Unit 2 Design Solutions Solutions to Unit 2 Design and Simulation Problems Problem 2. is a simulation exercise where students are required to design and simulate a counter. The problem has 4 parts of equal difficulty, so that different students can be assigned different parts. We ask students to do the following preparation and lab work:. Read Unit 2 in the course textbook, completing Study Guide parts through 5. 2. Read Section 2.2, Simulating Flip-Flops with SimUaid in the SimUaid User s Guide on the CD. 3. Answer the following questions: (a) How can a D flip-flop be set to logic without using the clock input? (b) How can it be set to logic without using the clock input? (c) Explain the term Asynchronous Input. 4. Design a counter that counts in the sequence assigned to you. Use D flip-flops, NAND gates, and inverters. Draw your circuit explicitly showing all connections to gate and flip-flop inputs. Explicitly means that you should draw in all wires, don t just label the inputs and outputs. Show switches connected to the Preset and Clear inputs of the flip-flops. Use one switch for all clears and a separate switch for each preset. 5. Explain in detail how you can set the flip-flops to the two missing states not in the prescribed counting sequence without using the clock input. Your explanation should describe each change you make to a switch position. After you have cleared or set a flip-flop, in what position ( or ) should you leave the switches? 6. After a proctor has approved your preparation, go to one of the computer labs and work through the exercise for simulating a D flip-flop using SimUaid, found in Section 2.2 Simulating Flip Flops with SimUaid of the SimUaid User s Guide on the CD. 7. Enter your circuit from part 4 into SimUaid. In the space below, draw the complete determined experimentally using your SimUaid circuit. Include the 6 states in the counting sequence and the 2 states not in the sequence. The complete solution for problem 2.(a) follows. The solutions for parts (b) through (n) are similar, so only the state table, D flip-flop input equations (derived using Karnaugh maps), and the s determined in part 6 are given. The D flip-flop input equations can also be derived using LogicAid by entering a state table with zero input variables. 2.(a) C B A X C B A X C B A X X X X X X X X X X D C = C'B A + C B' D B = B'A + C D A = B' + C'A 273 2 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.
Unit 2 Design Solutions 2.(a) (contd) PREC S D Q C C' CLK R Q' PREB S D Q B B' R Q' PREA S D Q A A' CLR Q' R 2.(b) X X X X X X *D C = C'B + B'A D C = C'B + C B' *D B = C'A' + C A *D A = B' + C'A 274 2 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.
2.(c) X X X X X X *D C = A' + B *D B = C'A' + B A' *D A = C B' + B A' D A = C B' + C A' Unit 2 Design Solutions 2.(d) X X X X X X *D C = C' + B'A + B A' *D B = B'A *D A = C B' + B A' D A = C B' + C A' 2.(e) X X X X X X D C = C'B + B A D B = C' + B' D A = C'B A' + C A 2.(f) X X X X X X D C = C' + B D B = C'A + B A D A = C'A + C A' 275 2 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.
Unit 2 Design Solutions 2.(g) X X X X X X D C = C'A + C'B + B A D B = C' D A = C'B + C A 2.(h) X X X X X X *D C = C'B' *D B = B'A + C'B A' *D A = C'B + C'A' D A = C'B + B'A' D A = C'A' + B A state graph 2.(i) X X X X X X *D C = C'B' + C B A' *D B = C A' + C'A D B = C A' + B'A *D A = B A' 2.(j) X X X X X X D C = B'A + C'B A' D B = B'A + B A' + C D A = B' + C A' 276 2 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.
2.(k) X X X X X X *D C = C'B' + B'A *D B = C B' *D A = B'A + B A' D A = B'A + C'B Unit 2 Design Solutions 2.(l) X X X X X X D C = A D B = C'A' + B A D A = C'A' + C'B + B A' 2.(m) X X X X X X D C = B' + C A D A = C'B A' + C B' D B = B A' + C 2.(n) X X X X X X D C = C'B + A D A = C'B' + C'A D B = C'B' + A + C B 277 2 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.
Unit 2 Design Solutions 278 2 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.