EE 210. LOGIC DESIGN LAB.

College of Engineering Electrical Engineering Department EE 210. LOGIC DESIGN LAB. (1 st semester 1426-27) Dr. Messaoud Boukezzata Office: EE 11 Phone: 063 8000 50 Ext 3152 1

College of Engineering Electrical Engineering Department EE 210: Logic Design Lab. (1 st semester 1426-27) Instructor: Dr. Messaoud Boukezzata Office: EE 11 Phone: 063 8000 50 Ext 3152 A- Course Outline: Weeks Topic Date 1 st Exp. 1: Introduction to Logic Lab. & Kits 24/09/05 2 nd Exp. 2: Introduction to Logic Gates 01/09/05 3 rd Exp. 3: Minimization of Boolean functions 08/10/05 4 th First Mid-Term Exam 15/10/05 5 th Exp. 4: Xilinx Software Tutorial 22/10/05 6 th Exp. 5: Design Full Adder & 4-bit Full Adder 12/11/05 7 th Exp. 6: Design 4-bit Adder/subtractor 19/11/05 8 th Second Mid-Term Exam 26/11/05 9 th Exp. 7: Decoders 03/12/05 10 th Exp. 8: Introduction to Flip-Flops 10/12/05 11 th Exp. 9: Counters 17/12/05 12 th Final Exam 31/01/06 B- Marks Distribution: Quizes, Attendance& Experiment preparation 10 1 st midtermexam 25 2 nd midterm exam 25 Final exam 40 Total marks 100 C- References: 1- Text Book: M. Morris Mano, Digital Design, Int l 3 rd Edition, Prentice Hall (2002). 2- Lab. Notes: EE 210: Logic Design Lab., edited by KSU, (2 nd semester 1424-25). Instructor Dr. Messaoud Boukezzata Vice-Dean for academic affairs Dr. Abdul Rahman Al-Marshood 2

College of Engineering Electrical Engineering Department Preface For the first time, we have constructed and started the Lab. experiments in the Electrical Engineering Department of Qassim University, on the basis of what it is done in similar department in the King Saud University of Riyadh. However, some experiments are well adapted to be more representative to the Lab. possibilities. Of course, these rearrangements have maintained intact the heart of the subject and the main aim of each session. The only lack that we should fill up in the near future is to provide a recent version of the Xilinx software, needed for acquiring high level of simulations skills. The student version of ISE 4.2i is not sufficient to implement a correct simulation design due to its limit function. We have tried to upgrade this version via internet site of Xilinx foundation (www.xilinx.com/downloads), by downloading new files offered but the student version is given free not upgradeable. So, we think that the best solution is to purchase a commercial version adapted to educational uses as ISE 7.0 which may be the best solution. That s exactly what is we have finally opted to do with the permission of our higher responsibles: Dr. Sulayman Al Yahia, the Dean of the college of Engineering, and Dr. Abdulrahman Al Marshoud, the Vice-Dean of the College for academic affairs & Head of the Electrical department. We think that the student will find in this laboratory notes a helpful document for his Lab. Reports and a complement manual for the course text book in order to understand some details of chapters missed or not found in the course sessions. We hope that all these efforts will not be interrupted after the first start-working of Lab. sessions (EE 210) as programmed, but followed by other efforts, other improvements, and other acquisitions for enabling the logic design laboratory to reach its outstanding state. Finally, we would like to thank Dr. Sulayman Al Yahia for his ambition and his determination to push the College of Engineering to reach a well confirmed level of technical science, and to thank Dr. Abdulrahman Al Marshoud for his enthusiasm, his 3

perseverance and his obstinate approach for doing always what it is requested in the best manner and in due time. Buraydah: The 5/11/1426 H (07/12/2005) Dr. Messaoud Boukezzata Associate Professor 4

