Question

我在CheckSyntax期间遇到以下代码的错误，我试过了。错误说：

"Line 48. parse error, unexpected VARIABLE Line 53. Undefined symbol 'InOutDetector'.
 Line 57. InOutDetector: Undefined symbol (last report in this block)".

你能让我知道我该如何解决这个问题？

这是我的代码的图片，因为我无法粘贴它。 https://www.dropbox.com/s/ay8pjq4ojoep6ry/RoomLightController.png?dl=0

entity Room_Light_Controller is
port (
        clk, sA, sB: IN STD_LOGIC;
                    sL:     OUT STD_LOGIC
    );
end Room_Light_Controller;

architecture Behavioral of Room_Light_Controller is
  -- assuming sensors are variables sA and sB, and lights switch is sL
 SIGNAL People                                    : INTEGER:=0;
 SIGNAL AllowNextCount                    : BIT:='0';

    --unsigned int People=0;                      -- counter for people inside the room
    --char AllowNextCount=0;              -- boolean indicating if allowing next count or not
    --short int InOutDetector;        -- 1 = entering; -1 = exiting
begin
    variable InOutDetectorDetector:   integer;
         process (clk)
                 begin
         if ((sA = '0') and (sB = '1')) then
             -- entering
             InOutDetector := 1;
         end if;
         if ((sA = '1') and (sb = '0')) then
             -- exiting
             InOutDetector := -1;
                     end if;
         if ((sA ='1') and (sB = '1') and (AllowNextCount = '1')) then
             -- only when both sensors are touched validate the people counter
             People := People+InOutDetector;
             -- count once then block counting until the same person has finished entering/exiting
             AllowNextCount <= '0';
         end if;
         if ((sA = '0') and (sB = '0')) then
             -- it gets 0;0 only when someone has finished entering/exiting
             -- pr at turn on; so now allow to counting again
             AllowNextCount <= '1';
                   end if;
         if (People > 0) then
                                      sL <= '1'; -- Turn/keep lights on as long as People greater than 0
         else
                                      sL <= '0'; -- otherwise, turn them off
         end if;
         end process;
end Behavioral;

Answer 1

在进程中声明变量并将其重命名为（InOutDetector）。您在流程中使用了（InOutDetector）。

然后，如果您想在clk上升沿运行该过程，请完成您的过程，例如以下代码：

process(clk)
   variable InOutDetector : integer;
begin
   if clk = '1' and clk'event then
      -- your code
   end if;
end process;

但是，如果您不想使用clk上升沿，只需使用您读取的参数完成灵敏度列表或在流程中检查它（sA，sB，AllowNextCount，People）并从流程中删除clk敏感度清单。

还要注意不完整的if语句。锁存器可能来自不完整的case或if语句。

Answer 2

除了错误Amir注意到名称不匹配并且变量声明在错误的位置，分配给People时还有一个错误：

library ieee;
use ieee.std_logic_1164.all;

entity Room_Light_Controller is
    port (
        clk, sA, sB:    in std_logic;
        sL:             out std_logic
    );
end entity Room_Light_Controller;

architecture Behavioral of Room_Light_Controller is
  -- assuming sensors are variables sA and sB, and lights switch is sL
    signal people:          integer :=  0;
    signal allownextcount:  bit     := '0';

    --unsigned int People=0;              -- counter for people inside the room
    --char AllowNextCount=0;              -- boolean indicating if allowing next count or not
    --short int InOutDetector;            -- 1 = entering; -1 = exiting
begin
    -- variable InOutDetectorDetector:   integer;
    process (clk)
        variable InOutDetector:   integer; -- as per Amir
    begin
        if sA = '0' and sB = '1' then
            -- entering
            InOutDetector := 1;
        end if;
        if sA = '1' and sb = '0' then
            -- exiting
            InOutDetector := -1;
        end if;
        if sA ='1' and sB = '1' and AllowNextCount = '1' then
            -- only when both sensors are touched validate the people counter
            People <= People + InOutDetector;  -- was :=, signal assignment
            -- count once then block counting until the same person has finished entering/exiting
            AllowNextCount <= '0';
        end if;
        if sA = '0' and sB = '0' then
            -- it gets 0;0 only when someone has finished entering/exiting
            -- pr at turn on; so now allow to counting again
            AllowNextCount <= '1';
        end if;
        if People > 0 then
            sL <= '1'; -- Turn/keep lights on as long as People greater than 0
        else
            sL <= '0'; -- otherwise, turn them off
        end if;
    end process;
end architecture Behavioral;

People是一个信号，需要信号分配符号（<=）而不是变量赋值符号（:=）。

在两次更改之后，VHDL设计规范进行了分析和阐述。

注意添加了一个context子句，使你的代码成为一个Minimal，Verifiable和Complete示例。

另请参阅帮助中心网页Minimal, Complete, and Verifiable example 最小和可读部分，

..使用一致的命名和缩进，并在需要时包含注释以解释部分代码。

如果要编译此代码，则可能需要约束整数。

为了执行效率，可以使用elsif合并所有独立的if语句。这在小型设计中几乎不是问题，但为sA和sB描述的二进制模式是互斥的（对于类型std_logic而言并非详尽无遗）。

您忽略了提供完整的错误消息，这些消息似乎是从XST输出的。从历史上看，推荐的设计流程包括仿真，如果没有其他目的，则可以从VHDL分析中提供更好的语法错误消息。

XST历来假定您正在处理一个没有语法错误的设计描述，并且在提供足够的错误消息方面非常明显。

错误消息前缀（例如ERROR：HDLParsers：1209）可以告诉您如何通过Xilinx的支持站点和/或文档找到问题。

VHDL语法问题

2 个答案: