July 27, 2011 -- Modern field programmable gate arrays (FPGAs) are great for a wide range of high-speed, complex signal processing but can be difficult to interface to external systems. Microprocessors are great for interfacing to other systems, especially when equipped with Ethernet for communications, but don't offer the same levels of performance.

Until recently, designers either had to work around the weak spots of the chosen device or combine the two devices; the latter approach presents new difficulties when the data rate between the signal processing and general processor is significant. Enter FPGA devices with built-in microprocessors, combining modern 32-bit microcontrollers and Ethernet media access controllers (MACs) with FPGA resources.

This article presents my experience with designing a nontrivial multiprocessor system, using three networked Xilinx Virtex-4FX-based controllers.

By Robert S. Grimes. (Grimes is President of RSG Associates.)