Verification of an Audio Control Protocol

We analyze a simple version of a protocol developed by Philips for the physical layer of an interface bus that connects the various devices of some stereo equipment (tuner, CD player,...). The protocol, which uses Manchester encoding, has to deal with a signiicant uncertainty in the timing of events, due to both hardware and software constraints. We present a formal speciication of the protocol, and a proof of correctness for the case where the tolerance of the clocks used within the system is less than 1 17. A counterexample shows that the protocol fails for tolerances greater than or equal to this value. The veriication is carried out using a model of linear hybrid systems, which is similar to the phase transition system model of Manna and Pnueli, and the model of linear hybrid automata of Alur, Henzinger and Ho. The semantics of linear hybrid systems is deened via a translation to the timed I/O automata model of Lynch and Vaandrager. Note: The rst and third author were supported by Esprit BRA 7166 concur 2.

[1]  Aaas News,et al.  Book Reviews , 1893, Buffalo Medical and Surgical Journal.

[2]  Nancy A. Lynch,et al.  Liveness in Timed and Untimed Systems , 1994, Inf. Comput..

[3]  F. Vaandrager.  Forward and Backward Simulations Part I : Untimed Systems , 1993 .

[4]  Zohar Manna,et al.  Verifying Hybrid Systems , 1992, Hybrid Systems.

[5]  F. Vaandrager,et al.  A Comparison of Additivity Axioms in Timed Transition Systems. , 1993 .

[6]  G. G. Stokes.  "J." , 1890, The New Yale Book of Quotations.

[7]  Joseph Sifakis,et al.  An Overview and Synthesis on Timed Process Algebras , 1991, CAV.

[8]  Willem Otto David Griffioen.  Analysis of an Audio Control Protocol with Bus Collision , 1994 .

[9]  Amy P. Felty,et al.  The Coq proof assistant user's guide : version 5.6 , 1990 .

[10]  Thomas A. Henzinger,et al.  Hybrid Automata: An Algorithmic Approach to the Specification and Verification of Hybrid Systems , 1992, Hybrid Systems.

[11]  Nancy A. Lynch,et al.  Correctness of At-Most-Once Message Delivery Protocols , 1993, FORTE.

[12]  Kirsten Mark Hansen,et al.  Specifying and verifying requirements of real-time systems , 1991, SIGSOFT '91.

[13]  Leslie Lamport,et al.  Hybrid Systems in TLA+ , 1992, Hybrid Systems.

[14]  T. Henzinger,et al.  Automatic Symbolic Veri cation of Embedded Systems , 1996 .

[15]  Nancy A. Lynch,et al.  Hierarchical correctness proofs for distributed algorithms , 1987, PODC '87.

[16]  Martín Abadi,et al.  An old-fashioned recipe for real time , 1994, TOPL.

[17]  Martin S. Roden.  Digital Communication Systems Design , 1988 .

[18]  Wang Yi,et al.  Real-Time Behaviour of Asynchronous Agents , 1990, CONCUR.

[19]  Nancy A. Lynch,et al.  Forward and backward simulations, part II: timing-based systems , 1993 .

[20]  Frits W. Vaandrager,et al.  Proof-Checking a Data Link Protocol , 1994, TYPES.

[21]  Leslie Lamport,et al.  The temporal logic of actions , 1994, TOPL.

[22]  Editors , 1986, Brain Research Bulletin.

[23]  Zohar Manna,et al.  From Timed to Hybrid Systems , 1991, REX Workshop.