t_control.vhd

完成空调的温度控制功能。当大于一定温度时

library ieee;
use ieee.std_logic_1164.all;

entity t_control is
	port(t_low,t_high : in std_logic;
		Rd,clk : in std_logic;
		ch : out std_logic_vector(1 downto 0));
end t_control;

architecture behave of t_control is
	type s_m is (s0,s1,s2);
	signal cur_state : s_m;
	signal next_state : s_m;
	signal tt : std_logic_vector(1 downto 0);
	
	begin
	tt <= t_low & t_high;
	
	
	func1 : process(tt,cur_state)
		begin
		case cur_state is
		when s0 => if tt = "00" then next_state <= s0;
				elsif tt = "01" then next_state <= s1;
				else next_state <= s2;
			   end if;
				
				
		when s1 => if	tt = "00" then next_state <= s0;
				elsif tt = "01" then next_state <= s1;
				else next_state <= s2;
			   end if;
				
				
		when s2 => if	tt = "00" then next_state <= s0;
				elsif tt = "01" then next_state <= s1;
				else next_state <= s2;
			   end if ;
		end case;
		end process;
		
	reg : process(clk,Rd)
		begin
		if Rd = '0' then cur_state <= s0;
		elsif clk'event and clk = '1' then cur_state <= next_state;
		end if ;
	      end process;
	      
	func2 : process(cur_state)
		begin
		case cur_state is
		when s0 => ch <= "00";
		when s1 => ch <= "10";
		when s2 => ch <= "01";
		end case;
		end process;
	end behave;