A Configurable Router for Embedded Network-on-Chip Support in Field-Programmable Gate Arrays

Abstract

The scaling of VLSI technology has allowed extensive integration of processing resources on a single chip. Consequently, programmable chips is able to have a high logic and memory capacity for implementation of complex systems. Field-programmable gate arrays (FPGAs) with their embedded memory and other specialized functionality have become viable alternatives in many cases to costly application-specific integrated circuits as a system-on-chip (SoC) substrate. However, on-chip bus-based interconnects are no longer suitable for complex SoC design because of its limited scalability. The network-on-chip (NoC)paradigm has therefore emerged as a scalable approach for addressing this challenge.

FPGAs can also adopt the NoC paradigm in order to support more complex SoC implementations. The elements for NoC support can be implemented in conventional programmable logic within an FPGA, however, a dedicated approach for these NoC elements can lead to better performance and more efficient utilization of on-chip FPGA resources. A fixed network topology can be a disadvantage in NoC platforms due to misalignment with application requirements. It is therefore desirable to incorporate a certain level of configurability even for embedded NoC support within an FPGA.

This thesis presents the design and implementation of a configurable router intended as a dedicated embedded module for NoC support in an FPGA. The goal is to provide a general NoC infrastructure for the FPGA platform that balances trade-offs with regard to logic complexity, resource utilization, and flexibility. The configurable router provides flexibility in implementing a variety of network topologies with the convenience of a 3-bit input to the router for configuration. All of the necessary routing functionality for each topology is implemented in logic for performance and area efficiency. The overall router design provides general NoC support with reduced complexity, thereby achieving area efficiency and an adequate clock frequency for typical operation in conjunction with embedded soft processors.

Synthesis results are presented at the router level in order to characterize the hardware overhead for implementations in programmable logic as well as standard-cell technology, and at the system-level in order to evaluate overall system resource utilization. Operational results are shown at router level to demonstrate correctness and at system level to demonstrate functionality of the multiprocessor systems that utilizes the configurable router.