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The microcontroller as metaobject

Thu, 02/13/2014 - 6:28am
Joshua Israelsohn, Director, JAS Technical Media

Pretty much everyone in our industry is familiar with the long evolution of microcontrollers. So familiar that it’s easy to miss changes in our industry and society, both positive and negative, that accompanied that evolution just as we tend not to see daily changes in our own aging faces.

The ubiquitous micro
Microcontrollers, as a component class, progressed from among the most complex of electronic components to the most readily accessible—ironically, perhaps—while the capabilities of those devices increased many-fold. Early embedded designs surrounded microcontrollers with copious amounts and various types of glue logic. MSI (medium-scale integration) multiplexers, counters, registers, and decoders, and SSI (small-scale integration) flip-flops and asynchronous combinatorial gates made up for microcontroller’s limited I/O and built-in functions beyond those of the core ALU (arithmetic-logic unit).

Modern microcontrollers, by contrast, have replaced virtually all glue-logic functions, converting much logic-circuit design to programming. The shift from hardware to software design simplifies and speeds product development, prototyping, debugging, manufacturing, product maintenance, and derivative-product design.

Of course deep sub-micron semiconductor processes have allowed microcontroller manufacturers to do far more than simply subsume the ye olde glue logic. Virtually all microcontroller manufacturers offer devices with a variety of on-chip analog circuits and blocks to support communication protocols such as LIN, CAN, or USB. Instead of standing at the heart of a large and complex design, for many applications the microcontroller has become the software-hardware interface to applications built more of code than of components: microcontroller as metaobject.

Although application-specific functional requirements extend beyond the resource capability of many micros, the modern device represents a substantial configurable and programmable subsystem—a fact that has permanently altered much of product design except at the periphery.

Packaging innovations have advanced designs’ physical manifestations along with the electronic since the advent of SMT (surface-mount technology). The replacement of all but a few hand-placed components with machine-placed versions has greatly increased assembly throughput, in-line quality, and product reliability.

Finding future engineers
STEM (Science, Technology, Engineering, and Mathematics) education is a central topic in education policy at the national level and among many of the states that benefit from significant employment in the high-tech sector. Among these subjects, electrical engineering has enjoyed an advantage in capturing the attentions and imaginations of young minds dating back to the time when you first could buy vacuum tubes at your neighborhood Rexall.

Indeed, thanks to an extraordinary distribution system, for much of the history of electrical engineering, students and young hobbyists had access to most of the same range of electronic components as OEMs. Many of the best known among the first several generations of IC designers caught the design bug while growing up; for many, thanks to the allure of radio.

The internet is now our link to faraway places, interesting strangers and, increasingly, things. The internet of things is a microcontroller-based universe with many opportunities for the industry and many attractions for the nascent engineer.

Much of the technology would be difficult to reach if not out of reach altogether, however, were it not for a budding sector providing electromechanical interfaces and software driver libraries for subminiature ICs. For students, in particular, microcontroller-centric board sets from companies like Arduino (www.arduino.cc) and, starting in Spring 2014, Tessel (www.tessel.io) provide processor boards, application-specific I/O add-ons, and prototyping grids for custom circuitry (Figures 1).

Gone in a flash
The addition of flash memory to most microcontroller families has simplified a host of tasks ranging from rapid prototyping to in-field product updates. The robustness of flash memory for program and configuration storage is a great asset but convenient access to these memory areas can also represent a security risk.

Through the Smart Grid initiative, the utility-power sector has gain significant insight into the security issues that attend distributed networks of semi-autonomous interconnected hardware. The challenge is to maintain equipment’s full flexibility for configuration, programming, telemetry, and data communication while guarding against unauthorized access.

A second authentication issue affects all electronics but particularly systems that use pre-programmed microcontrollers. Counterfeit components are a reliability issue in any system but in space, military, civilian aircraft, automotive, and medical applications, counterfeit parts can pose significant safety issues. Few semiconductor manufacturers have developed authenticatable components verifiable through the supply-chain while the need continues to grow. The ubiquity, centrality, and accessibility of microcontrollers make this a global problem and a national urgency.

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