我的VHDL代码输出依赖于重置

时间:2012-10-16 22:19:28

标签: vhdl

再次,它是我的! 首先,我想说我几天前学习了VHDL,而且我在这方面相当新手,所以我倾向于犯愚蠢的错误。任何建议都会很棒。 我为一个可以用作内存控制器的模块编写了VHDL代码。

这是我的代码:

library IEEE;
use IEEE.std_logic_1164.all;
use IEEE.std_logic_arith.all;
use IEEE.std_logic_unsigned.all;
use ieee.numeric_std.all;
entity memory_controller is
port(clk: in std_logic;
     reset: in std_logic;
     bus_id: in std_logic_vector(7 downto 0);
     read_write, burst: in std_logic;
     ready: in std_logic;
     oe, we: out std_logic;
     addr_1, addr_2: out std_logic_vector(7 downto 0)
     );
end memory_controller;
architecture behavioral of memory_controller is
    type statetype is (idle, decision, wr, rd1, rd2, rd3, rd4);
    signal present_state, next_state : statetype;
    signal addr_int : integer range 0 to (2**addr_1'length)-1;
    begin
    Synch_reset: process(clk)
    begin
        if (rising_edge(clk)) then
            if (reset ='0') then
                present_state <= next_state;  
            else
                present_state <= idle;   
            end if;
        end if;
    end process;  
    decision_logic: process(present_state, read_write, ready, burst)
    begin
        case present_state is
            when idle => 
                oe <= '0'; we <= '0'; addr_int <= 0;
                addr_1 <= std_logic_vector(to_unsigned(addr_int, addr_1'length));
                addr_2 <= std_logic_vector(to_unsigned(addr_int, addr_2'length));
                if(bus_id = "11110011") then
                    next_state <= decision;
                else
                    next_state <= idle;
                end if;
            when decision =>
                if (read_write = '1') then 
                    next_state <= rd1;
                else 
                    next_state <= wr;
                end if;
            when wr =>
                we <= '1';
                if (ready = '1') then 
                    next_state <= idle;
                else
                    next_state <= wr;
                end if;
            when rd1 =>
                oe <= '1';
                if(ready = '0') then
                    next_state <= rd1;
                else
                    if(burst = '0') then
                        next_state <= idle;
                    else 
                        next_state <= rd2;
                        addr_int <= addr_int + 1;
                addr_1 <= std_logic_vector(to_unsigned(addr_int, addr_1'length));
                addr_2 <= std_logic_vector(to_unsigned(addr_int, addr_2'length));
                    end if;
                end if;
            when rd2 =>
                oe <= '1';
                if(ready = '1') then
                    next_state <= rd3;
                    addr_int <= addr_int + 1;
                addr_1 <= std_logic_vector(to_unsigned(addr_int, addr_1'length));
                addr_2 <= std_logic_vector(to_unsigned(addr_int, addr_2'length));
                else
                    next_state <= rd2;
                end if;
            when rd3 =>
                oe <= '1';
                if(ready = '1') then 
                    next_state <= rd4;
                    addr_int <= addr_int + 1;
                addr_1 <= std_logic_vector(to_unsigned(addr_int, addr_1'length));
                addr_2 <= std_logic_vector(to_unsigned(addr_int, addr_2'length));
                else
                    next_state <= rd3;
                end if;
            when rd4 =>
                oe <= '1';
                if(ready = '1') then 
                    next_state <= idle;
                else 
                    next_state <= rd4;
                end if;
         end case;
     end process;
end behavioral;

这是我的测试平台:

Library IEEE;
USE IEEE.std_logic_1164.all;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;
entity memory_controller_tb is
end memory_controller_tb;
architecture test of memory_controller_tb is
component memory_controller
port(clk: in std_logic;
     reset: in std_logic;
     bus_id: in std_logic_vector(7 downto 0);
     read_write, burst: in std_logic;
     ready: in std_logic;
     oe, we: out std_logic;
     addr_1, addr_2: out std_logic_vector(7 downto 0)
     );
end component;
signal clk: std_logic;
signal reset: std_logic;
signal read_write, burst, oe, we: std_logic;
signal addr_1, addr_2: std_logic_vector(7 downto 0);
signal ready: std_logic;
signal bus_id: std_logic_vector(7 downto 0);
signal StopClock : boolean := FALSE;
begin
UUT :memory_controller
port map( clk => clk,
          reset => reset,
          bus_id => bus_id,
          read_write => read_write,
          burst => burst,
          ready => ready,
          oe => oe,
          we => we,
          addr_1 => addr_1,
          addr_2 => addr_2);
clk_process: process
begin
while not StopClock loop
clk <= '0';
wait for 5 ns;
clk <= '1';
wait for 5 ns;
end loop;
end process clk_process;
stim: process is
begin
reset <= '1', '0' after 50 ns;
bus_id <= "11110011";
wait for 5 ns;
read_write <= '0';
wait for 5 ns;
ready <= '1';
bus_id <= "11110011";
wait for 5 ns;
read_write <= '1';
assert (ready <='1' and burst <= '1')
report "Illegal state"
severity error;
assert (ready <= '1' and burst <='0')
report "Illegal state"
severity error;
wait for 5 ns;
ready <= '0';
wait for 5 ns;
burst <= '0';
wait for 5 ns;
ready <= '1';
wait for 5 ns;
burst <= '1';
wait for 5 ns;
ready <= '0';
wait for 5 ns;
ready <= '1';
wait for 5 ns;
ready <= '1';
end process;
end test;

configuration CFG_memory_controller of memory_controller_tb is
    for test
        for UUT : memory_controller
        end for;
    end for;
end;

当突发被断言时,它应该通过read1 read2 read3和read4断言就绪(如在突发= 1时它应继续读取2,读取3,读取4如果准备就绪为1)并且不得进入如果复位在任何时间之间变为0,则为空闲状态。但它确实适合我。如何更改程序以使其不依赖于重置?

此外,当地址复位以返回空闲状态时,地址不会复位为0。当我尝试更改代码时,它表示我试图从多个地方断言地址。

此外,我认为我的测试台编写技巧很糟糕,是否有任何规则或指导要遵循,或者您是否必须为此发展本能?

谢谢!

1 个答案:

答案 0 :(得分:0)

你有一个组合循环:你在组合过程中读写信号addr_int,这会导致各种各样的问题。创建一个信号next_addr_int并在时钟进程中分配它,或者将所有内容放在一个时钟进程中。

代码的其他问题:

  • std_logic_arithstd_logic_unsigned已弃用。请改用ieee.numeric_std
  • 这样的转化会让您的代码难以理解:addr_1 <= std_logic_vector(to_unsigned(addr_int, addr_1'length));请改用unsigned代替std_logic_vector
  • 在您的重置条款中,由于您检查reset = '0',人们会认为重置是低有效的。相反,请检查reset = '1'并反转ifelse部分。我想这些工具不会介意你的编码风格,但它会让人感到困惑。