VHDL警告Xst:1293 FF/Latch的恒定值为0

Question

互联网上没有一个答案对我有效，因为我是VHDL的初学者。

我正在用vhdl制作一个带有按钮和LED的密码接口。我的程序按照预期正确地模拟。

基本上，我希望LED闪烁时输入错误的密码，但不断发光时，输入正确的密码。你可以看到，这在模拟中起作用。

模拟图像 (在模拟中先输入错误的密码，然后输入正确的密码)

综合时，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.
.
.
.

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正在被裁剪，但我需要它。变量ncount用于使用变量dcount创建4秒的延迟，而dcount用于创建0.5秒的延迟。如果没有变量ncount，我就不能创建4秒的延迟。

全部警告如下：

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 6 XC6SLX9 TQG144。求你帮帮我。

Answer 1

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(其值范围)

在变量中添加约束可以解决这个问题。

我的程序在将变量(如i、dcount、ncount)转换为信号后能够在没有任何警告的情况下进行合成，这一事实使我认为问题是If语句的范围。由于变量赋值操作在嵌套的if语句中，因此合成器没有发现所需范围内变量值的变化，而假定它具有恒定值。信号的范围比变量好得多。

然而，我上面提到的原因可能是错误的，因为我是初学者。但这是解决我问题的密码。

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。我会把所有的回应都提出来。我有很好的经历。谢谢你。