VHDL 警告 Xst:1293 FF/Latch 的常数值为 0

VHDL Warning Xst:1293 FF/Latch has a constant value of 0

None 互联网上的答案对我有用,因为我是 VHDL 的初学者。

我正在使用按钮和 LED 在 vhdl 中制作密码界面。 我的程序按预期正确模拟。

基本上,我希望 LED 在输入错误密码时闪烁,但在输入正确密码时持续发光。你可以看到,这在模拟中有效。

SIMULATION IMAGE (模拟时先输入错误密码再输入正确密码)

合成时,出现以下主要警告:

Optimizing unit <safehouse> ...
WARNING:Xst:1293 - FF/Latch <entry_pass.ncount_6> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.ncount_7> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
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.
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VHDL 代码是:

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;

entity safehouse is
    Port ( keyled : out  STD_LOGIC_VECTOR(0 TO 4);
              keypad : in STD_LOGIC_VECTOR(0 to 7);
              clk : in STD_LOGIC );
end safehouse;

architecture safehouse of safehouse is

signal temp : std_logic_vector(0 to 7) := "00000000";

begin

entry_pass: process(clk,keypad,temp)

    type integer_vector is array (0 to 3) of integer;
    variable i : integer := 0;
    constant passoriginal : integer_vector := (2,5,2,6);
    variable passcode : integer_vector := (0,0,0,0);
    variable dcount : integer := 0;
    variable ncount : integer := 0;

begin
    if (rising_edge(clk)) then

            keyled(4) <= '1';

            if i < 4 then

                keyled(0) <= '1';

                if (temp /= keypad) then
                    case keypad is
                        when "10001000" => 
                            passcode(i) := 1;
                            keyled(i+1) <= '1';
                            i := i + 1;
                        when "10000100" => 
                            passcode(i) := 2;
                            keyled(i+1) <= '1';
                            i := i + 1;
                        when "10000010" => 
                            passcode(i) := 3;
                            keyled(i+1) <= '1';
                            i := i + 1;
                        when "10000001" => 
                            passcode(i) := 10;
                            keyled(i+1) <= '1';
                            i := i + 1;
                        when "01001000" => 
                            passcode(i) := 4;
                            keyled(i+1) <= '1';
                            i := i + 1;
                        when "01000100" => 
                            passcode(i) := 5;
                            keyled(i+1) <= '1';
                            i := i + 1;
                        when "01000010" => 
                            passcode(i) := 6;
                            keyled(i+1) <= '1';
                            i := i + 1;
                        when "01000001" => 
                            passcode(i) := 11;
                            keyled(i+1) <= '1';
                            i := i + 1;
                        when "00101000" => 
                            passcode(i) := 7;
                            keyled(i+1) <= '1';
                            i := i + 1;
                        when "00100100" => 
                            passcode(i) := 8;
                            keyled(i+1) <= '1';
                            i := i + 1;
                        when "00100010" => 
                            passcode(i) := 9;
                            keyled(i+1) <= '1';
                            i := i + 1;
                        when "00100001" => 
                            passcode(i) := 12;
                            keyled(i+1) <= '1';
                            i := i + 1;
                        when "00011000" => 
                            passcode(i) := 14;
                            keyled(i+1) <= '1';
                            i := i + 1;
                        when "00010100" => 
                            passcode(i) := 0;
                            keyled(i+1) <= '1';
                            i := i + 1;
                        when "00010010" => 
                            passcode(i) := 15;
                            keyled(i+1) <= '1';
                            i := i + 1;
                        when "00010001" => 
                            passcode(i) := 13;
                            keyled(i+1) <= '1';
                            i := i + 1;
                        when others => 
                            keyled(4) <= '1';
                    end case;
                    temp <= keypad;
                end if;

            else

                if passcode = passoriginal then

                    dcount := dcount + 1;
                    if dcount >= 50000000 then

                        keyled <= ('1','1','1','1','1');

                        dcount := 1;
                        ncount := ncount + 1;

                        if ncount >= 8 then

                            i := 0;
                            passcode := (0,0,0,0);
                            keyled <= ('0','0','0','0','1');

                            ncount := 1;
                        end if;     
                    end if;

                else

                    dcount := dcount + 1;
                    if dcount >= 50000000 then
                        if (ncount rem 2) = 0 then

                            keyled <= ('1','1','1','1','1');

                        else

                            keyled <= ('0','0','0','0','1');

                        end if;
                        dcount := 1;
                        ncount := ncount + 1;

                        if ncount >= 8 then

                            i := 0;
                            keyled <= ('1','0','0','0','1');

                            ncount := 1;
                        end if;
                    end if;                                                                             
                end if;     
            end if;             
    end if;
end process;

end safehouse;

我知道变量 ncount 正在被修剪,但我需要它。 变量 ncount 用于创建 4 秒的延迟,使用变量 dcount 用于创建 0.5 秒的延迟。 没有变量 ncount 我无法创建 4 秒的延迟。

完整的警告是:

WARNING:Xst:1710 - FF/Latch <keyled_4> (without init value) has a constant value of 1 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.

