交通信号灯+VHDL

交通信号灯是城市道路上的重要设施，VHDL是一种硬件描述语言，可以用于数字电路设计。因此，可以使用VHDL设计交通信号灯控制器。

以下是一个基于VHDL的交通信号灯控制器的示例代码：

entity traffic_light is
    port (
        clk : in std_logic;
        reset : in std_logic;
        north_south_red : out std_logic;
        north_south_yellow : out std_logic;
        north_south_green : out std_logic;
        east_west_red : out std_logic;
        east_west_yellow : out std_logic;
        east_west_green : out std_logic
    );
end traffic_light;

architecture Behavioral of traffic_light is
    type state_type is (north_south_go, north_south_prepare_to_stop, east_west_go, east_west_prepare_to_stop);
    signal current_state, next_state : state_type;
    signal timer : integer range 0 to 100000000;
begin
    process (clk, reset)
    begin
        if reset = '1' then
            current_state <= north_south_go;
            timer <= 0;
        elsif rising_edge(clk) then
            current_state <= next_state;
            case current_state is
                when north_south_go =>
                    north_south_red <= '0';
                    north_south_yellow <= '0';
                    north_south_green <= '1';
                    east_west_red <= '1';
                    east_west_yellow <= '0';
                    east_west_green <= '0';
                    timer <= timer + 1;
                    if timer = 50000000 then
                        next_state <= north_south_prepare_to_stop;
                        timer <= 0;
                    end if;
                when north_south_prepare_to_stop =>
                    north_south_red <= '0';
                    north_south_yellow <= '1';
                    north_south_green <= '0';
                    east_west_red <= '1';
                    east_west_yellow <= '0';
                    east_west_green <= '0';
                    timer <= timer + 1;
                    if timer = 10000000 then
                        next_state <= east_west_go;
                        timer <= 0;
                    end if;
                when east_west_go =>
                    north_south_red <= '1';
                    north_south_yellow <= '0';
                    north_south_green <= '0';
                    east_west_red <= '0';
                    east_west_yellow <= '0';
                    east_west_green <= '1';
                    timer <= timer + 1;
                    if timer = 50000000 then
                        next_state <= east_west_prepare_to_stop;
                        timer <= 0;
                    end if;
                when east_west_prepare_to_stop =>
                    north_south_red <= '1';
                    north_south_yellow <= '0';
                    north_south_green <= '0';
                    east_west_red <= '0';
                    east_west_yellow <= '1';
                    east_west_green <= '0';
                    timer <= timer + 1;
                    if timer = 10000000 then
                        next_state <= north_south_go;
                        timer <= 0;
                    end if;
            end case;
        end if;
    end process;
end Behavioral;

该代码使用有限状态机实现了交通信号灯的控制逻辑。在每个状态下，控制器会设置相应的LED灯的状态，并在一定时间后转移到下一个状态。