DIGITAL CIRCUITS AND LOGIC DESIGN LABORATORY MANUAL Spring, 2014

DIGITAL CIRCUITS AND LOGIC DESIGN LABORATORY MANUAL Spring, 2014 Jack Ou Engineering Science Sonoma State University A SONOMA STATE UNIVERSITY PUBLICATION

CONTENTS 1 Linux Tutorial 1 1.1 Login to Redhat 1 1.2 Basic Stuffs 1 1.2.1 Finding Your Way with pwd 1 1.2.2 Listing Directories and Files with ls 2 1.2.3 Changing Directories with cd 2 1.2.4 Creating Directories with mkdir 3 1.2.5 Removing Directories with rmdir 3 1.2.6 To copy a file 4 1.2.7 Removing a file 4 1.3 Starting Cadence 5 2 Your First Verilog Program 7 2.1 References 7 2.2 Objectives 7 2.3 Procedure 8 2.4 Submission Checklist 8 iii

iv CONTENTS 3 Model a NAND Based NOR Gate with Verilog 9 3.1 References 9 3.2 Objectives 9 3.3 Procedure 10 3.4 Submission Checklist 10 4 NAND Based Logic Gates 11 4.1 Reference 11 4.2 Objectives 11 4.3 Parts 11 4.4 NAND-based Inverter 12 4.5 NAND-based NOR Gate 13 4.6 Submission Checklist 13 5 Half Adder 15 5.1 Reference 15 5.2 Objectives 15 5.3 Parts 15 5.4 Modeling a Half Adder with Verilog 16 5.5 Implement a Half Adder Using 74XX Logic Gates 16 5.6 Submission Checklist 17 6 Two-Bit Binary Multiplier 19 6.1 Reference 19 6.2 Objectives 19 6.3 Description 20 6.4 Submission Checklist 21 7 2-Line to 4-Line Decoder 23 7.1 Reference 23 7.2 Objectives 23 7.3 Parts 24 7.4 Analysis 24 7.5 Verilog Modeling 25 7.6 Implement the 2-line to 4-line decoder using 74LS155 chip 26 7.7 Submission Checklist 26 8 Verilog Modeling Styles 27

CONTENTS v 8.1 Reference 27 8.2 Objectives 27 8.3 Analysis 28 8.4 Design Verification 28 8.4.1 Gate-Level Modeling 28 8.4.2 Dataflow Modeling 28 8.4.3 Behavioral Modeling 29 9 Pseudo Random Number 31 9.1 Reference 31 9.2 Objectives 31 9.3 Parts 31 9.4 Circuit Implementation 32 9.5 Display the Wave on the Mixed Signal Scope 32 9.6 Submission Checklist 33 10 Flip-Flops 35 10.1 Reference 35 10.2 Objectives 35 10.3 Parts 36 10.4 Before You Start 36 10.5 Flip-flops 36 10.5.1 D flip-flop 36 10.5.2 JK flip-flop 36 10.5.3 T flip-flop 38 10.6 Post lab 38 11 Clocked Sequential Circuit 39 11.1 Verilog Modeling 39 11.2 Hardware Implementation 39 11.3 Submission Checklist 40 12 Universal Shift Register 43 12.1 Reference 43 12.2 Objectives 43 12.3 Parts 44 12.4 Model the Universal Shift Register in Verilog Model 44 12.5 Hardware Implementation 45

vi CONTENTS 12.6 Submission Checklist 45 13 Synchronous Counter 47 13.1 Datasheet 47 13.2 Hardware Implementation 48 13.3 Submission Checklist 48

CHAPTER 1 LINUX TUTORIAL 1.1 Login to Redhat Start the machine in the Redhat environment with the following user name and password: User: r2d2 Password: student 1.2 Basic Stuffs 1.2.1 Finding Your Way with pwd pwd displays the path and name of the directory you are currently in, giving you the full picture of where you are. (Right Click Open Terminal) [r2d2@localhost ]$ pwd /home/r2d2 Digital Circuits and Logic Design Laboratory Manual, First Edition. Copyright c 2014,J. Ou. 1

2 LINUX TUTORIAL 1.2.2 Listing Directories and Files with ls Your Linux system is made up of directories and files that store a variety of information. Using the ls, you can find out exactly what is in your Linux system and thereby find out what is available to you. You can list the files and directories of a directory you are currently in. [r2d2@localhost ]$ pwd /home/r2d2 [r2d2@localhost ]$ ls ade_viva.log CDS.log.CDSHOME instruct models store cadence class libmanager.log panic.log cdb2oa.log design linux.tutorial.text share CDS.log Desktop mentor simulation CDS.log.1 download mgc start [r2d2@localhost ]$ 1.2.3 Changing Directories with cd To explore Linux and its capabilities, you ll need to move around among the directories. You do so using the cd command, which takes you from the directory you are currently in to one that you specify. To move to a specific directory, type cd plus the name of the directory. In the example below, we move down in the directory to a subdirectory called design. [r2d2@localhost ]$ pwd /home/r2d2 [r2d2@localhost ]$ ls ade_viva.log CDS.log.CDSHOME instruct models store cadence class libmanager.log panic.log cdb2oa.log design linux.tutorial.text share CDS.log Desktop mentor simulation CDS.log.1 download mgc start [r2d2@localhost ]$ pwd /home/r2d2 [r2d2@localhost ]$ ls ade_viva.log CDS.log.CDSHOME instruct models store cadence class libmanager.log panic.log cdb2oa.log design linux.tutorial.text share CDS.log Desktop mentor simulation CDS.log.1 download mgc start [r2d2@localhost ]$ cd design [r2d2@localhost design]$ pwd /home/r2d2/class [r2d2@localhost design]$

BASIC STUFFS 3 Type cd.. to move up one level. [r2d2@localhost class]$ pwd /home/r2d2/design [r2d2@localhost design]$ cd.. [r2d2@localhost ]$ pwd /home/r2d2 [r2d2@localhost ]$ ls ade_viva.log CDS.log.CDSHOME instruct models store cadence class libmanager.log panic.log cdb2oa.log design linux.tutorial.text share CDS.log Desktop mentor simulation CDS.log.1 download mgc start [r2d2@localhost ]$ 1.2.4 Creating Directories with mkdir You might think of directories as being drawers in a file cabinet; each drawer contains a bunch of files that are somehow related. For example, you might have a couple of file drawers for your unread magazines, one for your to-do lists, and maybe a drawer for your work projects. Similarly, directories in your Linux system act as containers for other directories and files. You create new directories using the mkdir command. [r2d2@localhost ]$ pwd /home/r2d2 [r2d2@localhost ]$ mkdir drawer [r2d2@localhost ]$ ls ade_viva.log CDS.log.CDSHOME drawer mgc start cadence class instruct models store cdb2oa.log design libmanager.log panic.log CDS.log Desktop linux.tutorial.text share CDS.log.1 download mentor simulation [r2d2@localhost ]$ cd drawer [r2d2@localhost drawer]$ pwd /home/r2d2/drawer [r2d2@localhost drawer]$ 1.2.5 Removing Directories with rmdir You can remove a directory using rm -r followed by the directory name. [r2d2@localhost ]$ pwd

4 LINUX TUTORIAL /home/r2d2 [r2d2@localhost ]$ mkdir drawer [r2d2@localhost ]$ cd drawer/ [r2d2@localhost drawer]$ pwd /home/r2d2/drawer [r2d2@localhost drawer]$ cd.. [r2d2@localhost ]$ rm -r drawer [r2d2@localhost ]$ ls ade_viva.log CDS.log.CDSHOME instruct models store cadence class libmanager.log panic.log cdb2oa.log design linux.tutorial.text share CDS.log Desktop mentor simulation CDS.log.1 download mgc start [r2d2@localhost ]$ 1.2.6 To copy a file You can copy a file by using the following syntax. cp existingfile new file [r2d2@localhost ]$ pwd /home/r2d2 [r2d2@localhost ]$ ls ade_viva.log CDS.log.CDSHOME instruct models store cadence class libmanager.log panic.log cdb2oa.log design linux.tutorial.text share CDS.log Desktop mentor simulation CDS.log.1 download mgc start [r2d2@localhost ]$ cp CDS.log CDS.log.bak [r2d2@localhost ]$ ls ade_viva.log CDS.log.bak download mgc start cadence CDS.log.CDSHOME instruct models store cdb2oa.log class libmanager.log panic.log CDS.log design linux.tutorial.text share CDS.log.1 Desktop mentor simulation [r2d2@localhost ]$ 1.2.7 Removing a file Use rm followed by the name of the file to be deleted. [r2d2@localhost ]$ ls ade_viva.log CDS.log.bak download mgc start

STARTING CADENCE 5 cadence CDS.log.CDSHOME instruct models store cdb2oa.log class libmanager.log panic.log CDS.log design linux.tutorial.text share CDS.log.1 Desktop mentor simulation [r2d2@localhost ]$ rm CDS.log.bak [r2d2@localhost ]$ ls ade_viva.log CDS.log.CDSHOME instruct models store cadence class libmanager.log panic.log cdb2oa.log design linux.tutorial.text share CDS.log Desktop mentor simulation CDS.log.1 download mgc start [r2d2@localhost ]$ 1.3 Starting Cadence 1. Start a NEW terminal.(right click Open Terminal) 2. Go to the design directory. 3. Type rm -rf cmrf7sf.v1.9.0.2.ml to remove the existing start-up directory. 4. Open the course webpage with a FireFox browser. 5. Download cmrf7sf.tar from the course website. 6. Type tar -xvf cmrf7sf.tar to extract the tar file. 7. Go to the cmrf7sf.v1.9.0.2.ml directory. 8. Type virtuoso & at the command prompt to start Cadence. [r2d2@localhost ]$ pwd /home/r2d2 [r2d2@localhost ]$ cd design [r2d2@localhost design]$ pwd /home/r2d2/design [r2d2@localhost design]$ ls AMSDesigner cmrf7sfml envexp spb16.5 AMSDInADE cmrf7sf.v1.9.0.2.ml libconvert.txt tmpcphmsg AnaSimTech cmrf8sfdm mentor [r2d2@localhost design]$ cd cmrf7sf.v1.9.0.2.ml [r2d2@localhost cmrf7sf.v1.9.0.2.ml]$ pwd /home/r2d2/design/cmrf7sf.v1.9.0.2.ml [r2d2@localhost cmrf7sf.v1.9.0.2.ml]$ virtuoso & [1] 16648

CHAPTER 2 YOUR FIRST VERILOG PROGRAM 2.1 References 1. Section 3.10, M. M. Mano and M. D. Ciletti, Digital Design, 4th edition, Upper Saddle River, NJ. 2. ES210 lecture notes from January 15. 2.2 Objectives After completing this lab, you will be able to: 1. Create a Cadence design library. 2. Use Verilog to model a simple combinational circuit. 3. Compile and run a verilog file. 4. Use SimVision to view waveforms. Digital Circuits and Logic Design Laboratory Manual, First Edition. Copyright c 2014,J. Ou. 7

