CSM51Asolution_chapter8

# X0 the sequential network is shown in figure 826 q1 j

This preview shows page 1. Sign up to view the full content.

This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: tion of a JK ip- op is PS 0 1 NS 01 0- 1-1 -0 JK Input the inputs J1 ; K1 ; J2 , and K2 to the JK ip- ops are Q 2 Q1 x = 0 x = 1 00 01 10 0-,00-,-1 -1,0- PS J2 K2 ; J1 K1 0-,11-,-1 -0,0- Switching expressions for these ip- op inputs are J2 = Q1 x K2 = x0 An expression for the output is J1 = Q02 x K1 = 1 z = Q2 x0 The sequential network is shown in Figure 8.26. Q1 J CK 1 1 CK x K Q’ Q J CK 2 K x’ Q’ Q Q2 z Figure 8.26: Network for Exercise 8.23 Since the output at time t depends on the inputs at time t , 3; t , 2; t , 1, it is necessary to store these in the state register. That is, the register consists of three ip- ops such that Exercise 8.24 Q2 t = xt , 3 Q1 t = xt , 2 Q0 t = xt , 1 148 Solutions Manual - Introduction to Digital Design - February 22, 1999 Consequently, the state description is Q2 t + 1 Q1 t + 1 Q0 t z = = = = Q1 t Q0 t xt xt , 3  xt , 2  xt , 1  xt = Q2  Q1  Q0  x D2 = Q1 D1 = Q0 D0 = x If we use D ip- ops, we get The sequential network is shown in Figure 8.27. Z Q0 X D Q D Q Q1 D Q FF0 Q’ FF1 Q’ FF2 Q’ CK Figure 8.27: Network for Exercise 8.24 Exercise 8.25 We have to store the last input to be able to recognize the sequence 11; therefore, we need: S0 : xt , 1 = 0 S1 : xt , 1 = 1 The state table is PS NS,z Coding S0 as 0 and S1 as 1, the resulting state table is Input PS Q x=0 x=1 0 0,0 1,0 1 0,0 1,1 NS,z S0 S1 x=0 x=1 S0 ; 0 S1; 0 S0 ; 0 S1; 1 Input Solutions Manual - Introduction to Digital Design - February 22, 1999 149 We only need one JK ip- op. Since its excitation function is PS NS 01 1 0- 11 -1 -0 JK the inputs are J=x K = x0 The output is described by z = Qx The sequential network is shown in Figure 8.28. Z X CK J CK K Q’ Q Figure 8.28: Network for Exercise 8.25 Exercise 8.26 The state corresponds to the count. That is, st + 1 = st + 1 mod 3 Using a radix-2 representation for the count we get the following state table PS Input Q 2 Q1 x = 0 x = 1 00 00 01 01 01 10 10 10 00 NS Since the excitation function of a SR ip- op is PS...
View Full Document

## This note was uploaded on 03/26/2010 for the course CS 187154200 taught by Professor Ercegovac,m.d. during the Winter '09 term at UCLA.

Ask a homework question - tutors are online