105 lines
3.6 KiB
VHDL
105 lines
3.6 KiB
VHDL
library ieee;
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use ieee.std_logic_1164.all;
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use ieee.numeric_std.all;
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entity scrolling_controller is
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port(
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clk : in std_logic;
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rst : in std_logic;
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on_off : in std_logic;
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cnt_start : out std_logic;
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cnt_done : in std_logic;
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next_char : out std_logic;
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hex_char : in std_logic_vector(4 downto 0);
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seg_data : out std_logic_vector(3 downto 0);
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seg_off : out std_logic;
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seg_shift : out std_logic;
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seg_write : out std_logic;
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seg_clear : out std_logic
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);
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end entity scrolling_controller;
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architecture Behavioral of scrolling_controller is
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type state_type is (s_off, s_wait, s_update);
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signal state : state_type;
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begin
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process(clk)
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begin
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if clk'event and clk='1' then
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if rst = '1' then
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state <= s_off;
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seg_clear <= '1';
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cnt_start <= '0';
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next_char <= '0';
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seg_data <= (others => '0');
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seg_off <= '0';
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seg_shift <= '0';
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seg_write <= '0';
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else
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case state is
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when s_off =>
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if on_off = '0' then
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state <= s_off;
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seg_shift <= '0';
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seg_write <= '0';
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seg_clear <= '0';
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cnt_start <= '0';
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next_char <= '0';
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else
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state <= s_update;
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seg_data <= hex_char(3 downto 0);
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seg_shift <= '1';
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seg_write <= '1';
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seg_clear <= '0';
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seg_off <= hex_char(4);
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cnt_start <= '1';
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next_char <= '1';
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end if;
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when s_wait =>
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if on_off = '1' then
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state <= s_off;
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seg_clear <= '1';
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cnt_start <= '0';
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next_char <= '0';
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elsif cnt_done = '0' then
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state <= s_wait;
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seg_shift <= '0';
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seg_write <= '0';
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seg_clear <= '0';
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cnt_start <= '0';
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next_char <= '0';
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else -- cnt_cone = '1'
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state <= s_update;
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seg_shift <= '0';
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seg_write <= '0';
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seg_clear <= '0';
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cnt_start <= '1';
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next_char <= '1';
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end if;
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when s_update =>
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if on_off = '0' then
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state <= s_wait;
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seg_data <= hex_char(3 downto 0);
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seg_shift <= '1';
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seg_write <= '1';
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seg_clear <= '0';
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seg_off <= hex_char(4);
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cnt_start <= '0';
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next_char <= '0';
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else
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state <= s_off;
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seg_clear <= '1';
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cnt_start <= '0';
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next_char <= '0';
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end if;
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end case;
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end if;
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end if;
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end process;
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end Behavioral;
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