8 YOUR FIRST VERILOG PROGRAM 2.3 Procedure 1. Start virtuoso and create a library called es210. 2. Open a terminal, and create a folder called verilogsandbox. This is where you will store Verilog files and execute Verilog simulations. 3. Use either emacs or vi to create fig3p37.v. The complete program is given on slide 18 of the lecture notes. 4. Execute fig3p37.v according to the instructions in the lecture notes. 5. Are you able to get the same results? 6. What is D when A = B = C = 0? 7. What is E when A = B = C = 1? 8. Replace G3 in fig3p37.v with an XOR gate and execute the simulation. Are the results of the simulation different? 2.4 Submission Checklist 1. With G3 set to an OR gate, what is D when A = B = C = 0? (1 point) 2. With G3 set to an OR gate, what is D when A = B = C = 1? (1 point) 3. Replace G3 with an XOR gate, re-run the simulation, are the results of the simulation different? Why or why not? (2 points) 4. Please submit fig3p37.v with G3 changed to an XOR gate? (2 points) 5. Please submit a screen capture of the SimVision simulation. (2 points)

CHAPTER 3 MODEL A NAND BASED NOR GATE WITH VERILOG 3.1 References 1. Section 3.10 and section 4.12, M. M. Mano and M. D. Ciletti, Digital Design, 4th edition, Upper Saddle River, NJ. 2. ES210 lecture notes from January 23,2014. 3.2 Objectives After completing this lab, you will be able to: 1. Read a random test vector from a file. 2. Test a digital circuit with a random test vector. 3. Model the behavior of a NAND based NOR gate with Verilog. Digital Circuits and Logic Design Laboratory Manual, First Edition. Copyright c 2014,J. Ou. 9

10 MODEL A NAND BASED NOR GATE WITH VERILOG 3.3 Procedure 1. Go to the course webpage and download the following files to the verilogsandbox directory. (a) flip_me.v and flip_me_tb.v: You will not use these files directly in this lab. You can, however, use them (along with the lecture notes) to learn how to generate random test vectors. (b) bit_str_a_0.txt and bit_str_a_1.txt: random test vectors. You can use these files test the behavior of the NAND based NOR gate. (c) nor_with_nand.v and nor_with_nand_tb.v: Use these files as starting templates. A G 1 C B G 2 D E G 3 G 4 F Figure 3.1 A NOR gate constructed using only NAND gates. 2. Figure 3.1 shows the construction of a NOR gate using only NAND gates. G1, G2, G3 and G4 are instance names of the NAND gates. A and B are the inputs and F is the output. C, D and E are wire names assigned to the nodes indicated in Figure 3.1. 3. Edit nor_with_nand.v so that we can model the behavior of the NAND based NOR. Please do not use any NOR gate in your verilog code. Please use the instance names and wire names indicated in Figure 3.1. 4. Next, construct the test bench for the NOR gate. You may use nor_with_nand_tb.v as a starting point. You may also wish to take a look at flip_me_tb.v. 5. Apply the random test vectors and show that the circuit does indeed behave as a NOR gate. 3.4 Submission Checklist 1. A print-out of nor_with_nand.v. (2 points) 2. A print-out of nor_with_nand_tb.v. (2 points) 3. A screen capture of waveforms of A, B, and F. (3 points)

CHAPTER 4 NAND BASED LOGIC GATES 4.1 Reference 1. Yannis Tsividis, A First Lab in Circuits and Electronics, John Wiley and Sons. 2. 7400 Quad 2-input NAND Gates. (ES 210 webpage datasheets) 4.2 Objectives After completing this experiment, you will be able to 1. Build a NOT gate with a NAND gate. 2. Learn to characterize a NOT gate. 3. Build a NAND based NOR gate. 4.3 Parts A digital multimeter Digital Circuits and Logic Design Laboratory Manual, First Edition. Copyright c 2014,J. Ou. 11

12 NAND BASED LOGIC GATES +5 V power supply, a second power supply (e.g. ± 25 V supply) A breadboard Wires 1 HD74LS00 (TTL NAND gates) 4.4 NAND-based Inverter 1. Figure 4.1 shows the implementation of a NOT gate using a 2-input NAND gate. 2. Build the NOT gate with one of the four NAND gates in the HD74LS00 chip. The numbers in Figure 4.1 represent the pin numbers of one of NAND gates in the HD74LS00 chip. For example, pin 14 is the power supply pin that should be connected to a 5 V power supply. Pin 7 should be connected to ground. 3. Sweep the input from 0 to 5 V and record your results in Table 4.1. Does this circuit behave as a NOT gate? Figure 4.1 A NAND gate implementation of a NOT gate V A 0.0 V 1.0 V 2.0 V 3.0 V 4.0 V 5.0 V V out Table 4.1 V out vs. V A

NAND-BASED NOR GATE 13 4.5 NAND-based NOR Gate 1. The symbol and truth table for a NOR (i.e. NOT OR) gate are shown in Figure 4.2. Figure 4.3 shows the implementation of a NOR gate using only NAND gates. 2. Use the Boolean algebra to prove that the circuit in Figure 4.3 is indeed a NOR gate. 3. Build the NOR gate as shown in Figure 4.3. Verify the functionality of your circuit by checking the voltages at the pins indicated in Table 4.2. Figure 4.2 The truth table for a NOR gate Figure 4.3 The NAND implementation of a NOR gate 1 4 3 6 11 8 0.0 V 0.0V 0.0 V 5.0V 5.0 V 5.0V 5.0 V 0.0V Table 4.2 Voltages of a NOR gate. Pin numbers are shown in the top row. 4.6 Submission Checklist 1. Submit Table 4.1. (2 points)

