DSPs vs. FPGAs for multiprocessing

Life used to be easy. If you were working on a multi-processor signal processing application, you would write down the requirements, check the specs of the devices on offer from the major DSP vendors, and just pick the chip that suited best.

Times have changed, and today's engineers are blessed with far more choice. The big FPGA vendors have stepped up their offerings for signal processing, and choosing the best solution can seem complex.

For distributed applications, the choice of interconnect technology can also obviously have a crucial effect on the overall solution. Crunching the data is all very well, but your system needs to have the right interfaces to move it around between the different processors, and off-load the results. What do the DSP and FPGA vendors have to offer in this area?

In this article, we'll look at what's available for multi-processor systems (which inevitably tends to mean the high-performance end of the market), and how you can make the best choice between DSP, FPGA or a hybrid mixture of the two. We'll look fairly briefly at issues involved in the two types of chip, but concentrate more on system-level factors.

For high-performance signal processing applications, of course there are other options beyond DSPs and FPGAs. Massively parallel processors from vendors like picoChip are one alternative, but unfortunately often require the use of the vendor's proprietary toolset. (See Analysis: BDTI benchmarks picoChip PC102.) ASICs and ASSPs are also well-suited to certain signal processing tasks, but their high up-front costs rule them out except in high volume applications.

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