3级比较器

Question

我想做一个具有一定容差的比较器。

我已经了解了两个信号之间的差异（希望如此）现在我想比较一个数字（稍后会决定）并分别转发相等不相等和可接受的信号。

我

让评论部分帮助您理解我的方法。

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use ieee.numeric_std.all;
use ieee.std_logic_unsigned.all;
entity threelvlcomp is
    port ( 
        input1    : in  std_logic_vector(15 downto 0);
        input2    : in  std_logic_vector(15 downto 0);
        outputeq  : out std_logic;
        outputneq : out std_logic
    );
end threelvlcomp;
architecture Behavioral of threelvlcomp is
signal temp : std_logic_vector(15 downto 0);
signal dif  : std_logic_vector(15 downto 0);
--CONSTANT limit      : INTEGER := 1;
begin
  dif <= std_logic_vector(unsigned(input1)) + std_logic_vector(unsigned(not(input2) + 1));
  --dif <= input1 + not(input2)+ "1";
  --dif <= input1 + not(input2) + "1"; 
    outputeq <= '1' when dif < '1'  else
            '0';
        outputneq <= '1' when dif > '1' else
            '0';

-- IF dif = "0000" THEN
-- outputeq   <= '1';
-- outputneq  <= '0';
-- outputacc  <= '0';
--ELSE IF dif /= '0' THEN
-- outputeq   <= '0';
-- outputneq  <= '1';
--outputacc  <= '0';
--ELSE IF dif <= "0.5"; 
-- outputeq   <= '0';
-- outputneq  <= '0';
-- outputacc  <= '1';
--ELSE
-- outputeq   <= '1';
-- outputneq  <= '1';
-- outputacc  <= '1';
--END IF; 
--  If(dif = 0) then outputeq <='1'; else outputeq <= '0';end if;
--  If(dif >= -0.5 and dif <= 0.5) then outputacc <='1'; else outputacc <= '0';end if;
--  If(dif /= 0) then outputneq <='1' else outputneq <= '0';end if;
end Behavioral;

Answer 1

我还没有测试过这段代码。但在我看来，这就是你想做的。它至少应该可以帮助您解决已签名/未签名的问题。

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use ieee.numeric_std.all;
--use ieee.std_logic_unsigned.all; --do not use this it is confusing you
entity threelvlcomp is
    port ( 
        input1    : in  std_logic_vector(15 downto 0);
        input2    : in  std_logic_vector(15 downto 0);
        outputeq  : out std_logic;
        outputneq : out std_logic
    );
end threelvlcomp;
architecture Behavioral of threelvlcomp is
signal temp : unsigned(15 downto 0);
signal dif  : signed(16 downto 0);
--CONSTANT limit      : INTEGER := 1;
begin
-- you want a signed number here so we need to signed extend with a zero
  dif <= (signed('0'input1)) + (not signed('0'&input2)) + 1; 
  --dif <= input1 + not(input2)+ "1";
  --dif <= input1 + not(input2) + "1"; 
    outputeq <= '1' when dif < 1  else
            '0';
        outputneq <= '1' when dif > 1 else
            '0';
end Behavioral;