14 NAND BASED LOGIC GATES 2. Use the Boolean algebra to prove that the circuit in Figure 4.2 is indeed a NOR gate. (3 points) 3. Submit Table 4.2. (2 points)

CHAPTER 5 HALF ADDER 5.1 Reference 1. 7408 Quad 2-input AND Gate data sheet. (ES 210 webpage datasheets) 2. 7486 Quad 2-input XOR Gate data sheet. (ES 210 webpage datasheets) 5.2 Objectives After completing this experiment, you will be able to 1. Model a half adder using Verilog. 2. Build a Verilog test bench for a half adder circuit. 3. Implement a half adder circuit on a breadboard with 74XX logic gates. 5.3 Parts A digital multimeter Digital Circuits and Logic Design Laboratory Manual, First Edition. Copyright c 2014,J. Ou. 15

16 HALF ADDER +5 V power supply A breadboard Wires 1 74LS86 (XOR gate) 1 74LS08 (AND gate) 5.4 Modeling a Half Adder with Verilog A B S C Figure 5.1 A half adder circuit. 1. Figure 5.1 shows the gate level implementation of a half adder circuit. Please develop the Verilog model for this half adder. You can start by downloading the half_adder.v template from the course website. 2. Next, write the Verilog test bench for half_adder.v. Name the test bench half_adder_tb.v. You can start with either flip_me_tb.v template or nand_based_nor_tb.v from last week. Your test bench should have the following capabilities: (a) It should be able to read random binary numbers as inputs. (b) It should write the inputs (A and B) and the outputs (S and C) to an output file called half_adder_tb.out. 5.5 Implement a Half Adder Using 74XX Logic Gates 1. Implement the half adder circuit shown in Figure 5.1. You may use 74LS86 as the XOR gate and the 74LS08 as the AND gate. (a) According to the 74LS86 data sheet, what is the nominal supply voltage? (b) What should be the DC voltage at pin #14 of the 74LS86 chip? (c) What should be the DC voltage at pin #7 of the 74LS86 chip? (d) According to the 74LS08 data sheet, what is the nominal supply voltage? (e) What should be the DC voltage at pin #14 of the 74LS08 chip? (f) What should be the DC voltage at pin #7 of the 74LS08 chip? 2. Complete the truth table in Table 5.1. Does this circuit behave a s half adder?

SUBMISSION CHECKLIST 17 V A V B V C V S 0.0 V 0.0V 0.0 V 5.0V 5.0 V 5.0V 5.0 V 0.0V Table 5.1 Truth table of a half adder circuit. 5.6 Submission Checklist You may work on this lab with a partner. The lab is due in the beginning of the next lab. (i.e. 02.13.14) 1. A copy of half_adder.v. (1 point) 2. A copy of half_adder_tb.v. (2 points) 3. A copy of half_adder_tb.out. (3 points) 4. The answer to the following questions: (1 point) (a) According to the 74LS86 data sheet, what is the nominal supply voltage? (b) What should be the DC voltage at pin #14 of the 74LS86 chip? (c) What should be the DC voltage at pin #7 of the 74LS86 chip? (d) According to the 74LS08 data sheet, what is the nominal supply voltage? (e) What should be the DC voltage at pin #14 of the 74LS08 chip? (f) What should be the DC voltage at pin #7 of the 74LS08 chip? 5. Submit Table 5.1. (4 points) 6. Please provide some feedback about this lab. e.g. Were you able to finish the lab on time? Is the instruction clear? Are there any typos or errors about this experiment? Any comment to help improve this lab is helpful? (4 points)

CHAPTER 6 TWO-BIT BINARY MULTIPLIER 6.1 Reference 1. Section 4.5 and section 4.7, M. M. Mano and M. D. Ciletti, Digital Design, 4th edition, Upper Saddle River, NJ. 2. ES210 lecture notes from February 12,2014. 6.2 Objectives After completing this experiment, you will be able to 1. Model a two-bit multiplier using Verilog. 2. Build a Verilog test bench for a two-bit multiplier circuit. Digital Circuits and Logic Design Laboratory Manual, First Edition. Copyright c 2014,J. Ou. 19

20 TWO-BIT BINARY MULTIPLIER A 0 B 1 B 0 A 1 B 1 B 0 G 3 G 2 G 1 G 0 W0 C 0 W3 W1 HA1 HA2 C 3 C 2 W2 C 1 Figure 6.1 Two-bits Multiplier. 6.3 Description 1. Figure 6.1 shows the gate level implementation of a two-bit multiplier circuit. A 0, A 1, B 0 and B 1 are inputs of the multiplier. C 0, C 1, C 2 and C 3 are the outputs. Please develop the Verilog model for this multiplier. You can start by downloading the half_adder.v template from the course website. Please observe the following naming convention as you develop the model. (a) Use G0, G1, G2, and G3 to identify instances of the AND gate in Figure 6.1. (b) Use HA0 and HA1 to identify instances of the half-adder cell in Figure 6.1. (c) Use W0, W1, W2 and W3 to identify the wires indicated in Figure 6.1. (d) The multiplier module should be named: mult_2_2_4.v 2. Please use the following questions to guide your thought process as you develop the model for the two-bit multiplier, i.e. mult_2_2_4.v. (a) Module Declaration i. What are the inputs? ii. What are the outputs? iii. How should the input ports be connected to the AND gates? iv. How should the outputs be connected to the AND gates and the half-adder cells? (b) Program Body i. How should the AND gate be implemented?