Session 1. INTRODUCTION TO LOGIC DESIGN LAB. & KITS 5

College of Engineering Electrical Engineering Department EE 210: Logic Design Lab. Session 1. I-1 Objectives: INTRODUCTION TO LOGIC DESIGN LAB. AND KITS The first session is devoted to explore and to know the logic design laboratory environment prior to experience practical duties. I-2 Materials & Components Needed: Logic Design Kit, logic IC's, Computers and their simulation capabilities and divers logic components. I-3 Digital IC's and logic gates overview: I-3-1 What is the IC?: An IC is an electronics circuit miniaturized and fabricated in a chip of an area of some cm square and encapsulated in divers standard shapes of packages. In our Lab. Experiments we should need to IC's of 14, 16 or more DIP pins (Dual-In line Package). Figure I-1: Example of 2 IC s with a different number of pins 6

I-3-2 Biasing: In the 74 series 14-pins we should find, in some times, the ground Gnd is connected to 0 V through the pin number 7 and to V cc = 5 Volts through the pin number 14, but in other times Gnd to pin 11 and V cc to pin 4 (as in the case of 7478 Dual JK Flip-Flop) and also in another times Gnd to pin 10 and V cc to pin 5 (as in case of 7493 4-bit binary counter). I-3-3 Handling: (make attention to static discharge and always try to do your manipulations without destroying these fragile IC s. So, keep care with them). I-3-4 Interconnections: According to the circuit design, interconnections are well defined and must be implemented in their good positions, otherwise, short circuit will be dangerous for all the kit laboratory including all the gates to be used. I-3-5 Pins assignment: See p.439 of the text book for pin assignment of some most used logic IC s in this lab. An example of a 3-input NAND is given in the following figure. Figure I-2: Another example of an IC with pins assignment for 7411 I-3-6 Inputs and outputs: not always in the same places, it depends on the IC logic diagram and function. I-3-7 Logic state: 0 (low) and 1 (high) are the logic states for common experiments. I-4 Introduction to Logic Lab. Kit: I-4-1 Circuits wiring: Each student should have 63 colored wires of different lengths (very small, small, long and very long). According to the position and the connected points to be wired you should use the appropriate lengths for the circuit wiring. I-4-2 Unconnected (floating inputs): It depends of the circuit under test. The output should not change when floating inputs take 1 or 0. 7

I-4-3 Power supply: 5 Volts indicated as V cc. I-4-4 Display: Displayed results are given by LED s or seven segment display. I-4-5 Testing: When finished, implementation is tested in order to confirm theoretical results which must be the same, otherwise errors are expected to be found and removed from the implementation. I-5 Logic lab. testing instruments, Components and tools: Figure I-3: Presentation of the kit lab. which will be used in our sessions. I-6 Review Questions: Try to identify different elements of the 74 IC s family, keep with you for frequent uses an appendix which should regroups all of the used IC s. I-7 Next Experiment Assignment: Read the procedure of Session 2 and prepare the following: The truth table of simple gates as AND, OR, NOT, NAND, NOR, XOR, and XNOR. 8

Take in mind the difference of pin assignment between 2-input, 3-input, and 4-input gates. I-8 Appendix: Figure I-4: The most used of digital gates in IC package 9

Session 2. INTRODUCTION TO LOGIC GATES 10

College of Engineering Electrical Engineering Department EE 210: Logic Design Lab. Session 2. II-1 Objectives: INTRODUCTION TO LOGIC GATES Study the function and verify the truth table of AND, OR, NOT, NAND and NOR gates. II-2 Materials & Components Needed: Logic Design Kit, 7400, 7402, 7404, 7408 and 7432 IC s, LED and connecting wires II-3 Procedure: Construct the truth tables for the following gates and diagrams and verify its operation: II-3-1) NOT: First, use a 7404 chip and build the circuit below (Figure II-1). Verify its truth table. Figure II-1: Test of the inverter gate. Table II-1: Truth table of the inverter gate. Second, connect to inverters in cascade. What will be final output? 11

Figure II-2: Test of two inverters. Table II-2: Truth table of two inverters. II-3-2) AND: First, use a 7408 chip and build the circuit as it is shown in the below figure. Verify its truth table. Figure II-3: Test of AND gate. Table II-3: Truth table of AND gate. Second, connect the three AND gates with respect to the diagram given below. Figure II-4: Logic circuit with AND gates. 12

