我有一個D觸發器的VHDL代碼和一個結構上使用它的T觸發器:它包括一個D輸入,D輸入被T存儲爲Q,a時鐘。但是我的模擬給了我一個只有紅色直線「U」的輸出的波形。我認爲這是因爲從Q到D的反饋,並且在開始時未初始化。但我不知道如何寫它。這是代碼:使用VHDL中的D觸發器的T觸發器的測試臺
- 這是DFF:
library IEEE;
use IEEE.STD_LOGIC_1164.all;
entity d_flip_flop is
port(
clk : in STD_LOGIC;
din : in STD_LOGIC;
reset : in STD_LOGIC;
dout : out STD_LOGIC
);
end d_flip_flop;
architecture d_flip_flop_arc of d_flip_flop is
begin
dff : process (din,clk,reset) is
begin
if (reset='1') then
dout <= '0';
elsif (rising_edge (clk)) then
dout <= din;
end if;
end process dff;
end d_flip_flop_arc;
--TFF:
library IEEE;
use IEEE.STD_LOGIC_1164.all;
entity tff_using_dff is
port(
clk : in STD_LOGIC;
t : in STD_LOGIC;
reset : in STD_LOGIC;
dout : out STD_LOGIC
);
end tff_using_dff;
architecture tff_using_dff_arc of tff_using_dff is
component d_flip_flop is
port(
clk : in STD_LOGIC;
din : in STD_LOGIC;
reset : in STD_LOGIC;
dout : out STD_LOGIC
);
end component d_flip_flop;
signal ip : std_logic;
signal op : std_logic;
begin
ip <= op xor t ;
u0 : d_flip_flop port map (clk => clk,
din => ip,
reset => reset,
dout => op);
dout <= op;
end tff_using_dff_arc;
--and電流測試平臺:
library IEEE;
use IEEE.STD_LOGIC_1164.all;
entity T_FF_tb is
end T_FF_tb;
architecture T_FF_tb of T_FF_tb is
component tff_using_dff is
port(
clk : in STD_LOGIC;
t : in STD_LOGIC;
reset : in STD_LOGIC;
dout : out STD_LOGIC
);
end component;
signal clk,t,reset: std_logic:='0';
signal dout: std_logic:='0';
begin
U0: tff_using_dff port map(clk,t,reset,dout);
clk<=not clk after 5 ns;
t<= not t after 30 ns;
end T_FF_tb;