CENG232 Lab 3 Solved

1      Introduction
This assignment aims to make you familiar with Verilog language, related software tools, and the FPGA boards. There are two parts in this assignment. The first part is a Verilog simulation of an imaginary flip-flop design, which you are required to implement and test on your own. The second part consists of simulation and implementation (on FPGA) of MarsAdventure system.

2            Part 1: DF - Flip Flop (Warming - 25 pts)
You are given a specification of a new type of flip-flop, and a new chip that uses the flip-flop. This is an individual part. Your task is to implement these in Verilog, and prove that they work according to their specifications by simulation (this part will only be tested with testbenches not with FPGAs).

2.1
Implement the following DF flip-flop in Verilog with respect to the provided truth table. An DF flip-flop has 4 operations when inputs D and F are: 00 (set to 1), 01 (no change), 10 (set to 0), 11 (complement). Please note that the DF Flip-Flop changes its state only at rising clock edges.

 

2.2
Implement the following chip that contains two DF flip-flops which has output Y. Use the following module definitions for the modules:

module df(input d, input f, input clk, output reg q) module icplusplus(input d0, input f0, input d1, input f1, input clk, output q0, output q1, output y)

Table 1: DF - flip-flop truth table.

D
F
Q
Qnext
0
0
0
1
0
0
1
1
0
1
0
0
0
1
1
1
1
0
0
0
1
0
1
0
1
1
0
1
1
1
1
0
 

Figure 1: icplusplus module, inputs and outpus.

2.3     Simulation
A sample testbench for df-flipflop module will be provided to you. It is your responsibility to extend the testbench, and also to write a testbench for icplusplus module.


3         Part 2: F1 Career (75 pts)
In this part of the homework, you will test your implementations on FPGAs (not with testbenches). This is an individual part. You will only share FPGAs for testing. Everyone will send their own verilog file and any kind of cheating is not allowed.

3.1      Problem Definition
Take a seat on F1...

In all around the world, there may be one job for only 20 positions available.The name of this job is f1 driver. Imagine Redbull Racing has canceled the contract with one of their drivers, namely Max Verstappen. After seeing this news, you decide to apply Redbull Racing to become their new young driver. But it is not easy to be appointed.

 

You should succeed in various tests. After passing all the tests, you come to the last step. That is the intelligence test. In this test, you are going to solve their mathematical test. To impress them, you decided to design a hardware that helps you to solve their problem. They are going to give you a number and you will apply operations to that number.

In this problem the Redbull Racing test committee will provide you some numbers and according to provided options you will apply some mathematical operations to these numbers. Each number provided consist of 4 bits. There are two different operations to be done on this number. You will apply different operations for prime numbers and non-prime numbers.

Here is the detailed specification list that Redbull Racing provided to you. To be successful you have to be highly careful to obey all of the specifications:

1.     Each number given by Redbull racing committee consists of a 4-bit number.

2.     If the number is only divisible by itself and one it is a prime number and otherwise it is a non-prime number.

3.     The user can choose the operation he/she wants by using the selection switch. If the selection is 0, the system will execute the prime number operation. If the selection is 1, the system will execute the non-prime number operation.

4.     In the time of executing the prime number operation, the system will basically find the next or previous prime number of the given prime number according to the mode of the system. The provided number should be written to digit0 variable (it triggers the right most seven segment display) and the next or the previous number should be written to digit1 variable (it triggers the second right most seven segment display).

5.     If the user selects the prime number operation and the mode is 1, the system will find the next prime number after the currently provided prime number. If the next prime number is larger than the maximum number that can be represented by a 4-bit number then the system returns the minimum prime number possible. (i,e. if the current prime number is 7 the next prime number will be 11. If the current prime number is 13, the next prime number will be 2 because the next prime number is larger than 15 (maximum number that can be represented by a 4-bit number)).

6.     After each operation in the mode 1 of the prime number operation, the count1 (it triggers the left most seven segment display) variable should be increased by one (we do not check if that number is provided before). count1 variable basically counts the number of prime number operations executed in the mode 1. Unfortunately count1 is a 1 digit number, and after it reaches 9 it has to start counting from 0. (i.e, 7,8,9,0,1···).

7.     If the user selects the prime number operation and the mode is 0, the system finds the previous prime number before the currently provided prime number. If there is no previous prime number exists, the system returns the maximum prime number possible. (i,e. if the current prime number is 7 the previous prime number will be 5. If the current prime number is 2 (smallest possible prime number), the next prime number will be 13 (maximum possible prime number with 4-bits) because there is no previous prime number).

8.     After each operation in the mode 0 of the prime number operation, the count0 (it triggers the second left most seven segment display) variable should be increased by one (we do not check if that number is provided before). count0 variable basically counts the number of prime number operations executed in the mode 0. Unfortunately count0 is a 1 digit number, and after it reaches 9 it has to start counting from 0. (i.e, 7,8,9,0,1···).

9.     If the prime number operation (selection=0) is selected and a non-prime number is given to the system, then the system should activate the warning led and the system must not do any operation (all the other values should stay same without any change). After the warning situation disappears the warning led must be turned off again.

10.   In the time of executing the non-prime number operation, the system will basically shift the provided number to the left or right according to the mode of the system. The provided number should be written to digit0 variable (it triggers the right most seven segment display) and the shifted number should be written to digit1 variable (it triggers the second right most seven segment display).

11.   If the user selects the non-prime number operation and the mode is 1, the system will shift the number to left by one. After the shift, the left most bit of the number will be discarded and the right most bit of the number will be instantiated as 0. (i.e, 1010 will become 0100 after the shift).