SUBMISSION CHECKLIST 21 ii. How should instances of the half adder cells be called? 3. Next, write the Verilog test bench for mult_2_2_4.v. Name the test bench mult_2_2_4_tb.v. You can start with with any test bench you have used previously. Your test bench should have the following features: (a) It should be able to read random binary numbers as inputs. (b) It should write the input values and the output values to an output file called mult_2_2_4.out. Please use the following questions to guide your thought process. i. What should be declared as the outputs of the test bench? ii. How many bit files do you need? iii. How should mult_2_2_4.v module be invoked? 6.4 Submission Checklist You may work on this lab with a partner. The lab is due in the beginning of the next lab. 1. A copy of mult_2_2_4.v. (1 point) 2. A copy of mult_2_2_4_tb.v. (2 points) 3. A copy of mult_2_2_4.out. (3 points) 4. Please provide some feedback about this lab. e.g. Were you able to finish the lab on time? Are you becoming more comfortable with writing code in Verilog? Are there any typos or errors about this experiment? Any comment to help improve this lab is helpful? (4 points)

CHAPTER 7 2-LINE TO 4-LINE DECODER 7.1 Reference 1. Dual 74LS155 Decoders/Demultiplexers data sheet. (ES 210 web page datasheets) 7.2 Objectives After completing this experiment, you will be able to 1. Use Karnaugh map to deduce the gate level implementation of a 2-line to 4-line decoder. 2. Model the 2-line to 4-line decoder using Verilog. 3. Implement a 2-line to 4-line decoder with a 74LS155 chip. Digital Circuits and Logic Design Laboratory Manual, First Edition. Copyright c 2014,J. Ou. 23

24 2-LINE TO 4-LINE DECODER 7.3 Parts A digital multimeter +5 V power supply A breadboard Wires 1 74LS155 (2-line to 4-line decoder) 4 200 Ω resistors 4 red LEDs 7.4 Analysis 1. The truth table for a 74LS155 2-line to 4-line decoder is shown in Figure 7.1. You may assume that G1=L and C1=H for this experiment. The inputs of the decoder are Select A and Select B and the outputs are 1Y0, 1Y1, 1Y2 and 1Y3. Figure 7.1 The truth table for a 2-line to 4-line decoder. 2. Please repeat the following steps for each of the outputs. (a) Draw the Karnaugh map for Select A, Select B and one of the outputs (e.g. 1Y0 ). (b) Use the ones in the Karnaugh map to determine the Boolean expression for the output. (c) Simplify the Boolean expression so that it can be implemented with an NAND gate and inverter(s). (Hint: Use DeMorgan s theorem.) 3. Draw the gate level implementation of the decoder.

VERILOG MODELING 25 7.5 Verilog Modeling 1. You will model the 2-line to 4-line decoder in Verilog. Please follow the following naming convention for the Verilog module: (a) The module should be called decode24.v. (b) The inputs of the module are A and B. (c) The output of the module is Y, which is an array of four elements. (d) Please use the assign statements to implement the Boolean expressions. (e) Prepare a test bench for the decode24.v. The test bench should be called decode24_tb.v. The test bench should produce an output file called decode24.out. (f) You can download encode83.v and encode83_tb.v from the course website for your reference. V CC + 1 C1 VCC 16 2 G1 C2 15 3 B G2 14 4 1Y3 A 13 5 1Y2 2Y3 12 R LED 6 1Y1 2Y2 11 R LED 7 1Y0 2Y1 10 + R LED V 8 GND 2Y0 9 B + R LED 74LS156 V A Figure 7.2 Schematic of a 2-line-to 4-line decoder.

26 2-LINE TO 4-LINE DECODER 7.6 Implement the 2-line to 4-line decoder using 74LS155 chip 1. Implement the decoder circuit shown in Figure 7.2 with a 74LS155 chip and record the results in Table 7.1. V A V B V Y 0 V Y 1 V Y 2 V Y 3 0.0 V 0.0V 0.0 V 5.0V 5.0 V 5.0V 5.0 V 0.0V Table 7.1 Truth table of the decoder. 7.7 Submission Checklist You may work on this lab with a partner. The lab is due in the beginning of the next lab. 1. The Karnaugh map associated with each output (4 point) 2. Gate level schematic of the decoder. (6 points) 3. A copy of decode24.v. (2 points) 4. A copy of decode24_tb.v. (2 points) 5. A copy of decode24.out. (2 points) 6. Submit Table 7.1. (4 points) 7. Please provide some feedback about this lab. e.g. Were you able to finish the lab on time? Is the instruction clear? Are there any typos or errors about this experiment? Any comment to help improve this lab is helpful? (4 points)

CHAPTER 8 VERILOG MODELING STYLES 8.1 Reference 1. Section 4.11-4.12, M. M. Mano and M. D. Ciletti, Digital Design, 4th edition, Upper Saddle River, NJ. 2. Lecture notes from 02.24.14. 8.2 Objectives After completing this experiment, you will be able to 1. Perform gate-level modeling, dataflow modeling and behavioral modeling. 2. Implement a Boolean function with a MUX. Digital Circuits and Logic Design Laboratory Manual, First Edition. Copyright c 2014,J. Ou. 27

