七段显示器上写数字的简单过程的问题

Question

我是初学者，但仍然不敢相信我无法编写如此简单的代码来工作。 我有 Digilent Nexys2 FPGA，编程 xilinx ISE 我的目标是在两个不同的七段显示器上打印数字“2”和“1”（我想用眼睛看到“21”。A、B、C、D、E、F、G、P 是显示器的led（kathodes），AN0和AN1是显示器的阳极，0亮）。

我试图在那里投资的逻辑是，FPGA 将如此快速地重复这个“过程”，以至于我的眼睛只能检测到灯亮。 我认为我应该将 clk 放入进程敏感度列表的原因是每次时钟发生变化时，它都会进入进程并执行我的命令，对吗？ 我在这里犯了什么逻辑错误？ 我试图做出 if else 语句，其中 IFrising_edge (clk) then "1" 将显示 else "2" 但它仍然导致一些错误.. 到底是什么？我应该让这个过程计时吗？

这是我想合成它时收到的警告

WARNING:Xst:647 - Input <clk> is never used. This port will be preserved and left unconnected if it belongs to a top-level block or it belongs to a sub-block and the hierarchy of this sub-block is preserved. 

这是我在尝试生成编程位文件时收到的警告

WARNING:PhysDesignRules:367 - The signal <clk_IBUF> is incomplete. The signal does not drive any load pins in the design.
WARNING:Par:288 - The signal clk_IBUF has no load.  PAR will not attempt to route this signal.
WARNING:Par:283 - There are 1 loadless signals in this design. This design will cause Bitgen to issue DRC warnings.
WARNING:PhysDesignRules:367 - The signal <clk_IBUF> is incomplete. The signal does not drive any load pins in the design.

和

这是 UCF- 文件：

NET "clk" LOC = B8;
NET "A" LOC = L18;
NET "B" LOC = F18;
NET "C" LOC = D17;
NET "D" LOC = D16;
NET "E" LOC = G14;
NET "F" LOC = J17;
NET "G" LOC = H14;
NET "P" LOC = C17;
NET "AN0" LOC = F17;
NET "AN1" LOC = H17;
NET "AN2" LOC = C18;
NET "AN3" LOC = F15;

这里是代码本身：

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;

entity disp is
    Port ( 
        clk : in STD_LOGIC;
        A : out  STD_LOGIC;
      B : out  STD_LOGIC;
      C : out  STD_LOGIC;
      D : out  STD_LOGIC;
      E : out  STD_LOGIC;
      F : out  STD_LOGIC;
        G : out  STD_LOGIC;
        P : out  STD_LOGIC;
        AN0 : out  STD_LOGIC;
        AN1 : out  STD_LOGIC;
        AN2 : out  STD_LOGIC;
        AN3 : out  STD_LOGIC
    );
end disp;
-- main idea: writing "21" on seven segment display.
architecture BEHAV of disp is
begin
    process (clk)
    begin
        --writing '1' ( AN0 is on )
        AN0 <='0';
        AN1 <='1';
        AN2 <='1';
        AN3 <='1';
        A <='1';
        B <='0';
        C <='0';
        D <='1';
        E <='1';
        F <='1';
        G <='1';
        P <='1';
        --writing '2' ( AN1 is on )
        AN0 <='1';
        AN1 <='0';
        AN2 <='1';
        AN3 <='1';
        A <='0';
        B <='0';
        C <='1';
        D <='0';
        E <='0';
        F <='1';
        G <='0';
        P <='1';
    end process;
end BEHAV;

Answer 1

仅将时钟放在敏感度列表中是不够的。你需要一个 if 语句

If rising_edge (clk) then --where all assingments here End if;

但这还不够。您还需要更好地弄清楚七段的刷新逻辑。我没有时间，否则我也会告诉你的。

Answer 2

所以， Morten 先生和 Adeel 是对的。 Morten 的代码是正确的，但它“发生”得如此之快，以至于眼睛无法检测到，所以看起来 2 放在了 1 上。所以我添加了计数器，这是代码。

显示数字的速度取决于常数“速度”

