93、顺序电路设计示例：VHDL 实现

顺序电路设计示例：VHDL 实现

1. T - Bird 尾灯状态机

T - Bird 尾灯状态机使用 VHDL 进行设计。该状态机的状态转换与特定状态图定义一致，采用输出编码状态分配，利用了每个状态下尾灯输出值不同的特点。

以下是其 VHDL 代码：

entity Vtbird is 
  port ( CLOCK, RESET, LEFT, RIGHT, HAZ: in STD_LOGIC;
         LIGHTS: buffer STD_LOGIC_VECTOR (1 to 6) );
end;
architecture Vtbird_arch of Vtbird is
constant IDLE: STD_LOGIC_VECTOR (1 to 6) := "000000";
constant L3  : STD_LOGIC_VECTOR (1 to 6) := "111000";
constant L2  : STD_LOGIC_VECTOR (1 to 6) := "110000";
constant L1  : STD_LOGIC_VECTOR (1 to 6) := "100000";
constant R1  : STD_LOGIC_VECTOR (1 to 6) := "000001";
constant R2  : STD_LOGIC_VECTOR (1 to 6) := "000011";
constant R3  : STD_LOGIC_VECTOR (1 to 6) := "000111";
constant LR3 : STD_LOGIC_VECTOR (1 to 6) := "1111