A low power architecture for embedded perception

Recognizing speech, gestures, and visual features are important interface capabilities for future embedded mobile systems. Unfortunately, the real-time performance requirements of complex perception applications cannot be met by current embedded processors and often even exceed the performance of high performance microprocessors whose energy consumption far exceeds embedded energy budgets. Though custom ASICs provide a solution to this problem, they incur expensive and lengthy design cycles and are inflexible. This paper introduces a VLIW perception processor which uses a combination of clustered function units, compiler controlled dataflow and compiler controlled clock-gating in conjunction with a scratch-pad memory system to achieve high performance for perceptual algorithms at low energy consumption. The architecture is evaluated using ten benchmark applications taken from complex speech and visual feature recognition, security, and signal processing domains. The energy-delay product of a 0.13μ implementation of this architecture is compared against ASICs and general purpose processors. Using a combination of Spice simulations and real processor power measurements, we show that the cluster running at 1 GHz clock frequency outperforms a 2.4 GHz Pentium 4 by a factor of 1.75 while simultaneously achieving 159 times better energy delay product than a low power Intel XScale embedded processor.