Optimizing unit <safehouse> ...
WARNING:Xst:1293 - FF/Latch <entry_pass.ncount_6> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.ncount_7> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.ncount_8> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.ncount_11> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.ncount_9> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.ncount_10> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.ncount_14> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.ncount_12> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.ncount_13> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.ncount_17> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.ncount_15> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.ncount_16> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.ncount_20> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.ncount_18> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.ncount_19> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.ncount_23> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.ncount_21> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.ncount_22> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.ncount_26> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.ncount_24> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.ncount_25> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.ncount_29> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.ncount_27> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.ncount_28> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.ncount_30> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.ncount_31> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.dcount_26> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.dcount_29> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.dcount_27> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.dcount_28> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.dcount_30> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.dcount_31> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.i_3> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.i_4> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.i_5> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.i_6> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.i_7> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.i_8> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.i_9> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.i_10> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.i_11> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.i_12> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.i_13> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.i_14> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.i_15> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.i_16> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.i_17> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.i_18> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.i_19> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.i_20> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.i_21> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.i_22> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.i_23> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.i_24> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.i_25> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.i_26> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.i_27> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.i_28> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.i_29> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.i_30> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.i_31> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.ncount_4> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.ncount_3> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.
WARNING:Xst:1896 - Due to other FF/Latch trimming, FF/Latch <entry_pass.ncount_5> has a constant value of 0 in block <safehouse>. This FF/Latch will be trimmed during the optimization process.

我使用的FPGA开发板是:Xilinx Spartan 6 XC6SLX9 TQG144。 请帮帮我。

我自己解决了这个问题。谢谢大家。

用信号替换变量并添加约束(它们的值范围)

给变量添加约束可能会解决问题。

在将变量(如 i、dcount、ncount)更改为信号后,我的程序能够在没有任何警告的情况下进行综合,这一事实让我认为问题出在 Scope If 语句。由于对变量的赋值操作是在嵌套的 if 语句中进行的,因此合成器没有在所需范围内发现变量值的变化,并假定它具有常量值。信号的范围比变量好很多。

但是,由于我是初学者,所以我上面所说的原因可能是错误的。但这是解决我问题的代码。

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;

entity safehouse is
    Port ( keyled : out  STD_LOGIC_VECTOR(0 TO 4);
              keypad : in STD_LOGIC_VECTOR(0 to 7);
              clk : in STD_LOGIC );
end safehouse;

architecture safehouse of safehouse is

signal temp : std_logic_vector(0 to 7) := "00000000";
signal dcount : integer range 0 to 100000000 := 0;
signal ncount : integer range 0 to 10 := 0;
signal i : integer range 0 to 5;

begin

entry_pass: process(clk,keypad,temp,dcount,ncount,i)

    type integer_vector is array (0 to 3) of integer;
    constant passoriginal : integer_vector := (2,5,2,6);
    variable passcode : integer_vector := (0,0,0,0);

begin
    if (rising_edge(clk)) then

            keyled(4) <= '1';

            if i < 4 then

                keyled(0) <= '1';

                if (temp /= keypad) then
                    case keypad is
                        when "10001000" => 
                            passcode(i) := 1;
                            keyled(i+1) <= '1';
                            i <= i + 1;
                        when "10000100" => 
                            passcode(i) := 2;
                            keyled(i+1) <= '1';
                            i <= i + 1;
                        when "10000010" => 
                            passcode(i) := 3;
                            keyled(i+1) <= '1';
                            i <= i + 1;
                        when "10000001" => 
                            passcode(i) := 10;
                            keyled(i+1) <= '1';
                            i <= i + 1;
                        when "01001000" => 
                            passcode(i) := 4;
                            keyled(i+1) <= '1';
                            i <= i + 1;
                        when "01000100" => 
                            passcode(i) := 5;
                            keyled(i+1) <= '1';
                            i <= i + 1;
                        when "01000010" => 
                            passcode(i) := 6;
                            keyled(i+1) <= '1';
                            i <= i + 1;
                        when "01000001" => 
                            passcode(i) := 11;
                            keyled(i+1) <= '1';
                            i <= i + 1;
                        when "00101000" => 
                            passcode(i) := 7;
                            keyled(i+1) <= '1';
                            i <= i + 1;
                        when "00100100" => 
                            passcode(i) := 8;
                            keyled(i+1) <= '1';
                            i <= i + 1;
                        when "00100010" => 
                            passcode(i) := 9;
                            keyled(i+1) <= '1';
                            i <= i + 1;
                        when "00100001" => 
                            passcode(i) := 12;
                            keyled(i+1) <= '1';
                            i <= i + 1;
                        when "00011000" => 
                            passcode(i) := 14;
                            keyled(i+1) <= '1';
                            i <= i + 1;
                        when "00010100" => 
                            passcode(i) := 0;
                            keyled(i+1) <= '1';
                            i <= i + 1;
                        when "00010010" => 
                            passcode(i) := 15;
                            keyled(i+1) <= '1';
                            i <= i + 1;
                        when "00010001" => 
                            passcode(i) := 13;
                            keyled(i+1) <= '1';
                            i <= i + 1;
                        when others => 
                            keyled(4) <= '1';
                    end case;
                    temp <= keypad;
                end if;

            else

                if passcode = passoriginal then

                    dcount <= dcount + 1;
                    if dcount >= 50000000 then

                        keyled <= ('1','1','1','1','1');

                        dcount <= 1;
                        ncount <= ncount + 1;

                        if ncount >= 8 then

                            i <= 0;
                            passcode := (0,0,0,0);
                            keyled <= ('0','0','0','0','1');

                            ncount <= 1;
                        end if;     
                    end if;

                else

                    dcount <= dcount + 1;
                    if dcount >= 50000000 then
                        if (ncount rem 2) = 0 then

                            keyled <= ('1','1','1','1','1');

                        else

                            keyled <= ('0','0','0','0','1');

                        end if;
                        dcount <= 1;
                        ncount <= ncount + 1;

                        if ncount >= 8 then

                            i <= 0;
                            keyled <= ('1','0','0','0','1');

                            ncount <= 1;
                        end if;
                    end if;                                                                             
                end if;     
            end if;             
    end if;
end process;

end safehouse;

这是我在这个网站上的第一个问题。我会赞成每一个回应。我有一个很好的经历。谢谢。