CE 433 Lab Spring 2022
Course Project
Name: David Lee and Max Krauss
Email: djlee1@fortlewis.edu, mtkrauss@fortlewis.edu

Yoshi Nightmare - Course Project

The objective of this project was to take a an old verilog game and change the input parameters to be able to use the Buttons on the Basys3 FPGA board to control Yoshi in the game. Another objective was to add FLC logo into the background. Since we had extra time, we decided to try and play using a joystick instead of the pushbuttons. This sllowed for more intuitive controls and made the game more fun to play.

Materials and Methods:
Gvim, Vivado, Python, Basys 3 FPGA Board, B103 348 (joystick) and the master files found on gitHub. The Website details on what each of the files can do are here.

The first thing that was decided to accomplish was to get the buttons on the FPGA board to control yoshi. After we were successfully able to do, that we added the skyhawk background and finally we decided try making a joystick function as the controller.

Results:

Using Buttons to control Yoshi's Motion:

In order to do this we had to figure out what was were being called to make Yoshi move if we were to use the NES controller, which the game had previously used. This was done using a module called nes controller. This module was taking the data, latch and clock from the NES controller and translating it to the Up, Left, and Right motion. Once this was figured out, we had to reassign the control inputs from the nes controller module to the pushbuttons of the Basys3. We thought that we might have to use a debounce module to make the buttons function but we did not since we didnt care about how fast or slow the button was released.


Figure 1: These are the instantiations needed in the display_top module in order to utilize the pushbuttons on the Basys3. The lines commented out where the inputs and outputs needed for the nes controller. The instantiation for the nes_controller module was also commented out.


Figure 2: This was the assignment changes we had to make in order to make the pushbuttons control Yoshi's movement in the game.


Figure 3: We had to make the highlighted change so that we could use button C to start the game from the menu.

We also had to make changes to our constraint file that allowed for the calling of rgb[11:0] values instead of vgaRed, vgaGreen and vgaBlue that were in our constraint file initially.

Using Creating a Skyhawk background:
To do this we used a python script found on the main website. This script took an image and created a .v file containing the xilinx block ram of the images color data. With this rom file we were able to upload this as the background and resynthesize the project to be able to see the logo as our background.



Figure 4: Shows the Python Script Used 1 of 2


Figure 5: Shows the Python script used 2 of 2


Figure 6: Image used to create the background. This was a 256x256 sized image just like the original background image for the game.


Figure 7: The Final Background in game

Figure 8: This is the video using button control with the skyhawk background

Joystick control of Yoshi's Motion:
Since we had extra time we tried to use a joystick to control the motion. This was fairly straight forward since we just had to change the constraint file and attach the joystick to the board.


Figure 9: Shows what elements changed in the display_top module to make the joystick work


Figure 10: Shows the changes made in the constraint file to connect the joystick


Figure 11: Shows the joystick connected

n/a
Figure 12: Shows us playing the game using the joystick

We were not able to implement this part correctly since the joystick is analog and not digital. This makes yoshi always moves right unless the joystick is moved left. This created the false idea of functionality. However, while it may not operate like it should or as intented it is still more fun to play with the joystick over the buttons even if there is a slight bug. With more time, we would be able to use the JXADC inputs on the Basys3 to implement this correctly since they are analog inputs.

5. Discussion
This Project was fun to complete. Even though all the verilog code was provided, you had to be able to understand what was happening in order to make the correct changes to the files. Once we read through the files enough to understand what was needed to be changed this project was straight forward. The biggest challenge about this project was the synthesising in vivado because of how long it took. During this project we were averaging about a 40-50 minute synthesis time, which makes the testing excruciatingly long. Overall this project was able to be successfully completed. In order to make this project better we would either need a Digital joystick or create JXADC inputs to change the input values of the joystick to make it function better/correctly.