Random Number Generation

1. Random Number Generation Section 3.10 Section 4.12

2. Outline • Observations from the last week’s lab • Anatomy of a Verilog Program • More about Verilog • Including a file • Test a Module with a Random Sequence • Example: NAND Implementation of a NOT Gate • The NAND Implementation of a NOR Gate • Implementation Using 74LS00

3. Observations from Last Thursday’s Lab (1) • The verilog code should be saved in a *.v file, e.g. • fig3p37.v is the file name • to execute the simulation, you need to type verilog +gui fig3p37.v &

4. Observations from Last Thursday’s Lab (2) Correction: Remove semicolon from the end of timescale line.

5. Observations from Last Thursday’s Lab (3) Correction: Use a backward quote (`), not a single quote (‘)

6. Observations from Last Thursday’s Lab (4) fig3p37 is the module name. I1 is the instance of the module. Comment: You need both modules! Definition of the module

7. Observations from Last Thursday’s Lab (5) System!   Source file "fig3p37.v" cannot be opened for                                   reading                                           [Verilog-SFCOR] Solution: [r2d2@localhost verilogSandBox]$ chmod 755 fig3p37.v

8. Question // comments out a line

9. Question: How do I get the play button back? If you comment out $stop and stop the simulation by using Initial #200 $finish, you will not get the play button. What do you do then?

10. Solution: Simulation ->Reinvoke Simulator

11. Solution: Simulation ->Reinvoke Simulator Select Yes

12. You Get the Play Button Back! Play button

13. Review of What We have Learned • A minimalist’s view of a verilog Module • A minimalist’s view of a module test bench

14. Anatomy of a Verilog Module module fig3p37 (A,B,C,D,E); output D,E; input A,B,C; wire w1; and G1(w1,A,B); not G2(E,C); or G3(D,w1,E); endmodule

15. module....endmodule module fig3p37 (A,B,C,D,E); output D,E; input A,B,C; wire w1; and G1(w1,A,B); not G2(E,C); or G3(D,w1,E); endmodule Always start the verilog program with the keyword pair module…endmodule The keyword module must always be terminated by the keyword endmodule.

16. output/input module fig3p37 (A,B,C,D,E); output D,E; input A,B,C; wire w1; and G1(w1,A,B); not G2(E,C); or G3(D,w1,E); endmodule output/input wire

17. Program Body module fig3p37 (A,B,C,D,E); output D,E; input A,B,C; wire w1; and G1(w1,A,B); not G2(E,C); or G3(D,w1,E); endmodule Program body

18. Anatomy of a Test Bench Test Bench `timescale module module_tb (, , ,)…endmodule ouput,reg Invoke the module Define the input vector

19. Use `include to reference a file Troubleshooting Exercise: verilog +gui fig3p37.v &

20. Introduce a Random Test Vector • flip_me function Q: What is the function of this module?

21. flip_me_tb.v • Test Bench Definition: Feed a random sequence of binary numbers to flip_me.v A=random input B=flipped version of A

22. Test Bench for flip_me.v Reference: Mano page 170-174.

23. `timescale Comment out time scale Each time interval is one second.

24. include flip_me.v

25. Define outputs,reg We will read random numbers from a file. The random numbers are stored in t_A. vectornum is the index of the t_A. At the falling edge of the t_clock, a random numbers stored in t_A is transferred to A.

26. flip_me.v is called.

27. 1000 time intervals will be simulated.

28. Clock Generation t_clock is initially 0. t_clock is flipped every 5 time intervals. The period of t_clock is 10 time intervals.

29. Read numbers from an input file Random number is stored in t_A.

30. Update at NegEdge of t_clock At negative edge of t_clock, transfer the random number from t_A to A.

31. Monitor Numbers Monitor numbers

32. Waveforms

33. Run Verilog Using Command-line $monitor only displays the results when A changes. Actual sequence: 101011001011…

34. Implement NOR with NANDs G1 E C F G3 G4 D G2 A, B as inputs C,D, E as wires F as output

35. nor_with_nand.v

36. nor_with_nand_tb.v Use flip_me_tb.v as a guide. Complete the code for nor_with_nand_tb.v