CS211 Project Flappy Bird.

SUSTech Digital Logic Project.

Full score exceeded.

Image tearing may happen under certain scenarios due to the fact that the update frequency of the physical simulation system is too low and the game rendering is running under 1080p@60Hz. You may adjust the updating frequency by manually profiling the GAMESYS_CLK_GEN.sv module. Notice that the corresponding in-game velocities has to be modified in CONSTANTS.vh file. You may encounter such case in which the gravity happens to be too heavy. In that case you need to add a counter to determine the update frequency of the vertical velocity of the player position.

For a better viewing experience it may be forcibly required to perform such profiling.

P.S. Due to the fact that we are left roughly one week to finish this project, this issue cannot be fixed right at the moment writing this document.

You shall follow the following steps in the order they are listed to prevent unknown errors from occurring. The following steps are performed in Vivado 2017 to generate the corresponding bitstream file from the source code.

Import all the files with .sv and .vh extension in the Sources folder. For convenience, you may create a new Vivado Project and simply copy the all the contents in the Sources folder into %ProjectName%\%ProjectName%.srcs\sources_1\new.

Import the constraint file in the Constraints File. Notice that this constraint works only for the model xc7a35tcsg324-1, Artix 7 made by Xilinx. You may need to modify the constraint file to adapt to other models. The detailed pin specification is listed in the next section.

Instantiate a Vivado IP Block Memory Generator with its name specified as blk_mem_gen_3. You shall select the Single Port ROM option in the Basic tab.

In the Port A Options tab you need to specify the Port A Width as 16 (which happens to be the size of a single pixel in ARGB 4/4/4/4 format), and Port A Depth as 25344. The size is predetermined by the size of the corresponding file. Untick the Primitive Output Register option to reduce the read latency to 1 clock cycle.

In Memory Initialization tab, you shall tick the Load Init File option, and load the Coe File from Source\assets\bkgnd.coe.

In the following asset loading procedures, we will only change the Port A Depth option and the Coe File specification. You shall repeat the above process with only these two parameters changed for the corresponding scenario.

Port A Depth: 3264

Coe File: Source\assets\bird_0.coe

Port A Depth: 3264

Coe File: Source\assets\bird_1.coe

Port A Depth: 240

Coe File: Source\assets\tube_1d.coe

In the file Sources\GAMESYS_GRAPH_PROC_S_PANEL.sv, you shall change the following code segments to match the corresponding paths of the font files on your computer.

initial begin
        $readmemh("%Absolute_Path%\\Sources\\fonts\\font_0.mem", font_lib, 0);
        $readmemh("%Absolute_Path%\\Sources\\fonts\\font_1.mem", font_lib, 1);
        $readmemh("%Absolute_Path%\\Sources\\fonts\\font_2.mem", font_lib, 2);
        $readmemh("%Absolute_Path%\\Sources\\fonts\\font_3.mem", font_lib, 3);
        $readmemh("%Absolute_Path%\\Sources\\fonts\\font_4.mem", font_lib, 4);
        $readmemh("%Absolute_Path%\\Sources\\fonts\\font_5.mem", font_lib, 5);
        $readmemh("%Absolute_Path%\\Sources\\fonts\\font_6.mem", font_lib, 6);
        $readmemh("%Absolute_Path%\\Sources\\fonts\\font_7.mem", font_lib, 7);
        $readmemh("%Absolute_Path%\\Sources\\fonts\\font_8.mem", font_lib, 8);
        $readmemh("%Absolute_Path%\\Sources\\fonts\\font_9.mem", font_lib, 9);
        $readmemh("%Absolute_Path%\\Sources\\fonts\\font_a.mem", font_lib, 10);
        $readmemh("%Absolute_Path%\\Sources\\fonts\\font_b.mem", font_lib, 11);
        $readmemh("%Absolute_Path%\\Sources\\fonts\\font_c.mem", font_lib, 12);
        $readmemh("%Absolute_Path%\\Sources\\fonts\\font_d.mem", font_lib, 13);
        $readmemh("%Absolute_Path%\\Sources\\fonts\\font_e.mem", font_lib, 14);
        $readmemh("%Absolute_Path%\\Sources\\fonts\\font_f.mem", font_lib, 15);
    end

You shall initialize the following clocking wizards with the corresponding name.