28 VERILOG MODELING STYLES 8.3 Analysis 1. We will implement the following Boolean function with an 8-to-1 MUX in this lab. F (A, B, C, D) = (0, 2, 5, 7, 11, 14) (8.1) 2. Start by constructing the truth table for F. You may use A, B, C as the selector bits for the MUX, D as the input, and F as the output. (1 point) 3. Construct a schematic for implementing F with an 8-to-1 MUX. You may use D along with D and 0 as inputs to the 8-to-1 MUX. (1 point) 8.4 Design Verification We will verify the functionality of the circuit through simulation. We will simulate the circuit three times, each time with a different model of 8-to-1 MUX. To help you focus on learning the differences of the three modeling styles, we will provide test bench files and templates for this exercise. You will, however, have to write some code. 8.4.1 Gate-Level Modeling 1. Please download chap4p32a_tb.v from the course website. This test bench uses mux81a, which is an 8-to-1 MUX implemented with gate-level modeling. S is an array of bits that correspond to A, B, C, and D. The output of the simulation is stored in chap4p32a_tb.out. Please answer the following questions about the test bench: (1 point) (a) How are the assign statements related to the schematic of F? (b) Why do we only pass S[0:2] to mux81a? 2. You will develop a gate-level Verilog model for mux81a. The name for the 8- to-1 MUX is mux81a.v. You may use the 2-to-1 MUX model from the course website. Please submit a print-out of mux81a.v (3 points) 3. Execute the test bench and submit a print-out of chap4p32a_tb.out. (1 point) 8.4.2 Dataflow Modeling 1. Please download chap4p32b_tb.v from the course website. This test bench uses mux81b, which is an 8-to-1 MUX implemented with dataflow modeling. 2. Please download mux81b.v from the course website. mux81b.v is a template that you can use. The program body has been removed. Please use the

DESIGN VERIFICATION 29 assign keyword along with the conditional operator (?:) to implement the MUX. You will only have to write one line of code. Submit a print-out of mux81b.v. (2 points) 3. Please save the output in chap4p32b_tb.out and submit it. (1 point) 8.4.3 Behavioral Modeling 1. Please download chap4p32c_tb.v from the course website. This test bench uses mux81c, which is an 8-to-1 MUX implemented using behavioral modeling. 2. Please download mux81c.v from the course website. mux81c.v is a template that you can use. The program body has been removed. Please use the always keyword along with the if-else staetment to implement the MUX. (2 points) 3. Please save the output in chap4p32c_tb.out and submit it. (1 point)

CHAPTER 9 PSEUDO RANDOM NUMBER 9.1 Reference 1. http://en.wikipedia.org/wiki/linear_feedback_shift_register 9.2 Objectives After completing this experiment, you will be able to 1. Generate a 4-bit pseudo number sequence. 2. Use a universal shift register. 3. Use Agilent DSO-X 2002A mixed signal scope/function generator. 9.3 Parts 1. 1 74LS194 4-bit bi-directional universal shift register Digital Circuits and Logic Design Laboratory Manual, First Edition. Copyright c 2014,J. Ou. 31

32 PSEUDO RANDOM NUMBER 2. 1 74LS86 XOR gate 3. Agilent DSO-X 2002A 9.4 Circuit Implementation We will implement the 4-bit pseudo random number circuit shown in Figure 9.1. The pseudo random sequence is created by continuously feeding the output of the XOR gate back to the input of the shift register (i.e. Shift Right Serial)). In order to shift the bits (i.e. Q A, Q B, Q C, and Q D ) to the right by one bit, S0 is connected to V CC and S1 is connected to ground. The output of the shift register is updated at the rising edge of the clock. We will use the pseudo random number circuit later in the course. If you do not wish to take apart the circuit at the end of the lab, you can check out the 74LS194 chip and 74LS86 chip and return them at the end of the semester. V CC + 1 2 3 4 5 6 7 8 CLR SR SER A B C D SL SER GND V CC 16 Q A 15 Q B 14 Q C 13 Q D 12 CLK 11 S1 10 S0 9 74LS86 CLK 74LS194 Figure 9.1 A 4-bit pseudo random generator. 9.5 Display the Wave on the Mixed Signal Scope 1. We will examine the waveforms at the outputs (Q A, Q B, Q C and Q D ) of the shift register. We will start by generating a clock and feeding it to pin #11 of the 74LS194 chip. (a) Press default setup.

SUBMISSION CHECKLIST 33 (b) Press Wave Gen. (c) Set Waveform to square. (d) Set Frequency to 1 khz. (e) Set Amplitude to 5.00 Vpp. (f) Set Offset to 2.5 V. (g) Set Duty Cycle to 50 percent. 2. Connect the output of the function generator (i.e. Gen Out) to pin #11 of the 74LS194 chip. 3. Connect the digital probes to Q A, Q B, Q C and Q D of the 74LS194 chip. 4. Press Auto Scale. 5. Press Trigger (a) Set trigger type to Edge. (b) Set the source to WaveGen. (c) Set the edge to rising. 6. Press Mode/Coupling. (a) Set Mode to normal. (b) Adjust the Hold-off until the waveforms are triggered properly. 9.6 Submission Checklist Please submit brief responses to the following questions: 1. What is the relationship between Q A, Q B, Q C and Q D? (1 point) 2. According to the 74LS194 data sheet, what is Q A when CLEAR is set to 0? (1 points) 3. What are the appropriate values for S0 and S1 if we want to shift content of the shift register to the left? (2 points) 4. The circuit function will not function correctly if Q A = Q B = Q C = Q D = 0. What can you do to force the circuit to produce the correct result? (hint: read the wikipedia entry on linear feedback shift register in addition to the data sheet for 74LS194) (2 points)

