Synchronization Constraints for Interconnect Synthesis

Interconnect synthesis tools ease the burden on the designer by automatically generating and optimizing communication hardware. In this paper we propose a novel capability for FPGA interconnect synthesis tools that further simplifies the designer's effort: automatic cycle-level synchronization of data delivery. This capability enables the creation of interconnect with significantly reduced hardware cost, provided that communicating modules have fixed latency and do not apply upstream backpressure. To do so, the designer specifies constraints on the lengths, in clock cycles, of multi-hop logical communication paths. The tool then uses an integer programming-based method to insert balancing registers into optimal locations, satisfying the designer's constraints while minimizing register usage. On an example convolutional neural network application, the new approach uses 43% less area than a FIFO-based synchronization scheme.