Mealy Machines & Moore Machines

VLSI Circuits & Systems

Lecture 8Mealy and Moore MachinesMealy Machine

Characterized by Outputs are a function of both inputs and current state9/26/20082ECE 561 - Lecture 4

Moore machine

Characterized by Outputs are a function current state only

9/26/20083ECE 561 - Lecture 4

Difference b/w Mealy & Moore Machines

Example 3Ahmad Almulhem, KFUPM 2010Problem: Design of A Sequence Recognizer Design a Moore machine to detect the sequence (111). The circuit has one input (X) and one output (Z).Example 3 (cont.)Ahmad Almulhem, KFUPM 2010Step1: State Diagram Sequence to be detected:111S0/0S1/0S2/0S3/110110001Example 3 (cont.)Ahmad Almulhem, KFUPM 2010Step2: State TableUse binary encodingUse JK-FF and D-FF

S0/0S1/0S2/0S3/110110001Example 3 (cont.)Ahmad Almulhem, KFUPM 2010Step4: Draw CircuitFor step3, use k-maps as usual

JA = XBKA = XDB = X(A+B)Z = A.BDraw a Moore circuit to detect 110 sequence.Design a Moore circuit which gives output z=1 if three consecutives 1 but z=0 if 4 or more consecutive 1 occurs.Prepared by Shiraz HusainDesign a Moore sequential network that has one input and one output. When it recieves 011, z=1 and remains 1 until second time 011 occurs after this output becomes 0 and remains 0 until next time 011 occurs and so on.Prepared by Shiraz HusainNextStateLogic

OutputLogic

StateMemory(F/F)

CLOCK

Inputs

Excitation

CurrentState

Outputs

NextStateLogic

OutputLogic

StateMemory(F/F)

CLOCK

Inputs

Excitation

CurrentState

Outputs