你的满意是我的目的

有问题可以留贴，有空给解答。。。

有问题，必解答。。。。

我准备用可编程器件 做几个 有创意的案例 不要传统的数字钟 密码锁 交通灯等 比如 用点阵显示简单动画 这类的…… 麻烦给出出建议

比如说我写了两个子程序，程序A是八段数码管1，2，3，4，5这样变，程序B是5，4，3，2，1这样变，然后我想根据情况执行，比如我按下一个键A，这时候就执行程序A，按下键B就执行程序B，我该用什么语句写这个？

一个按键选择嘛，程序A，B单独同时工作，只是你的按键选择数码管输出程序A还是程序B的值

不知道为什么不在这个帖子里留问题，有问题必解答

八位数码管扫描显示程序，要求显示12345678 间隔四秒显示56789ABC 间隔四秒显示3456789A 再隔4秒显示
456789AB 我这里有12345678显示的程序如下
LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
USE IEEE.STD_LOGIC_UNSIGNED.ALL;
ENTITY chenyongqiang IS
PORT ( CLK : IN STD_LOGIC;
SG : OUT STD_LOGIC_VECTOR(6 DOWNTO 0); --段控制信号输出
BT : OUT STD_LOGIC_VECTOR(7 DOWNTO 0) );--位控制信号输出
END;
ARCHITECTURE one OF chenyongqiang IS
SIGNAL CNT8 : STD_LOGIC_VECTOR(2 DOWNTO 0);
SIGNAL A : INTEGER RANGE 0 TO 15;
BEGIN
P1: PROCESS( CNT8 )
BEGIN
CASE CNT8 IS
WHEN "000" => BT <= "00000001" ; A <= 1 ;
WHEN "001" => BT <= "00000010" ; A <= 2 ;
WHEN "010" => BT <= "00000100" ; A <= 3 ;
WHEN "011" => BT <= "00001000" ; A <= 4 ;
WHEN "100" => BT <= "00010000" ; A <= 5 ;
WHEN "101" => BT <= "00100000" ; A <= 6 ;
WHEN "110" => BT <= "01000000" ; A <= 7 ;
WHEN "111" => BT <= "10000000" ; A <= 8 ;
WHEN OTHERS => NULL ;
END CASE ;
END PROCESS P1;
P2: PROCESS(CLK)
BEGIN
IF CLK'EVENT AND CLK = '1' THEN CNT8 <= CNT8 + 1;
END IF;
END PROCESS P2 ;
P3: PROCESS( A ) --译码电路
BEGIN
CASE A IS
WHEN 0 => SG <= "0111111"; WHEN 1 => SG <= "0000110";
WHEN 2 => SG <= "1011011"; WHEN 3 => SG <= "1001111";
WHEN 4 => SG <= "1100110"; WHEN 5 => SG <= "1101101";
WHEN 6 => SG <= "1111101"; WHEN 7 => SG <= "0000111";
WHEN 8 => SG <= "1111111"; WHEN 9 => SG <= "1101111";
WHEN 10 => SG <= "1110111"; WHEN 11 => SG <= "1111100";
WHEN 12 => SG <= "0111001"; WHEN 13 => SG <= "1011110";
WHEN 14 => SG <= "1111001"; WHEN 15 => SG <= "1110001";
WHEN OTHERS => NULL ;
END CASE ;
END PROCESS P3;
END;

有免费解答问题，咋不能问。。。

楼主麻烦看一下程序是什么问题，谢谢！
---------------hugong
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;
entity test_yunsuan is
Port ( CLK : in STD_LOGIC;
disvaluein : in STD_LOGIC_VECTOR (3 downto 0);
disvalueout0 : out STD_LOGIC_VECTOR (3 downto 0);
disvalueout1 : out STD_LOGIC_VECTOR (3 downto 0));
end test_yunsuan;
architecture ben of test_yunsuan is
signal A:std_logic_vector(7 downto 0):="00000000";
signal B0:std_logic_vector(7 downto 0):="00000000";
signal B1:std_logic_vector(7 downto 0):="00000000";
signal X:std_logic_vector(7 downto 0):="00000000";
begin
process(CLK)
variable flag:std_logic;
begin
IF CLK' EVENT AND CLK='1' THEN
case disvaluein is
when "1101" =>B0<=B0&A;
flag:='1';
when "1110" =>B0<=B0&A;
flag:='0';
when "1111" =>B1<=B1&A;
if flag='1' then
X<=(((B0(7)&B0(6)&B0(5)&B0(4))+(B1(7)&B1(6)&B1(5)&B1(4)))*"1010")+(B0(3)&B0(2)&B0(1)&B0(0))+(B1(3)&B1(2)&B1(1)&B1(0));
else X<=((B0(7)&B0(6)&B0(5)&B0(4))*"1010")-((B1(7)&B1(6)&B1(5)&B1(4))*"1010")+(B0(3)&B0(2)&B0(1)&B0(0))-(B1(3)&B1(2)&B1(1)&B1(0));
end if;
when others =>A<=A&disvaluein;
X<=X&disvaluein;
end case;
END IF;
end process;
end ben;
错误信息：Error (10327): VHDL error at test_yunsuan.vhd(33): can't determine definition of operator ""+"" -- found 5 possible definitions
程序中的这一句这一句：
X<=(((B0(7)&B0(6)&B0(5)&B0(4))+(B1(7)&B1(6)&B1(5)&B1(4)))*"1010")+(B0(3)&B0(2)&B0(1)&B0(0))+(B1(3)&B1(2)&B1(1)&B1(0));

你这个是库的问题，无法决定你的加法器的运算，并且你的程序这样写得比较有问题，你把这几个库实现什么功能看一下吧，你就知道怎么修改了

听说十五个字可以得经验，我来试试，顺便帮卤煮顶一下，卤煮不用谢

大神想问下 这个循环哪里出错了 （n位加法器）
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use ieee.std_logic_arith.all;
use ieee.std_logic_unsigned.all;
entity adder is
generic(N:integer);
Port ( cin: in STD_LOGIC;
a,b: in STD_LOGIC_vector(N downto 1);
c:out std_logic_vector(N downto 1);
cout:out std_logic
);
end adder;
architecture behaviour of adder is
signal m:std_logic_vector(N-1 downto 1);
begin
c(1) <= a(1) xor b(1) xor cin;
m(1) <= (a(1) AND b(1)) OR (a(1) AND cin) OR (b(1) AND cin);
for i in 2 TO N-1 loop
c(i) <= a(i) XOR b(i) XOR m(i-1);
m(i) <= (a(i)AND b(i)) OR (m(i-1) AND a(i)) OR (m(i-1) AND b(i));
end loop;
c(N) <= a(N) XOR b(N) XOR m(N-1);
cout <= (a(N) AND b(N)) OR (a(N)AND m(N-1)) OR (b(N) AND m(N-1));
end behaviour;