CS 140L Lecture 7 Transformation between Mealy and Moore Machines

1. CS 140L Lecture 7Transformation between Mealy and Moore Machines Professor CK Cheng CSE Dept. UC San Diego

2. Outlines • Framework • Procedure • Example: Transform • Example: State Diagram • Example: Output Sequence

3. Transform from Mealy to Moore Machine Mealy Machine: y(t) = f(x(t), s(t)) Moore Machine: y(t) = f(s(t)) s(t+1) = g(x(t), s(t)) x(t) x(t) C1 C2 y(t) C1 C2 y(t) CLK CLK s(t) s(t) Moore Machine Mealy Machine

4. Transform from Mealy to Moore Machine Algorithm Input: State Table of Mealy machine 1) For each NS, z = Si,yj create a state Si(j) 2) For each new state Si(j), repeat the row PS = Si 3) Replace NS, z = Si,yj with state Si(j). Set output z = yj for row PS = Si(j)

5. Example Mealy Machine: PS A B 00 A,0 A,1 01 A,1 B,0 10 B,0 B,0 (x,y) (NS, z) Moore Machine: PS A0 A1 B (x,y) 00 A0 A0 A1 01 A1 A1 B 10 B B B z 0 1 0

6. State Diagram 00/0, 01/1 10/0, 01/0 Mealy Machine 10 01 10/0 00 B A 10 A0/0 B/0 00/1 10 00 01 00 Moore Machine A1/1 01

7. Timing Diagrams Time step x y S z S z 0 0 0 A 0 A0 0 1 0 1 A 1 A0 0 2 1 0 A 0 A1 1 3 0 0 B 1 B 0 4 0 1 A 1 A1 1 5 0 1 A 1 A1 1 A Mealy A1 1 Moore The output shifts by one clock from Mealy to Moore machine