Just four days into this year, Microprocessor Report’s Max Baron declared 2010 to be the “Year of the Microcontroller.” If true, it’s been a long time coming. Texas Instruments introduced the first microcontroller—the 4-bit TMS1000—in 1974. Unlike the 4- and 8-bit microprocessors that preceded it, the TMS1000 “computer on a chip” combined a 4-bit processor with 1 kbyte of masked ROM, 64 4-bit nybbles of RAM, and some simple I/O ports, all on one piece of silicon. Other microcontrollers quickly followed, including the 8-bit 8048 from Intel, the 8-bit 6801 from Motorola Semiconductor (now Freescale) based on the company’s 6800 architecture, and the Mostek MK3870 based on Fairchild’s 8-bit F8 microprocessor architecture.
So, what transforms the year 2010 into the “Year of the Microcontroller”? Several shifts of tectonic proportions are taking place in the dusty, noisy arena of embedded design to make this year special. One change is the exponential rise in ASIC and SOC development costs. With the advent of nanometer lithographies, the complexities of manufacturability, crosstalk, physical design problems, towering design-tool stack, and sheer gate count all conspire to drive ASIC/SOC design and development costs into the tens of millions of dollars. Consequently, such custom devices are only justified by unit production volumes in the tens or hundreds of millions. Not many projects can qualify. Consequently, embedded designers must turn to ASSPs (application-specific standard products), FPGAs, and microcontrollers to satisfy the needs of lower-volume products.
At the same time, there’s finally a big movement from 8-bit microcontrollers to 32-bit architectures. The design community has resisted this move for years, aided by microcontroller vendors’ reluctance to adopt more advanced device geometries. Microcontrollers have, in some ways, served as fillers for obsolete semiconductor fabs and have consistently stayed several generations behind the leading edge of semiconductor fabrication. As long as 8-bit architectures could do the job, there was no reason to move up.
However, embedded designs must increasingly deal with media files—images, sound, music, and even video. The limited 64-kbyte address space of an 8-bit processor architecture is woefully inadequate to handle such files. As a patch, microcontroller designers have been adding address block-switching circuitry to microcontrollers for years. But, that’s been nothing more than a stopgap measure. The real solution, known all along, was to jump to 32-bit architectures.
And, that’s exactly what’s happening right now. Existing microcontroller vendors including Cypress Semiconductor, Freescale, Microchip, and Texas Instruments are adopting popular 32-bit microprocessor architectures such as the various ARM and MIPS processors, because there are already software developers familiar with these architectures and because the development tools for these architectures are readily available. At the same time, the availability of these processors as IP cores combined with the evolving and growing semiconductor foundry business has enabled the appearance of new fabless microcontroller vendors. Texas Instruments bought one such vendor, Luminary Micro and its Stellaris microcontroller product line, just last year.
Because of rapidly shrinking device geometries and rapidly expanding peripheral suites, the microprocessor core no longer consumes much of a microcontroller’s die area or power. For example, in his editorial declaring the “Year of the Microcontroller,” Max Baron noted that the ARM Cortex-M3 processor core in the Stellaris LM3S1439 microcontroller consumes about 3 percent of the chip’s power. The rest is consumed by memory and peripherals. Baron also wrote: “The size of the CPU is sometimes dwarfed by the silicon real estate occupied by the other resources, but it does become a major differentiator in MCUs priced in the $1.00 range and below, where fewer peripherals and smaller memories are employed to reduce the die size and the selling price of the chip.”
So, it’s no wonder that Microprocessor Report has declared 2010 the “Year of the Microcontroller.” And, all embedded system designers benefit.
