Combining FPGAs & Atom x86 CPUs for SBC design flexibility

This product how-to design article describes how an embedded X86 single board computer’s feature set need no longer be set in stone, and shows how this was done in Kontron’s PCIe/104 MICROSPACE MSMST SBC with an Intel Atom E600C processor and an Altera Cyclone IV GX FPGA.

Field Programmable Gate Array (FPGA) technology has been a useful design resource for quite some time and continues to be a mainstay because it delivers many of the same benefits of x86 processor architectures.

The various common advantages include multifunctionality, a healthy and broad-based ecosystem and a proven installed base of supported applications. Combining x86 processor boards with FPGA-controlled I/Os expands these benefits even further, allowing dedicated I/Os to support a wider range of application requirements.

Employing next-generation x86 processors with FPGAs onto a single hardware platform provides the ability to eliminate chipsets so that different areas of applications can be built on the same platform requiring only the exchange the IP cores.

New x86-based embedded computing platforms combined with FPGAs enable a new realm of applications – providing highly adaptable feature options for designs that have previously been restricted due to lack of interface or I/O support.

By understanding the collective advantages of this approach, designers can reduce Bill of Material (BOM) costs and maintain long-term availability with legacy interfaces and dedicated hardware-based I/O. Further, legacy systems now have a bridge to tap into the latest processor enhancements such as graphics media acceleration, hyperthreading and virtualization for greater success in matching exacting requirements.

This is a significant advancement in bridging newer technologies with older systems implemented in military, industrial automation and manufacturing environments.

Blending x86 and FPGAs for adaptable design options
Most x86 architecture designs are paired with a chipset, usually a two-piece component with a specific set of integrated features. Ethernet, memory control, audio, graphics, and a defined set of input/output interfaces such as PCI, PCI Express, SATA , and LPC are routinely integrated options.

However many of these chipsets are moving away from the legacy interconnects (e.g., IDE and PCI) commonly found in deeply established environments such as military, industrial automation or manufacturing systems for safety and operations.

As a result, these industries have not been able to take advantage of processor advancements and subsequent improvements in power and performance.

The availability of new x86 processors in combination with an FPGA presents an entirely new design approach that virtually take away embedded limitations from a predetermined feature set. These capabilities distinguish the Intel Atom E6x5C processor series as a milestone in x86 technologies, and a departure from using a chipset with a fixed definition.

Instead the Intel Atom E6x5 processor is combined with a flexible and programmable Altera FPGA on a single compact multi-chip module. By incorporating PCI Express rather than the Intel-specific Front Side Bus, the FPGA is connected directly to the processor rather than to a dedicated chipset, resulting in maximum flexibility and long-term design security.

Designers further have ready access to increased performance integrated into smaller form factors that offer very low thermal design power (TDP).

Because the FPGA can be programmed to support modern as well as legacy interfaces, OEMs now have a workable migration path from non-x86 to x86 architectures – enabling slower moving technology-based market applications to progress to next-generation processing technologies.

Cementing this approach as an appealing long-term design solution, Loring Wirbel of FPGA Gurus estimates that the CAGR for FPGAs will continue at a strong 8.6 percent which will put the FPGA market at US$7.5 billion worldwide by 2015.

Market snapshot of design obstacles
Historically, development of new x86 technology was driven by performance requirements. However more recently, an increasingly high degree of integration and energy efficiency have become increasingly prominent factors affecting broad market interest in x86.

For example, an industry-first performance-per-watt ratio has been achieved by the Intel Atom processor, manufactured in 45nm technology with a TDP of less than two watts at 1.6 GHz performance. Corresponding low power consumption has enabled fanless designs and completely closed housings that meet both space-constrained and rugged design requirements.

Based on these key factors, flexible x86 technology has become more deeply integrated into embedded applications. At the same time, more interfaces are moving away from chipsets with dedicated controllers, while nearly all of today’s relevant interfaces are pre-integrated in chipsets.

This convenience is somewhat counter to the needs of embedded design, as the deeper an embedded PC has to be embedded, the more dedicated and tailored the necessary interfaces become. A certain design cost and overhead results, as many of the available standard PC interfaces are no longer necessary to embedded designs.

Further, many industrial applications rely on the older, but proven, ISA bus in order to protect investments, yet new processors no longer provide support for the ISA interface. Processing advancements once required PCI to ISA implementations, which were more cost-effective than porting ISA-based I/O cards to PCI or PCI Express.

The latter was expensive and unwieldy, demanding additional space for add-on components. This is also a short-term design choice as PCI support is not anticipated as a long-term chipset feature.

