PPT Slide

7 – Sequential Logic Examples

© 1996 Gaetano Borriello

Traffic light controller as two communicating FSMs

30

• Without separate timer

  • S0 would require 7 states
  • S1 would require 3 states
  • S2 would require 7 states
  • S3 would require 3 states
  • S1 and S3 have simple transformation
  • S0 and S2 would require many more arcs
    • C could change in any of seven states

• By factoring out timer

  • greatly reduce number of states
    • 4 instead of 20
  • counter only requires seven or eight states
    • 12 total instead of 20

traffic light controller

timer

TL

TS

ST

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