Extending Legacy Peripherals into the Future with CompactPCI Bridging Technology

September 18, 2024

Blog

In 2008, a CompactPCI (cPCI) system was deployed onboard the International Space Station (ISS) as part of a scientific instrument called the DEvice for the study of Critical LIquids and Crystallization (DECLIC)[1]. DECLIC is used to observe the formation of crystals in microgravity and was outfitted with new experiments via SpaceX resupply mission as recently as 2021.

Since its introduction in 1995, industry has relied on the open and interoperable cPCI standard in long-life systems like aerospace and other demanding transportation, automation, and control applications. But the performance demands of modern applications mean systems built around the original cPCI standard are now due for an upgrade.

Of course, higher performance alternatives are available. But how do you migrate to these options while remaining compatible with the legacy instrumentation and peripherals on a platform like DECLIC that are also increasingly difficult to source?

A Serial Upgrade Path for Legacy CompactPCI Systems

When considering an upgrade path, engineers have many options, such as moving to other modular architectures like VPX. However, cPCI remains a more cost-effective solution while delivering comparable performance and the CompactPCI Serial standard makes this value proposition even more compelling.

First ratified in 2011, CompactPCI Serial delivers high-speed serial PCIe connections in place of cPCI’s older parallel PCI backplane. It also introduces support for fault-tolerant star and redundant mesh backplane topologies that improve performance scalability and reliability, respectively.

New CompactPCI Serial modules encompass a variety of CPU and storage options; high-speed interfaces such as SATA, USB 3.0, and Gigabit Ethernet, support a range of use case-specific features that make cPCI technology more relevant than ever in a range of different verticals.

But for organizations that have made significant investments of time, money, and effort in building, integrating, and maintaining peripheral instrumentation and equipment around a cPCI system, the decision to upgrade is much more nuanced than improved performance and flexibility. To take advantage of the upgraded features of CompactPCI Serial while protecting existing investments, these organizations have limited options:

1. Adopt innovative bridging solutions
2. Design a drop-in replacement

Bridging Legacy Peripherals to CompactPCI Serial

By bridging CompactPCI Serial with other standards, engineers can preserve legacy investments, maintain compatibility with existing instrumentation and I/O, and simultaneously upgrade their core compute and switching infrastructure. Specifically, a bridged CompactPCI Serial system based on a hybrid backplane allows continued use of specialized boards that may not be available on all standards, thereby avoiding full redesigns and extending platform lifecycles (Figures 1A and 1B).

 

 

(Figures 1A and 1B. CompactPCI Serial bridging cards like the SXP-JAM and ECX-PCIE enable the deployment of hybrid backplane systems that can support existing investments in legacy peripherals and also deliver the flexibility and performance of modern open hardware standards, Source: EKF Elektronik GmbH)

An example of this is a cPCI platform populated with cards that are no longer supported by the original manufacturer but are also not yet available in CompactPCI Serial format. In lieu of completely redesigning the older system, companies can use specialized adapters that allow older cards to function alongside newer components within a single hybrid system*.

This approach can connect cPCI, CompactPCI Express (cPCIe), and other legacy cPCI solutions to CompactPCI Serial, as well as non-PICMG cards like PMCs, XMCs, MXM, M.2, and PCIe, mPCIe, and ePCIe cards. These adapters can even bridge PCI Express for Instrumentation (PXIe) technology to CompactPCI Serial in a hybrid backplane design**.

Drop-In Replacements

Another option for upgrading a legacy system to a newer backplane technology like CompactPCI Serial is to develop custom, drop-in replacement hardware for older peripheral cards that are no longer available. However, this is easier said than done, as it will almost inevitably introduce firmware compatibility issues in addition to hardware challenges.

Drop-in replacement hardware can be developed precisely to the physical specifications of a legacy device, and even improved within given design constraints to address things like updated certifications and regulatory requirements. But since many legacy systems were hard-coded based on specific assumptions about the use case and hardware configurations, system firmware, drivers, and even legacy operating systems can have dependencies on components that are no longer present in an upgraded system.

In this scenario, engineers may work with a vendor such as EKF to develop custom hardware that can serve as a drop-in replacement. EKF has a philosophy of supporting any design based on the CompactPCI family of standards (cPCI/Serial/PXIe) and is committed to keeping its product portfolio holistic and ensuring long-term availability for all system designs.

In addition to a deep partner network and decades of experience developing long-lifecycle standards-based systems, organizations can add the benefit of working with a specialized vendor like EKF Elektronik with expertise in designing for harsh edge environments. This includes hardening solutions against extreme shock, vibration, temperature, and electromagnetic interference (EMI) requirements using specialty mounts, ruggedized front panels, EMC-shielded housings, and more.

A Bridge to the Future for Legacy Peripherals

CompactPCI and its successors are essential in fields ranging from industrial automation to aerospace but can present significant design challenges as long-lifecycle systems reach end of life in these and other markets. As performance demands increase and critical legacy components become harder to procure, organizations that rely on cPCI-based can believe they are forced to undergo expensive and complete redesigns far earlier than necessary.

Utilizing bridging technology, these organizations can now easily connect cPCI Serial not just to older cPCI standards, but also to other technologies like PXI and XMC. Engineers can continue using specialized, hard-to-procure peripherals like FlexRay, MVB, or specialty I/O modules while incrementally upgrading their system performance over a hybrid backplane. Alternatively, they can partner with a third-party vendor to develop custom drop-in replacements for components that can no longer be effectively sourced.

Proven cPCI installations can therefore remain relevant for many years, as new integration options allow customers to retain key parts of their existing infrastructure and also take advantage of emerging technologies like NVIDIA GPU accelerators, PCI Express Gen 4 (and 5) interfaces, high-speed mass storage, high performant FPGA, and more. All while moving steadily towards the stable, next-generation destination of CompactPCI Serial.

References:

1. Science@Nasa. (2021, August 27). Two experiments to help humans “go farther / stay longer” in space. Phys.org. https://phys.org/news/2021-08-humans-longer-space.html

*A company working in a field where hardware is designed to be in circulation for decades recently found it was unable to source the necessary components when repairing one of its systems. An I/O board the system relied on was no longer available. Complicating matters further, the I/O bus was hard-coded and the system was built on older standards such as VMEbus and PICMG 1.0.

Leveraging CompactPCI Serial bridging technology, the organization was able to overcome this hurdle, replacing the legacy I/O board that delivered the same functionality with enhanced performance.

**Certain applications require highly-specialized systems with limited compatibility. One company relied on hardware designed to work with the PXI specification. Seeking to reduce overhead, the company transitioned from PXI and PXI Express to CompactPCI Serial using bridging capabilities enabled by solutions like the ECX-PCIE card from EKF Elektronik GmbH. 

This gave the company access to the same functionality at significantly reduced cost, while also streamlining system scalability.