September 9, 2009 -- Microcontrollers, in many ways, are the indispensable engines of our world. With hundreds of billions of them in use, MCUs play a variety of different but equally important roles in almost every electronics application imaginable. Inexpensive, easy to use and well understood, MCUs are an integral part of a design engineer's toolkit—and her or she can choose from thousands of controllers and controller variations.

But controllers do run into limits. The general-purpose input and output (GPIO) ports available for a microcontroller are usually limited in number. Many applications require more ports than are available on the microcontroller. And because GPIOs are used for a number of functions like serving as a gateway to numerous peripherals and buses, managing LEDs and interrupt sources, oftentimes more is better.

FPGAs, however, can be deployed to overcome this barrier by adding four 8-bit ports to any 8-bit microcontroller. With the broad IP libraries available from FPGA vendors today, it's a relatively straightforward endeavor. Take the 8051s soft microcontroller core. It can be configured as an 8-bit microcontroller, without sacrificing power budget, cost or board real estate.

By Mike Brogley. (Brogley is IP and Solutions Product Marketing Manager for Actel Corp.)