这里是主要代码本身，等待您的回复（我还能做些什么来让这更简单？）

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;

    entity disp is
    Port ( 
        SW : in STD_LOGIC; 
        rst : in STD_LOGIC;
        clk : in STD_LOGIC;
        led : out STD_LOGIC;
        A : out  STD_LOGIC;
        B : out  STD_LOGIC;
        C : out  STD_LOGIC;
        D : out  STD_LOGIC;
        E : out  STD_LOGIC;
        F : out  STD_LOGIC;
        G : out  STD_LOGIC;
        P : out  STD_LOGIC;
        AN0 : out  STD_LOGIC;
        AN1 : out  STD_LOGIC;
        AN2 : out  STD_LOGIC;
        AN3 : out  STD_LOGIC
    );
    end disp;

architecture BEHAV of disp is

    constant bitwidth : integer := 32; 
    constant Speed : integer := 10; 
    signal   carry : std_logic_vector (bitwidth downto 0);
    signal   counter, counter_reg : std_logic_vector (bitwidth-1 downto 0) :=(others => '0');
    constant value_one : std_logic_vector (bitwidth-1 downto 0) :="00000000000000000000000000000001";
    signal drive_an : std_logic :='0';

    component adder is
        Port ( 
            C_in : in  STD_LOGIC;
            A : in  STD_LOGIC;
            B : in  STD_LOGIC;
            C_out : out  STD_LOGIC;
            Sum : out  STD_LOGIC;
            SW : in STD_LOGIC);
    end component; 

begin

    carry(0) <= '0';
    g_counter: for N in 0 to bitwidth-1 
    generate    FOUR_ADDER: adder port map (
        C_in => carry(N),   A => counter_reg(N), B => value_one(N), C_out => carry(N+1), Sum => counter(N), SW => SW);
    end generate;     
    led <= carry(bitwidth);

    process (clk,rst) begin 
        if rst = '1' then 
            counter_reg <= (others => '0'); 
        elsif rising_edge(clk) then
            counter_reg <= counter; 
            if counter_reg (Speed)= '1' then
                drive_an <= not drive_an; 
                counter_reg <= (others => '0'); 
                if drive_an = '0' then
                    AN0 <= '0';         
                    AN1 <= '1';         
                    AN2 <= '1';         
                    AN3 <= '1';         
                    A   <= '1';         
                    B   <= '0'; 
                    C   <= '0';         
                    D   <= '1';         
                    E   <= '1';         
                    F   <= '1';         
                    G   <= '1';         
                    P   <= '1';
                else
                    AN0 <= '1';         
                    AN1 <= '0';         
                    AN2 <= '1';         
                    AN3 <= '1';         
                    A   <= '0';         
                    B   <= '0';         
                    C   <= '1';         
                    D   <= '0';         
                    E   <= '0';         
                    F   <= '1';         
                    G   <= '0';         
                    P   <= '1';
                end if;
            end if;     
        end if;
    end process; 
end BEHAV;

如果有人需要测试它： 这是加法器的代码

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;

entity adder is
    Port ( 
        C_in : in  STD_LOGIC;
        A : in  STD_LOGIC;
        B : in  STD_LOGIC;
        C_out : out  STD_LOGIC;       
        Sum : out  STD_LOGIC;     
        SW : in STD_LOGIC
    );
end adder;


architecture Behavioral of adder is
begin
    Sum <= C_in xor (a xor (b xor SW));
    C_out <= (a and (b xor SW)) or (C_in and (a xor (b xor SW)));
end Behavioral;

这是 UCF 文件

NET "clk" LOC = B8;
NET "A" LOC = L18;
NET "B" LOC = F18;
NET "C" LOC = D17;
NET "D" LOC = D16;
NET "E" LOC = G14;
NET "F" LOC = J17;
NET "G" LOC = H14;
NET "P" LOC = C17;
NET "AN0" LOC = F17;
NET "AN1" LOC = H17;
NET "AN2" LOC = C18;
NET "AN3" LOC = F15;
NET "led" LOC = J14;