Traffic Light Controller

library IEEE;
use IEEE.std_logic_1164.all;

entity trafficlightcontroller is
  port
  (
    clk       : in  std_logic;
    reset     : in  std_logic;
     ambulance : in std_logic;
     smr          : in  std_logic;
     sml          : in  std_logic;
     ssr          : in  std_logic;
    rlmr          : out std_logic;
     almr         : out std_logic;
     glmr         : out std_logic;
     rlsr         : out std_logic;
     alsr         : out std_logic;
     glsr         : out std_logic
  );
end entity;

architecture rtl of trafficlightcontroller is

  -- Build an enumerated type for the state machine
  -- r=red;a=amber;g=green;c=car waiting;m=main road;s=side road
     type state_type is (rmgs, rmas, rmrs, amrs, gmrs, gmrcs, ramrs, rmacs, rmrcs, ramrcs, rmras, rmrs2);

  -- Signals to hold the states
     signal present_state, next_state : state_type;
      signal divclk, reset2, reset2b, reset3, reset3b, reset10, reset20, reset20b, count2, count2b, count3, count3b, count10, count20, count20b: std_logic;

      component timer is
            generic (
                trigger_cnt:    natural := 20
            );
            port (
                 clk:        in      std_logic;
                 reset:      in      std_logic;
                 count:      buffer  std_logic
            );
      end component timer;

      component clockdivider
            port(clkin : in std_logic;
         dividedclk : out std_logic
            );
        end component clockdivider;
      begin

      timer2 : timer generic map (trigger_cnt => 2) port map(divclk,reset2,count2);
      timer2b : timer generic map (trigger_cnt => 2) port map(divclk,reset2b,count2b);
      timer3 : timer generic map (trigger_cnt => 3) port map(divclk,reset3,count3);
      timer3b : timer generic map (trigger_cnt => 3) port map(divclk,reset3b,count3b);
      timer10 : timer generic map (trigger_cnt => 10) port map(divclk,reset10,count10);
      timer20 : timer generic map (trigger_cnt => 20) port map(divclk,reset20,count20);
      timer20b : timer generic map (trigger_cnt => 20) port map(divclk,reset20b,count20b);
      divider : clockdivider port map(clk, divclk);

  process (present_state, reset, ssr)
  begin
    if reset = '0' then
        reset2 <= '0';
        reset2b <= '0';
        reset3 <= '0';
        reset3b <='0';
        reset10 <= '0';
        reset20 <= '0';
        reset20b <= '0';
      rlmr <= '1';
        almr <= '0';
        glmr <= '0';
        rlsr <= '1';
        alsr <= '0';
        glsr <= '0';
        next_state <= rmrs;
     --Various casses for side road sensor being pressed
    elsif ssr = '0' and present_state=gmrs then
        next_state <= gmrcs;
     elsif ssr = '0' and present_state=rmas then
        next_state <= rmacs;
     elsif ssr = '0' and present_state=rmrs then
        next_state <= rmrcs;
     elsif ssr = '0' and present_state=ramrs then
        next_state <= ramrcs;
     --Various cases for emergency vehicle approach:
     --Lights will go to their amber state and then red.
     --Due to thr present state design, triggering the emergency vehicle override when in a red + amber state will result in those cars
     --missing a "turn" of green.
     elsif ambulance = '0' and present_state=gmrs then
        next_state <= amrs;
     elsif ambulance = '0' and present_state=ramrs then
        next_state <= amrs;
     elsif ambulance = '0' and present_state=ramrcs then
        next_state <= amrs;
     elsif ambulance = '0' and present_state=rmgs then
        next_state <= rmas;
     elsif ambulance = '0' and present_state=rmras then
        next_state <= rmas;
     --maintain red light until vehicle has passed
     elsif ambulance = '0' and present_state=rmrs then
        next_state <= rmrs;
     elsif ambulance = '0' and present_state=rmrcs then
        next_state <= rmrcs;
     elsif ambulance = '0' and present_state=rmrs2 then
        next_state <= rmrs2;
     else

      -- Determine the next state synchronously, based on
      -- the current state and the input
      case present_state is

          --Red light main; green side road
        when rmgs=>
             reset2 <= '0';
             reset2b <= '0';
             reset3 <= '0';
             reset3b <= '0';
             reset20 <= '0';
             reset20b <= '0';
             rlmr <= '1';
             almr <= '0';
            glmr <= '0';
            rlsr <= '0';
             alsr <= '0';
             glsr <= '1';
             reset10 <= '1';
             --if count is complete then move to next state
             if ( count10='1' ) THEN
                next_state <= rmas;
             --otherwise, return to current state
             else
                next_state <= rmgs;
             end if;

          --Red light main; amber side road
        when rmas=>
             reset2 <= '0';
             reset2b <= '0';
             reset3b <= '0';
             reset10 <= '0';
             reset20 <= '0';
             reset20b <= '0';
             rlmr <= '1';
             almr <= '0';
            glmr <= '0';
            rlsr <= '0';
             alsr <= '1';
             glsr <= '0';
             reset3 <= '1';
             if ( count3='1' ) THEN
                next_state <= rmrs;
             else
                next_state <= rmas;
             end if;

