Dr.Mohamed Elmahdy Winter 2015 Eng.Yasmin Mohamed. Problem Set 6. Analysis and Design of Clocked Sequential Circuits. Discussion: 7/11/ /11/2015

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1 Dr. Elmahdy Winter 2015 Problem Set 6 Analysis and Design of Clocked Sequential Circuits Discussion: 7/11/ /11/2015 *Exercise 6-1: (Problem 5.10) A sequential circuit has two JK flip-flops A and B, two inputs x and y, and one output z. The flip-flop input equations and circuit output equation are J a = Bx + B y J b = A x K a = B xy K b = A + xy z = Ax y + Bx y a) Draw the logic diagram of the circuit. b) Tabulate the state table and draw the state diagram. c) Derive the state equations for A and B. Exercise 6-2: (Problem 5.16) Design a sequential circuit with two D flip-flops A and B and one input x_in. a) When the x_in = 0, the state of the circuit remains the same. When x_in = 1, the circuit goes through the state transitions from 00 to 01, to 11, to 10, back to 00, and repeats. b) When the x_in = 0, the state of the circuit remains the same. When x_in = 1, the circuit goes through the state transitions from 00 to 11, to 01, to 10, back to 00, and repeats. Exercise 6-3: (Problem 5.18) Design a sequential circuit with two JK flip-flops A and B and two inputs E and F. If E = 0, the circuit remains in the same state regardless of the value of F. When E = 1 and F = 1, the circuit goes through the state transitions from 00 to 01, to 10, to 11, back to 00, and repeats. When E = 1 and F = 0, the circuit goes through the state transitions from 00 to 11, to 10, to 01, back to 00 and repeats. Exercise 6-4: (Problem 5.19) Page 1

2 Dr. Elmahdy Winter 2015 A sequential circuit has three flip-flops A, B and C; one input x_in; and one output y_out. The state diagram is shown in the figure below. The circuit is to be designed by treating the unused states as don t care conditions. Analyze the circuit obtained from the design to determine the effect of the unused states. a) Use D flip-flops in the design. b) *Use JK flip-flops in the design. Exercise 6-5: (Problem 5.29) Write a behavioral description of the state machine described by the state diagram shown in figure of exercise 4-4. Write a test bench and verify the functionality of the description. Page 2

3 Dr. Elmahdy Winter 2015 Exercise 6-6: (Problem 5.20) Design the sequential circuit specified by the state diagram of the figure below, using T flip-flops. Page 3

Dr. Elmahdy Winter 2015 *Exercise 6-7: (Problem 5.31) How should the code below be written so that the circuit has the same behavior when the assignments are made with = instead of <=?

4 Dr. Elmahdy Winter 2015 *Exercise 6-7: (Problem 5.31) How should the code below be written so that the circuit has the same behavior when the assignments are made with = instead of <=? *Exercise 6-8 (5.8 in book ) Derive the state table and the state diagram of the sequential circuit shown in Fig. P 5.8. Explain the function that the circuit performs. (HDL see Problem 5.36.) Page 4

5 Dr. Elmahdy Winter 2015 Exercise 6-9 (5.11 in book ) For the circuit described by the state diagram of Fig.5.16, (a)* Determine the state transitions and output sequence that will be generated when an input sequence of is applied to the circuit and it is initially in the state 00. (b) Find all of the equivalent states in Fig.5.16 and draw a simpler, but equivalent, state diagram. (c) Using D flip-flops, design the equivalent machine (including its logic diagram) described by the state diagram in (b). Page 5

Sequential Logic Circuits

Sequential Logic Circuits By Dr. M. Hebaishy Digital Logic Design Ch- Rem.!) Types of Logic Circuits Combinational Logic Memoryless Outputs determined by current values of inputs Sequential Logic Has memory