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Synthesis of multiple rail phase encoding circuits. Andrey Mokhov, Crescenzo D’Alessandro, Alex Yakovlev Microelectronics System Design Group, School of EECE, Newcastle University, UK {andrey.mokhov, crescenzo.dalessandro , alex.yakovlev} @ ncl.ac.uk. Outline. Phase encoding
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Synthesis of multiple railphase encoding circuits Andrey Mokhov, Crescenzo D’Alessandro, Alex Yakovlev Microelectronics System Design Group, School of EECE, Newcastle University, UK {andrey.mokhov, crescenzo.dalessandro, alex.yakovlev}@ncl.ac.uk UK Asynchronous Forum, September 2008
Outline • Phase encoding • Conditional partial order graphs • Circuit synthesis • Phase detector • Matrix phase encoder • One hot phase encoder • Binary phase encoder • Conclusions and future work Outline UK Asynchronous Forum, September 2008
Phase encoding • Self-synchronous data communication protocol introduced by D'Alessandro et al [ PATMOS’05 ] • Reliability to single event upsets • High information capacity • No scalable implementations of multiple rail controllers ‘abdc’ symbol sensitive interval 4-wire channel: 4! = 24 symbols > 24 = 16 binary symbols log(n!) ≈ n·log(n) Phase encoding UK Asynchronous Forum, September 2008
Comparison with DI communication protocols Phase encoding UK Asynchronous Forum, September 2008
n-wire phase encoding channel Phase encoding UK Asynchronous Forum, September 2008
Outline • Phase encoding • Conditional partial order graphs • Circuit synthesis • Phase detector • Matrix phase encoder • One hot phase encoder • Binary phase encoder • Conclusions and future work Outline UK Asynchronous Forum, September 2008
Conditional Partial Order Graphs [ DATE’08 ] Conditional Partial Order Graphs UK Asynchronous Forum, September 2008
Controllers synthesis using CPOGs • CPOG model can be used for phase encoding controllers specification and synthesis: • Vertices correspond to the signal transitions in the channel • Conditional arcs determine the order of the transitions • 2-wire phase encoder specification example: Conditional Partial Order Graphs UK Asynchronous Forum, September 2008
Outline • Phase encoding • Conditional partial order graphs • Circuit synthesis • Phase detector • Matrix phase encoder • One hot phase encoder • Binary phase encoder • Conclusions and future work Outline UK Asynchronous Forum, September 2008
Phase detector • Decodes phase encoded symbols by detecting the relative order between all the pairs of transitions • Consists of n(n-1)/2 mutual exclusion (mutex) elements Circuits synthesis UK Asynchronous Forum, September 2008
Outline • Phase encoding • Conditional partial order graphs • Circuit synthesis • Phase detector • Matrix phase encoder • One hot phase encoder • Binary phase encoder • Conclusions and future work Outline UK Asynchronous Forum, September 2008
Matrix phase encoder • Generates phase encoded symbols given the matrix X = {xkj} of pairwise comparisons of the output transitions 1 → 2 → 3 1 → 3 → 2 2 → 1 → 3 2 → 3 → 1 3 → 1 → 2 3 → 2 → 1 Circuits synthesis UK Asynchronous Forum, September 2008
Matrix phase encoder (implementation) Circuits synthesis UK Asynchronous Forum, September 2008
Matrix phase encoder (implementation) Circuits synthesis UK Asynchronous Forum, September 2008
Outline • Phase encoding • Conditional partial order graphs • Circuit synthesis • Phase detector • Matrix phase encoder • One hot phase encoder • Binary phase encoder • Conclusions and future work Outline UK Asynchronous Forum, September 2008
One hot phase encoder • Generates phase encoded symbols given one hot data X = {x1…xn!} Circuits synthesis UK Asynchronous Forum, September 2008
One hot phase encoder (logic optimisation) • The synthesised CPOG can be optimised Circuits synthesis UK Asynchronous Forum, September 2008
One hot phase encoder (controller) Circuits synthesis UK Asynchronous Forum, September 2008
Outline • Phase encoding • Conditional partial order graphs • Circuit synthesis • Phase detector • Matrix phase encoder • One hot phase encoder • Binary phase encoder • Conclusions and future work Outline UK Asynchronous Forum, September 2008
Binary phase encoder • Data is normally given in binary form • Binary phase encoder generates phase encoded symbols given binary encoded data Circuits synthesis UK Asynchronous Forum, September 2008
Outline • Phase encoding • Conditional partial order graphs • Circuit synthesis • Phase detector • Matrix phase encoder • One hot phase encoder • Binary phase encoder • Conclusions and future work Outline UK Asynchronous Forum, September 2008
Conclusions and future work • The work presents a scalable approach for synthesis of multiple rail phase encoding circuits • The approach uses the CPOG model in order to avoid exponential explosion of STG specifications due to duplication of events • Phase encoders are synthesised for matrix, one hot, and binary source encodings, but the approach can be easily adapted for the other encodings e.g. m-of-n encoding • The future work includes the development of automated synthesis tools based on the presented theoretical techniques Conclusions and future work UK Asynchronous Forum, September 2008
End Thank you! Questions? UK Asynchronous Forum, September 2008
STG specification explosion UK Asynchronous Forum, September 2008
STG specification explosion UK Asynchronous Forum, September 2008
First scenario STG specification explosion UK Asynchronous Forum, September 2008
First scenario Second scenario STG specification explosion Event duplication! UK Asynchronous Forum, September 2008
STG specification explosion + Reduces event duplication + Can be synthesised automatically (e.g. Petrify) – Difficult for manual design – Not visual – Contains a lot of additional places to track the choices – Very time consuming to generate UK Asynchronous Forum, September 2008
End Thank you! More Questions? UK Asynchronous Forum, September 2008