Table II-4: Truth table of the tested AND logic circuit. II-3-3) OR: Use a 7432 chip and build the circuit below. Verify its truth table. Figure II-5: Test of OR gate. Table II-5: Truth table of OR gate. table. II-3-4) NAND: First, use a 7432 chip and build the circuit below. Verify its truth Figure II-6: Test of NAND gate. Table II-6: Truth table of NAND gate. Second, keep one of the wires floating (disconnect) and check the output. Is the floating input considered low or high?. 13

II-3-5) NOR: Use a 7402 chip and build the circuit below. Verify its truth table. Figure II-7: Test of NOR gate. Table II-7: Truth table of NOR gate. II-3-6) XOR: Use a 7486 chip and build the circuit below. Verify its truth table. Figure II-8: Test of XOR gate. Table II-8: Truth table of XOR gate. II-4 Review Questions: II-4-1. Using Boolean Algebra, show how could you implement the following gates using ONLY NOR gates. i) NOT, ii) AND, iii) OR. II-4-2. Draw the circuit of the following Boolean equation using basic gates: F(A,B,C) = AB + C. II-4-3. Construct the truth table of the following circuit: Figure II-9: Simple logic test circuit gate. 14

Table II-9: Truth table of the tested logic circuit. II-5 Next Experiment Assignment: Read the procedure of Session 3 and prepare the following: The truth table for the given Boolean equation. Draw its schematic equivalent circuit very neatly. Minimize the circuit to only two literals then draw the minimized circuit. Session 3. 15

MINIMIZATION OF BOOLEN FUNCTIONS College of Engineering Electrical Engineering Department EE 210: Logic Design Lab. Session 3. MINIMIZATION OF BOOLEAN FUNCTIONS III-1 Objectives: Boolean functions minimization and implementation III-2 Materials & Components Needed: 16

Logic Design Kit, 7400, 7404, 7410 s, LED and connecting wires III-3 Procedure: III-3-1) Obtain the Boolean function F(A, B, C) of the circuit given below. Figure III-1: Training test with multi-level simple logic gates. III-3-2) Construct its truth table (you should use an extra sheet to draw this table, and you should take A, B, C as inputs and F as final output). Fill the table given below (you should take attention to the connections between elements and you should also expect to use different colors of wires for minimize errors). Then, connect the above circuit and verify its truth table with previous step. How many IC components we should need when the implementation is done only with 7400 and 7410 together, and when the inverters were taken from a 7404 IC.? A B C A B C AB C A BC AC F 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1 Table III-1: Truth table of the previous circuit. III-3-3) Minimization of the Boolean function to only a minimum of literals: Simplify this circuit by using the map method. 17

III-3-4) Find the logic diagram of the simplified Boolean function F(A, B, C) by using only one 7410 IC. III-3-5) Suppose you have obtained the simplified circuit by using the appropriate technique and you have found a circuit similar to what is shown in the following figure (Fig.III-2). Connect the simplified circuit without disconnecting the first one, already done in previous step. Again, verify its truth table. III-3-6) Compare the results obtained in III-3-2) and III-3-5). III-3-7) What do you observe if inverters 7404 are available? Figure III-2: Minimized circuit obtained by k-map method. A B C B AB AC F 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1 Table III-2: Truth table of the simplified circuit. IV- Review Questions: Verify the truth table of the logic circuit shown below. Simplify its Boolean function to only three literals. Redraw the diagram of the minimized circuit. 18

Show how could you verify your results theoretically and experimentally. Figure III-2: Home work training test with multi-level simple logic gates. V- Next Experiment Assignment: Install Xilinx Software in your computer (or use the software already installed in some of the platforms in the computer center). List all problems you might face during installation. Session 4. 19

XILINX SOFTWARE TUTORIAL College of Engineering Electrical Engineering Department EE 210: Logic Design Lab. Session 4. IV-1 Objectives: XILINX SOFTWARE TUTORIAL This tutorial steps the student through using the Xilinx Foundations Software to implement a simple logic design such as session 1 of these Lab. experiments. 20

