EET202/3 DIGITAL ELECTRONICS II

1. EET202/3 DIGITAL ELECTRONICS II CHAPTER 3 : Sequencing and Control Semester 1 Session 2017/2018

2. Sequencing and Control 3.1 ~ Outline ~ State Diagram Mealy Model Moore Model OBJECTIVES OF THIS CHAPTER CO2: Ability to analyze and convert ASM chart to logical circuit and vice versa

3. State diagram • Graphical representation of a state table. • Provides the same information. • A state is represented by a circle. • The binary number inside the circle identifies the state of the flip-flops. • The source circle is the current/present state. • The destination circle is the next state. • Transition between states are indicated by directed lines connecting the circles. • There are two types of state diagram: • Mealy Model • Moore Model

4. Mealy Model Input (X) Output (Y) State • The directed lines are labeled by two binary numbers separated by a slash, e.g. 0/1 input=0 and output=1 of the present state • Output depends on the state of the flip-flop and input.

5. Mealy Model State Diagram • From the State Diagram, we can find the State Table. • There are 4 states (A, B, C, D), one input (X), and one output (Y). • One row for each current state. • From State A, the 0 and 1 input transitions have been filled in along with the outputs. State Table

6. 0/0 1/0 1/0 0/0 1/0 A B C D 0/0 1/1 0/0 Mealy Model • From the state diagram, complete the state table.

7. 0/0 1/0 1/0 0/0 1/0 A B C D 0/0 1/1 0/0 Mealy Model • From the state diagram, complete the state table.

8. Mealy Model Example 1: (1) From the state diagram, complete the state table. State Diagram

9. Mealy Model Example 1 (cont.): (1) From the state diagram, complete the state table. State Diagram

10. Mealy Model Example 1 (cont.): (2) Determine the Boolean equation using K-Map: • (3) Then, draw the Mealy Model complete circuit (use D FF) :

11. Moore Model • The output is included under a slash below the state in a circle. • Output depends only on the state of the flip-flop (present state output). Input X Input Y State Output

12. 0 1 0 1 1 A/0 B/0 C/0 D/0 0 1 1 0 E/1 0 Moore Model Example 2: From the state diagram, complete the state table.

13. 0 1 0 1 1 A/0 B/0 C/0 D/0 0 1 1 0 E/1 0 Moore Model Example 2 (cont.): From the state diagram, complete the state table.

14. Moore Model Example 3: (1) From the state diagram, complete the state table.

15. Moore Model Example 3 (cont.): (1) From the state diagram, complete the state table.

16. Moore Model Example 3 (cont.): • (2) Determine the Boolean equation using K-Map: • (3) Then, draw the Mealy Model complete circuit (use D FF) :

17. Exercise (FE 2012)

18. (a) (c) (b)

19. Mealy Model (MTE 2007) • Given is a state diagram for the sequence detector system. The input and output for the system is labeled as X and Z, respectively. Assume initial state is S0. i) Generate the corresponding state table. [10 m] ii) Design the logic circuit using D-FFs. [15 m] iii) Produce the corresponding Algorithm State Diagram (ASM) chart. [10 m]

20. 3 states : S0, S1, S2 1 input : X 1 output : Z

21. Moore Model (MTE 2009) • Refer to the state diagram, assume that the X1 and X2 are inputs to the circuit while Z1 and Z2 are the outputs. Assume initial state is S0. Produce the corresponding state table.

22. 3 states : S0, S1, S2 2 inputs : X1, X2 2 outputs : Z1, Z2 Answer MTE 2009

23. Exercise 1 i) Generate the corresponding state table. [10 m] ii) Design the logic circuit using D-FFs. [15 m]

25. Exercise 2 i) Generate the corresponding state table. [10 m] ii) Design the logic circuit using D-FFs. [15 m]