Mealy state machine
•
In the theory of computation, a Mealy machine is a finite state transducer that
generates an output based on its current state and input. This means that the state
diagram will include both an input and output signal for each transition edge.
•
•
In contrast, the output of a Moore finite state machine depends only on the machine's
current state; transitions are not directly dependent upon input.
The use of a Mealy FSM leads often to a reduction of the number of states.
•
However, for each Mealy machine there is an equivalent Moore machine.
Mealy state machine
Moore state machine
•
In the theory of computation, a Moore machine is a finite state transducer
where the outputs are determined by the current state alone (and do not
depend directly on the input). The state diagram for a Moore machine will
include an output signal for each state. Compare with a Mealy machine,
which maps transitions in the machine to outputs.
•
The advantage of the Moore model is a simplification of the behavior.
Moore state machine
Example
• Q3.Derive a minimal state table for a single-input and
single-output Moore-type FSM that produces an output
of 1 if in the input sequence it detects either 110 or 101
patterns. Overlapping sequences should be detected.
(Show the detailed steps of your solution.)
State Diagram
Reset
w=0
w=0
w=1
A/z=0
w=0
w=1
B/z=0
E/z=0
w=1
F/z=1
w=1
w=1
w=0
C/z=0
w=0
State Diagram
D/z=1
w=1
Sate Table (Moore FSM)
Present
state
Next State
w=0
Output
Z
w=1
A
A
B
0
B
E
C
0
C
D
C
0
D
A
F
1
E
A
F
0
F
E
C
1
6 states need 3 flip-flops
State
state
state
state
state
Assignment (Mealy FSM):
A: Got no 1
B: Got”1”
C: Got”11”
D: Got”10”
Reset
1/0
1/0
0/0
1/0
B
A
1/1
0/0
0/0
State Diagram
C
0/1
D
Sate Table (Mealy FSM)
Present
state
Next State
w=0
Output Z
w=1
w=0
w=1
A
A
B
0
0
B
D
C
0
0
C
D
C
1
0
D
A
B
0
1
4 states need 2 flip-flops