IV-2 Materials & Components Needed: Logic Design Kit, PC with Xilinx already installed. IV-3 Example Design Problem: A majority voter has three 1-bit inputs (A, B, C) and one 1-bit output (M) as seen in the following figure. The output M takes on the majority value of the three inputs. The truth table shown below fully illustrates its function. Whenever two or more inputs are 0 then the output M is 0. Whenever two or more inputs are 1 then the output M is 1. Figure IV-1: Bloc diagram of the presented problem. Table IV-1: Truth table of the majority voters. IV-4 Solution to Design Problem: According to the truth table given above and using K-map method, we can easily find the Boolean equation, one solution of the majority voter problem. So, we can give the gate representation. 21

Figure IV-2: Home work problem. IV-5 Xilinx Software: The Xilinx Foundations software used in this session can be installed from a copy which comes with your class textbook. To do the requested tasks in this session, follow the steps as explained during the Lab. experimentation. IV-6 Review Questions: * use XOR gates in your design. IV-7 Next Experiment Assignment: Read the procedure of the next Session and prepare the following: Construct the truth table for the full adder. Using Xilinx Software design and simulate the full adder circuit. Provide your schematic design and simulation results on hard copies. 22

Session 5. 23

FULL ADDER IMPLEMENTATION & SIMULATION College of Engineering Electrical Engineering Department EE 210: Logic Design Lab. Session 5. FULL ADDER IMPLEMENTATION AND SIMULATION V-1 Objectives: In this Lab., you will compile and simulate a 4-bit full adder using an HDL language program. 24

V-2 Materials & Components Needed: VHDL Simulator, Computers and a Technical Data-book reference for Logic Design Gates V-3 Procedure: V-3-1 Background: According to the example given bellow (see figure 1), we should first write the HDL program and second try to run it using a Verilog simulator. Figure V-1-a: Full adder logic circuit. Figure V-1-b: Schematic of the 4-bit full adder. V-3-2 HDL Program: For figure 1-a, the program is given as follow: //** add4.v File **. //** Full Adder **. module fulladder(sum, c_out, x, y, c_in); 25

output sum, c_out; input x, y, c_in; wire a, b, c; xor (a, x, y); xor (sum, a, c_in); and (b, x, y); and (c, a, c_in); or (c_out, c, b); endmodule Now, if you feel be able to write the program for the second figure (Fig. 1-b) you will go to experience it. //** 4-Bit Adder **. module FourBitAdder(sum, c_out, x, y, c_in); output [3:0] sum; output c_out; input [3:0] x, y; input c_in; wire c1, c2, c3; fulladder fa0(sum[0], c1, x[0], y[0], c_in); fulladder fa1(sum[1], c2, x[1], y[1], c1); fulladder fa2(sum[2], c3, x[2], y[2], c2); fulladder fa3(sum[3], c_out, x[3], y[3], c3); endmodule //******************************************* // VeriLogger Pro: Basic Verilog Simulation //******************************************* //**add4test.v File *************************** module testbed(); reg c_in; reg [3:0] y; reg [3:0] x; wire c_out; wire [3:0]sum; FourBitAdder A1(sum, c_out, x, y, c_in); initial begin x = 4'b0001; y = 4'b0001; c_in = 1'b0; #25 x = 4'b0001; y = 4'b0010; #25 x = 4'b0010; y = 4'b0011; #25 x = 4'b0001; y = 4'b1111; #25 x = 4'b0001; y = 4'b1111; c_in = 1'b1; #25 x = 4'b1000; y = 4'b1111; c_in = 1'b0; #25 x = 4'b0001; y = 4'b0001; c_in = 1'b1; #25 x = 4'b0001; y = 4'b0010; #25 x = 4'b0010; y = 4'b0011; #25 x = 4'b0011; y = 4'b1111; #25; 26

end initial #250 $finish; endmodule V-3-3 Simulation: As you can see, this used version of simulation program can t support more than six lines, so we will choose to run another program according to this limitation. module fulladd4(sum, c_out,a,b,c_in); output [3:0] sum; output c_out; input [3:0] a,b; input c_in; assign {c_out, sum} = a + b + c_in; initial begin $monitor( time %0d ns, A= %b, B= %b, C= %b, C_IN= %b, C_OUT= %b, SUM %b, A, B, C_IN, C_OUT, SUM) end endmodule Lab. session V-3-4 Application: Follow the procedure application explained directly during the V- Review Questions: Try to review the theoretical aspects of the adder subtractor logic circuit. How could you use the same chip (IC 7483) for constructing the diagram which can perform the addition and the subtraction without major modifications? V- Next Experiment Assignment: You need the following components for the preparation of the next experiment: - 7483-7486. 27

