An FPGA Compliant Single-Rail Encoded Asynchronous Pipeline

• Published in: IEEE access Vol. 9; pp. 160186 - 160194
• Main Authors: Ghafoor, Adnan, Mughal, Muhammad Waqar, Khan, Arbab A.
• Format: Journal Article
• Language: English
• Published: Piscataway IEEE 2021; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Adaptive delay; asynchronous pipeline; auto place-and-route; Clocks; Complex systems; Data paths; Delay; Delays; Encoding; Field programmable gate arrays; Handshaking protocols; Latches; Logic gates; microprocessor; Microprocessors; Pipelines; RISC; Subsystems; System on chip
• ISSN: 2169-3536; 2169-3536
• DOI: 10.1109/ACCESS.2021.3130954

Asynchronous systems are native to a full custom domain. Their implementation using auto place-and-route tools requires dynamic calibration of interconnects delays in addition to the placement of predefined static delay elements. This paper presents a completion detector for a single-rail bit encoded datapath that, as an adaptive-delay element, eliminates the need to insert any predefined delay element and caters to routing delays dynamically. A programmable pulse-generator is also proposed that empowers the designers to generate clock signals based on the timing report obtained from the CAD tool to drive various synchronous subsystems and embedded resources like BRAMs in FPGAs. Employing these components, we present an asynchronous pipeline model with implicit control to expedite migration from the traditional synchronous pipelines to their asynchronous counterparts. A single-rail bit encoded datapath has been used to utilize chip area effectively instead of a delay-insensitive dual-rail datapath, and a two-phase handshake protocol has been adopted as opposed to a four-phase handshake protocol to lower handshaking overhead. A RISC processor validates the proposed asynchronous pipeline model, exhibiting a smooth functionality and power-delay parameter comparable to that of a synchronous pipeline, in addition to ease of routing and avoiding clock skews in a complex system-on-chip.