vhdl交通灯

VHDL（VHSIC Hardware Description Language）是一种硬件描述语言，可以用于设计数字电路和系统。下面是一个简单的 VHDL 代码示例，用于模拟交通灯的控制器：

entity traffic_controller is
    port (
        clk: in std_logic;
        reset: in std_logic;
        green: out std_logic;
        yellow: out std_logic;
        red: out std_logic
    );
end traffic_controller;

architecture traffic_arch of traffic_controller is
    type state_type is (s1, s2, s3);
    signal current_state, next_state: state_type;
begin
    process (clk, reset)
    begin
        if reset = '1' then
            current_state <= s1;
        elsif rising_edge(clk) then
            current_state <= next_state;
        end if;
    end process;
    
    process (current_state)
    begin
        case current_state is
            when s1 =>
                green <= '1';
                yellow <= '0';
                red <= '0';
                next_state <= s2;
            when s2 =>
                green <= '0';
                yellow <= '1';
                red <= '0';
                next_state <= s3;
            when s3 =>
                green <= '0';
                yellow <= '0';
                red <= '1';
                next_state <= s1;
        end case;
    end process;
end traffic_arch;

这个代码实现了一个包含三个状态的有限状态机，用于控制交通灯的三种状态：绿灯，黄灯和红灯。在每个状态下，输出不同的控制信号，控制交通灯的颜色。通过时钟信号和复位信号控制状态迁移，实现交通灯的正常工作。