Figure 1 | Expansion diagram of FMM micro overlay with two fat pipe PCI Express inks


ble to touch a pin without being grounded. This eliminates the possibility of electro - static damage through the connector. The covers on both sides protect the board from electrostatic damage and debris.


Backplane to the future If the backplane can be chosen quickly and well, OpenVPX systems can be deployed faster. And historically, high- speed switched serial f abric presented the most compelling demand for a ne w backplane architecture. The bandwidth of the OpenVPX backplane is greatly improved over the VMEbus 40-60 MBps range. The OpenVPX backplane can be configured into many network topolo- gies such as mesh, star , dual-star, ring, or daisy chain. These networks permit multiple signals to be routed such that several cards can talk to each other simultaneously, achieving an aggregate bandwidth well over 100 GBps.


The OpenVPX backplane profile supports 10 GbE, PCI Express, Serial RapidIO, and SATA for nonvolatile memory. New revisions of these standards will push the limits of differential copper pairs; Open- VPX provides for coax and f iber-optic connections for higher -speed data and other signal formats.


OpenVPX COTS backplanes can also pro- vide more options if problems arise later in the design or manufacturing phase. For example, a multi-Gigahertz tested Fabric Mapping Module (FMM) can connect to the backplane and modify its topology , making it more flexible. It provides quick- turn backplane customization, thus elimi - nating interconnect conflicts. Dawn VME Products’ FMMs use BGA (Ball Grid Array) substrate technology as a “micro overlay,” similar in function to o verlays used on VME backplanes e xcept that FMMs can be used on VPX backplanes and are tuned for high-speed signal trans - mission (Figure 1). They can:


■ Directly connect PCI Express or SerialRapidIO to multiple cards or cards and switches


■ Link SATA from a CPU card to a Solid State Drive (SSD) carrier


■ Enable XMC cards to talk to other XMC cards


Dawn engineers have successfully used Fabric Mapping Modules to solve many OpenVPX application problems in the design phase.


Designing with OpenVPX for rapid deployment At one time, VME was found in military systems aplenty. But modern weapon and other embedded defense systems are becoming more modular and much sim - pler and faster to service using LR Us. Thus VME is being outpaced. OpenVPX, on the other hand, f acilitates VPX LRU development by providing system-level, multivendor interoperability.


Since these embedded defense systems and VPX LRUs must often be developed and deployed rapidly, it is very important that potential conflicts between various profiles are eliminated as quickly as pos- sible during the OpenVPX design phase. SWaP and thermal management, in addi- tion to connector and backplane techni - cal considerations, must be addressed and resolved faster so that adv anced capabilities can be swiftly engaged to the war fighter. CS


Brian Roberts is Senior Designer at Dawn VME Products. He has 21 years of design ex- perience developing electronic products with Commercial and Military compa-


nies based in Silicon Valley. He can be contacted at robertsb@dawnvme.com.


Dawn VME Products 510-657-4444


www.dawnvme.com VME and Critical Systems / Spring 2011 25


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