Session 6. 28

DECODERS College of Engineering Electrical Engineering Department EE 210: Logic Design Lab. Session 6. VI-1 Objectives: Implementation of decoders applications. VI-2 Materials & Components Needed: DECODERS Logic Design Kit, logic IC type 7447 (BCD to seven-segment display) and 74138 (3-to-8 lines decoder), and wire connections. 29

VI-3 Summary of theory: The decoder is a combinational logic circuit that converts binary information from n input lines to a maximum 2 n unique output lines. The decoders are used whenever an output or group of outputs is to be activated on the occurrence of a specific input combination. They are so useful for many practical applications such as seven segment display interfacing and implementation of some logic circuits as it is considered a minterm generator. The 74138 decodes one of eight lines dependant on the conditions of the three binary select inputs and the three enable inputs. Two active-low and one active-high enable inputs reduce the need for external gates or inverters when expending. VI-4 Procedure: 1. Using the built-in Seven-Segment Display in the lab. kit, display the numbers from 0 to 9. (input switches, D is the MSB Most Significant Bit- and A is the LSB Low Significant Bit-). 2. Connect the 74138 decoder as shown in its data sheet specifications given in the following figure and verify its truth table. 3. Design, implement and test a full adder using 74138 with some gates. You can take into consideration what you have taken in the course notes (use 4 inputs NAND gates). Figure VI-1: Presentation of the 3 x 8 (74138) IC decoder. VI-5 Review Questions: * As you have studied the circuit of the decoder you can anticipate the study of a multiplexer logic circuit. To identify different elements of the 74151 IC s, keep with you for frequent uses an appendix which should regroups all information concerning this circuit. 30

VI-7 Next Experiment Assignment: Read the procedure of Session 7 and prepare the following: How to connect the 16-pin of the IC to the other elements of the circuit, and to know what is the function of the selection inputs, data inputs, enable input and the outputs. Think to have one frequently used application of the 8-to-1 line multiplexer including the 74151 IC type. Session 7. DESIGN WITH MULTIPLEXERS 31

College of Engineering Electrical Engineering Department EE 210: Logic Design Lab. Session 7. VII-1 Objectives: DESIGN WITH MULTIPLEXERS In this experiment, you will design a combinational circuit and implement it with multiplexers, as explained in the following paragraphs. The multiplexer to be used is an IC type 74151, shown in the figure given below. The internal construction of the 74151 is similar to the diagram presented here. VII-2 Materials & Components Needed: Logic Design Kit, logic IC type 74151 and wire connections. VII-3 Example Design Problem Shares Voting: 32

A small corporation has 10 shares of stock, and each share entitles its owner to one vote at a stockholder s meeting. The ten shares of stock are owned by four people as follows: Mr. W: 1 share Mr. X: 2 shares Mr. Y: 3 shares Mrs. Z: 4 shares Each of these persons has a switch to close when voting yes and to open when voting no for his or her shares. It is necessary to design a circuit that displays the total number of shares that vote yes for each measure. VII-4 Solution to Design Problem: We need a seven-segment display and a decoder to display the required number. If all shares vote no for a measure, the display should be blank. (Note that binary input 15 into the 7447 blanks all seven segments.) If 10 shares vote yes for a measure, the display should show 0. The eight inputs are designated D0 through D7. The selection lines (C, B, and A) select the particular input to be multiplexed and applied to the output. A strobe control S acts as an enable signal. The function table specifies the value of output Y as a function of the selection lines. Output W is the complement of Y. For proper operation, the strobe input S must be connected to ground. Figure VII-1: Presentation of the 8-to-1 (74151) IC multiplexer. VII-5 Experiment circuit: Use four 74151 multiplexers to design the combinational circuit that converts the inputs from the stock owners switches into the BCD digit for the 7447. 33

