CSE 260 Digital Computers: Organization and Logical Design. Lab 4. Jon Turner Due 3/27/2012

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1 CSE 260 Digital Computers: Organization and Logical Design Lab 4 Jon Turner Due 3/27/2012 Recall and follow the General notes from lab1. In this lab, you will be designing a circuit that implements the well-known minesweeper game. If you re not familiar with minesweeper, visit ( to see how it works. Your circuit will display the game board on an external monitor, using the VGA output from the S3 board. You will use a provided vgadisplay module to drive the display and another provided component to copy provided patterns to game-board locations. Because of the limits on the display resolution imposed by the VGA display module, we will limit ourselves to game boards with a 10x10 array of squares, and each square will use a 10x10 block of pixels (the provided VGA display module supports 160 pixels per row and 120 rows). Your minesweeper module should use the following entity declaration. entity minesweeper is port( clk, reset: in std_logic; -- client-side interface x, y: in std_logic_vector(3 downto 0); newgame, markit, steponit: in std_logic; level: in std_logic_vector(2 downto 0); -- interface to external display hsync, vsync: out std_logic; dispval: out std_logic_vector(2 downto 0)); end minesweeper; The x,y inputs define a current square on the game board. Since the S3 board does not have a mouse, we ll use the knob to control the values of x and y. When newgame is asserted, the minesweeper module should start a new game by selecting random locations for the mines and covering all the squares on the board. The number of mines is controlled by the level input. When the markit input goes high, the minesweeper module should mark the current square by displaying a flag to indicate the presence of the mine. If the square is already marked, it should be unmarked. The markit input should be ignored if the current square is already uncovered. When the steponit input goes high, the minesweeper module should uncover the current square (assuming it is not already uncovered). If the square contains a mine, the game is over, and the minesweeper module should uncover all the squares, showing the locations of the mines. One important feature of the minesweeper game is that uncovered squares that are adjacent to mines are labeled with the number of mines that are adjacent to those squares. Your minesweeper module should implement this feature. When a square is uncovered that has no neighboring squares containing mines, all adjacent squares are safe and can be uncovered. Most implementations of the game do this automatically. Your minesweeper module is not required to do this, but if you implement this feature, you can get some extra credit (details below). The rule for automatically uncovering a square is simply that a covered square can be - 1 -

2 uncovered if one of its neighboring squares (x,y) is uncovered and square (x,y) has no neighboring cells that contain mines. To implement the game, you will need to make some decisions about how to represent the game board. One natural approach is to use one or more 10x10 arrays to represent certain properties. For example, you might have an ismined array for which ismined(x,y)=1 whenever square (x,y) contains a mine. You might also have a neighboringmines array for which neighboringmines (x,y) is equal to the number of mines adjacent to square (x,y). The exact representation is up to you. Given a representation of the game board, the implementation of the minesweeper module naturally divides into two parts. One part changes the game board state, based on the inputs from the user. The other part periodically generates a display of the game board on the VGA display. You will find the job of implementing the minesweeper module a lot easier of you think about these two parts as separate tasks. To simplify the second part, you will be provided with a copypattern module, which will copy a pre-defined 10x10 block of pixels to a specified location on the game board. For example, there is a pattern that represents a covered square, a pattern that represents an uncovered square with 3 neighboring squares containing mines, etc. Using copypattern, it is reasonably straightforward to create a graphical representation of the game board on the VGA display. The copypattern module also supports a highlight feature that can be used to display the current square using colors that contrast with the normal colors. To initialize the game board, your circuit will need to select random locations for mines. You will be provided with a module called random that can be used for this purpose. The output of random is a 16 bit pseudo-random value that changes on every clock tick. Your circuit can use it to decide where to place mines on the game board. Note that you will need to do this over multiple clock ticks (say one clock tick for each position on the board). Once you have set the locations of the mines, you may need to initialize other parts of your game board state, again by iterating over all positions on the board. Detailed instructions: 1. (10 points) Write a high level overview of your design for minesweeper. Your overview should start with a brief description of what the circuit does (in your own words), followed by a list of the inputs and outputs, with an explanation of how each of these is used. Next, describe how your circuit implements the required functionality. I suggest you start by explaining how you represent the game board, and what are the major components of your circuit. These will include things like any arrays that you use to store information about the game board, the controller for the circuit and any timers or other registers used by your circuit. For each component, give a brief description of its purpose and how it is used. 2. (10 points) Draw a block diagram of your circuit showing how the various components are connected to each other. For components like registers and timers, you need not show low level details, but every register/timer should be shown as a separate block with appropriate control inputs (such as load or increment). Similarly, each of the arrays used to store information about your game board should be shown as a block. 3. (10 points) Draw a state diagram for the minesweeper module s controller. Include a list of states with a brief explanation of each state. Indicate actions initiated by the controller, either on state changes, or while it remains in a given state