CHAPTER 10 FLIP-FLOPS 10.1 Reference 1. The experiment on pseudo random number circuit. 2. Section 5.4, M. M. Mano and M. D. Ciletti, Digital Design, 4th edition, Upper Saddle River, NJ. 3. ES210 lecture notes from March 12,2014. 10.2 Objectives After completing this experiment, you will be able to 1. Use a D flip-flop. 2. Use a JK flip-flop. 3. Use a T flip-flop. Digital Circuits and Logic Design Laboratory Manual, First Edition. Copyright c 2014,J. Ou. 35

36 FLIP-FLOPS 4. Model flip-flops in Verilog. 10.3 Parts 1. 1 74LS194 4-bit bit-directional universal shift register 2. 1 74LS86 XOR gate 3. Agilent DSO-X 2002A 4. 1 74LS76A Dual JK flip-flop with set and clear (Look under the datasheet link) 5. 1 74HC175 Quad D flip-flop with reset, positive-edge trigger (Look under the list of 7400 TTL logic family link) 10.4 Before You Start Please make sure your 4-bit pseudo random number circuit is functional before coming to the lab. You can verify that you have a functional circuit by observing the waveforms on the digital scope. Please review the experiment from last week as necessary. If you have borrowed 74LS194 and 74LS86, please fill out the appropriate paperwork and return it to the instructor. 10.5 Flip-flops 10.5.1 D flip-flop We will use 74HC175 as the D flip-flop in this experiment. There are four D flipflops on this chip. We will use only one of them in this experiment. The supply voltage (i.e. V CC ) for this chip is 5 V. The chip comes with a master reset input. We set MR to V CC to enable the chip. Please build the circuit shown in Figure 10.1. Observe D 0, CLK and Q on the mixed signal scope. Do a screen capture and attach the image as part of the submission for this lab. Please comment on the waveforms you have observed in this experiment. Does the circuit behave as a D flip-flop? (3 points) 10.5.2 JK flip-flop We will use Motorola s dual JK flip-flop (74LS76A) for this experiment. This chip comes with a set and a clear feature. In order to place the chip in its normal operation, we need to set S D and C D to high. Please also note that pin 5 and 13 are designated as V CC and and ground respectively. Before you build the circuit as

FLIP-FLOPS 37 V CC + 1 2 3 4 5 6 7 8 CLR SR SER A B C D SL SER GND V CC 16 Q A 15 Q B 14 Q C 13 Q D 12 CLK 11 S1 10 S0 9 74LS86 CLK Q 1 2 3 4 5 6 7 8 MR Q 0 Q 0 D 0 D 1 Q 1 Q 1 GND V CC 16 Q 3 15 Q 3 14 D 3 13 D 2 12 Q 2 11 Q 2 10 CP 9 74LS194 74HC175 Figure 10.1 D flip-flop. shown in Figure 10.2, please study the mode select truth table in the data sheet. We will use Q A and the output of the XOR gate as the the inputs to J and K of the flipflop. Build the circuit as shown in figure 10.2. Do a screen capture as before. Save the image and comment on the waveforms you observe. Are you able to explain what happen to the output at each negative edge of the clock? (3 points) V CC + 1 2 3 4 5 6 7 8 CLR SR SER A B C D SL SER GND V CC 16 Q A 15 Q B 14 Q C 13 Q D 12 CLK 11 S1 10 S0 9 74LS86 CLK 1 2 3 4 5 6 7 8 CP S D C D J V CC K 16 Q 15 Q 14 GND 13 12 11 10 9 Q 74LS194 74LS76A Figure 10.2 JK flip-flop.

38 FLIP-FLOPS 10.5.3 T flip-flop A JK flip-flop can easily be configured to a T flip-flop by connecting the J terminal to the K terminal as shown in Figure 10.3. Are you able to deduce the mode select truth table for a T flip-flop from a JK flip-flop? Build the circuit as shown in Figure 10.3. Capture the screen and save it to a file. Analyze the waveforms and comment on whether the T flip-flop is functional. What do you expect to see when T is equal to 0? What do you expect to see when T is equal to 1? (3 points) V CC + 1 2 3 4 5 6 7 8 CLR SR SER A B C D SL SER GND V CC 16 Q A 15 Q B 14 Q C 13 Q D 12 CLK 11 S1 10 S0 9 74LS86 CLK 1 2 3 4 5 6 7 8 CP S D C D J V CC K 16 Q 15 Q 14 GND 13 12 11 10 9 Q 74LS194 74LS76A Figure 10.3 T flip-flop. 10.6 Post lab We will to use use flip-flops in Verilog simulation later in the semester. Therefore, it is important that you know how to model the flip-flops in Verilog. 1. Build the behavioral model for a JK flip-flop (i.e. using case...endcase. ) Please take a look at the lecture notes for more details. Submit a print-out of the Verilog module. (1 point) 2. Test it with a test bench. Submit a print-out of the test bench. (1 point) 3. Prove that you have a working model for the JK flip-flop by showing the appropriate waveforms. Submit a screen capture of the waveforms. (1 point) 4. Next, build the Verilog model for T flip-flop using an existing model of a JK flip-flop. Submit a print-out of the module. (1 point) 5. Test it with a test bench and show that the T flip-flop is functional by showing the appropriate waveforms. (2 points)

