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Explore the challenges and solutions in designing coarse-grained FPGAs and reconfigurable ASICs, including granularity issues and the benefits of reconfigurable systems. Learn about architectures like PipeRench and RaPiD that enable fast and efficient logic implementation.
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Topics • Coarse-grained FPGAs. • Reconfigurable systems. • Reconfigurable ASICs.
FPGA granularity • Typical LEs implement a small amount of logic. • Waste a lot of space/power on connecting logic elements. • Specialized adder logic tries to solve this problem for a special case. • Can build FPGAs with larger elements.
Granularity issues • How big is the logic element? • How flexible should it be? • What interconnection network is needed? • How do you program it?
Reconfigurable systems • Reconfigure logic on-the-fly: • application characteristics may change over time. • Issues: • Reconfiguration time. • Reconfiguration memory cost. • Power consumption. • Synthesis for reconfiguration.
PipeRench • Reconfigurable pipeline: • Each stage of the pipeline can be reconfigured quickly and independently. • Allows virtual pipeline that is longer than physical pipeline.
RaPiD architecture • Coarse-grained computational architecture: • Soft control can be reconfigured on every cycle. • Hard control can be reconfigured only in configuration mode. • Interconnect network allows computational elements to be arranged in pipelines.
Reconfigurable ASICs • Problems with ASICs: • Mask cost. • Manufacturing time. • Solution---mix ASIC and FPGA: • Reconfigurable logic on bottom. • Custom wiring on top.