3 4. (30 points) Create a new project called lab 4 in the lab4 folder of your SVN repository. Add all the provided source files in your project. Write a new VHDL module that implements the minesweeper circuit, based on your block. Make sure that your VHDL is consistent with the design from the first two steps. Be sure to include appropriate comments in your code. Turn in a printed copy. 5. (10 points) Create a new VHDL testbench that can be used to verify the operation of the minesweeper module. Your testbench should exercise all the key features of the game. Note, you may want to start with a limited testbench, then run the simulation so that you can see where the mines are placed in the initial game. Then you can use this information to add further tests to your testbench that will exercise all the features of the game. Turn in a printed copy of your testbench. 6. (15 points) Simulate the minesweeper module by itself using your testbench. Check the output carefully for errors and modify the module as necessary to ensure that it works correctly. Include a copy of the final simulation output in your lab report. Include at least two views of your simulation output. Provide a zoomed-out view that provides an overview and shows how your circuit operates on a large time-scale. This view should show changes to the game board as the player makes moves. You should also provide one or more zoomed-in views that show details of those parts of the simulation where the state of the game board is being copied to the VGA display. Think carefully about how you can verify that the state of the game board is being correctly transferred to the external display. You may assume that the copypattern module works correctly. Make sure that your simulation includes all appropriate internal signals. Add notes to the printed copy, identifying all the places where something interesting is happening, in response to the input changes. 7. (5 points) In the repository, you will find a partial implementation of a top level circuit that can be used to implement your circuit on the S3 board. Complete the implementation of the top module in order to control your minesweeper module. Use the binaryinputmodule and connect the appropriate outputs from binaryinputmodule to the minesweeper module. You can use the knob to control the x and y inputs of the minesweeper module. Connect inbits(11..8) to the x input and inbits(3..0) to the y input. Use btn(1) to control the newgame input, btn(2) to control the markit input and btn(3) to control the steponit input. 8. (5 points) Using the provided testtop testbench, simulate the complete circuit. The provided testbench merely verifies that the top level connections to the minesweeper circuit have been made correctly. In your simulation output, be sure to show that the inputs to your minesweeper module do respond correctly to the button pushes, knob turns and switch settings in the testbench. You need not verify that the internal operation of the minesweeper module is correct, since you already did this in the earlier simulation. 9. (15 points). Generate a bit file for your circuit and load it onto one of the S3 boards in the lab. Use the knob to generate a sequence of input values to your circuit. Verify that the circuit works as expected. Demonstrate your circuit to one of the TAs and have them date and initial your lab report, to document that you have completed this step. You will be doing this assignment with a partner who will be assigned to you. You and your partner should work together, trying out ideas for the design of the minesweeper module and working out the details on paper. You should work together on the VHDL and both of you - 3 -

4 should fully understand how the circuit works. When simulating the circuit, check the simulation output together and check each other to reduce the likelihood of mistakes. In addition to the specific items listed above, you should fill out the attached project contribution form listing each partner s contributions to all parts of the project. If you worked together roughly equally on all parts, you can simply say so. So long as both of you made roughly equivalent contributions to the project, you will both receive equal credit. However, if one of you contributed far more than the other, I want to know that, and credit will be assigned accordingly. The form should be signed by both partners and turned in with your assignment. If you and your partner cannot agree on your relative contributions, you should each fill out a separate copy of the form, stating what you think your contribution was. Do not forget to commit your changes back to the repository. This is a good lab to get creative on, if you have the time and want to go further. Here are some things you can do to earn extra credit. These are just suggestions. If you have other ideas for how to extend the game, that s fine too. 1. Automatically uncover safe squares. A square is safe if it is adjacent to an uncovered square that has no adjacent squares containing mines. 2. Change the look of the game board by re-designing the patterns and/or changing the color scheme. 3. Increase the size of the game board. The more challenging version of this makes the game board size increase with the level input. 4. Add a count-down timer, using the lcddisplay to show the time remaining in the game, and stop the game if the time runs out before all unmined squares have been exposed. 5. Add a smiley-face to show when the player has won the game. 6. Change the way the buttons, knob and switches are used to provide the inputs to your minesweeper module. This may require replacing the generic binaryinmod with a new circuit that is designed especially for the minesweeper application. You are be required to turn in your lab report for the basic lab (as described above) on the stated due date. Please do not include extensions in this report. You will be allowed an additional two days for any extensions to the basic lab. Do not attempt the extensions until you have completed the basic lab. You will be graded only on the required elements listed above. Extra credit score will affect your course grade only at the end of the semester when final letter grades are assigned. For anyone who is on the borderline between two letter grades, extra credit can push you over the top. To claim extra credit, turn in an appendix to your lab report (2 days after you turn in the required part of the report). It should start with a list of all the extensions you implemented, along with a brief description of each one. Your appendix should include VHDL source for any part of your code that implements an extension. Please mark the changes to the code with notes indicating which extension the change applies to. Your appendix should also include a simulation of your revised minesweeper module, appropriately annotated to show that your extensions work. You also must demonstrate your extensions on the S3 board. When you demo, you will need to have your list of extensions already written out. The TA or I will initial each extension on the list that you successfully demonstrate. If your lab partner is not interested in doing extensions, it is ok to do this as an individual

5 If you turn in an appendix that covers a single extension, you can earn up to 50 extra points. Each additional extension can add more points, depending on the difficulty of the extension

6 Project Contribution Form (show your %-age contribution to each part) Name Name design overview block diagram minesweeper testminesweeper minesweeper sim top testtop simulation demo on S3 board signatures - 6 -