四人抢答器显示系统怎么用74LS48来设置
VHDL\u8bed\u8a00\u7f16\u62a2\u7b54\u5668 \u56db\u4eba\u62a2\u7b54\u5668library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
entity QDQ4R is
port(sta:in std_logic;
clk :in std_logic;
rst :in std_logic;
a,b,c,d :in std_logic;
lb :out std_logic;
t_limit :out std_logic_vector(3 downto 0);
led :out std_logic_vector(3 downto 0);
seg :out std_logic_vector(3 downto 0));
end QDQ4R;
architecture bhe of QDQ4R is
signal tem :std_logic_vector(3 downto 0);
signal scq :std_logic;
signal s :std_logic;
signal t :std_logic;
signal ns :std_logic;
signal s_sta :std_logic;
constant w1 :std_logic_vector:="0001";
constant w2 :std_logic_vector:="0010";
constant w3 :std_logic_vector:="0011";
constant w4 :std_logic_vector:="0100";
begin
tem<=d&c&b&a;
s<=a or b or c or d;
ns<=not(a or b or c or d);
p1: process(sta,ns)
begin
if sta='1' then
s_sta<='1';
elsif(ns'event and ns='1')then
s_sta<='0';
end if;
end process p1;
p2: process(rst,s_sta,s,t)
begin
if rst='1' then
led<="0000";
elsif(s'event and s='1')then
if (s_sta='1' and t='1') then
case tem is
when "0001"=> led<="0001";
when "0010"=> led<="0010";
when "0100"=> led<="0100";
when "1000"=> led<="1000";
when others=> led<="0000";
end case;
end if;
end if;
end process p2;
p3: process(clk,s_sta)
variable lb_cnt :std_logic_vector(1 downto 0):="10";
begin
if(s='1') then
if (clk='1' and clk'event) then
if lb_cnt>"00" then
lb<=clk;
lb_cnt:=lb_cnt+1;
else
lb_cnt:="10";
lb<='0';
end if;
end if;
end if;
end process p3;
p4: process(s)
begin
if(rst='1') then
seg<="0000";
elsif(s'event and s='1') then
case tem is
when "0001" =>seg<=w1;
when "0010" =>seg<=w2;
when "0100" =>seg<=w3;
when "1000" =>seg<=w4;
when others =>seg<="0000";
end case;
end if;
end process p4;
p5: process(clk,s_sta)
variable s_time :std_logic_vector(3 downto 0):="1010";
begin
if(clk'event and clk='1') then
if(sta='1' and s_time>"0000") then
t<='1';
s_time:=s_time-1;
t_limit<=s_time;
else
s_time:="1010";
t<='0';
end if;
end if;
end process p5;
end bhe;
\u8bf7\u56de\u5934\uff0c
\u6211\u75af\u72c2\u4e86
\u53d8\u6210\u4e00\u4e2a\u9ed1\u70b9\uff0c\u7136\u540e\u6d88\u5931\u3002\u6211\u6361\u8d77
\u800c\u6f02\u4eae\u662f\u4e00\u4e2a\u516c\u8ba4\u7684\u8868\u793a\u8d5e\u6210\u7684\u4fda\u8bed
\u5fae\u6cab\u5f62\u6210\u7684\u94bb\u77f3\u591a\u5230\u65e0\u6570\uff0c
\u53ef\u4ee5\u5bf9\u7740\u5c71\u5ddd\u6cb3\u6d77\u54c8\u54c8
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bc1951b8d79ec89118469730
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