VGA彩色信号发生器

LIBRARY IEEE ; 
-- 显示器彩条发生器
USE IEEE.STD_LOGIC_1164.ALL ; 
USE IEEE.STD_LOGIC_UNSIGNED.ALL ; 
ENTITY COLOR IS


PORT ( CLK, MD : IN STD_LOGIC ;--扫描时钟/显示模式选择时钟

HS, VS, R, G, B : OUT STD_LOGIC); --行场同步/红 绿 蓝
END COLOR ; 
ARCHITECTURE behav OF COLOR IS
SIGNAL HS1, VS1, FCLK, CCLK : STD_LOGIC ;
SIGNAL MMD : STD_LOGIC_VECTOR(1 DOWNTO 0) ; --方式选择
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 : STD_LOGIC_VECTOR(3 DOWNTO 1) ; --X 横彩条 
SIGNAL GRBY : STD_LOGIC_VECTOR(3 DOWNTO 1) ; --Y 竖彩条 
SIGNAL GRBP : STD_LOGIC_VECTOR(3 DOWNTO 1) ; 
SIGNAL 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;
                end if;
            end if;
     end process;
     PROCESS( MMD ) 
                BEGIN 
                    IF MMD = "00" THEN GRBP <= GRBX ; --选择横彩条 
                    ELSIF MMD = "01" THEN GRBP <= GRBY ; --选择竖彩条 
                    ELSIF MMD = "10" THEN GRBP <= GRBX XOR GRBY;--产生棋盘格 
                    ELSE GRBP <= "000" ; 
                    END IF ; 
     END PROCESS ;
     PROCESS( CLK ) 
                        BEGIN 
                            IF CLK'EVENT AND CLK = '1' THEN -- 12MHz 13 分频 
                                IF FS = 24 THEN FS <= "0000" ; 
                                ELSE FS <= FS + 1 ; 
                                END IF ; 
                            END IF ; 
    END PROCESS ; 
    FCLK <= FS(2) ; 
    PROCESS( FCLK )
                      begin
                          IF FCLK'EVENT AND FCLK = '1' THEN
                              IF CC = 48 THEN CC <= "00000";                                ELSE CC <= CC + 1 ; 
                              END IF; 
                          END IF ;
   end process;
   CCLK <= CC(4) ; 
   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 ;