library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_arith.all;
use ieee.std_logic_unsigned.all;
entity light is
port (start:in std_logic;					--定義初始化信號,高電平有效
		clk: in std_logic;					--定義參考時鐘
	car_zhi:in std_logic;				--定義儀器監(jiān)測到的支路有無車輛的標(biāo)志,有為高電平
	man_zhi:in std_logic;				--定義儀器監(jiān)測到的支路有無行人的標(biāo)志,有為高電平
	g_zhu,y_zhu,r_zhu:out std_logic;	--定義主干道綠、黃、紅燈，亮為高電平
		g_zhi,y_zhi,r_zhi:out std_logic	    --定義支路綠、黃、紅燈，亮為高電平
	  );
end light;
architecture beh of light is
signal counter_g_zhu:integer range 0 to 255; --定義對主干道綠燈亮的計數(shù)器
signal counter_flash1:integer range 0 to 255; --定義主干道綠燈向紅燈轉(zhuǎn)換的計數(shù)器
signal counter_flash2:integer range 0 to 255; --定義支路綠燈向紅燈轉(zhuǎn)換的計數(shù)器
signal counter_judge1:integer range 0 to 255; --定義對支路綠燈亮的計數(shù)器
signal counter_judge2:integer range 0 to 255; --定義對支路連續(xù)5秒無車輛和行人的計數(shù)器
signal f1_g_zhu,f2_g_zhu:std_logic; 		--定義主干道綠燈亮的標(biāo)志,亮為高電平
signal f_g_zhi:std_logic;					--定義支路綠燈亮的標(biāo)志,亮為高電平
signal gtor_zhu: std_logic;				--定義主干道綠燈向紅燈轉(zhuǎn)換的標(biāo)志,高電平開始轉(zhuǎn)換
signal rtog_zhu: std_logic;				--定義主干道紅燈向綠燈轉(zhuǎn)換的標(biāo)志,高電平開始轉(zhuǎn)換
signal judge:std_logic;					--判斷支路是否由綠燈向紅燈轉(zhuǎn)換的標(biāo)志,高電平開始判斷
begin
process(clk)
begin
if clk'event and clk='1' then
 if start='1' then  						--當(dāng)start為高電平時, 對系統(tǒng)初始化
  f1_g_zhu<='1';							--主干道綠燈亮,黃燈和紅燈滅
  f2_g_zhu<='1';
  g_zhu<='1';
  y_zhu<='0';							
  r_zhu<='0';
  g_zhi<='0';							--支路紅燈亮,綠燈和黃燈滅
  y_zhi<='0';
  r_zhi<='1';
  judge<='0';							--支路由綠燈向紅燈轉(zhuǎn)換的標(biāo)志初始為無效
  counter_g_zhu<=0;						--所有計數(shù)器初始為零
  counter_flash1<=0;
  counter_flash2<=0;
  gtor_zhu<='0';							--主干道紅綠燈相互轉(zhuǎn)換的標(biāo)志初始化為無效
  rtog_zhu<='0';
else 
  if f1_g_zhu='1' then					--當(dāng)主干道為綠燈時,開始計數(shù)
   counter_g_zhu<=counter_g_zhu+1;
   if counter_g_zhu>=15 then			--當(dāng)主干道綠燈已亮15個clk時(實為240個,即2分
    if (car_zhi='1') or (man_zhi='1') then	--鐘),開始判斷支路是否有行人或車輛等待,若有將主
     gtor_zhu<='1'; 						--干道由綠燈轉(zhuǎn)為紅燈的標(biāo)志置為高電平有效
	 f1_g_zhu<='0';						--將標(biāo)志置零,不再繼續(xù)判斷
    end if;
   end if;
  end if;
  if gtor_zhu='1' then 					--當(dāng)為高電平時,主干道開始由綠燈向紅燈轉(zhuǎn)換
   counter_flash1<=counter_flash1+1;		
   if counter_flash1<=3 then 				--當(dāng)計數(shù)在3(實為5,即綠燈閃2.5秒)以內(nèi),設(shè)置主干道
    f2_g_zhu<=not f2_g_zhu; 			--綠燈閃爍
    g_zhu<=f2_g_zhu;
   elsif counter_flash1<=6 then			--當(dāng)計數(shù)在3~6(實為5~10)時,主干道黃燈亮
    	y_zhu<='1';
   else y_zhu<='0';						--當(dāng)計數(shù)在超過6(實為10,即5秒)時,主干道黃燈滅
 	    r_zhu<='1';						--紅燈亮
	    gtor_zhu<='0';					--將轉(zhuǎn)換標(biāo)志清零,結(jié)束轉(zhuǎn)換
		g_zhi<='1';						--支路綠燈亮
	    f_g_zhi<='1';					--支路綠燈亮標(biāo)志置1
		r_zhi<='0'; 						--支路紅燈滅
	    counter_flash1<=0;				--計數(shù)器清零,為下一次作準(zhǔn)備
		judge<='1';						--啟動判斷支路是否由綠燈向紅燈轉(zhuǎn)換
		counter_judge1<=0;				--將判斷計數(shù)器清零
		counter_judge2<=0;
   end if;
  end if;
  if judge='1' then 						--當(dāng)判斷標(biāo)志為高電平時,開始啟動判斷支路是否由綠
   counter_judge1<=counter_judge1+1;	--燈向紅燈轉(zhuǎn)換
   if counter_judge1<10 then				--在計數(shù)不超過10(實為40,即20秒)時,判斷是否有車
    if (car_zhi='0') and (man_zhi='0') then --輛和行人
     counter_judge2<=counter_judge2+1;
	  if counter_judge2>=4 then			--若連續(xù)4個clk(實為10個,即5秒)支路上沒有車輛
	   rtog_zhu<='1'; 					--和行人時,啟動轉(zhuǎn)換,高電平有效
	   judge<='0'; 						--同時將標(biāo)志judge置0,結(jié)束本次判斷
 	  end if;
   else counter_judge2<=0;				--若在4個clk之內(nèi)有車輛和行人出現(xiàn),將計數(shù)器清零,
   end if;								--重新開始計數(shù)
  else  rtog_zhu<='1';					--若計數(shù)超過10,則無論支路有無車輛和行人,都啟動
    	judge<='0'; 						--支路由綠燈向紅燈的轉(zhuǎn)換,同時將標(biāo)志judge置0
  end if;
 end if;    
 if rtog_zhu='1' then 					    --當(dāng)支路由綠燈向紅燈轉(zhuǎn)換的標(biāo)志有效時，啟動轉(zhuǎn)換
   counter_flash2<=counter_flash2+1;		--計數(shù)
   if counter_flash2<=3 then 				--同前,支路綠燈閃
    f_g_zhi<=not f_g_zhi;
    g_zhi<=f_g_zhi;
   elsif counter_flash2<=6 then			--然后黃燈亮
    	y_zhi<='1';		
   else	y_zhi<='0';
 	    r_zhi<='1';						--再紅燈亮
	    rtog_zhu<='0';					--將標(biāo)志清零,結(jié)束本次轉(zhuǎn)換
		g_zhu<='1';						--主干道綠燈亮
	    f1_g_zhu<='1';					--將主干道綠燈亮標(biāo)志置1,開始啟動主干道綠燈是否
		f2_g_zhu<='1'; 					--向紅燈轉(zhuǎn)換的判斷
		r_zhu<='0'; 						--主干道紅燈滅
		counter_flash2<=0;				--計數(shù)器清零,為下一次轉(zhuǎn)換作準(zhǔn)備
		counter_g_zhu<=0;
   end if;
  end if; 
 end if;
end if;
end process ; 
end beh;