Combinational versus sequential logic

3/13/98


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Table of Contents

Combinational versus sequential logic

Basic memory element: D flip-flop

D flip-flop timing

Building Synchronous Circuits

Cascading D flip-flops

Timing Requirements

Clock skew

Metastability and asynchronous inputs

Synchronizer failure

Minimizing synchronizer failures

Handling asynchronous inputs

Handling asynchronous inputs (cont'd)

Registers

Shift registers

Universal shift register

Design of universal shift register

Shift-register applications

Finite state machines

Some examples: Ring and Johnson counters

Counter design procedure

Example: Design a 3-bit up counter

Example: Design a 3-bit up counter (con’t)

Example: Design a 3-bit up counter (con’t)

Another example: A 5-state counter

5-state counter design (con’t)

5-state counter design (con’t)

Self-starting counters

Self-starting counters (cont'd)

Binary counter

Four-bit binary synchronous up-counter

Offset counters

Finite state machines

Finite state machine representations

State machine model

FSM design procedure

FSM design procedure

Moore versus Mealy machines

Specifying outputs for a Moore machine

Specifying outputs for a Mealy machine

Comparison of Mealy and Moore machines

Mealy and Moore example

Example: serial adder

Example: vending machine

Example: vending machine (state diagram)

Vending machine (symbolic state transition table)

Example: vending machine (state encoding)

Vending machine (two-level logic implementation)

FSM implementation

Synchronous versus asynchronous FSMs

Author: Carl Ebeling

Email: cse-webmaster@cs.washington.edu

Home Page: http://www.cs.washington.edu//education/courses//370/CurrentQtr