git.zerfleddert.de Git - raggedstone/blob - heartbeat/source/heartbeat.vhd

   1 library ieee;
   2
   3 use ieee.std_logic_1164.all;
   4 use ieee.std_logic_unsigned.all;
   5
   6 entity heartbeat is
   7 generic (
   8         divider : std_logic_vector(31 downto 0) := "00000000001111101111000101001000"
   9 );
  10
  11 port (
  12         clk_i : in std_logic;
  13         nrst_i : in std_logic;
  14         led2_o : out std_logic;
  15         led3_o : out std_logic;
  16         led4_o : out std_logic;
  17         led5_o : out std_logic;
  18         led6_o : out std_logic;
  19         led7_o : out std_logic;
  20         led8_o : out std_logic;
  21         led9_o : out std_logic
  22 );
  23
  24 end heartbeat;
  25
  26 architecture rtl of heartbeat is
  27 begin
  28
  29 process(clk_i, nrst_i)
  30 variable counter : std_logic_vector(31 downto 0);
  31 variable state : std_logic_vector(7 downto 0) := "00000001";
  32 variable direction : std_logic := '0';
  33 begin
  34
  35 if (rising_edge(clk_i)) then
  36         if nrst_i = '0' then
  37                 counter := (others => '0');
  38         else
  39                 led2_o <= state(0);
  40                 led3_o <= state(1);
  41                 led4_o <= state(2);
  42                 led5_o <= state(3);
  43                 led6_o <= state(4);
  44                 led7_o <= state(5);
  45                 led8_o <= state(6);
  46                 led9_o <= state(7);
  47                 counter := counter + 1;
  48                 if counter = divider then
  49                         if state(3) = '1' then
  50                                 direction := '1';
  51                         end if;
  52
  53                         if state(0) = '1' then
  54                                 direction := '0';
  55                         end if;
  56
  57                         if direction = '0' then
  58                                 state(7 downto 1) := state(6 downto 0);
  59                                 state(0) := '0';
  60                         else
  61                                 state(6 downto 0) := state(7 downto 1);
  62                                 state(7) := '0';
  63                         end if;
  64                         counter := (others => '0');
  65                 end if;
  66         end if;
  67 end if;
  68 end process;
  69 end architecture;