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The Embedded Smart Car: USB

SUSAN WOOLEY

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One of my favorite possessions is my 1997 Firebird TransAm. It is red and very fast with a big V8, a six speed, racing tires and heavy-duty suspension. When the T-top is open, you can accelerate into third and hear the gas guzzling into the cylinders while simultaneously feeling the wind pulling back your face and hair. But now it sits in my garage because it is impractical to drive with its 10-miles-per-gallon appetite. Although I can't bear to part with it, I ponder its future in a world of "smart cars."
I am struck by the parallel between this TransAm and today's design of industrial control systems. It has been the tendency when designing industrial control systems to include all the bells and whistles from LCDs to desk-top software to unlimited power running 24/7. Going forward, it is difficult to justify this power-greedy, dedicated single-board PC for tasks such as controlling a few lines of digital I/O, measuring some A/D or doing some data logging. Once the total cost of initial hardware plus operating expenses for a year is calculated, it becomes clear that this is not viable either financially or environmentally. More importantly, technology has progressed to the point where there are so many more choices for elegant and efficient ways to implement control systems, that the "muscle-car" approach to embedded systems is becoming less relevant. Enter the ubiquitous USB.
USB is a serial communication channel stacked with market advantages including multiple channels per CPU chip set, comparable or faster speeds than the old blue collar PC/104 ISA bus, availability in Host or Device mode, and support on x86 platforms, ARMs and microcontrollers. By itself this doesn't necessarily save energy or ease system designs, but what it does do is act as an enabler to reach such a goal, rather like the smaller cars inching their way into the market at a time when gas shortages are forcing fuel prices up and long lines are making small cars attractive.
At the same time USB is making deep inroads into systems everywhere, another phenomenon is taking place: cheap processor intelligence is being built into virtually every controller chip released today. This runs the gamut from sensors to communication chips to A/D and D/A chips to power chips to microcontrollers. Compare this to just a few years back when nothing had built-in intelligence and "bit banging" was the term of the day.  A 12" x 12" controller board has been shrunk into a single chip solution with USB, I2C, or SPI output! These chips are ready to roll. Remember how smaller engines made compact cars more viable?
And perhaps more important than all of these hardware advancements is the growing number of software options available to system designers today. Not surprisingly, USB support is included in an overwhelming number of them. So, gone are the days when DOS was the only inexpensive OS for an embedded system, thereby mandating an x86 platform. Today, there are ample software platforms supporting USB for ARMs and microcontrollers as well as traditional PC-based systems. The accompanying development tool chains are readily available, often free to download and certainly easier to use. This trend results in more and more simple device-side I/O controllers outputting USB, I2C, or SPI, while the Host is operating under another OS altogether. Distributed control, which was once the more complicated option, is becoming easier than shoehorning control onto single board computers that need complicated, custom drivers for each operating system to make applications run.
So, if we pause a moment, step back from our current project and look at the big picture, it takes only a couple of moments to realize we are on the brink of some radical changes in the implementation of traditionally blue collar control system or PC/104-type embedded system.  The impetus to change or upgrade legacy systems will be driven not from a need for additional performance, but rather from a need to reduce operating costs and conserve energy, which is possible when we maximize the newer, more efficient technology that is at our fingertips.
These are exciting times. Are we ready to head down this road? You bet we are. Ladies and gentlemen, start your engines!