一、总体设计思想
电子拔河游戏机是一种能容纳甲乙双方参赛游戏电路。由一排发光二极管表示拔河的“电子绳”。由甲乙双方通过按纽开关使发光二极管向一方的终点延伸，当延伸到某方的最后一个发光二极管时， 则该方获胜，连续比赛多局以定胜负。
1.基本原理
本电路要求使用9个发光二极管，开机后只有中间一个发亮，此即拔河的中心点。游戏双方各持一个按钮，迅速地、不断地按动，产生脉冲，谁按得快，亮点就向谁的方向移动，每按一次，亮点移动一次。亮点移到任一方终端二极管时，这一方就获胜，此时双方按钮均无作用，输出保持，只有复位后才使亮点恢复到中心。最后用数码管显示获胜者的盘数。
由设计内容可知，首先需要一个十进制的计数器，用于对双方按钮的次数计数，并通过译码器显示在数码管上。设计要求用50MHz的频率，而设计用到的是1K Hz的频率，所以要设计一个程序进行分频。其次，显视控制部分设计要求在发光二极管上显示游戏状态，双方每按十次，亮点向先按十次移动一次，对脉冲进行计数，每十次移一位。需接入一个清零端 ，用于复位。再次，运用VHDL程序语言进行各个模块的程序编写，控制电路的正常运行。最后，将以上程序组装起来，就可得到所需要的拔河游戏机
library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
entity bahe is
port (a,b,rst,clk:in std_logic;
sg,led:out std_logic_vector(8 downto 0);
bt:out std_logic_vector(7 downto 0));
end bahe;
----------------------------------
architecture one of bahe is
component cnt10
port (clk,rst,en:std_logic;
cout:out std_logic;
cq:out std_logic_vector(3 downto 0));
end component;
component scan
port (clk :in std_logic;
a1, a2,a3,b1,b2,b3:in std_logic_vector(3 downto 0);
sg:out std_logic_vector(8 downto 0);
bt: out std_logic_vector(7 downto 0));
end component;
component lmov
port (kl ,kr:in std_logic_vector(3 downto 0) ;
led:out std_logic_vector(8 downto 0);
en : out std_logic;
rst:in std_logic);
end component;
signal e,f,ca1,ca2,cb1,cb2:std_logic;
signal cqa1,cqa2,cqa3,cqb1,cqb2,cqb3:std_logic_vector(3 downto 0);
begin
u1: cnt10 port map (en=>e,rst=>rst,clk=>a,cout=>ca1,cq=>cqa1);
u2: cnt10 port map (en=>e,rst=>rst,clk=>ca1,cout=>ca2,cq=>cqa2);
u3: cnt10 port map (en=>e,rst=>rst,clk=>ca2,cq=>cqa3);
u4: cnt10 port map (en=>e,rst=>rst,clk=>b,cout=>cb1,cq=>cqb1);
u5: cnt10 port map (en=>e,rst=>rst,clk=>cb1,cout=>cb2,cq=>cqb2);
u6: cnt10 port map (en=>e,rst=>rst,clk=>cb2,cq=>cqb3);
u7: scan port map (a1=>cqa1,a2=>cqa2,a3=>cqa3,b1=>cqb1,
b2=>cqb2,b3=>cqb3,clk=>clk,sg=>sg,bt=>bt);
u8:lmov port map (en=>e,kl=>cqa2,kr=>cqb2,rst=>rst,led=>led);
end architecture one;
library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
entity cnt10 is
port(clk,rst,en:std_logic;
cout:out std_logic;
cq:out std_logic_vector(3 downto 0));
end;
architecture one of cnt10 is
begin
process(clk,rst,en)
variable cqi:std_logic_vector(3 downto 0);
begin
if rst='1' then
cqi:=(others=>'0');
elsif clk'event and clk='1' then
if en='1' then
if cqi<9 then cqi:=cqi+1;
else cqi :=(others=>'0');
end if ;
end if;
end if;
if c qi=9 then cout<='0' ;
else cout<='1';
end if;
cq<=cqi;
end process;
end;
library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
entity scan is
port (clk :in std_logic;
a1,a2,a3,b1,b2,b3:in std_logic_vector(3 downto 0);
sg:out std_logic_vector(8 downto 0);
bt: out std_logic_vector(7 downto 0));
end;
architecture one of scan is
signal cnt4:std_logic_vector(2 downto 0);
signal a:std_logic_vector(3 downto 0);
signal clk1:std_logic;
begin
p1:process(cnt4)
begin
case cnt4 is
when "000"=>bt<="10000000";a<=a1;
when "001"=>bt<="01000000";a<=a2;
when "010"=>bt<="00100000";a<=a3;
when "011"=>bt<="00000100";a<=b1;
when "100"=>bt<="00000010";a<=b2;
when "101"=>bt<="00000001";a<=b3;
when others=>bt<="00000000";
end case ;
end process p1;
---------------------------------
p2:process (clk)
variable ct:integer range 0 to 50000;
begin
if clk'event and clk='1' then --1000HZ
if ct<49999 then
ct:=ct+1;
clk1<='0';
else
ct:=0;
clk1<='1';
end if;
end if;
end process p2;
process(clk1)
begin
if clk1'event an d clk1='1' then
if cnt4<5 then
cnt4<=cnt4+1;
else
cnt4<="000";
end if;
end if;
end process;
------------------------------------
process (a)
begin
case a is
when "0000"=>sg<="100000000";
when "0001"=>sg<="111110001";
when "0010"=>sg<="001001000";
when "0011"=>sg<="001100000";
when "0100"=>sg<="000110010";
when "0101"=>sg<="000100100";
when "0110"=>sg<="000000100";
when "0111"=>sg<="111110000";
when "1000"=>sg<="000000000";
when "1001"=>sg<="100011111";
when "1010"=>sg<="000100100";
when "1011"=>sg<="000011000";
when "1100"=>sg<="010001100";
when "1101"=>sg<="001001000";
when "1110"=>sg<="001000000";
when "1111"=>sg<="000011111";
when others=>null;
end case ;
end process;
end;
library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
entity lmov is
port (kl ,kr:in std_logic_vector(3 downto 0) ;
led:out std_logic_vector(8 downto 0);
en : out std_logic;
rst:in std_logic);
end ;
architecture one of lmov is
begin
process(rst,kl,kr)
begin
if rst='1' then led<="111101111";en<='1';
elsif kl-kr=1 then led<="111011111";en<='1';
elsif kl-kr=2 then led<="110111111";en<='1';
elsif kl-kr=3 then led<="101111111";en<='1';
elsif kl-kr=4 then led<="011111111";en<='0';
elsif kr-kl=1 then led<="111110111";en<='1';
elsif kr-kl=2 then led<="111111011";en<='1' ;
elsif kr-kl=3 then led<="111111101";en<='1';
elsif kl-kr=4 then led<="111111110";en<='0';
elsif kr-kl=0 then led<="111101111";en<='1';
else null;
end if;
end process;
end;