In Clocking Options tab, select MMCM and Frequency Synthesis, Phase Alignment and Jitter Optimization: Balanced.

In Output Clocks tab, enable only clk_out1 with Output Freq (MHz) Requested: 148.5, matching the clocking frequency required for VGA 1080p@60Hz output. In order to fetch the assets one clock ahead, you need to match the block memory clock with the VGA clock (this is just for convenience).

You need to set MAIN.sv as the top file. (Right click on the file to set it as the top file). Then use Flow Navigator to generate the corresponding bitstream file. There is also a pre-generated one for validation placed under the root folder (named MAIN.bit).

The following ports have their rightmost bit as LSB. For example, the VGA red signal is declared as wire [3:0] red, in which red[0] is the LSB.

Port	Direction	Width(bit)	Function Description
clk	input	1	Base Clock Signal (100 MHz)
btn_jmp	input	1	Jump Button
btn_h_level	input	1	Increase Level Button
btn_l_level	input	1	Decrease Level Button
reset	input	1	Reset Game
led_failed	output	1	Indicating Failure
led_level	output	8	Indicating Difficulty Level
led_score	output	1	Debug
led_jmp	output	1	Indicating whether the jump button is pressed and detected
led_pause	output	1	Indicating whether the game is paused
led_dest_1	output	8	Manipulating the 7-seg led display to indicate score
led_dest_2	output	8	Manipulating the 7-seg display to indicate position of the player
led_en	output	8	Manipulating the 7-seg display switches to display 8 digits
red	output	4	VGA Output Signal
green	output	4	VGA Output Signal
blue	output	4	VGA Output Signal
hsync	output	1	VGA hsync Signal
vsync	output	1	VGA vsync Signal

The system has three states: 1) Initialized (Or Reinitialized) and paused. 2) Failed and paused. 3) Running.

Users could interact with the system through 2 difficulty adjustment buttons, 1 jump button, and 1 reset button. Users could check the status of the game through either onboard LEDs or on-screen indicators.

When the jump button is pressed, the game will start and the player entity will jump up a specific height. Every time the jump button is pressed, the vertical velocity of the player entity will be reset to a specific value, resulting in the player jumping a certain height immediately regardless of its velocity in the last game frame. The player’s velocity decreases and will eventually be heading to the ground by the *gravity* implemented in the physical simulation subsystem. Displacements and accelerations are implemented according to the real physics laws (though without drag forces).

When the player entity collides with the wall (drawn on the screen with green color) or falls to the ground (the very bottom part on the screen), the system detects the failure through the score calculation & collision detection subsystem, terminates the current game and freezes everything, leaving the score panel (at the bottom of the screen) appearing as red (When the game is running, the score panel appears as green).

Difficulty adjustment buttons are used to switch the horizontal speed of the wall entities between different levels.

When the reset button is pressed, the game reinitializes, resets the score panel, re-randomizes all obstacles, and reset player’s attributes.

The obstacles (walls) appeared in the game have *randomized* vertical position and height (As long as they are generated or recycled, they will have newly assigned values). Random numbers are generated using Generalized Ring Oscillators and LHCAs.

The entire game is drawn using priority rendering. When a position in the canvas has multiple objects in its place, object with higher priority is rendered.

The game also displays a background (showing colored skies with randomized white clouds), a real-time on-screen score indicator, and all the game objects using either *cached bitmap* (implemented through Block Memory Generator IP Core) or positional judgement inside the system. The game has excellent details.

The game supports 1920 * 1080 @60Hz VGA output.