CHAPTER 11 CLOCKED SEQUENTIAL CIRCUIT 11.1 Verilog Modeling 1. Using fig5p16.v and fig5p16_tb.v as a starting point, modify the verilog files in order to model the operation of the sequential circuit in Figure 11.1. 11.2 Hardware Implementation 1. We have shown in class that the state diagram in Figure 11.1 can be converted into the schematic in Figure 11.2. 2. Please build the circuit shown in Figure 11.2. To generate the input (x), you will need to build the same random number generator you built last week. You will need generate the clock signal from the mixed signal scope and use it to drive both the random number generator and the flip-flops. Please use the datasheets available from google doc. Digital Circuits and Logic Design Laboratory Manual, First Edition. Copyright c 2014,J. Ou. 39

40 CLOCKED SEQUENTIAL CIRCUIT Figure 11.1 The state diagram of a sequential circuit. (a) Use 74LS175N as the D flip-flop. What should be the voltage supplied to terminal 1? (b) Use 74LS32N as the OR gate. (c) Use 74LS08 as the AND gate. 11.3 Submission Checklist 1. Submit a print-out of state, next state, x, y, and clock used in verilog simulation. (10 points) 2. Display A, B, clock, x and y on the mixed signal scope, save the waveform as a graphic file, and submit a print out of the waveform. (10 points)

SUBMISSION CHECKLIST 41 Figure 11.2 The state diagram of the sequential dircuit in Figure 11.1

CHAPTER 12 UNIVERSAL SHIFT REGISTER 12.1 Reference 1. The experiment on pseudo random number circuit. 2. Section 6.1-6.2, M. M. Mano and M. D. Ciletti, Digital Design, 4th edition, Upper Saddle River, NJ. 3. ES210 lectures from 4.2.2014. 12.2 Objectives After completing this experiment, you will be able to 1. Generate a behavioral model in Verilog for the universal shift register. 2. Build a universal shift register from D flip-flop and 4-to-1 MUX. 3. Troubleshoot and debug a non-trivial sequential circuit. Digital Circuits and Logic Design Laboratory Manual, First Edition. Copyright c 2014,J. Ou. 43

44 UNIVERSAL SHIFT REGISTER 12.3 Parts 1. MC74HC175N (D flip-flop) 2. 74LS153 (4-to-1 MUX) 12.4 Model the Universal Shift Register in Verilog Model 1. We are going to model the universal shift register shown in Figure 12.1. The universal shift register has four distinct modes of operations shown in Figure 12.2. Figure 12.1 Construction of a Universal Shift Register. Figure 12.2 Mode Control of the shift register. 2. Use the lecture notes as a guide and build the Verilog models associated with the universal shift register. The shift register can be modeled both behaviorally and structurally. In this experiment, you will model the shift register behaviorally.

HARDWARE IMPLEMENTATION 45 3. Please go to the course website and download the bit files required for this experiments. You will also be able to download the templates for the shift register and the test bench. Please modify the templates before you execute the program. 12.5 Hardware Implementation 1. Please build a shift-right register using only D flip-flops and 4-to-1 MUXs shown in Figure 12.1. In particular, (a) Use MC74HC175N as the D flip-flop. (b) Use 74LS153 as the 4-to-1 MUX. (c) Please read the spec sheet carefully and determine the voltage that must be supplied to terminal 15 of the MUX chip. Also read the data sheet carefully so as to set the MUX to read binary numbers from C 1. 12.6 Submission Checklist 1. A hard-copy of shift_register_4_beh.v, as well as the waveform generated with the test bench. (10 points) 2. Demonstrate the shift-right property of the shift register on the mixed signal oscilloscope. Save and printout the waveform displayed on the mixed signal scope. (10 points)

CHAPTER 13 SYNCHRONOUS COUNTER 13.1 Datasheet 1. You will learn to operate DM74LS193 as an up counter in this experiment. Please download the datasheet from the google drive for this experiment. 2. According to the datasheet, the direction of counting is determined by which count input is pulsed while the other count input is held HIGH. (a) We will build a synchronous counter that counts up from 0000. (b) Using the connection diagram on page 1 of the datasheet as a reference, what should be connected to pin #4? What should be connected to pin #5? Please assume that a clock of 1 KHz with a low of 0V and a high of 5 V is available for pulsing an input. 3. According to the Recommended Operating Conditions section of the datasheet, what value should be used for V CC? 4. What bias voltage should provided for pin #8? Digital Circuits and Logic Design Laboratory Manual, First Edition. Copyright c 2014,J. Ou. 47

48 SYNCHRONOUS COUNTER 5. According to the datasheet, this counter was designed to be cascaded without the need for external circuitry. What outputs are used for this purpose? Are they needed in this experiment? 6. What is the purpose of the clear input? Should it be set to a high level or a low level? According to the timing diagram on page 3 of the datasheet, how are Q A, Q B, Q C and Q D affected by the clear input? Figure 13.1 Partial Logic Diagram 7. You will use the paritial Logic Diagram in Figure 13.1 to answer the following question. (a) What is w1 if CLEAR=1? What is w1 if CLEAR=0 and LOAD=1? (b) What is the output of gate X in Figure 13.1 if LOAD=1? (c) What is w2 if CLEAR =0? (d) Replace the circuitry in the red retangle in Figure 13.1 by applying the De- Morgan s theorem. What is the signal provided to the reset terminal of the T flip-flop when LOAD=1 and CLEAR=0? 13.2 Hardware Implementation 1. Build a frequency divider with DM74LS193. Observe the outputs at Q A, Q B, Q C, and Q D. Does the circuit behave as a frequency divider? 13.3 Submission Checklist 1. A screen shot of the divider outputs. (10 points) 2. Please answers all the questions in this lab. (20 points)