            --Red main; red side road
            --Used for change over from green on side road to green on main; also used for emergency vehicle approach
            when rmrs=>
             reset2 <= '0';
             reset2b <= '0';
             reset3 <= '0';
             reset10 <= '0';
             reset20 <= '0';
             reset20b <= '0';
             rlmr <= '1';
             almr <= '0';
            glmr <= '0';
            rlsr <= '1';
             alsr <= '0';
             glsr <= '0';
             reset3b <= '1';
             if ( count3b='1' ) THEN
                next_state <= ramrs;
             else
                next_state <= rmrs;
             end if;

          --Amber main; red side road
        when amrs=>
             reset2 <= '0';
             reset2b <= '0';
             reset3b <= '0';
             reset10 <= '0';
             reset20 <= '0';
             reset20b <= '0';
             rlmr <= '0';
             almr <= '1';
            glmr <= '0';
            rlsr <= '1';
             alsr <= '0';
             glsr <= '0';
             reset3 <= '1';
             if ( count3='1' ) THEN
                next_state <= rmrs2;
             else
                next_state <= amrs;
             end if;

          --Green main; red side road
          when gmrs=>
             reset2 <= '0';
             reset2b <= '0';
             reset3 <= '0';
             reset3b <= '0';
             reset10 <= '0';
             reset20b <= '0';
            rlmr <= '0';
             almr <= '0';
            glmr <= '1';
            rlsr <= '1';
             alsr <= '0';
             glsr <= '0';
             reset20 <= '1';
             next_state <= gmrs;

          --Green main; red side road; car waiting
          when gmrcs=>
             reset2 <= '0';
             reset2b <= '0';
             reset3 <= '0';
             reset3b <= '0';
             reset10 <= '0';
             reset20 <= '0';
            rlmr <= '0';
             almr <= '0';
            glmr <= '1';
            rlsr <= '1';
             alsr <= '0';
             glsr <= '0';
             reset20 <= '1';
             if ( count20='1' ) THEN
                next_state <= amrs;
             else
                next_state <= gmrcs;
             end if;

         --Red main; amber side road; car waiting
         when rmacs=>
             reset2 <= '0';
             reset2b <= '0';
             reset3 <= '0';
             reset10 <= '0';
             reset20 <= '0';
             reset20b <= '0';
            rlmr <= '1';
             almr <= '0';
            glmr <= '0';
            rlsr <= '0';
             alsr <= '1';
             glsr <= '0';
             reset3 <= '1';
             if ( count3='1' ) THEN
                next_state <= rmrcs;
            else
                next_state <= rmacs;
            end if;

        --Red main; red side road; car waiting
        when rmrcs=>
             reset2 <= '0';
             reset2b <= '0';
             reset3b <= '0';
             reset10 <= '0';
             reset20 <= '0';
             reset20b <= '0';
             rlmr <= '1';
             almr <= '0';
            glmr <= '0';
            rlsr <= '1';
             alsr <= '0';
             glsr <= '0';
             reset3b <= '1';
             if ( count3b='1' ) THEN
                next_state <= ramrcs;
             else
                next_state <= rmrcs;
             end if;

        --Red + amber main; red side road; car waiting
        when ramrcs=>
             reset2 <= '0';
             reset3 <= '0';
             reset3b <= '0';
             reset10 <= '0';
             reset20 <= '0';
             reset20b <= '0';
             rlmr <= '1';
             almr <= '1';
            glmr <= '0';
            rlsr <= '1';
             alsr <= '0';
             glsr <= '0';
             reset2 <= '1';
             if ( count2='1' ) THEN
                next_state <= gmrcs;
             else
                next_state <= ramrcs;
             end if;

        --Red + amber main; red side road
        when ramrs=>
             reset2b <= '0';
             reset3 <= '0';
             reset3b <= '0';
             reset10 <= '0';
             reset20 <= '0';
             reset20b <= '0';
             rlmr <= '1';
             almr <= '1';
            glmr <= '0';
            rlsr <= '1';
             alsr <= '0';
             glsr <= '0';
             reset2 <= '1';
             if ( count2='1' ) THEN
                next_state <= gmrs;
             else
                next_state <= ramrs;
             end if;

        --Red main; red + amber side road
        when rmras=>
             reset2b <= '0';
             reset3 <= '0';
             reset3b <= '0';
             reset10 <= '0';
             reset20 <= '0';
             reset20b <= '0';
             rlmr <= '1';
             almr <= '0';
            glmr <= '0';
            rlsr <= '1';
             alsr <= '1';
             glsr <= '0';
             reset2 <= '1';
             if ( count2='1' ) THEN
                next_state <= rmgs;
             else
                next_state <= rmras;
             end if;

        --Red main; red side road
        --Used for changeover between green on main and green on side road
        when rmrs2=>
             reset2 <= '0';
             reset3 <= '0';
             reset10 <= '0';
             reset20 <= '0';
             reset20b <= '0';
             rlmr <= '1';
             almr <= '0';
            glmr <= '0';
            rlsr <= '1';
             alsr <= '0';
             glsr <= '0';
             reset3b <= '1';
             if ( count3b='1' ) THEN
                next_state <= rmras;
             else
                next_state <= rmrs2;
             end if;

      end case;
    end if;
  end process;

  --Every clock tick, the next state is selected as the present state.
  state_clocked: process(clk)
  begin
     if ( rising_edge( clk ) ) THEN
        present_state <= next_state;
     end if;
end process state_clocked;

end architecture;