Implementation of Formal Verification

1
Implementation of Formal Verification

• Vending Machine
• By Gulesen Uzun
• Instructor Prof. Khaled Elleithy

2
Abstract State Machine(ASM)

• Covers both verification and validation, using
  mathematical reasoning
• Makes the faithfulness of the definitions
• Links the high-level definition in a transparent
  way to its implementation
• Provides a convenient basis for turning the
  abstract definitions into executable models
• Simplifies the (mathematical or machine checked)
  justification of the correctness of the design

3
Mealy Moore Machines

• In Mealy, the output is a function only of the
  state of the machine
• In Moore, the output is a function of the state
  of the machine AND of the inputs
• The project is designed through a Moore machine

4
Machine Specifications

• Consists of 16 states
• Possible inputs are all coins, eject and a gum
  release button
• Has a logical money counter to track the total
  money
• Releases the gum once receives at least 15 cents
• Gives the change back when applicable

5
Methods Used in Project

• Made the design using ASM properties
• Made necessary assumptions and minimizations
• Verified the truth-ness of Vhdl code using
  Maxplus2
• Ran appropriate simulations to verify the
  correctness of the state algorithm

Simulation effectiveness
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Snap Shots from the Simulation

• A dime and a nickel is inserted, gum release
  button hit and the gum is delivered

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Snap Shots from the Simulation

• A quarter is inserted and eject button is hit,
  quarter is given back with no gum

8
References

• http//www.di.unipi.it/boerger/ASMTutorialEtaps.h
  tml
• http//www.bridgeport.edu/matanya/vlsi/ictutor.ht
  ml
• Contemporary Logic Design, Randy H. Katz,
  Berkeley, California, 1993
• Introduction to Digital Systems, Milos Ercegovac,
  Thomas Lang, Jaime H. Moreno, 1998

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Conclusions

• State diagram is the blueprint of the Vhdl code.
• The way the diagram is might have added
  redundancy in the code but also added accuracy
  and efficiency
• The machine could have been designed in different
  ways depending on what the cost values are.
• The project simply stands for an analysis of a
  behavior of a vending machine.