RTD Embedded Technologies, Inc.
|
www.rtd.com
14
LAN25255HR/LAN35255HR User’s Manual
4
Functional Description
Block Diagram
4.1
The Figure below shows the functional block diagram of the LAN25255HR. The various parts of the block diagram are discussed in the
following sections.
Figure 7:LAN25255HR Block Diagram
BroadCom Gig-Ethernet Switch
4.2
The main component of the LAN25255HR is the BroadCom BCM53115 Gigabit Ethernet switch. This is an industrial temperature rated, 5 port
Gigabit Ethernet switch. This switch contains 5 full-duplex 10/100/1000 BASE-TX Ethernet transceivers for network interfacing. One of these
ports is used in conjunction with the WG82574IT for a host port. This allows the LAN25255HR to work as its own mini-server in a stacked
system. In a stand-alone system the BroadCom switch acts as a basic Ethernet switch. Any port can be used as an upstream port to supply a
connection to the 3 other ports.
Intel WG82574IT Gigabit Ethernet Controller
4.3
The LAN25255HR has an onboard Gigabit Ethernet controller, the Intel WG82574IT. The Intel WG82574IT is an industrial rated Gigabit
Ethernet controller which features Auto-Crossover for MDI/MDI-X, 9KB Jumbo Frame support, 40KB packet buffer size and IPv4/6 support.
This controller connects to the host CPU through a x1 PCI Express link on the PCIe/104 connector and interfaces through the fifth port of the
Ethernet switch to provide a host port for stacked systems.
Onboard LEDs and External LED Connectors
4.4
The LAN25255 has onboard LEDs for each of the five Ethernet ports on the board. The setting for the onboard LEDs is to show link activity,
status and speed at 10/100/1000M. To bring the LEDs out of an enclosed system, there are two 0.1 inch DIL connectors (CN14 & CN15) that
can be wired to external LED circuitry. These signals are can source or sink 24 mA and the connector has jumper options for 3.3 volt or ground
to facilitate external LED configuration.