12.   After each operation in the mode 1 of the non-prime number operation, the count1 (it triggers the left most seven segment display) variable should be increased by one (we do not check if that number is provided before). count1 variable basically counts the number of non-prime number operations executed in the mode 1. Unfortunately count1 is a 1 digit number, and after it reaches 9 it has to start counting from 0. (i.e, 7,8,9,0,1···).

13.   If the user selects the non-prime number operation and the mode is 0, the system will shift the number to right by one. After the shift, the right most bit of the number will be discarded and the left most bit of the number will be instantiated as 0. (i.e, 1010 will become 0101 after the shift).

14.   After each operation in the mode 0 of the non-prime number operation, the count0 (it triggers the second left most seven segment display) variable should be increased by one (we do not check if that number is provided before). count0 variable basically counts the number of non-prime number operations executed in the mode 1. Unfortunately count0 is a 1 digit number, and after it reaches 9 it has to start counting from 0. (i.e, 7,8,9,0,1···).

15.   Realize that both operations use the same count and digit variables. To not lose the count information of both operations, you should store them somewhere and initialize to count variables when that operation is called. You do not have to store the last values of the digit variables.

16.   If the non-prime number operation (selection=1) is selected and a prime number is given to the system, then the system should activate the warning led and the system must not do any operation (all the other values should stay same without any change). After the warning situation disappears the warning led must be turned off again.

17.   If the selection is switched from 0 to 1 and a non-prime number is provided to the system then the count variables should be updated with last values of non-prime number operation counts. And the digit values must be filled with the non-prime number operation values.

18.   If the selection is switched from 1 to 0 and a prime number is provided to the system then the count variables should be updated with last values of prime number operation counts. And the digit values must be filled with the prime number operation values.

19.   Initially, count1, count0, digit1, digit0 must be set to 0.

20.   If the clear switch is provided as 1, then all of the variables ( count1, count0, digit1, digit0 and warning) must be set to 0. And also the system must not do any operation while the clear switch is on. If the clear switch is set to 0, then the system will behave normally.

3.2       Sample Input/Output
•   The values in Current State column, which are seperated by “,” are defined as: number, clear, mode, selection, count1, count0 , digit1, digit0 respectively.

•   The values in Next State column, which are seperated by “,” are defined as: count1, count0, digit1, digit0, warning, respectively.

Table 2: Sample inputs and outputs.

current state
CLK
next state
1011, 0, 0, 0, 0, 0, 0, 0
↑
0, 1, 7, b, 0
0111, 0, 1, 0, 0, 1, 7, b
↑
1, 1, b, 7, 0
0111, 0, 1, 1, 1, 1, b, 7
↑
1, 1, b, 7, 1
0110, 0, 1, 1, 1, 1, b, 7
↑
1, 0, C, 6, 0
0101, 0, 0, 0, 1, 0, C, 6
↑
1, 2, 3, 5, 0
1111, 1, 1, 1, 1, 2, 3, 5
↑
0, 0, 0, 0, 0
In line 5 we stored a prime number, and the previous values for the prime number counts were 1 1 (we switched from non-prime to prime, their count values are different). Because of that, the new values of the counts become 1

2.

3.3       Input/Output Specifications
•   number represents 4-bit code.

•   CLK is the clock input for the module.

•   selection is used for the selection of operation (prime/non-prime).

selection = 0 ⇒ prime operation selection = 1 ⇒ non-prime operation

•   mode is used to choose the direction of the operations mode = 0 ⇒ the previous prime number will be found and the count0 will be incremented (selection=0) mode = 1 ⇒ the next prime number will be found and the count1 will be incremented (selection=0) mode = 0 ⇒ the number will be shifted to right and the count0 will be incremented (selection=1) mode = 1 ⇒ the number will be shifted to left and the count1 will be incremented (selection=1)

•   digit0 will show the current prime number and digit1 will show the next or previous prime number. (selection =0)

•   digit0 will show the current non-prime number and digit1 will show the left shifted or right shifted non-prime number. (selection =1)

•   count0 will show the number of previous prime numbers counted and count1 will show the number of next prime numbers counted. (selection =0)

•   count0 will show the number of right shifted non-prime numbers and count1 will show the number of left shifted non-prime numbers. (selection =1)

•   warning shows the warning situations. warning = 0 ⇒ no warning occured.

warning = 1 ⇒ warning occured.

•   clear is used for performing clearing operation. clear = 0 ⇒ no clear operation will be done. clear = 1 ⇒ all of the variables ( count1, count0, digit1, digit0 and warning) must be set to 0.

3.4       FPGA Implementation
You will be provided with a Board232.v file (and a ready-to-use Xilinx project), which will bind inputs and outputs of the FPGA board with your Verilog module. You are required to test your Verilog module on the FPGA boards.

Table 3: Inputs and output variables

Name
Type
Size
number
Input
4 bits
Clock (CLK)
Input
1 bit
selection
Input
1 bit
mode
Input
1 bit
clear
Input
1 bit
digit1
Output
8 bits
digit0
Output
8 bits
count1
Output
8 bits
count0
Output
8 bits
warning
Output
1 bit
Table 4: Button descriptions.

Name
FPGA Board
Description
number
SW7, SW6, SW5, SW4
Left-most 4 switches (A)
Clock (CLK)
BTN0
Right-most button (B)
selection
SW0
Right-most switch (C)
mode
SW1
The switch next to SW0 (D)
clear
SW2
The switch next to SW1 (E)
digit0
7-segment display
Right-most 7-segment display (F)
digit1
7-segment display
Second right-most 7-segment display (G)
count0
7-segment display
Left-most 7-segment display (H)
count1
7-segment display
Second left-most 7-segment display (I)
warning
LD7
Left-most led (J)
Figure 2: Board with the button informations.