vgal.vhd

实现模拟阴极射线管的彩色显示的行扫描和场扫描

LIBRARY  IEEE;
USE  IEEE.STD_LOGIC_1164.ALL;
USE  IEEE.STD_LOGIC_UNSIGNED.ALL;
ENTITY  VGAL  IS
PORT(   CLK, MD : IN STD_LOGIC;
       HS,VS,R,G,B: OUT STD_LOGIC);--行场同步/红,绿,蓝
END ENTITY VGAL;
ARCHITECTURE behave OF VGAL IS
SIGNAL  HS1,VS1,FCLK,CCLK : STD_LOGIC;  --方式选择
SIGNAL  MMD : STD_LOGIC_VECTOR(1 DOWNTO 0);
SIGNAL  FS : STD_LOGIC_VECTOR(3 DOWNTO 0);
SIGNAL  CC : STD_LOGIC_VECTOR(4 DOWNTO 0); --行同步/横彩条生成
SIGNAL  LL : STD_LOGIC_VECTOR(8 DOWNTO 0); --场同步/竖彩条生成
SIGNAL  GRBX,GRBY : STD_LOGIC_VECTOR(3 DOWNTO 1);--X彩条和Y彩条
SIGNAL  GRBP,GRB : STD_LOGIC_VECTOR(3 DOWNTO 1);
BEGIN
GRB(2) <= (GRBP(2) XOR MD) AND HS1 AND VS1;
GRB(3) <= (GRBP(3) XOR MD) AND HS1 AND VS1;
GRB(1) <= (GRBP(1) XOR MD) AND HS1 AND VS1;
PROCESS(MD)
BEGIN
    IF (MD'EVENT AND MD='0') THEN
         IF MMD ="10" THEN MMD <="00";
            ELSE MMD <= MMD+1;--三种模式
         END IF;
    END IF;
END PROCESS;

PROCESS(MMD)
BEGIN
      IF MMD = "00" THEN GRBP <= GRBX;
 ELSIF MMD ="01" THEN GRBP <= GRBY;
 ELSIF MMD ="10" THEN GRBP <= GRBX XOR GRBY;
 ELSE GRBP <="000"; 
END IF;
END PROCESS;

PROCESS (CLK)
BEGIN
   IF (CLK'EVENT AND CLK ='1') THEN  --12MHz 13分频
     IF FS =12 THEN FS <= "0000";
     ELSE FS <= FS+1; 
     END IF;
   END IF;
END PROCESS;
FCLK <= FS(3) ; CCLK <= CC(4) ;
PROCESS (FCLK)
BEGIN 
   IF FCLK'EVENT AND FCLK = '1' THEN
      IF CC = 29 THEN CC <="00000";
      ELSE CC <= CC+1;
      END IF;
   END IF;
END PROCESS;

PROCESS(CCLK)
BEGIN 
   IF CCLK'EVENT AND CCLK ='0' THEN
     IF LL = 481 THEN LL <="000000000";
     ELSE LL <= LL+1;
     END IF;
   END IF;
END PROCESS;

PROCESS(CC,LL)
BEGIN
   IF  CC > 23 THEN HS1 <='0'; --行同步
     ELSE HS1 <= '1';
   END IF;
   IF LL > 479 THEN VS1 <= '0'; 	--场同步
     ELSE VS1 <= '1';
   END IF;
END PROCESS;

PROCESS(CC,LL)
BEGIN
   IF CC < 3 THEN GRBX <= "111"; --横彩条
 ELSIF CC < 6 THEN GRBX <= "110";
 ELSIF CC < 9 THEN GRBX <= "101";
 ELSIF CC < 12 THEN GRBX <= "100";
     ELSIF CC < 15 THEN GRBX <= "011";
     ELSIF CC < 18 THEN GRBX <= "010";
     ELSIF CC < 21 THEN GRBX <= "001";
       ELSE GRBX <= "000";
       END IF;
       IF LL < 60 THEN GRBY <= "111"; --竖彩条
 ELSIF LL < 120 THEN GRBY <= "110";
 ELSIF LL < 180 THEN GRBY <= "101";
 ELSIF LL < 240 THEN GRBY <= "100";
     ELSIF LL < 300 THEN GRBY <= "011";
     ELSIF LL < 360 THEN GRBY <= "010";
     ELSIF LL < 420 THEN GRBY <= "001";
       ELSE GRBY <= "000";
     END IF;
   END PROCESS;
HS <= HS1; 
VS <= VS1; 
R <= GRB(2); 
G <= GRB(3);
B <= GRB(1);
END behave;