Cyclone IV EP4CE22上VHDL乒乓游戏显示更新异常问题

在Cyclone IV FPGA（EP4CE22）上使用VHDL实现乒乓游戏，采用ModelSim作为仿真工具。完成基础游戏逻辑开发后，遇到显示无法正确更新的问题：球和paddle位置固定或闪烁，疑似时序或显示更新方式存在问题。

VHDL代码实现 #

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;

-- entity start
entity PingPongGame is
    Port ( clk : in STD_LOGIC;
           reset : in STD_LOGIC;
           vga_hsync : out STD_LOGIC;
           vga_vsync : out STD_LOGIC;
           vga_red, vga_green, vga_blue : out STD_LOGIC_VECTOR(7 downto 0);
           paddle_up, paddle_down : in STD_LOGIC);
end PingPongGame;
-- entity end

--architecture start
architecture Behavioral of PingPongGame is
    signal h_counter : integer range 0 to 799 := 0;
    signal v_counter : integer range 0 to 524 := 0;
    signal row, col : integer range 0 to 639 := 0;
    signal ball_x, ball_y, paddle_y : integer range 0 to 479 := 0;
    signal ball_x_velocity, ball_y_velocity : integer := 1;
    signal ball_color, paddle_color, background_color : STD_LOGIC_VECTOR(7 downto 0);
    signal ball_visible, paddle_visible : STD_LOGIC := '0';
    
begin
    -- VGA timing process
    VGA_TIMING: process (clk, reset)
    begin
        if reset = '1' then
            h_counter <= 0;
            v_counter <= 0;
            row <= 0;
            col <= 0;
        elsif rising_edge(clk) then
            if h_counter < 799 then
                h_counter <= h_counter + 1;
            else
                h_counter <= 0;
                if v_counter < 524 then
                    v_counter <= v_counter + 1;
                else
                    v_counter <= 0;
                end if;
            end if;
        end if;
    end process;

    -- Synchronize VGA signals
    vga_hsync <= '1' when (h_counter < 96) else '0';
    vga_vsync <= '1' when (v_counter < 2) else '0';

    -- Calculate row and col positions
    row <= v_counter - 2;
    col <= h_counter - 96;

    -- Ball, paddle, and background colors
    ball_color <= "11110000"; -- Example color for the ball (adjust as needed)
    paddle_color <= "00001111"; -- Example color for the paddle (adjust as needed)
    background_color <= "00000000"; -- Example background color (adjust as needed)

    -- Game logic for ball movement and collision detection
    process (clk)
    begin
        if rising_edge(clk) then
            if row = ball_y and col = ball_x then
                ball_visible <= '1';
            else
                ball_visible <= '0';
            end if;
            
            if row >= paddle_y and row < paddle_y + 32 and col = 10 then
                paddle_visible <= '1';
            else
                paddle_visible <= '0';
            end if;
            
            if ball_visible = '1' then
                ball_x <= ball_x + ball_x_velocity;
                ball_y <= ball_y + ball_y_velocity;

                -- Collision detection with top and bottom boundaries
                if ball_y <= 0 or ball_y >= 472 then
                    ball_y_velocity <= -ball_y_velocity; -- Reverse vertical velocity
                end if;

                -- Collision detection with paddle
                if col = 10 and paddle_visible = '1' then
                    ball_x_velocity <= -ball_x_velocity; -- Reverse horizontal velocity
                end if;

                -- Scoring logic (ball goes out of bounds)
                if ball_x <= 0 or ball_x >= 632 then
                    ball_x <= 320;
                    ball_y <= 240;
                    ball_x_velocity <= 1; -- Reset velocity
                    ball_y_velocity <= 1; -- Reset velocity
                end if;
            end if;

            -- Paddle control
            if paddle_up = '1' and paddle_y > 0 then
                paddle_y <= paddle_y - 1;
            elsif paddle_down = '1' and paddle_y < 448 then
                paddle_y <= paddle_y + 1;
            end if;
        end if;
    end process;

    -- Output VGA colors based on game logic
    process (ball_visible, paddle_visible)
    begin
        if ball_visible = '1' then
            vga_red <= ball_color;
            vga_green <= ball_color;
            vga_blue <= ball_color;
        elsif paddle_visible = '1' then
            vga_red <= paddle_color;
            vga_green <= paddle_color;
            vga_blue <= paddle_color;
        else
            vga_red <= background_color;
            vga_green <= background_color;
            vga_blue <= background_color;
        end if;
    end process;
    
end Behavioral;
--architecture end

已尝试的排查步骤 #

• 检查VGA时序信号，确认无误；
• 验证球与paddle的移动逻辑，运行符合预期；
• 确认VGA控制器针对Cyclone IV FPGA配置正确。

问题更新 #

问题已解决
经详细排查，该显示更新异常问题并非出自VHDL代码本身，而是与FPGA配置及ModelSim仿真相关。

内容的提问来源于stack exchange，提问作者user19026118