Connect the circuit using the configuration given above with respect to the following specifications: a) In the first 74151: - Connect S 2, S 1, S 0 to A, B, C respectively, and, - I 0 = I 1 = I 4 = I 5 = D, and, - I 2 = I 3 = I 6 = I 7 = D respectively. b) In the second 74151: - Connect S 2, S 1, S 0 to A, B, D respectively, and, - I 0 = I 1 = I 3 = I 5 = I 7 = C, and, - I 2 = I 6 = D, and, - I 4 = D respectively. c) In the third 74151: - Connect S 2, S 1, S 0 to A, D, C respectively, and, - I 0 = I 1 = I 3 = I 7 = B, and, - I 4 = B, and, - I 2 = I 6 = D, and, - I 5 = D; and, respectively. d) In the fourth 74151: - Connect S 2, S 1, S 0 to B, C, D respectively, and, - I 0 = I 1 = I 3 = I 6 = I 7 = A, and, - I 4 = A, and, - I 5 = D, respectively. The decoder and the seven-segment display, you can use those built-in directly from the Kit Lab. Test the work of the circuit. Obviously, if you observe any errors try to correct them. 34

Figure VII-2: Logic circuit with 74151 IC multiplexer. VII-6 Review Questions: * To the combinational logic circuit side, we have another side which is the sequential logic circuits. The first element of the sequential circuit type is a flip-flop. Revise your course notes and see how which IC from the 74 family s can function as a flip-flop. What is the different type of flip-flops we can find in our frequent uses. VII-7 Next Experiment Assignment: Read the procedure of Session 8 and prepare the following: Design and implement a binary counter by using flip-flops. Write an HDL the program of the obtained circuit. Use the testbencher.pro to run your program. Give the final results of simulation. 35

36

Session 8. INTRODUCTION TO FLIP-FLOPS College of Engineering Electrical Engineering Department EE 210: Logic Design Lab. Session 8. INTRODUCTION TO FLIP-FLOPS 37

VIII-1 Objectives: In this experiment, we can construct, test and investigate the operation carried out by flipflops. We should see the extreme importance of these kinds of logic circuits in the construction of counters, registers and memories. VIII-2 Materials & Components Needed: - Logic Design Kit. - logic IC type 7474 (Dual D-type edge-triggered Flip-Flop). - 7476 (Dual JK Master-Slave Flip-Flop). - Wires. VIII-3 Summary of theory: A flip flop is known as a sequential logic element. It is, not surprisingly, a fundamental building block for creating sequential logic circuits. Some examples of this type of circuit include shift registers and counters. These types of circuit depend not only on a set of inputs, but also their past inputs to work correctly. For example, let us say you want to design a circuit that will count from zero to three, in steps of one, every time a switch is pressed. A simple switch can only have two possible states. It can either be switched on, or switched off. Yet each time the switch is pressed, we want the circuit to display a different output state. For example: Press switch once. The output changes from 0 to 1. Press switch again. The output changes from 1 to 2. Press switch again. The output changes from 2 to 3. From this example it can be seen that the circuit will only work correctly if it somehow 'remembers' its previous state. Flips flops have the ability to remember their past history and are often referred to as bistable devices. VIII-4 IC Flip-Flops: IC type 7474 consists of two D positive-edged-triggered flip-flop with preset and clear. Similarly, the IC type 7476 consists also of two JK master-slave flip-flops with preset and clear. The pin assignment for each flip-flop is shown in the following figures. 38

Figure VIII-1: internal structure of 7447 BCD-to-7-segments display decoder VIII-5 Experiment circuit: First, connect the 7474 IC to the lab. kit using only one D Flip-Flop as represented in the figure shown below. Verify the function table of this Dual D-type edge-triggered Flip-Flop. Compare the obtained results with theoretical data as what you have seen in the course sessions. 39

Figure VIII-2: Pin assignment of Dual D-type edge-triggered Flip-Flop 7474 Second, repeat the same procedure with the 7476 IC which is given in the next figure. Verify the function table of the Dual JK Master-Slave Flip-Flop. Compare the results. Figure VIII-3: Pin assignment of Dual JK-type edge-triggered Flip-Flop 7476 VIII-6 Review Questions: 40

Review the internal structure of different 74 IC s family that can function as counters. Note the specificity of each type of these counters. VIII-7 Next Experiment Assignment: Read the procedure of Session 9 and design a two decade counter with sevensegment displaying system. 41

