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使用了状态机，增加了可读性和用户体验。
1 library IEEE; 2 use IEEE.STD_LOGIC_1164.ALL; 3 use IEEE.STD_LOGIC_ARITH.ALL; 4 use IEEE.STD_LOGIC_UNSIGNED.ALL; 5 entity main is 6 Port ( clk : in STD_LOGIC; 7 rst : in STD_LOGIC; 8 led : out STD_LOGIC_VECTOR (5 downto 0); 9 an : out STD_LOGIC_VECTOR (3 downto 0); 10 seg : out STD_LOGIC_VECTOR (6 downto 0)); 11 end main; 12 13 architecture Behavioral of main is 14 signal sclk: std_logic; 15 signal now_state,next_state: std_logic_vector(1 downto 0); 16 signal ledt: std_logic_vector(5 downto 0); 17 signal led_state: std_logic_vector(5 downto 0); 18 signal cnt0:integer:=0; 19 signal cnt1:integer:=0; 20 signal cnt2:integer:=0; 21 signal disp_main:integer:=15; 22 signal disp_branch:integer:=12; 23 signal display:integer; 24 signal time_main:integer; 25 signal time_main_l:integer; 26 signal time_main_h:integer; 27 signal time_branch:integer; 28 signal time_branch_l:integer; 29 signal time_branch_h:integer; 30 signal time_long:integer:=12; 31 constant red_time:integer:=16; 32 constant green_time:integer:=12; 33 constant yellow_time:integer:=3; 34 signal an_sel: integer; 35 begin 36 led(0)<=led_state(0); 37 led(1)<=led_state(1); 38 led(2)<=led_state(2); 39 led(3)<=led_state(3); 40 led(4)<=led_state(4); 41 led(5)<=led_state(5); 42 process(clk) 43 begin 44 if(clk'event and clk='1') then 45 if(cnt0=25000000)then 46 cnt0<=0; 47 sclk<=not sclk; 48 else 49 cnt0<=cnt0+1; 50 end if; 51 end if; 52 end process; 53 54 process(clk) 55 begin 56 if(clk'event and clk='1') then 57 if(cnt2=50000) then 58 cnt2<=0; 59 if(an_sel=3)then 60 an_sel<=0; 61 else 62 an_sel<=an_sel+1; 63 end if; 64 else 65 cnt2<=cnt2+1; 66 end if; 67 end if; 68 end process; 69 70 process(now_state) 71 begin 72 case now_state is 73 when "00"=>time_long<=green_time;ledt<="010001";next_state<="01"; 74 when "01"=>time_long<=yellow_time;ledt<="100001";next_state<="11"; 75 when "11"=>time_long<=green_time;ledt<="001010";next_state<="10"; 76 when "10"=>time_long<=yellow_time;ledt<="001100";next_state<="00"; 77 when others=>time_long<=green_time;ledt<="010001";next_state<="00"; 78 end case; 79 end process; 80 81 process(rst,sclk) 82 begin 83 if(rst='1') then 84 now_state<="00"; 85 led_state<="000000"; 86 elsif(sclk'event and sclk='1') then 87 led_state(0)<=ledt(0); 88 led_state(1)<=ledt(1); 89 led_state(2)<=ledt(2); 90 led_state(3)<=ledt(3); 91 led_state(4)<=ledt(4); 92 led_state(5)<=ledt(5); 93 if(cnt1=time_long) then 94 now_state<=next_state; 95 cnt1<=0; 96 else 97 cnt1<=cnt1+1; 98 end if; 99 end if; 100 end process; 101 102 process(sclk,led_state,rst,cnt1) 103 begin 104 if (rst='1')then 105 disp_main<=red_time; 106 disp_branch<=green_time; 107 elsif(sclk'event and sclk='1') then 108 if(disp_main=0)then 109 if(led_state(0)='1')then 110 disp_main<=green_time; 111 elsif(led_state(1)='1')then 112 disp_main<=yellow_time; 113 elsif(led_state(2)='1')then 114 disp_main<=red_time; 115 end if; 116 else 117 disp_main<=disp_main - 1; 118 end if; 119 if(disp_branch=0)then 120 if(led_state(3)='1')then 121 disp_branch<=green_time; 122 elsif(led_state(4)='1')then 123 disp_branch<=yellow_time; 124 elsif(led_state(5)='1')then 125 disp_branch<=red_time; 126 end if; 127 else 128 disp_branch<=disp_branch - 1; 129 end if; 130 end if; 131 end process; 132 133 process(an_sel,disp_main,disp_branch) 134 begin 135 time_main<=disp_main; 136 if(time_main>=10)then 137 time_main_h<=1; 138 time_main_l<=time_main-10; 139 else 140 time_main_h<=0; 141 time_main_l<=time_main; 142 end if; 143 time_branch<=disp_branch; 144 if(time_branch>=10)then 145 time_branch_h<=1; 146 time_branch_l<=time_branch-10; 147 else 148 time_branch_h<=0; 149 time_branch_l<=time_branch; 150 end if; 151 case an_sel is 152 when 0=>an<="1110";display<=time_main_l; 153 when 1=>an<="1101";display<=time_main_h; 154 when 2=>an<="1011";display<=time_branch_l; 155 when 3=>an<="0111";display<=time_branch_h; 156 when others=>null; 157 end case; 158 case display is 159 when 0=>seg<=b"0000001"; 160 when 1=>seg<=b"1001111"; 161 when 2=>seg<=b"0010010"; 162 when 3=>seg<=b"0000110"; 163 when 4=>seg<=b"1001100"; 164 when 5=>seg<=b"0100100"; 165 when 6=>seg<=b"0100000"; 166 when 7=>seg<=b"0001111"; 167 when 8=>seg<=b"0000000"; 168 when 9=>seg<=b"0000100"; 169 when others=>null; 170 end case; 171 end process; 172 end Behavioral;