With FPGAs, software and IP cores now take on a more predominant role in embedded computing at the hardware level. So, rather than using a chipset with pre-configured I/O support, designers can utilize IP to customize I/O with software in a single board solution.

Consider the example of a global application requiring industrial Panel PCs with country-specific field busses and an extremely competitive BOM. Diversification of this type commonly requires using extension components, a costly and time-intensive design approach.

A configurable interface would be an ideal alternative, including the option to implement all required field busses, and would allow OEMs to be highly competitive with a single, globally applicable hardware platform that relied on a minimum of components.

Occasional changes in interface standards, newly published specifications and adjustments to individual protocols are also challenges, and effect sustainability of an embedded design.

Carrying out a long-term design with standard components may mean having to permanently change the hardware design, which in turn can lead to significantly increased costs based on ongoing test and certification requirements.

The evolving x86
By combining an x86 CPU core with an FPGA, designers are able to access pure IP – increasing design flexibility and streamlining the process for new applications. Only the IP cores must be maintained, providing a sharp contrast to the more difficult process of managing a range of different controller components.

Integrating the most current x86 processors with FPGAs ensures high-performance, open platforms that can utilize dedicated I/Os for proprietary interfaces and other application-specific features.

The full functionality of the complete chipset can even be implemented directly by an FPGA. And perhaps most importantly, this design approach provides long life with long-term interface support available.

Today’s more complex embedded systems often have unique I/O requirements resulting from the diverse devices that are part of the overall system. The x86-FPGA combined platform is well-suited for these applications, handling compute-intensive calculations and offering the option of relieving processor function from the controller and still implementing full hardware-based system functionality.

x86 CPUs & FPGAs: working together
Flexibility and openness characterize universal x86 technology. With flexible I/O execution, OEMs can precisely tailor I/O requirements to meet the needs of target applications. Conversely, FPGAs can manage tasks that could otherwise only be handled by dedicated controller components such as those used for real-time video signal processing ensuring quality control on manufacturing lines.

End devices such as cameras, sensors, actuators or servo drives are increasingly more digital and can now be connected directly to x86 hardware, bypassing the need for dedicated I/O cards.

Motion control for servo drives, which includes characteristic mapping and individual parameterization, can also be carried out by the x86-FPGA tandem. Even calculation of the path or trajectory can be shifted away from the servo regulator and onto the control for calculation via a fast field bus.

This requires fast industrial busses already available through different industrial Ethernet variants, and they in turn require specific processing mechanisms that can vary depending on the target application. These design challenges are readily managed by means of an FPGA-based Ethernet connection.

One hardware unit is capable of providing long-term support for all industrial Ethernet protocols – and the FPGA configuration required can be easily and flexibly adapted to future protocol developments by updating software along with its protocol stack.

Bridging the gap between current & legacy
Flexibility is a key factor associated with FPGA-based design, as performance can be adapted through updated programming rather than complex hardware revisions.

Redefining the basic function of these programmable circuits is a major advantage, and results from their use of reusable units of logic called IP cores.

These provide individual functionalities to the system, and enable the FPGA to take on features such as serial interfaces, industrial Ethernet controllers, user-defined I/Os or even the entire chipset functionality.

With the right combination of programming and peripheral boards, one system can manage a multitude of operations. For example, consider a sophisticated manufacturing environment incorporating the Kontron PCIe/104 MICROSPACE MSMST, the first embedded single board computer (SBC) to incorporate the configurable Intel Atom E600C processor series with industrial temperature range.

The Kontron MSMST pairs the Intel Atom E600 series processor with an Altera FPGA in a single package, dramatically simplifying application design. A single system could include a metal detector and a proximity detector to ensure safety requirements for materials traveling the production line, bar code scanner and reader, and a display application to view the data collected in real-time. Such a diverse and functional system could even be contained within reduced physical space, maximizing the advantages of small form factor, low power Atom-based features.

Further down the manufacturing line, the same physical board may be implemented as a completely different type of system. In this instance, perhaps the board is not just controlling whether the line is operating properly, but is also responsible for detecting objects that are improperly placed and therefore a threat to the safety of the production line.

The system could detect and recognize the object, and institute an automatic shutdown as a safety precaution. A similar system in an automotive manufacturing setting would detect proximity and initiate shutdown or other correction as needed to ensure safety of workers and equipment.

Platforms can be configured quickly and easily through validated IP cores, available for CAN-bus, serial interfaces (SPI Master / UART) and PCI-Express, I2C and GPIO. Interfaces can be executed by choosing the required IP core and corresponding High-Speed Mezzanine Cards (HSMCs) – wide availability of these components make SBCs such as the Kontron PCIe/104 MICROSPACE MSMST an ideal solution for dedicated RISC platforms.

