Many long-lived embedded systems need to be modernized without replacing their entire system architecture. Long lifecycles, availability, and controlled migration are particularly critical in the transportation, defense, industrial automation, and rugged computing sectors. QMC adds a new dimension to this migration.
Introduction: Modernization Pressure in Embedded Systems
Embedded computing requirements continue to increase as technologies such as edge processing, artificial intelligence (AI), and sensor fusion demand greater bandwidth and higher I/O density. Established hardware and software platforms accelerate integration and development while often supporting interoperability between solutions from different vendors, helping manufacturers to scale both production and deployment.
In some cases, however, system modernization necessitates a shift away from original frameworks, presenting engineering teams with a choice: system migration or full platform replacement. The right migration strategy can allow engineers to preserve much of the existing hardware and software investment. In contrast, full platform replacement typically involves reengineering from the ground up.
When PCIe-based system architectures require higher data throughput, greater reliability, and scalable thermal management, CompactPCI Serial offers a versatile migration strategy. Nevertheless, compact form factors and functional flexibility are becoming increasingly important in many applications.
CompactPCI Serial as a Stable PCIe-Based Platform
CompactPCI Serial combines PCIe with other high-speed serial interface standards, including Ethernet, SATA, and USB, via robust backplanes. Its flexible modularity is particularly useful in long–lifecycle defense, aerospace, industrial, and transportation applications, where the ability to quickly replace components with compatible alternatives helps reduce downtime and sourcing issues.
When designing compact, backplane-based systems, VPX is often considered. However, the I/O profile complexity, cost, and ecosystem requirements of VPX are often unnecessary in many commercial applications, making CompactPCI Serial an attractive alternative. By adding an additional mezzanine layer to CompactPCI Serial systems, engineers can gain higher integration density and flexibility to support modern application requirements.
The Next Layer of Modularity: QMC
The VITA 93 QMC standard provides an extra layer of modularity within modular board-level systems. By extending designs via interchangeable mezzanine layers, rather than replacing existing standards, QMC enables engineers to increase system functionality while preserving standards-based interoperability.
In practice, QMC can be used to integrate additional function modules and up to 40 I/Os per card. A quad–QMC carrier can expose as many as 160 I/Os within a single CompactPCI Serial slot, depending on the implementation. QMC is also designed to support PCIe Gen6 x16 signaling, providing greater interface bandwidth than PMC while offering a forward-looking roadmap beyond traditional XMC implementations.
A single-width QMC module measures 26 mm x 78.25 mm with a height of 4.7 mm, supporting ultra-compact integration. QMC allows compatible carrier boards to serve as modular building blocks within existing standards, adding system flexibility and capability without increasing size. The standard also accommodates managed–system implementations, including via intelligent platform management interfaces (IPMIs), as well as multiple stacking heights to support either air-cooled or conduction–cooled systems. In short, QMC expands the design options for CompactPCI Serial system architects.
From One Function Module to Multiple Functions per Slot
Traditionally, CompactPCI Serial carrier boards have provided a single PMC or XMC site per slot. QMC allows engineers to install multiple modules within comparable footprints, granting access to additional serial interfaces, digital and analog I/O, Ethernet and CAN connectivity, or user–reconfigurable FPGAs, for example. Figure 1 illustrates system extension using the TEWS Technologies TCPS210, a 3U CompactPCI Serial carrier module with three single-width QMC sites and rear I/O.
Figure 1: The TEWS Technologies TCPS210 QMC-enabled CompactPCI Serial carrier. (Image source: TEWS Technologies)
By adopting the QMC standard, engineers can achieve higher functional density with more configuration options and greater adaptability to support customer-specific system requirements. Possible multiple-function application examples include:
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Mixed I/O configurations on a single carrier
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Serial interfaces combined with digital I/O
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Data acquisition alongside communication interfaces
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Customer-specific variants without carrier redesign
Carrier Boards as the Bridge Between System Platforms and QMC
Beyond QMC-enabled CompactPCI Serial carrier boards, there are several approaches envisioned for enabling practical high-density QMC mezzanine functionality within established backplane architectures. TEWS Technologies has developed a concept for a QMC carrier for MicroTCA systems, enabling QMC-driven modernization in many telecom, defense, and scientific instrumentation applications optimized for size, weight, and power (SWaP).
Similarly, the TEWS Technologies TCPS211 CompactPCI Serial carrier will feature QMC sites and flexible front I/O, leveraging the VITA 93.1 QTM (QMC Transition Module) standard. Since many PMC carriers for CompactPCI Serial already use front I/O, this solution provides the logical next step for PCIe-based system modernization via QMC.
System Modernization Without Full Redesign
When reworking CompactPCI Serial systems, QMC carriers allow existing hardware infrastructure to remain in use, reducing time to market and helping support changes to interface and computing resource requirements as applications evolve. QMC simplifies new I/O integration by using familiar modular frameworks, lowering migration risk when compared to complete platform replacement.
By retaining many aspects of existing designs, system integrators benefit from scalable variant management across similar products. Moreover, QMC-based modernization can lower architecture costs when keeping a CompactPCI Serial baseline, instead of migrating systems to high-end alternative architectures.
Positioning QMC Across VPX and CompactPCI Serial
Designed specifically for SWaP alignment and military-grade robustness, VPX is widely used in high-end defense, aerospace, and rugged computing applications. Like CompactPCI Serial, engineers can support high-density mezzanine modularity by combining VPX with QMC and other standards within the VITA ecosystem.
Both VPX and CompactPCI Serial can adopt QMC through suitable carrier boards, bringing similar modularity benefits into the wider PICMG ecosystem. By enabling higher functional density and flexible I/O configuration across different platform architectures, QMC provides a streamlined approach when modernizing standards-based systems.
Ecosystem and Standardization
Leveraging standards-based architectures such as CompactPCI Serial, QMC, and VPX allows engineering teams to significantly reduce integration risk for long-term designs. These ecosystems typically comprise I/O boards, CPUs, carriers, chassis, and backplanes, so reliable vendor partnerships are critical for long-term support. Standards also allow multiple vendors to participate in the ecosystem, reducing reliance on a single supplier.
TEWS Technologies is helping engineers combine established standards such as CompactPCI Serial and MicroTCA with QMC to support system modernization. Manufacturers such as EKF and Elma can also offer unique perspectives for CompactPCI Serial CPU boards and backplanes, and chassis and system integration, respectively.
Conclusion
While CompactPCI Serial remains relevant for many long-life embedded systems, QMC enables engineers to expand these platforms through an additional mezzanine layer that increases functional density and configuration flexibility. By creating a practical modernization path for applications that need greater I/O flexibility, QMC supports accelerated integration and development without requiring a completely new system architecture