vhdl - 找到用于信号和常量值警告的 1 位锁存器

Question

两天来我一直在尝试调试此 VHDL 代码，但我就是看不出错误在哪里。这是代码:

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;


entity SSDDriver is
    Port ( cp : in std_logic;
              iin : in std_logic;
              an : buffer std_logic_vector (3 downto 0);
              --7=a, 6=b ...
              segments: out std_logic_vector (7 downto 0));
end SSDDriver;

architecture Behavioral of SSDDriver is
    signal cpo : std_logic;
    --broj BCD znamenki
    constant BCD_NUMBERS : integer := 4;
    --broj bitova ulaznog broja
    constant BITS : integer := 14;
    --broj kodiran BCD-om
    signal BCDNumber : std_logic_vector (BCD_NUMBERS*4-1 downto 0) := (others => '0');
    signal BCDForDecoder: std_logic_vector (3 downto 0);
    signal number: integer range  0 to 9999;
begin
    decoder: entity BCDToSSD port map (bcd => BCDForDecoder, segm => segments (7 downto 1));
    counter: entity djelitelj generic map (COUNTTO => 25000) port map (cpIn => cp, CpOut=> cpo);
    --tocka je uvijek ugasena
    segments(0) <= '1';

    process (iin)
    begin
        if iin='1' then
            number<=3245;
        else
            number<=1111;
        end if;
    end process;

    SwitchDisplay: process (cpo)
    begin
        if rising_edge(cpo) then
            if an="0111" then
                an<="1011";
                BCDForDecoder<=BCDNumber(11 downto 8);
            elsif an="1011" then
                an<="1101";
                BCDForDecoder<=BCDNumber(7 downto 4);
            elsif an="1101" then
                an<="1110";
                BCDForDecoder<=BCDNumber(3 downto 0);
            else
                an<="0111";
                BCDForDecoder<=BCDNumber(15 downto 12);
            end if;
        end if;
    end process SwitchDisplay;

    DoubleDabble: process (number)
        variable num : std_logic_vector (BITS-1 downto 0);
        variable bcd : std_logic_vector (BCD_NUMBERS*4-1 downto 0) := (others => '0');
        variable old_number: integer range 0 to 9999;
    begin
        if number/= old_number then
            num := conv_std_logic_vector(number, BITS);

            for i in 0 to BITS-1 loop
                bcd(BCD_NUMBERS*4-1 downto 1) := bcd(BCD_NUMBERS*4-2 downto 0);  
                bcd(0) := num(BITS-1);
                num(BITS-1 downto 1) := num(BITS-2 downto 0);
                num(0) :='0';

                if(i < BITS-1  and bcd(3 downto 0) > "0100") then 
                    bcd(3 downto 0) := bcd(3 downto 0) + "0011";
                end if;

                if(i < BITS-1 and bcd(7 downto 4) > "0100") then 
                    bcd(7 downto 4) := bcd(7 downto 4) + "0011";
                end if;

                if(i < BITS-1 and bcd(11 downto 8) > "0100") then 
                    bcd(11 downto 8) := bcd(11 downto 8) + "0011";
                end if;

                if(i < BITS-1 and bcd(15 downto 12) > "0100") then 
                    bcd(15 downto 12) := bcd(15 downto 12) + "0011";
                end if;
            end loop;
            BCDNumber <= bcd;
        else

        end if;

        old_number := number;
    end process DoubleDabble;
end Behavioral;

这里是生成的警告:

WARNING:Xst:2734 - Property "use_dsp48" is not applicable for this technology. WARNING:Xst:1780 - Signal > is never used or assigned. WARNING:Xst:737 - Found 1-bit latch for signal . WARNING:Xst:737 - Found 1-bit latch for signal . WARNING:Xst:737 - Found 1-bit latch for signal . WARNING:Xst:737 - Found 1-bit latch for signal . WARNING:Xst:737 - Found 1-bit latch for signal . WARNING:Xst:737 - Found 1-bit latch for signal . WARNING:Xst:737 - Found 1-bit latch for signal . WARNING:Xst:737 - Found 1-bit latch for signal . WARNING:Xst:737 - Found 1-bit latch for signal . WARNING:Xst:737 - Found 1-bit latch for signal . WARNING:Xst:737 - Found 16-bit latch for signal . WARNING:Xst:737 - Found 1-bit latch for signal . WARNING:Xst:737 - Found 1-bit latch for signal . WARNING:Xst:737 - Found 1-bit latch for signal . WARNING:Xst:737 - Found 1-bit latch for signal . WARNING:Xst:737 - Found 1-bit latch for signal . WARNING:Xst:2734 - Property "use_dsp48" is not applicable for this technology. WARNING:Xst:1426 - The value init of the FF/Latch bcd_0 hinder the constant cleaning in the block SSDDriver. WARNING:Xst:1293 - FF/Latch has a constant value of 0 in block . WARNING:Xst:1293 - FF/Latch has a constant value of 0 in block . WARNING:Xst:1293 - FF/Latch has a constant value of 0 in block . WARNING:Xst:1293 - FF/Latch has a constant value of 0 in block . WARNING:Xst:1293 - FF/Latch has a constant value of 0 in block . WARNING:Xst:1293 - FF/Latch has a constant value of 0 in block . WARNING:Xst:1293 - FF/Latch has a constant value of 0 in block . WARNING:Xst:1293 - FF/Latch has a constant value of 0 in block . WARNING:Xst:1293 - FF/Latch has a constant value of 0 in block . WARNING:Xst:1293 - FF/Latch has a constant value of 0 in block . WARNING:Xst:1293 - FF/Latch has a constant value of 0 in block . WARNING:Xst:1293 - FF/Latch has a constant value of 0 in block . WARNING:Xst:1293 - FF/Latch has a constant value of 0 in block . WARNING:Xst:1293 - FF/Latch has a constant value of 0 in block . WARNING:Xst:1293 - FF/Latch has a constant value of 0 in block . WARNING:Xst:1293 - FF/Latch has a constant value of 0 in block . WARNING:Xst:1710 - FF/Latch

and so on ...

由于这些警告，当我实现该模块时，我在 4 个 7 段显示器上只显示 0000。

此 VHDL 代码应采用整数变量(范围从 0 到 9999)并使用 4 个 7 段显示器显示该数字 ...

Answer 1

转换为同步设计的另一种方法是使您的逻辑真正异步。

在 DoubleDabble 过程中，只需注释最外层的 if 语句，这样您的 BCD 转换逻辑就会一直运行，然后看看它能把您带到哪里。您的逻辑不需要先前的整数值 (old_number)，它是“if number/= old_number”比较(不使用时钟信号和同步逻辑)使合成器适合。