Fault Detection Methods in Sequential System

Fault Detection Methods in Sequential System

• 1.
  Fault DetectionMethods inSequential Circuits Switching Theory and Logic Design – ETEC 205 ShivangDubey 20320802819
• 2.
  Methods ofFault Detection •PathSensitization • Boolean Difference • D-Algorithm • *FaultMatrix • *Partitioning • *State-TableAnalysis *: Beyond our approach
• 3.
  Fault • Physical defectwithina circuit; may/may not cause system failure
• 4.
  Stuck atFaults • Assumptions: Only 1 line is faulty  Faulty line set to ‘1’ or ‘0’  Fault line can be at output orinput gate To detect them weproduce test factors (input combinations) which is obtained from *Fault Equivalents model as well.
• 5.
  Approachesto Fault Detection •Circuit Test approach; experimenter iswell versed with circuitsand faultsoccurrence • TransitionChecking Approach; experimenter has leastknowledge of circuit but knows about the transition
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  Path SensitizationMethod • Forcombinationallogic circuits onepowerful approach to test generation relies on path sensitizing, the application of input such that the output depends directly on the condition of the lead being tested • Path sensitizationis based on the assumption that the failuremechanismina gate results inits inputs or outputs being stuck atone or stuck at zero This fault is then traced along a path to the network output and its effects are noted
• 9.
  BooleanDifference • Algebraic algorithmfor detecting faults • df/dxi = fxi(0) ⊕fxi(1)  Sa0 = xi*df/dxi = 1 [Stuck at0]  Sa1 = ͞xi*df/dxi = 1 [Stuck at 1]
• 10.
  x3x2(bar) x2 x2(bar) x1 x1x2 x3 y =x1x2 + x3x2(bar) Comparingboth terms on LHS to 1
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  D Algorithm • Formalversionof PathSensitizationMethod • Singular Cover: compactversion oftruth table  Each row is singular cube • PrimitiveD Cube: derivedfromSingular cover ofcorrect and faultysingular cover • PropagationD-Cube  Behaviors ofo/pandi/p
• 12.
  Propertiesof D Algorithm •0 ∩0 = 0 ∩ x = x ∩ 0 = 0 • 1 ∩ 1= 1∩ x = x ∩ 1 = 1 • x ∩ x = x • 1 ∩0 = D • 0 ∩ 1 = D’
• 13.
  ThankYou