Personal computers have resided on engineers' desktops for decades. But they weren't always the powerful, multifaceted tools that they are today. Once used solely for data processing, e-mail, and other mundane tasks, powerful hardware and sophisticated software have turned the humble PC into a valuable engineering design aid.
Gains in hardware have the PC approaching the performance of Unix workstations. A typical PC today can execute over 3 billion instructions per second, store more than 500 Gbytes of data, and create images with extremely high resolutions. And the advent of 64-bit PC processors has further blurred the line between PCs and workstations.
While the hardware is quite impressive, PCs can't do much without the application software that transforms these machines into flexible engineering tools. The existing cornucopia of PC engineering software enables users to perform tasks ranging from complex calculations, analysis, and visualization to programmable test and measurement functions. In addition, PC-based EDA software helps engineers create chips, boards, and systems at a fraction of the cost of its Unix counterparts.
FUNCTIONAL FLEXIBILITY Yesterday's rudimentary PC-based tools have matured into today's flexible applications, allowing the PC to better meet users' changing needs. A popular application for the desktop PC is virtual instrumentation. A virtual instrument consists of an industry-standard PC equipped with application software, plug-in boards, and driver software, which together perform the functions of traditional instruments. Virtual instruments are software-centered systems that exploit the computing power, productivity, display, and connectivity capabilities of desktop computers.PCs have all of the important components of a benchtop tool—display, processor, I/O, and software. But a benchtop instrument has fixed functionality. With virtual instruments, engineers build measurement and automation systems that perfectly suit their needs, instead of being limited by traditional fixed-function instruments.
One example is the LabView software from National Instruments (www.ni.com). This graphical development environment lets engineers design custom virtual instruments. Engineers create a graphical user interface on the computer screen through which they can operate the instrumentation program, control selected hardware, analyze acquired data, and display results. Users can customize their front panels with knobs, buttons, dials, and graphs to emulate control panels of traditional instruments, create custom test panels, or visually represent the control and operation of processes.
The company breaks down instrument functionality into modular pieces, which are then used to "build" the necessary application. Engineers can use hundreds of functions that are geared toward measurement and control applications. They still need plug-in PC hardware for data acquisition, but the software exploits the PC's programmability.
Software is the most important component of a virtual instrument. With the right software tool, engineers can efficiently create their own applications by designing and integrating the routines required by a particular process. They can also create an appropriate user interface that best suits the purpose of the application and those who will interact with it. Engineers can define how and when the application acquires data from the device; how it processes, manipulates, and stores the data; and the way results are presented to the user.
"The beauty of PC-based instrumentation," explains Jenifer Loy, LabView product manager, "is that as the PC changes, your instrument automatically gets upgraded." National offers a suite of modular products. It has solutions for both desktop PCs and laptops, using a PCMCIA slot for small-form-factor digitizing. The company's goal is to create tools that make engineers more efficient. The laptop's portability is needed because engineers do measurements in all types of locations (see "Bringing Test Out Of The Lab And Into The Field," below).
LabView 7 Express, the latest version of the software, streamlines the development of common measurement tasks by encapsulating functionality in more than 38 interactive virtual instruments (VIs). Users drop an Express VI on the block diagram and use dialog boxes to configure their acquisition, analysis, or presentation function with no programming. The goal was to provide the functionality of the LabView software with a faster, easier to use interface. What would take hours or even days with previous versions of the product can be done in minutes.
Data Translation (www.datatranslation.com) is another supplier of application-building software for test and measurement, control, and analysis using a PC. Although the company has supplied data-acquisition hardware for a long time, it decided several years ago to create its own software applications. Its product, called DT Measure Foundry, is an application-building package that lets users drag and drop control and display objects onto the screen and configure them by defining a list of properties. Users aren't required to wire one object to another, nor do they need to compile anything. For example, they can configure an oscilloscope panel to display a number of input channels from a data source, and then run the application.
Users can export their results to numerous analysis programs, including the Matlab software and Microsoft's popular Excel spreadsheet. The company's latest product for the PC is DT Measure Foundry/RT-Streaming, a software application that streams real-time data from an embedded DSP to a host PC. Full Windows control from the host PC allows a pre-compiled COFF file (DSP file format) to be executed seamlessly.
Tim Ludy, product marketing manager for Data Translation, points out that in recent years the PC has proven its value as an engineering tool. Before that, he explains, these types of applications could be hampered by the PC's limitations. For example, data acquisition could run out of I/O due to the PC's limited number of slots. Today, that's never a problem because the standard USB port can accommodate up to 127 devices.
OS LIMITATIONS Nonetheless, the PC still has drawbacks for real-time engineering applications. According to Ludy, the Windows operating system (OS) poses some limitations in measurement and control applications due to its response time. To address real-time applications, therefore, users often must seek solutions other than a standard PC running Windows. Data Translation addresses this problem with its Fulcrum series of data-acquisition boards that have their own on-board processors.National Instruments' Jenifer Loy agrees that the Windows OS can pose challenges for engineering applications. She explains that while the processing power of a desktop PC can easily acquire and analyze large amounts of data, the framework of a general-purpose OS makes it difficult to execute operations in precise intervals. General-purpose OSs are designed to quickly respond to user inputs like mouse and keyboard entries but aren't designed to execute applications requiring deterministic performance.
Deterministic performance is a critical component of control systems, such as those used to regulate shaker tables. The mathematics of control algorithms are based on a precise time interval (delta t) between input and output operations. If the controller is distracted by, say, a user keystroke and can't complete necessary calculations within the specified delta t, the system will struggle for stability.
