Software makes the difference

What are some of the trends and challenges facing engineers when defining and implementing embedded systems for measurement, control and monitoring of aerospace applications? Based on feedback from a broad range of customers and the expertise of technology providers, National Instruments (NI) has answered this question.

The offering for the embedded market comprises disjointed and complex tool chains, making it difficult for developers to create embedded systems which combine measurement and control functionalities. Solving this challenge requires standardised hardware and software platforms enabling even small teams of developers to experiment and solve problems quickly and efficiently. Compared with conventional tools, which offer almost no scope for system abstraction and are inclined to be characterised by cryptic hardware-dependent programming, a platform-based approach is more productive.

Graphical system design is one such classic platform-based approach, which breaks an application down into basic building blocks such as I/O, analysis, processing, programming, user interface and implementation platform and links them together using graphical programming techniques including timing and synchronisation. This platform-based approach enables the user to concentrate on innovation instead of having to grapple with complex system design problems.

Practical examples of how hardware components are combined with software architecture within the aerospace industry include the development of next generation navigation systems using software defined radio technology, rapidly deploying safety systems to deal with changing technology and addressing manufacturing challenges with intelligent tools and sensors. Users of the platform-based graphical system design rely on it to solve challenging tasks to do with control and monitoring of embedded systems.

Designs in shorter times

A constantly increasing number of new designs and escalating complexity are forcing embedded design teams to become more efficient and influencing their choice of technology.

Evidence of this is provided by the challenges facing the latest remotely piloted aircraft systems, where moving from a local pilot to a remote operator means integration of complex sensor, control and communication systems. Combining navigation, sensors, communications, health monitoring and flight controls means all of these systems need to work together to duplicate the necessary functionality of the pilot and be accepted into civilian airspace. New designs have to take into account these challenges and the need to adapt to deal with changes in other aircraft systems. Tasks that humans find challenging become incredibly complex for autonomous systems and rigorous simulation and testing processes have to be developed to validate the range of system interactions.

The same trend applies to the manufacture of aircraft and components where intelligent tools and communications between engineers, robotics and central systems are key to improving performance while maintaining quality. Historically, individual systems contained their own capabilities for a task within a single processor but the complexity of designs mean that information coming from multiple systems becomes relevant and new designs have to integrate their own data with complex information from many sources. Ultimately, regardless of the functional improvements of the system next generation systems in aerospace have to maintain the highest quality standards.

To support design teams with the development and certification of new designs, technologists are developing components, modules and even complete embedded platforms with an ever higher degree of integration and functionality. Ultimately, companies are working towards a comprehensive platform for embedded design incorporating communication, program execution, system I/O and the design software.

This trend began with commercial off-the-shelf (COTS) systems-on-chip (SoCs) and systems-on-module (SoMs) customised to specific embedded applications. Such components integrate all the electronic circuits and often feature the three main elements of an embedded system: a communication interface, processing and system-specific I/Os. Common examples include video digital signal processing (DSP), audio DSP, radio solutions, networking solutions, or a complete computing platform in a single chip or module.

Computers-on-module (CoMs) make up a special subcategory of SoMs. By integrating an entire computer or embedded subsystem into a single device, companies are providing more value to embedded designers through increased functionality, better integration, a more thoroughly tested design, a smaller package, and lower power consumption. SoCs and SoMs are typically offered as a standard component and are designed either for universal use or for vertical applications. The common tested design means that certification of products on a known SoC or SoM becomes easier and more focused on the application-specific software rather than certification of new hardware.

By building on a common COTS core of a SoC or SoM, aerospace design teams have greater confidence in developing new applications. With a history developing custom electronics for aerospace, companies find that with SoCs or SoMs, it is difficult to maintain differentiation with the final design. To maintain differentiation design teams augment the SoC or SoM with additional discrete components and programmable logic. With the addition of programmable logic, such as a field-programmable gate array (FPGA), to the design, teams can add specialised processing - proprietary know-how or so-called intellectual property – to improve performance and future-proof the design with the ability to update the logic at any time during development or even once they have deployed the embedded system.

The addition of FPGAs is now established practice so that SoCs are already being offered that combine both a full microprocessor and an FPGA in one single module. Currently, the most interesting component from NI's perspective is the Xilinx Extensible Processing Platform (EPP) ZynqTM-7000. The EPP family combines a Dual-Core processor ARM CortexTM-A9 and a Xilinx-7-FPGA. The flexibility of the processor to adapt to software challenges, along with the reliable performance of the FPGA, means that the EPP is already addressing aerospace applications such as vision processing and avionics displays. These components unite high performance and flexibility so that embedded developers can differentiate their design while benefiting from the advantages of a SoC.

Although the advancements in SoCs and SoMs are exciting, most fall short of offering a complete embedded platform. In the upcoming decade, software tools will play a more critical role in system design and development. In the past, many embedded designs were dictated by embedded hardware capabilities and mapping them to the system requirements. Due to the reduction in power, cost and size of embedded hardware over the last decade, hardware will no longer limit or dictate many embedded design choices; however productivity will. Embedded design productivity will be driven by tightly integrated software design tools that can use off-the-shelf hardware capabilities with an environment intuitive enough to be used by nearly all engineers and scientists, not only those trained in embedded software, firmware development or hardware description languages.

Software comes first

A software-first design paradigm is predicated on a system architecture that minimises fixed-function hardware. This includes obvious fixed-functionality devices such as application-specific integrated circuits (ASICs) and hardware filters. Although these fixed-function devices offer a lower per-piece component cost, they achieve that cost at the expense of future scalability. Software-defined hardware platforms, such as processors, DSPs and FPGAs, give system designers the flexibility to more completely change a device's behaviour without new electrical work. While these platforms have higher component costs, they can dramatically reduce design costs, increase market share, through faster time to market, and over time increase volume and drive down costs by making it possible to use one design across multiple devices.

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