交通灯的时间计数器不会增加

Question

我正在为作业编写简单的交集 "simulator"。它是这样的：用户输入每条车道上在红绿灯处停车的汽车数量，并定义换灯次数。当定时器值等于用户定义的时间时，灯应该改变它们的颜色。

time_counter中出现问题，过程如下

 time_counter_process: process (reset, clk)
begin
if reset = '1' then
    time_counter<=  "0000000";
elsif clk'event and clk='1' then
        if (state = state_1 and time_counter < state_1_time_value) then
            -- in state_1 one some lights are green and others red, simple
            time_counter <= time_counter + 1;

                if (state = state_1 and time_counter = state_1_time_value) then
                    time_counter <= "0000000";
                end if;

        etc...

        elsif state = state_6 and time_counter < state_6_time_value then

            time_counter <= time_counter + 1;

                if state = state_6 and time_counter = state_6_time_value then
                    time_counter <= "0000000";
                end if;


    end if;
end if;
end process time_counter_process;

我不知道为什么，但计时器没有正确递增。它保持在值“000000”。谁能告诉我为什么它不能正常工作？

为了更清楚起见，我还将展示状态如何变化

    begin
next_state<= state;
case state is
when state_1 =>
    if time_counter < state_1_time_value then
            traffic_signal_1 <= "10"; --green
            traffic_signal_2 <= "00"; -- red
            traffic_signal_3 <= "00";   
            traffic_signal_4 <= "10";
            traffic_signal_5 <= "00";
            traffic_signal_6 <= "00";


            elsif time_counter = state_1_time_value then

                    next_state<=state_2;
            end if;

Answer 1

您应该将大 if 语句与 case 语句交换 state 并将计数器条件实现为每个 when 选项中的 if 语句。

像time_counter = state_1_time_value这样的条件永远不会成立，因为信号在进程结束时更新。您所在的分支中 time_counter < state_1_time_value 为真，因此 time_counter = state_1_time_value 不可能也为真。

time_counter_process: process (reset, clk)
begin
  if (reset = '1') then
    time_counter<=  "0000000";
  elsif rising_edge(clk) then
    case state is
      when state_1 =>
        if (time_counter < state_1_time_value) then
          -- in state_1 one some lights are green and others red, simple
          time_counter <= time_counter + 1;
        else
          time_counter <= "0000000";
        end if;

-- etc...

    when state_6 =>
      if (time_counter < state_6_time_value) then
        time_counter <= time_counter + 1;
      else
        time_counter <= "0000000";
      end if;

    end case;
  end if;
end process time_counter_process;

顺便说一句，您应该在设计中更喜欢同步重置。

交通灯的时间计数器不会增加

Time counter for traffic lights wont increment

vhdl