《数字电》英文版 chapter5 Synchronous Sequential Circuit

Synchronous Sequential Circuit Chapter 5 ●●●●● Overview ●●●● ●●。●●

Synchronous Sequential Circuit Chapter 5 Overview

Universal mode/sg. ●●●●● ●●●● ●●0 System ●●● ●●●● Input Variables工 System Combinational output ogIC Variables State Excitation Variables Variables 0 Memory Flip- flops E CLOCK

Universal model System output Variables O0 Om Er Excitation Variables E0 Combinational logic System Input Variables I0 In S0 Sx State Variables Memory Flip￾flops CLOCK

●●●●● Basic concept:88i ●●●● Synchronous sequential circuit memory, usually consisting of flip-flops, update circuit states information All flip-flops share a common clock pulse input The clock input is not a binary value representing the time of day but rather a" synchronous"train of pulses. Synchronous memory changes its data only at certain time intervals The flip-flops can change state only on a clock pulse edge

Basic concept ⚫ Synchronous sequential circuit memory, usually consisting of flip-flops, update circuit states information. ⚫ All flip-flops share a common clock pulse input. ⚫ The clock input is not a binary value representing the time of day, but rather a ”synchronous” train of pulses. Synchronous memory changes its data only at certain time intervals . ⚫ The flip-flops can change state only on a clock pulse edge

●●●●● Basic concept ::o ●●●● The output of memory(flip -flops)defines the state of a sequential machine. It implies that the state variables are the flip-flop outputs. The next-state equation is the characteristics equation of the flip- lops used in circuit, Excitation variables are input to memory(flip-flops) When flip-flops are used for the system memory, the excitation variables are the inputs(J-K,R-S,D, t)to the flip-flops. Excitation variables are generated by the input combinational logic operating on the state variables and input variables

⚫ The output of memory (flip-flops) defines the state of a sequential machine. It implies that the state variables are the flip-flop outputs. The next-state equation is the characteristics equation of the flip￾flops used in circuit. ⚫ Excitation variables are input to memory (flip-flops). When flip-flops are used for the system memory, the excitation variables are the inputs (J-K, R-S, D, T) to the flip-flops. Excitation variables are generated by the input combinational logic operating on the state variables and input variables. Basic concept

Describe a ssc ●●●●● ●●●● ●●0 ●●● ●●●● Excitation variables Input Output (E) 以」 Combinational Memory Combination(O) transform CLK M (S al logIc (9) State variables Mealy model machine E三f(工,S) St+1= f( st, E)flip-flop characteristics equation o=g(I, St)

⚫ Mealy model machine ⚫ E = f( I, St ) ⚫ St+1 = f( St, E ) flip-flop characteristics equation ⚫ O = g( I, St ) Describe a SSC Combinational transform (f) Memory M Combination al logic (g) Input (I) (E) CLK State variables (S) Excitation variables Output (O)

●●●●● Describe a ssc ●●●● ●●0 ●●● ●●●● Excitation variables Input Output Combinational Memory Combinational (O) transform logic CLK M (S) State variables ● Moore model machine E≡f(工,St) St+1=f(st, E)flip-flop characteristics equation o=g( St)

⚫ Moore model machine ⚫ E = f( I, St ) ⚫ St+1 = f( St, E ) flip-flop characteristics equation ⚫ O = g( St ) Describe a SSC Combinational transform (f) Memory M Combinational logic (g) Input (I) (E) CLK State variables (S) Excitation variables Output (O)