Instead, engineers are choosing to implement control systems using real-time OSs. Real-time OSs run on the same type of hardware that's found in desktop PCs. However, the software architecture is developed so that you can achieve deterministic performance. The operating system adheres to a preemptive scheduling mechanism that allows you to specify execution priorities to parts of the system, thereby ensuring that critical sections of code always receive the necessary processor time.
While many test applications can benefit from real-time OSs, the expertise needed to develop applications for this platform has been a barrier to entry for many engineers. With tools such as LabView, engineers are able to develop applications for targets ranging from desktop systems to real-time platforms.
CONNECTIVITY IS KEY Network connectivity is a critical capability for today's engineering team. Imagine a design team working on a next-generation automobile. Each member of this team is working on a different part of the vehicle, but all parts need to be tested in real-world situations as one complete unit. Therefore, when prototypes undergo crash testing, multiple engineers need immediate access to test data. Engineering analysis tools must be able to easily retrieve networked data and share new results with other members of the team.Allen Razdow, vice president of products and services for Mathsoft Engineering and Education Inc. (www.mathsoft.com), sees connectivity—the PC's part in a larger infrastructure—as an important advance in the PC's ever-changing role. Mathsoft's flagship product is the Mathcad calculation and documentation software. Mathcad allows users to calculate, graph, and communicate technical ideas in a unified visual format.
The Mathcad software interface is meant to combine a white board and a word processor and can be thought of as the electronic equivalent of the back of an envelope. The tool produces worksheet-like documents that have live calculations that can be reused with different numbers and engineering units. The tool checks units as engineers go to ensure their consistency. It's worth recalling that the Hubble space telescope was initially out of focus because somewhere along the way, an engineer confused units in a calculation.
When Mathsoft was born in 1985, PCs were relatively new. No longer tethered to the mainframes of yore, engineers had, in their new desktop machines, some measure of personal control. But the circle is closing and PCs, inherently isolated, are being networked to form a larger computing infrastructure. That infrastructure extends far beyond an office, a building, or even a campus to encompass multiple organizations in physical locations around the world.
Calculations are a crucial part of the design process, especially in the early portions of the design cycle when the majority of the project's costs are committed. There are tens of thousands of calculations required in a big project, and too often they're not documented or archived. The PC, in its new wider role in the overall computing infrastructure, can be the central collection point for these many calculations, carefully documenting and archiving them throughout the entire process (see "PCs: A Tool For Technical Communication," p. 56).
The point of connectivity is driven home by Mathsoft's Mathcad Application Server, which allows engineers to interactively use the Mathcad software over the Web. The tool changes worksheets on the fly into HTML, and the parameters are changed to user-entry fields. With the Application Server, Mathcad is made accessible, enterprise-wide and beyond, to any and all personnel who must use it, even if they don't have Mathcad software on their own PC.
The MathWorks (www.mathworks.com) also provides calculation and analysis software for the PC. Its Matlab product, based on a high-level, text-based language, is the foundation for its entire product line. Matlab helps engineers analyze data with visualization and has connectivity to a variety of data sources.
Simulink, another MathWorks product, is a graphical design environment that lets users create models of their systems and then refine them until they're satisfied with the results. The simulation is done in C, and it can generate C code to run on an embedded system for a DSP processor. It can also generate code for an FPGA.
STANDARD INTERFACES Ken Karnofsky, the MathWorks' marketing director for DSP and communication products, notes that the PC has few limitations when compared with Unix workstations."One big advantage of the PC," he explains, "is the wealth of plug-and-play software and hardware interfaces." This allows engineers to first use the Matlab and Simulink software to design their concepts and fine-tune their systems. Then they can connect with third-party boards carrying DSPs and FPGAs, enabling rapid prototyping and development (see "PCs Bridge The Gap Between DSP And FPGA Designers," p. 58).
PCs are used across the design cycle, exploiting standard interfaces throughout: Matlab for research and exploration, Simulink to do the system design and nail down details, and then interfacing to PC-based EDA tools for implementation.
PC-based EDA tools aren't new. What's new is the power of today's versions. The OrCAD line of PC-based EDA software was one of the first and most successful lines, and it's now part of Cadence Design Systems. Martin Koechel, Cadence's senior product marketing manager for the OrCAD products (www.cadence.com), says, "From our experience, today's PCs have sufficient power and memory capacity to make the PC an effective engineering tool. PCB tools in general do not require the latest hardware to be effective engineering workstations."
Cadence offers several complementary product lines on the Microsoft Windows PC platform: the OrCAD series and the Cadence PCB Design Studio and PCB Design Expert series. The OrCAD tools provide engineers all they need to take a pc-board design from concept to completion on a desktop. OrCAD products are used primarily by the personal engineering market in education and research, and for fast prototyping by design teams.
Cadence PCB Design Studio is for companies looking for a soup-to-nuts board-design suite that can be scaled for large projects. For complex, high-speed, constraint-driven designs, PCB Design Expert provides a fully integrated design flow that spans design entry, through common electrical constraint management, to powerful auto-interactive floorplanning and routing.
The emergence and adoption of the PC have made it possible for engineering teams to accomplish more in less time. PCs have reduced the time it takes to perform complex analysis routines, made data sharing among colleagues instantaneous, and enabled custom visualization of real-world signals. Also, because computers are ubiquitous in today's workplace, this computing power is readily accessible to all engineers. Therefore, the PC is an essential tool for engineers to get their designs to market faster, at less cost, and with higher quality.