower indicates both a "power good" status and that the
"cable present signal" back to the host is being asserted.
The last PCIe-451 LED is the red, "POWER" LED which under normal conditions is OFF. It will be on
momentarily at power up then remain OFF. If ON, it is indicating a failure of one of the on-board
voltages. This LED blinking could indicate a problem with a lightly loaded, unstable power supply.
POSITION
SWITCH S1
SWITCH S2
SWITCH S3
1
OFF
OFF
ON
2
OFF
ON
ON
3
ON
OFF
ON
4
ON
OFF
OFF