Legacy designs supported by older interfaces such as ISA, RS232 and CAN often face issues because these interfaces are not supported by newer generation chipsets or dedicated hardware-designed I/O add-on cards.

PCI is anticipated to become obsolete, and it is becoming a deeper industry issue that current processor generations provide only PCI Express support, driving designers to implement alternatives such as PCI switches. This results in a design and performance trade-off, as switches must borrow resources that may be needed elsewhere within the application.

While new application designs benefit from continuing advancements in technology, designers need other options for improving performance within the 20-year installed base of actively deployed PCI-based applications.

Migrating these systems, which call for only 32-bit/66 MHz performance, to next-generation PCI Express or Gigabit Ethernet would be excessive and unrealistic. FPGAs provide an optimal solution, allowing designers to simply execute the right interface for the required I/O.

FPGA programming and IP cores
IP cores – or a code set that can be loaded to a board to define it for a selected application type – simplify application design, reduce development efforts, and improve time-to-market and total cost of ownership.

These factors can be further enhanced through the use of Kontron's library of finished development platforms, launched in conjunction with Intel's Atom E6x5C processor series and including a range of FPGA configurations with HSMC cards and corresponding IP cores.

Kontron’s IP core library is enabled by its strategic relationships with Intel and Altera, allowing OEMs and ODMs to focus on application design, but at the same time, avoid a lengthy process by unnecessarily covering the same ground.

Configurations consist of various form factors and validated, application-ready COTS platforms, with installation and support for a range of operating systems (e.g. Windows, VxWorks, Linux). Processors, FPGAs, IP cores, HSMC daughter cards, drivers, and board support packages (BSPs) are included, and enable valuable time savings for OEMs planning individual FPGA configurations and licensing FPGA stacks.

IP core offerings are not limited to available library platforms, and are intended for all OEM solutions that can benefit from the x86-FPGA tandem. Kontron’s Global Software Design Center offers FPGA programming as an optional software service, reducing R&D demands for custom-specific IP core development and implementation.

Overall, the IP core library and custom options for FPGA-based designs mean faster upgrades, more design flexibility and long-term guaranteed IP availability over lifecycles of dedicated components. Developers considering using FPGAs for the first time should lean toward suppliers with application-ready solutions; in most cases the implemented logic will still be the “basic technology” for the OEM application.

A key component to Kontron’s Original Design and Manufacturing (ODM) services gives OEMs the choice to apply individual board designs with the new, highly integrated Intel Atom SOC processor. With in-house programmed FPGAs, manufacturer-specific ASICs (PLC logic) or dedicated standard PCIe devices systems can be designed with additional communication ports, wireless connectivity, GPS services and video or audio streaming, in addition to versatile standard interfaces.

Only the processor and the respective components are required for these devices. This reduces both energy consumption and the use of materials for the components. Third party I/O Hubs can also be provided as an alternative to the Intel Platform Controller Hub EG20.

Figure 1. The Kontron PCIe/104 MICROSPACE MSMST is equipped with the Intel Atom E600C processor series ranging up to 1.3 GHz with up to 2 GB onboard DRAM system memory as well as the Altera Cyclone IV GX FPGA. The power optimized Intel Graphics Media Accelerator with up to 128 MByte, 18/24 Bit LVDS and SDVO interface is integrated in the processor.

A new approach with a future
An embedded computer’s feature set is no longer set in stone, a flexible advantage enabled by combining x86 architecture with FPGAs. Developers are free to program required interfaces and functions as needed.

The combination of the Intel Atom E6x5C processor with an Altera Arria II FPGA on pre-integrated embedded platforms (Figure 1, above ) is a significant advancement, moving the x86 architecture towards greater openness and flexibility.

Board level products integrating this design approach further changes the entire design supply chain. Even OEMs needing industry-specific technology are readily shifting towards a one-stop-shop, and purchasing an fully verified and validated x86-FPGA design including all standard interfaces required. This is a notable trend, and has OEMs working more closely than ever with board level vendors for platforms that are truly application-ready, with all required and “standard” IP cores.

A single hardware platform also shrinks the overall bill of materials (BOM) by eliminating chipsets. Ongoing costs are reduced as well, as designers can reconfigure the FPGA on the same hardware platform – exchanging only IP cores to suit different protocol requirements and developing new applications while avoiding full board redesigns.

This hardware-optimized approach is invaluable to the range of embedded arenas, providing a new competitive perspective by allowing customization on a common platform, increasing design differentiation and reducing time-to-market.

Christine Van De Graaf is a product manager in the Embedded Products Business Unit, Kontron.

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