CONSTANT T2:std_logic <= ’0’;
时间: 2023-11-03 20:05:53 浏览: 20
这是一个VHDL语言中的常量声明,声明了一个名为T2的std_logic类型的常量,其值为'0'。std_logic类型是VHDL中表示信号值的一种类型,它可以表示多个值,包括逻辑0、逻辑1、高阻态、未定义等。常量是在程序中定义的一个固定值,在程序执行过程中不会改变。在这个例子中,常量T2的值为逻辑0,也就是二进制的"00"。
相关问题
这段代码报错clk_out1没有声明怎么修改:LIBRARY IEEE; USE IEEE.STD_LOGIC_1164.ALL; PORT(clk:IN STD_LOGIC; clk_out1:out STD_LOGIC; clk_out10:OUT STD_LOGIC); END free_4; ARCHITECTURE fwm OF free_3 IS CONSTANT m : INTEGER:= 25000000; CONSTANT n : INTEGER:= 2500000; SIGNAL tmp :STD_LOGIC; SIGNAL tnp :STD_LOGIC; BEGIN PROCESS(clk,tmp) VARIABLE cout : INTEGER:=0; BEGIN IF clk'EVENT AND clk='1'THEN cout:=cout+1; IF cout<= THEN tmp<='0'; ELSIF cout<m*2 THEN tmp<='1'; ELSE cout:=0; END IF; END IF; END PROCESS; clk_cout1<=tmp; PROCESS(clk, tnp) VARIABLE cout : INTEGER:=0; BEGIN IF clk'EVENT AND clk='1' THEN cout:=cout+1; IF cout<=n THEN tnp<='0'; ELSIF cout<n*20 THEN tnp<='1'; ELSE cout:=0; END IF; END IF; END PROCESS; clk_out10<=tnp; END fwm;
在代码中,`clk_cout1` 出现在了 PORT 中,但是在 ARCHITECTURE 中没有定义,因此会报错。需要在 ARCHITECTURE 中定义 `clk_cout1` 信号,例如:
```
ARCHITECTURE fwm OF free_3 IS
CONSTANT m : INTEGER:= 25000000;
CONSTANT n : INTEGER:= 2500000;
SIGNAL tmp :STD_LOGIC;
SIGNAL tnp :STD_LOGIC;
SIGNAL clk_cout1 : STD_LOGIC; -- 添加这一行
BEGIN
PROCESS(clk,tmp)
VARIABLE cout : INTEGER:=0;
BEGIN
IF clk'EVENT AND clk='1'THEN
cout:=cout+1;
IF cout<= THEN
tmp<='0';
ELSIF cout<m*2 THEN
tmp<='1';
ELSE
cout:=0;
END IF;
END IF;
END PROCESS;
clk_cout1<=tmp; -- 修改这一行
PROCESS(clk, tnp)
VARIABLE cout : INTEGER:=0;
BEGIN
IF clk'EVENT AND clk='1' THEN
cout:=cout+1;
IF cout<=n THEN
tnp<='0';
ELSIF cout<n*20 THEN
tnp<='1';
ELSE
cout:=0;
END IF;
END IF;
END PROCESS;
clk_out10<=tnp;
END fwm;
```
此外,`clk_out1` 也没有被使用,如果不需要可以将其从 PORT 中删除。
这是我写的UART的VHDL文件:library ieee; use ieee.std_logic_1164.all; use ieee.std_logic_arith.all; use ieee.std_logic_unsigned.all; entity my_uart is port(clk_in:in std_logic; rx:in std_logic; tx:out std_logic; tcmd:in std_logic; tx_done:out std_logic; rx_ready:out std_logic; t_data:in std_logic_vector(7 downto 0); r_data:out std_logic_vector(7 downto 0)); end my_uart; architecture beheavior of my_uart is component baud is port(clk:in std_logic; bclk:out std_logic); end component; component rxd is port(bclk_in,rxd_in:in std_logic; rx_ready:out std_logic; rx_buffer:out std_logic_vector(7 downto 0)); end component; component txd is port(bclk_in:in std_logic; tx_cmd:in std_logic; txd_out:out std_logic; txd_done:out std_logic; tx_buffer:in std_logic_vector(7 downto 0)); end component; signal baud_clk:std_logic; begin B:baud port map(clk_in,baud_clk); R:rxd port map(baud_clk,rx,rx_ready,r_data); T:txd port map(baud_clk,tcmd,tx,tx_done,t_data); end beheavior;帮我写一个test benche文件,基于Modelsim进行仿真,以验证它的接受与发射功能
好的,以下是一个简单的 test bench 文件,可以用于验证你的 UART 模块的接收与发送功能。请将该代码保存为 tb_my_uart.vhd 文件,与你的 my_uart.vhd 文件一起在 ModelSim 中进行仿真。
```
library ieee;
use ieee.std_logic_1164.all;
entity tb_my_uart is
end tb_my_uart;
architecture behavior of tb_my_uart is
-- Component declaration for DUT
component my_uart is
port(
clk_in : in std_logic;
rx : in std_logic;
tx : out std_logic;
tcmd : in std_logic;
tx_done : out std_logic;
rx_ready : out std_logic;
t_data : in std_logic_vector(7 downto 0);
r_data : out std_logic_vector(7 downto 0)
);
end component;
-- Inputs
signal clk_in : std_logic := '0';
signal rx : std_logic := '0';
signal tcmd : std_logic := '0';
signal t_data : std_logic_vector(7 downto 0) := (others => '0');
-- Outputs
signal tx : std_logic;
signal tx_done : std_logic;
signal rx_ready : std_logic;
signal r_data : std_logic_vector(7 downto 0);
-- Clock period definitions
constant clk_period : time := 10 ns;
begin
-- Instantiate the DUT
uut: my_uart port map (
clk_in => clk_in,
rx => rx,
tx => tx,
tcmd => tcmd,
tx_done => tx_done,
rx_ready => rx_ready,
t_data => t_data,
r_data => r_data
);
-- Clock process definitions
clk_process :process
begin
clk_in <= '0';
wait for clk_period/2;
clk_in <= '1';
wait for clk_period/2;
end process;
-- Stimulus process
stim_proc: process
begin
-- Send a test character
t_data <= "01010101";
tcmd <= '1';
wait for 500 ns;
tcmd <= '0';
wait for 1000 ns;
-- Send another test character
t_data <= "10101010";
tcmd <= '1';
wait for 500 ns;
tcmd <= '0';
wait for 1000 ns;
-- Wait for a received character
wait until rx_ready = '1';
assert r_data = "11110000" report "Received incorrect data" severity error;
wait;
end process;
end behavior;
```
请注意,该 test bench 只是一个简单的示例,可能需要根据你的具体需求进行修改。在仿真过程中,你可以观察模拟波形,以验证你的 UART 模块是否正常工作。