Fast Predictive Handshaking in Synchronous FPGAs for Fully Asynchronous Multisymbol Chip Links: Application to SpiNNaker 2-of-7 Links

Asynchronous handshaken interchip links are very popular among neuromorphic full-custom chips due to their delay-insensitive and high-speed properties. Of special interest are those links that minimize bit-line transitions for power saving, such as the two-phase handshaken non-return-to-zero (NRZ) 2...

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Detalhes bibliográficos
Autores: Yousefzadeh, Amirreza, Plana, Luis A., Temple, Steve, Serrano Gotarredona, María Teresa, Furber, Steve B., Linares Barranco, Bernabé
Tipo de documento: artigo
Estado:Versión aceptada para publicación
Data de publicação:2016
País:España
Recursos:Universidad de Sevilla (US)
Repositório:idUS. Depósito de Investigación de la Universidad de Sevilla
OAI Identifier:oai:idus.us.es:11441/73808
Acesso em linha:https://hdl.handle.net/11441/73808
https://doi.org/10.1109/TCSII.2016.2531092
Access Level:Acceso aberto
Palavra-chave:Address event representation (AER)
Asynchronous links
Event-driven links
Field-programmable gate arrays (FPGAs)
Neuromorphic chips
Synchronization
Descrição
Resumo:Asynchronous handshaken interchip links are very popular among neuromorphic full-custom chips due to their delay-insensitive and high-speed properties. Of special interest are those links that minimize bit-line transitions for power saving, such as the two-phase handshaken non-return-to-zero (NRZ) 2-of-7 protocol used in the SpiNNaker chips. Interfacing such custom chip links to field-programmable gate arrays (FPGAs) is always of great interest, so that additional functionalities can be experimented and exploited for producing more versatile systems. Present-day commercial FPGAs operate typically in synchronous mode, thus making it necessary to incorporate synchronizers when interfacing with asynchronous chips. This introduces extra latencies and precludes pipelining, deteriorating transmission speed, particularly when sending multisymbols per unit communication packet. In this brief, we present a technique that learns to estimate the delay of a symbol transaction, thus allowing a fast pipelining from symbol to symbol. The technique has been tested on links between FPGAs and SpiNNaker chips, achieving the same throughput as fully asynchronous synchronizerless links between SpiNNaker chips. The links have been tested for periods of over one week without any transaction failure. Verilog codes of FPGA circuits are available as additional material for download.