我正在尝试在我自己的项目中使用LCD项目，但事实并非如此 完全理解这个项目，尤其是计数器，例如count1和count2 如果需要，我可以提供数据表！ 我希望我能对此得到澄清，我理解当计数器达到一定数量时会发生什么，但我不明白的是这个数字代表的是什么！ 我认为值得一提的是FPGA中使用的时钟是50MHz
代码是同伴
library ieee;
use ieee.std_logic_1164.all;
entity display is
port( clk : in std_logic;
rst : in std_logic;
byte_ready : in std_logic;
RS : out std_logic;
RW : out std_logic;
E : out std_logic;
DB : out std_logic_vector(7 downto 0);
rxdata : in std_logic_vector(7 downto 0) );
end entity display;
architecture rtl of display is
signal cnt : integer range 0 to 1000000; -- init counter
signal cnt2 : integer range 0 to 50000000; -- counter that resets every time byte i recieved
begin
clk_gen : process(clk, cnt, rst)
begin
if (rst = '0') then
cnt <= 0;
cnt2 <= 0;
else
if rising_edge(clk) and cnt < 1000000 then
cnt <= cnt + 1;
elsif rising_edge(clk) and cnt = 1000000 then
if (byte_Ready = '1') then
cnt2 <= 0;
end if;
if (cnt2 < 5000000) then
cnt2 <= cnt2 + 1;
end if;
end if;
end if;
end process clk_gen;
p_main : process(clk, rst)
begin
if (rst = '1') then
if rising_edge(clk) then
case cnt is -- INIT
when 100000 =>
RS <= '0';
RW <= '0';
E <= '1';
DB <= "00111000"; -- function set --kan ändras till 00111011 western eurpean #2
when 140000 =>
E <= '0';
when 150000 =>
E <= '1';
DB <= "00001011"; -- display off
when 190000 =>
E <= '0';
when 200000 =>
E <= '1';
DB <= "00000001"; -- display clear
when 300000 =>
E <= '0';
when 350000 =>
E <= '1';
DB <= "00000110"; -- entry mode
when 390000 =>
E <= '0';
when 400000 =>
E <= '1';
DB <= "00000010"; -- home command
when 440000 =>
E <= '0';
when 450000 =>
E <= '1';
DB <= "00001111"; -- display on
when 490000 =>
E <= '0';
when 500000 =>
RS <= '0';
E <= '1';
DB <= "00010000"; -- cursor shift left
when 550000 =>
E <= '0';
when 600000 =>
RS <= '1';
E <= '1';
DB <= "10100000"; -- output space
when 650000 =>
E <= '0';
when 700000 =>
RS <= '0';
E <= '1';
DB <= "00010000"; -- cursor shift left
when 750000 =>
E <= '0';
when others => null;
end case;
if (rxdata = "01111111") then -- if input is backspace
case cnt2 is
when 300000 =>
RS <= '0';
E <= '1';
DB <= "00010000"; -- cursor shift left
when 350000 =>
E <= '0';
when 400000 =>
RS <= '1';
E <= '1';
DB <= "10100000"; -- output space
when 450000 =>
E <= '0';
when 500000 =>
RS <= '0';
E <= '1';
DB <= "00010000"; -- cursor shift left
when 550000 =>
E <= '0';
when others => null;
end case;
elsif (rxdata = "00001101") then -- if input is enter
case cnt2 is
when 300000 =>
RS <= '0';
E <= '1';
DB <= "11000000"; -- go to second row
when 350000 =>
E <= '0';
when others => null;
end case;
else
case cnt2 is
when 300000 =>
RS <= '1';
E <= '1';
DB <= rxdata; -- output character
when 350000 =>
E <= '0';
when others => null;
end case;
end if;
end if;
end if;
end process p_main;
end architecture rtl;