Session 9. COUNTERS College of Engineering Electrical Engineering Department 42

EE 210: Logic Design Lab. Session 9. IX-1 Objectives: COUNTERS Design, simulation and implementation of a non-binary counter using Xilinx software package and Digilab educational kit. IX-2 Materials & Components Needed: Logic Design Kit, logic IC type 7474 (Dual D-type edge-triggered Flip-Flop), 7490 (Decade counter), and 7408 AND gates. IX-3 Summary of theory: The counter is a sequential circuit that goes through a prescribed sequence of states upon the application of the input pulses. It is normally built using flip-flops connected in cascade with a certain configuration depending on the counting sequence required. The n- bit counter needs n flip-flops and it can have a binary sequence of less than 2 n states. The BCD or Decimal counter is a binary counter that counts from 0000 state to 1001 state then goes back to 0000 state. IX-4 Design procedure of experiment circuit: - First, we suggest to construct a counter which can count from 0 to 99. - Second, to cover the two decades of counting, our purpose will concern the use of two decade counters 74LSLS90, an IC type 7474 (Dual D-type edge-triggered Flip-Flop), and some AND gates 7408. - For displaying the counting rhythm, we need two seven-segment displays. - And of course finally, some wires for connection. The monolithic 74LS90 counter contains four master-slave flip-flops and additional gating to provide a three stage binary counter for which the count cycle length is divided by 5. To use their maximum count length, the B input is connected to Q A output. The input count pulses are applied to input A. 43

Figure IX-1: Pins assignments of the 74LS90 decade counter Figure IX-2: Functional block diagram of the 74LS90 decade counter Not forget to use the following information given in the reset/count function table of the 74LS90 as presented below. Reset inputs Output Preset-1 Preset-2 Clear-1 Clear-2 Q D Q C Q B Q A 1 1 0 x 0 0 0 0 1 1 x 0 0 0 0 0 x x 1 1 1 0 0 1 x 0 x 0 Count 0 x 0 x Count 0 x x 0 Count x 0 0 x Count Table IX-1: Reset/count function table of 74LS90 44

IX-5 Experiment circuit: For the Lab. circuit, because the only counter available is the 7493, we should rearrange this experimentation in order to introduce this IC in replacement of the 7490 expected to be used in this session 9. The clock pulses are obtained from the generator built-in and its cycle time may be changed as desired. Also, the display system is furnished with the kit lab. and no need to the 7447 for decoding the binary bits to 7-segments display. Figure IX-3: Pins assignments of the 4-bit binary 74HC93 counter Figure IX-4: Functional block diagram of the 4-bit binary 74HC93 counter When all connections of the circuit is finished, and similarly as you have done with the 74LS90, do not forget to use the following information given in the reset/count function table of the 74HC93 as presented below. Reset inputs Output 45

Preset-1 Preset-2 Q D Q C Q B Q A 1 1 0 0 0 0 0 x Count x 0 Count Table IX-2: Reset/count function table of 74HC93 Connect the counter circuit as designed in the figure given below. Verify carefully your connections before the use of power supply. Test your counter. Verify its good function. To connect the rearranged circuit, try to differentiate the mode function between the 7490 and the 7493. Use the reset/count function table as given by the manufacturer data book or other technical documentation notes. Draw the two reset/count function tables for both 7490 and 7493. Compare the two tables. XI-6 Review Questions: Figure IX-5: Two decades counter circuit Design, construct, and test a counter that goes through the following sequence of binary states: 0, 1, 2, 3, 6, 7, 10, 11, 12, 13, 14, 15, and back to 0 to repeat. Note that binary states 4, 5, 8, and 9 are not used. The counter must be selfstarting; that is, if the circuit starts from any one of the four invalid states, the 46

count pulses must transfer the circuit to one of the valid states to continue the count correctly. 47

