Benchmark code often consists of synthetic code designed to represent a typical application. Benchmark suites can be used to compare different architectures across a wide variety of application types. Inspecting the planned functions of the solar controller reveals that most of the functions are low speed operations employing simple decisions logic. The single exception to this characterization is the code for a PID control loop. Therefore we’ll execute a PID control loop on the ATOM processor to verify that the processor can handle the bandwidth requirements of the future planned generator control software.
In another blog the number of candidate processors was reduced based on a requirement for low power consumption. All of the remaining candidate processors are members of the ATOM family. Since we have only a single processor family to evaluate for adequate performance, the job of evaluation is significantly reduced. There is only a single base architecture to consider.
Our evaluation of the ATOM processor for our application will be based on executing a PID loop on an actual ATOM processor. Based on simulations of the PID loop, the minimum acceptable performance will require 30 Million Instruction Per Second and a preferred performance of a bandwidth of 10x the basic rate to permit the RPM controller to increase sensitivity of the control loop. Keep in mind that this PID loop is to control a slow speed engine that operates at 650 RPM. Faster turning engines will require proportionately more processor power. The fastest way to begin the evaluation is to procure a development board based on the ATOM processor. Several companies manufacture development boards suitable for evaluation and initial software development purposes.
Atom™ Development Systems from Eurotech are designed to get products to market quickly. These systems all share an optimized BIOS, BSP, and a bill of material selected for low cost and extended availability.
Peartree is a Reference Platform and development kit for Intel's ultra-low-power Atom processor family. Aimed at developers wishing to create their own hardware based on Atom, the development platform is equipped with a Wi-Fi module and W-SIM (with connectable 3G module).
The phyCORE System on Module (SOM) for the ATOM processor is in development. When completed, it will be designed to plug into a PHYTEC Carrier Board that provides I/O connectors such as DB-9, RJ-45, USB, and power jack, as well as any other interface circuitry not provided on the phyCORE module itself.
Arrow's Intel Atom platform is a development kit and reference design for benchmarking, developing and testing embedded systems based on the Intel Atom 500 series of processors. The platform includes a host processor module, motherboard and touch screen LCD.
Advantech COM-Express SOM-5775, designed with Intel Atom processor Z500 series, takes advantage of the Atom platform in the new SOM-Express Micro form factor. It performs the same functions as traditional SOM-Express modules but with a smaller board size of 95 x 95mm. The pin definitions of SOM-5775 are the same as a standard COM-Express board and can work directly with existing carrier boards, while supporting DDR2 memory up to 1GB, 10/100 Mbps Ethernet, 8 USB 2.0 ports and PCIe interface, and the integrated graphic engine supports CRT and 24-bit LCD display modes.
The Intel® AtomTM processor and Intel® System Controller Hub US15W introduce a power optimized, highly integrated platform for a wide range of embedded applications. The TechOnline VirtualLab allows users to experience the benefits and features of the platform without needing to have access to local hardware. It also allows users to evaluate some of the software tools available from Intel that can be used to optimize software operation and performance on this new platform. Access to the lab is free for engineers, but requires a free registration to access the lab. The access process requires Java to be installed. If you have to install the SUN Java package as I did, it’s necessary to shutdown the browser and then restart it for the Java test to successfully complete.
Accessing the tools is an easy process. Just select the VirtuaLab that you want to use and a few seconds later you gain access to the lab. The tools and platform are all standard Intel products, so any work that you do on VirtuaLab can be used as you continue to develop your system if you choose to continue development with the Intel tool set.
Other companies also offer software development toolkits that provide different capabilities. Alternative software tools for developing ATOM programs can be licensed from Wind River3 – Wind River Complier and Workbench, and Green Hills Software(4) - MULTI® integrated development environment.
Wind River System’s Workbench product incorporates an Open product called “Eclipse” as part of their framework. Eclipse had is start in an Open Software development effort initiated by IBM in 2001. Eclipse is an open source community, whose projects are focused on building an open development platform comprised of extensible frameworks, tools and runtimes for building, deploying and managing software across the lifecycle. The Eclipse Foundation is a not-for-profit, member supported corporation that hosts the Eclipse projects and helps cultivate both an open source community and an ecosystem of complementary products and services. Wind River has been a major contributor to the Eclipse project, donating over 300,000 lines of code to the efforts.
Since this phase of development employs relatively little code, we can simply retarget the ‘C’ code used for the evaluation to a new development environment if we choose.
The ATOM processor actually performs the PID function 43 times faster than required. At first glance this would normally indicate that the processor is massively over powering the application. The minimum performance level allow the PID loop to operate at the ten-fold sample rate of the minimum acceptable performance. By supporting a higher sample rate we are able to control the RPM of the generator to a finer granularity. Put another way, the PID loop will consume about 20\% of the ATOM processor. This significant amount of processor performance assures us that the entire application can be completed using a single ATOM processor. As an alternative, we can increase the bandwidth of the PID controller. The PID controller will be used in the generator controller portion of the system to govern the speed of the diesel engine. By increasing the bandwidth of the controller we may be able to achieve better control over the engine speed. Constancy of engine speed is the primary factor in the quality of electricity produced by the generator.
We have used the Intel ATOM VirtuaLab to evaluate the processor fo and r suitability as the central processor in a moderately complex solar electric system. The ATOM has more than enough processing power to provide the required functionality, and the VirtuaLab provides a suitable evaluation platform.
VirtuaLab has many advantages: immediate access to an ATOM processor, no wait for shipping a development kit, someone else maintains the evaluation board, and Intel standard development tools are available without the need to host them locally. There are a few disadvantages: performance of the system is influenced by your Internet connection’s stability and speed, there may be configuration issues with your particular PC’s systems settings, and you don’t have hands-on control of the evaluation setup and test instruments. Still, the setup is free and quick – allowing you to perform quick evaluations. If you don’t want to use your own code in this process, there’s example code available that you can run on the evaluation board.
We’ve presented one way to evaluate the ATOM processor for fitness for use in a moderately complex control system. The criteria were very simple: the power consumption under 5W and execute PID code fast enough.
What criteria are you using for processor evaluation in your next project?
- Eurotech is an Associate Member of the Intel® Embedded Alliance.
- Advantech is a Premier Member of the Intel® Embedded Alliance
- Wind River Systems is an Associate Member of the Intel® Embedded Alliance
- Green Hills Software, Inc is an Affiliate Member of the Intel® Embedded Alliance
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