ECE201Notes(7)

# ECE201Notes(7) - ECE 201 Digital Logic Chapter 7 1 of 27...

This preview shows pages 1–7. Sign up to view the full content.

ECE 201 Digital Logic Chapter 7 1 of 27 Synchronous Sequential Networks 7.1 Structure and Operation of Clocked Synchronous Sequential Networks Sequential Logic – Digital Logic which contains both combinational elements and memory elements. Synchronous Sequential Logic – Sequential Logic whose behavior can be defined from the knowledge of its signals at discrete instants of time. Asynchronous Sequential Logic – Sequential Logic whose behavior depends on the order in which its inputs are changed and can be affected at any instant of time.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
ECE 201 Digital Logic Chapter 7 2 of 27 Characteristic Tables Characteristic Tables are used to state what the new output, Q(t+1) , of the Flip-flop will be given the present inputs and the past output, Q(t) . They are used to analyze a sequential circuit and determine the state table corresponding to it. J-K Flip-Flop R-S Flip-Flop J K Q(t+1) S R Q(t+1) 0 0 Q(t) No Change 0 0 Q(t) No Change 0 1 0 Reset 0 1 0 Reset 1 0 1 Set 1 0 1 Set 1 1 Q’(t) Toggle 1 1 ? Unknown D Flip-Flop T Flip-Flop D Q(t+1) T Q(t+1) 0 0 Reset 0 Q(t) No Change 1 1 Set 1 Q(t)’ Toggle
ECE 201 Digital Logic Chapter 7 3 of 27 7.2 Analysis of Synchronous Sequential Networks Sequential Circuit Example with Data Flip-Flops B y B’ Clk A A’ x Q’ Q’ Q Q D D A(t+1) = D A = A(t)x(t) + B(t)x(t) = Ax + Bx B(t+1) = D B = A’(t)x(t) = A’x y(t) = [A(t) + B(t)] x’(t) = (A + B) x’ Present State ---------- Input ------- Next State -------- Output -------- Flip-Flop Inputs -------------- A B x A B y D A D B 0 0 0 0 0 0 0 0 0 0 1 0 1 0 0 1 0 1 0 0 0 1 0 0 0 1 1 1 1 0 1 1 1 0 0 0 0 1 0 0 1 0 1 1 0 0 1 0 1 1 0 0 0 1 0 0 1 1 1 1 0 0 1 0

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
ECE 201 Digital Logic Chapter 7 4 of 27 D A = Ax + Bx D B = A’x y = (A + B) x’ Present State ---------- Input ------- Next State -------- Output -------- A B x A B y 0 0 0 0 0 0 0 0 1 0 1 0 0 1 0 0 0 1 0 1 1 1 1 0 1 0 0 0 0 1 1 0 1 1 0 0 1 1 0 0 0 1 1 1 1 1 0 0 Alternate Form of the State Table Present State ---------- Next x = 0 ------- State x = 1 -------- Output x = 0 -------- Output x = 1 -------- A B AB A B y y 0 0 0 0 0 1 0 0 0 1 0 0 1 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 0 1 0 00 0/0 0/1 0/1 0/1 1/0 1/0 1/0 1/0 11 10 01
ECE 201 Digital Logic Chapter 7 5 of 27 State Diagram U S N K I T C 0/0 0/1 1/1 1/1 1/0 1/0 1/0 1/0 1/1 0/1 0/1 0/0 0/0 0/0 State Input Output U 1 0 1 1 0 0 0 1

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
ECE 201 Digital Logic Chapter 7 6 of 27 Sequential Circuit Example with J-K Flip-Flops B Clk A x Q’ Q J K Q’ Q J K J A = B K A = Bx’ J B = x’ K B = A’x + Ax’ Present State ---------- Input ------- Next State -------- Flip-Flop Inputs -------------- A B x A B J A K A J B K B 0 0 0 0 1 0 0 1 0 0 0 1 0 0 0 0 0 1 0 1 0 1 1 1 1 1 0 0 1 1 1 0 1 0 0 1 1 0 0 1 1 0 0 1 1 1 0 1 1 0 0 0 0 0 1 1 0 0 0 1 1 1 1 1 1 1 1 1 1 0 0 0 00 1 1 1 0 0 0 1 0 01 10 11
This is the end of the preview. Sign up to access the rest of the document.

## This note was uploaded on 04/20/2008 for the course ECE 201 taught by Professor Ried during the Spring '08 term at Clemson.

### Page1 / 27

ECE201Notes(7) - ECE 201 Digital Logic Chapter 7 1 of 27...

This preview shows document pages 1 - 7. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online