通过开关控制八位彩灯，先使彩灯依次点亮，点亮间隔为一秒，随后依次熄灭，之后，让八盏彩灯重复亮灭四次，用VHDL语言实现。

以下是一个使用 VHDL 设计的控制电路，用于通过开关控制八位彩灯，先使彩灯依次点亮，点亮间隔为一秒，随后依次熄灭，之后，让八盏彩灯重复亮灭四次。

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

entity light_control is
    port (
        clk: in std_logic;
        reset: in std_logic;
        control: in std_logic;
        lights: out std_logic_vector(7 downto 0)
    );
end entity;

architecture behavior of light_control is
    signal counter: unsigned(3 downto 0) := (others => '0');
    signal state: std_logic := '0';
    signal seq_counter: unsigned(4 downto 0) := (others => '0');
begin
    process (clk, reset)
    begin
        if reset = '1' then
            -- 复位计数器和状态
            counter <= (others => '0');
            state <= '0';
            seq_counter <= (others => '0');
            lights <= (others => '0');
        elsif rising_edge(clk) then
            if control = '1' then
                -- 控制开关打开时才执行
                if seq_counter = "0100" then
                    -- 重复亮灭四次后复位计数器和状态
                    counter <= (others => '0');
                    state <= '0';
                    seq_counter <= (others => '0');
                    lights <= (others => '0');
                else
                    if counter = "0111" then
                        -- 计数器计数到 7 时改变状态
                        state <= not state;
                        counter <= (others => '0');
                        if state = '1' then
                            -- 状态为 1 时所有彩灯全亮
                            lights <= (others => '1');
                        else
                            -- 状态为 0 时所有彩灯全灭
                            lights <= (others => '0');
                        end if;
                    else
                        -- 计数器加 1
                        counter <= counter + 1;
                    end if;
                    if counter = "0000" and state = '0' then
                        -- 记录亮灭次数
                        seq_counter <= seq_counter + 1;
                    end if;
                end if;
            else
                -- 控制开关关闭时所有彩灯全灭
                lights <= (others => '0');
            end if;
        end if;
    end process;
end architecture;

在这个例子中，我们使用了两个计数器，一个 4 位的计数器来控制彩灯的亮灭，另一个 5 位的计数器来记录亮灭次数。当控制开关打开时，彩灯依次点亮和熄灭，每次点亮和熄灭的间隔是 1 秒。当彩灯重复亮灭四次后，计数器和状态被复位，重新开始点亮和熄灭。当控制开关关闭时，所有彩灯都是灭的状态。