lect9 Finite State Machines-b

lect9 Finite State Machines-b - CSE140: Components and...

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1 1 Sources: TSR, Katz, Boriello, Vahid, Perkowski CSE140: Components and Design Techniques for Digital Systems Tajana Simunic Rosing 2 Sources: TSR, Katz, Boriello, Vahid, Perkowski Today • Finite State Machines – Models for representing sequential circuits • Moore and Mealy – FSM implementation using various types of FFs – FSM Optimization • State minimization
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2 3 Sources: TSR, Katz, Boriello, Vahid, Perkowski More complex counter example 010 000 110 101 011 4 Sources: TSR, Katz, Boriello, Vahid, Perkowski Self-starting counter 010 000 110 101 011
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3 5 Sources: TSR, Katz, Boriello, Vahid, Perkowski Comparison of Mealy and Moore machines •M o o r e • Mealy • Synchronous Mealy state feedback inputs outputs reg combinational logic for next state logic for outputs inputs outputs state feedback reg combinational logic for next state logic for outputs inputs outputs state feedback reg combinational logic for next state logic for outputs 6 Sources: TSR, Katz, Boriello, Vahid, Perkowski D/1 E/1 B/0 A/0 C/0 1 0 0 0 0 1 1 1 1 0 reset current next reset input state state output 1–– A 00A B 0 01A C 0 00B B 0 01B D 0 00C E 0 01C C 0 00D E 1 01D C 1 00E B 1 01E D 1 Specifying outputs for a Moore machine • Output is only function of state – specify in state bubble in state diagram – example: sequence detector for 01 or 10
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4 7 Sources: TSR, Katz, Boriello, Vahid, Perkowski current next reset input state state output 1–– A 0 00A B 0 01A C 0 00B B 0 01B C 1 00C B 1 01C C 0 B A C 0/1 0/0 0/0 1/1 1/0 1/0 reset/0 Specifying outputs for a Mealy machine • Output is function of state and inputs – specify output on transition arc between states – example: sequence detector for 01 or 10 8 Sources: TSR, Katz, Boriello, Vahid, Perkowski Registered Mealy machine (really Moore) Inputs Outputs Current State output logic next state logic
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5 9 Sources: TSR, Katz, Boriello, Vahid, Perkowski Example: vending machine Release item after 15 cents are deposited Single coin slot for dimes, nickels No change 10 Sources: TSR, Katz, Boriello, Vahid, Perkowski Equivalent Mealy and Moore state diagrams •M o o r e m a c h i n e – outputs associated with state [0] 10¢ [0] [0] 15¢ [1] N’ D’ + Reset D D N N+D N N’ D’ Reset’ N’ D’ N’ D’ Reset 10¢ 15¢ (N’ D’ + Reset)/0 D/0 D/1 N/0 N+D/1 N/0 N’ D’/0 Reset’/1 N’ D’/0 N’ D’/0 Reset/0 • Mealy machine – outputs associated with transitions
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6 11 Sources: TSR, Katz, Boriello, Vahid, Perkowski Example: Moore implementation • Encode states and map to logic 0011 0111 XX1X 1111 Q1 D1 Q0 N D 0110 1011 Q1 D0 Q0 N D 0010 Q1 Open Q0 N D present state inputs next state output Q1 Q0 D N D1 D0 open 00 0 0 0 01 0 1 0 10 1 0 0 11 – 01 0 01 1 0 0 1 0 10 0 1 0 1 0 11 – – 1 12 Sources: TSR, Katz, Boriello, Vahid, Perkowski Example: Mealy implementation 10¢ 15¢ Reset/0 D/0 D/1 N/0 N+D/1 N/0 N’ D’/0 Reset’/1 N’ D’/0 N’ D’/0 Reset/0 present state inputs next state output Q1 Q0 D
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This note was uploaded on 02/14/2008 for the course CSE 140 taught by Professor Rosing during the Fall '06 term at UCSD.

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lect9 Finite State Machines-b - CSE140: Components and...

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