PEX 8648-AA RDK Hardware Reference Manual, Version 1.2
Copyright © 2010 by PLX Technology, Inc. All rights reserved
12
3.2 Non-Transparent
Operation
Only the Station 0 Ports – Ports 0, 1, 2, and 3 – support NT mode. By default, the NT Port is assigned to Port 1,
by way of DIP switch SW1. To use the NT function, however, DIP switch SW1 must be used to Set the PEX 8648
switch’s Strapping balls so that the switch is in NT mode. Mini-SAS connectors are used to connect to the Host on
the NT Port, by way of cables.
For further details regarding the various hardware configurations for NT mode, refer to Section
3.1
, “
PCI Express
Port Configuration
.”
For further details regarding DIP switch SW1, refer to
Table 3
, “
PEX 8648 RDK Base Board Hardware Strapping
DIP Switches – SW1, SW11, SW4, SW5, SW9, SW6, SW2, and SW10
.”
For details regarding the PEX_NT_RESET# sideband signal, refer to Section
3.12.3
, “
PEX_NT_RESET#
(TPV49)
.”
3.3
PCI Express Hot-Plug Circuitry
The PEX 8648 switch supports Hot-Plug on three downstream Ports, by way of dedicated 10-signal Parallel Hot-
Plug interfaces. In addition, a serial I
2
C interface, in conjunction with an external I/O Expander IC, can be used to
support Hot-Plug on any Port. The PEX 8648 RDK base board has external Hot-Plug circuitry that supports
Parallel Hot-Plug to Slot 5, and Serial Hot-Plug to Slot 8.
The PEX 8648 RDK base board supports Parallel Hot-Plug, only on Port 5 of Station 1, routed to Slot 5, and only
when Station 1 is configured as x4x4x4x4. To support Parallel Hot-Plug, Slot 5 has a dual-voltage Hot-Plug
Controller chip associated with it (U15), which controls power to this slot. If Port 5 is the upstream Port, the
Strapping signals that Set the upstream Port are used to bypass the Hot-Plug circuitry for Slot 5.
Note: Other Port configurations that include Port 5 – x8x8 or x8x4x4 – do not support Hot-Plug. In this case,
Port 5 routes to Slot 6, which does not include Hot-Plug circuitry.
The PEX 8648 RDK base board supports Serial Hot-Plug on Port 8 of Station 2 (U18). A serial I
2
C interface, with
an external I/O Expander IC (U17), supports Serial Hot-Plug functionality on this slot. Because Port 8 is the
primary slot on Station 2, Port configuration of Station 2 does not matter. Port 8 is always Hot-Plug-capable.
Figure 14
illustrates the PEX 8648 RDK base board PCI Express Hot-Plug circuitry.