Appendix LAB. s EXAMS MODEL 48

College of Engineering Electrical Engineering Department EE 210: Logic Design Lab. Exams Model. FIRST MID-TERM EXAM 1) Obtain the Boolean function F(A, B, C) of the above circuit. 2) Construct its truth table. 3) How many IC components we should need when using (7400 and 7410 together), and when the inverters were taken from a 7404 IC? 4) Simplify this circuit by using the map method. 5) Find the logic diagram of the simplified Boolean function F(A, B, C) by using only one 7410 IC. 6) Connect the obtained simplified circuit without disconnecting the original circuit and verify its truth table. 7) Compare the results obtained in 2) and 6). 8) What do you observe if inverters 7404 are available? Dr. Messaoud BOUKEZZATA 49

College of Engineering Electrical Engineering Department EE 210: Logic Design Lab. Exams Model. SECOND MID-TERM EXAM This circuit has A and B as the inputs and a LED as the output. A, and B are 4-bit numbers. When the LED is lighted red, his state is 1, otherwise it means that his state is 0. a) What is the first problem that you find when you want to construct this circuit on the Lab. Kit? (1 pt). b) Suppose you have only 3 IC s, one type 7402, one 7408, and one 7486. Construct the above circuit. (1 pt) c) What is the condition on the values of A i and B i which will give a red light of the LED. (3 pt) d) So, what is the function of this circuit? (2 pt) e) Find the Boolean function F(A i, B i ) i = 0, 1, 2, 3 corresponding to the state one at the output. (4 pt) f) Now, the available IC s are only 7402, 7404, and 7408, redraw the same circuit but using just what you have. (4 pt) g) Can you implement this last circuit on the Lab. Kit? (1 pt) h) If we remove A 2, A 3, and B 2, B 3, reconstruct the new circuit. (4 pt) Dr. Messaoud BOUKEZZATA 50

College of Engineering Electrical Engineering Department EE 210: Logic Design Lab. Exams Model. THIRD MID-TERM EXAM This circuit has been detailed in the course session but drawn with another output gate: i) What is this gate used in the output? j) So, what is the function of this circuit? k) Draw the version studied in the course session. l) Among the following IC numbers, find the correct IC number which corresponds to the given circuit: 74 00, 7408, 74 32, 74 86, 74 47, 74 74, 74 151, 74 138, 7493. m) Give the name of each IC cited above. n) What is the difference in function between 74 151 and 74 138. Dr. Messaoud BOUKEZZATA 51

College of Engineering Electrical Engineering Department EE 210: Logic Design Lab. Exams Model. FINAL-TERM EXAM Date: Tuesday, 1 st /01/1427 H Duration: 9,00 12,oo AM Ex. 01): suppose you have these to circuits: - Construct the truth table for the two circuits given above. - What do you remark? Ex. 02): From the figure presented below: a) Is this counter synchronous or asynchronous? b) Why? c) What is its limit of counting? d) Draw its function table and its graph pulse timing. Ex. 03): From the figure presented below: a) What is the difference between this figure and the figure presented in (Ex. 02)? 52

b) What is its limit of counting? c) Draw its function table and its graph pulse timing. Ex. 04): in this circuit, we have fours different components. a) What is the role of each of them. b) Why we have two 7490. c) Why we have two 7447. d) What is the function of the AND gate 7408. Dr. Messaoud BOUKEZZATA 53

College of Engineering Electrical Engineering Department EE 210: Logic Design Lab. Session 3. MINIMIZATION OF BOOLEAN FUNCTIONS Initial complicated Circuit: III-3-1) Obtain the Boolean function F(A, B, C) of the circuit given below. III-3-2) Construct its truth table (you should use an extra sheet to draw this table). Then, connect the above circuit and verify its truth table with previous step. How many IC components we should need when the implementation is done only with 7400 and 7410 together, and when the inverters were taken from a 7404 IC.? A B C A' B' C' AB'C' A'BC AC F 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1 54

Final minimized circuit: III-3-3) Minimization of the Boolean function to only a minimum of literals: Simplify this circuit by using the map method. III-3-4) Find the logic diagram of the simplified Boolean function F(A, B, C) by using only one 7410 IC. III-3-5) Suppose you have the simplified circuit as shown in the following figure, connect the simplified circuit without disconnecting the other original one. Again, verify its truth table. A B C B' AB' AC F 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1 III-3-6) Compare the results obtained in III-3-2) and III-3-5). III-3-7) What do you observe if inverters 7404 are available? 55