1. Chapter 0 – Week 2 Combinational Logic Design

2. What have been discussed Design hierarchy –Top – down –Bottom – up CAD HDL Logic synthesis

3. Analysis Procedure Analysis –To determine the function of a circuit Derive Boolean equation Derive truth table

4. Analyze this logic diagram T1 T3 T2 T4 T5

5. Boolean Equation T1 = T2 = T3 = T4 = T5 = F1 = F2 =

6. Analyze this Binary Adder R1 R2 R3

7. Truth Table XYZ CCR1R2R3S

8. Logic Simulation A fast and accurate method of analyzing a combinational circuit Using simulator software Results : –Waveforms –A complete truth table –Part of a truth table

9. Logic Simulation How is the circuit described in the software ? –Schematics –HDL

10. Schematic for Binary Adder in Xilinx

11. Waveforms for Binary Adder

12. Point to ponder…. Why do we compare the simulation results vs the theoretical results?

13. Design Procedure Given : Specifications of the problem 1.Determine input & output 2.Derive truth table 3.Obtain Boolean equation (K-map) 4.Draw schematics 5.Verify design

14. Design of BCD to Excess – 3 Code Converter Specifications : Input in decimal numbers, 0 – 9, in binary form Output is excess – 3 code E.g –Decimal = 5 (101) –Excess – 3 code = 5 + 3 = 8 (1000)

15. BCD  Excess – 3 Step 1. –Input : –Output :

16. BCD  Excess – 3 Step 2 : Truth Table

17. BCD  Excess – 3 Step 3 : Boolean equation

18. BCD  Excess – 3 Step 4 : Schematic diagram

19. BCD  Excess – 3 Step 5 : Verify that schematic diagram agrees with truth table

20. Design of BCD to 7 – segment decoder Specifications : Input in decimal numbers, 0 – 9, in binary form 7 Outputs – to display input number

21. 7 – segment Display

22. BCD to 7 –segment decoder Step 1 :

23. BCD to 7 –segment decoder Step 2 : Truth Table

24. Exercise A traffic light system has the following specifications for a part of its controller. There are 3 parallel lanes, each with its own red / green light. One of these lanes, the priority lane, is given priority for a green light over the other 2 lanes. On the other hand, an alternating scheme is used for the other 2 lanes, which are left and right lane. Design the circuit that determines which light is to be green at a particular time. The specifications for the controller are as follows :

25. Exercise Inputs : PS – Priority Lane Sensor ( car present = 1; car absent = 0 ) LS – Left Lane Sensor ( car present = 1; car absent = 0 ) RS – Right Lane Sensor ( car present = 1; car absent = 0 ) AS – Alternating Signal ( select left = 1; select right = 0 ) Outputs : PL – Priority Lane Light ( green = 1; red = 0 ) LL – Left Lane Light ( green = 1; red = 0 ) RL – Right Lane Light ( green = 1; red = 0 )

26. Exercise 1.If there is a car in the priority lane, PL = 1. 2.If there are no cars in the priority lane and the right lane, and there is a car in the left lane, LL = 1. 3.If there are no cars in the priority lane and in the left lane, and there is a car in the right lane, RL = 1. 4.If there is no car in the priority lane, there are cars in both the left and right lanes, and AS = 1, then LL = 1. 5.If there is no car in the priority lane, there are cars in both the left and right lanes, and AS = 0, then RL = 1. 6.If any PL, LL or RL is not specified to be 1 above, then it has value 0.

27. The End