在实验板8*8点阵稳定显示红色心形图案，实验板输入时钟选50MHz，实验板用EPM1270T144C5芯片。根据以上题目提供能在Quartus中运行的VHDL代码

以下是一个简单的VHDL代码示例，实现了在8x8点阵上稳定显示红色心形图案。

library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;

entity heart_display is
    port (
        clk : in std_logic;
        rst : in std_logic;
        led : out std_logic_vector(7 downto 0)
    );
end entity;

architecture rtl of heart_display is
    signal row : unsigned(2 downto 0);
    signal col : unsigned(2 downto 0);
    signal counter : unsigned(23 downto 0) := (others => '0');
    signal pattern : std_logic_vector(63 downto 0) := x"3C42818181423C00";
begin

    process (clk, rst)
    begin
        if (rst = '1') then
            counter <= (others => '0');
            row <= x"0";
            col <= x"0";
        elsif rising_edge(clk) then
            if (counter = to_unsigned(500000, 24) - 1) then
                counter <= (others => '0');
                col <= col + 1;
                if (col = "1000") then
                    col <= x"0";
                    row <= row + 1;
                    if (row = "1000") then
                        row <= x"0";
                    end if;
                end if;
            else
                counter <= counter + 1;
            end if;
        end if;
    end process;

    with row select
        led <= pattern(to_integer(unsigned(col))) & "00000000" when "000",
               pattern(to_integer(unsigned(col)) + 8) & "00000000" when "001",
               pattern(to_integer(unsigned(col)) + 16) & "00000000" when "010",
               pattern(to_integer(unsigned(col)) + 24) & "00000000" when "011",
               pattern(to_integer(unsigned(col)) + 32) & "00000000" when "100",
               pattern(to_integer(unsigned(col)) + 40) & "00000000" when "101",
               pattern(to_integer(unsigned(col)) + 48) & "00000000" when "110",
               pattern(to_integer(unsigned(col)) + 56) & "00000000" when "111",
               (others => '0') when others;

end architecture;

该代码中使用了一个计数器来控制LED点阵中的行和列扫描，同时根据扫描到的行来选择相应的图案。其中`pattern`变量存储了心形图案的二进制表示形式。请注意，该代码仅供参考，可能需要根据具体实验板和LED点阵的接口进行修改。