library ieee ;
use ieee.STD_LOGIC_1164.ALL ;
use ieee.STD_LOGIC_unsigned.ALL ;
ENTITY PWM_CONTROL IS 
	PORT(
	rst,Level,clk,Z_F : IN   STD_LOGIC ;
	z,f,level_display0,level_display1  : OUT  STD_LOGIC
	);
end PWM_CONTROL ;

architecture lqy of PWM_CONTROL is 
    signal cnt4 : std_logic_vector(1 downto 0) ;
    signal cnt16 :std_logic_vector(3 downto 0) ;
    signal agb :std_logic ;
    signal speed :std_logic_vector(3 downto 0) ; 
begin
--速度等級設置模塊
process(rst,level)
begin
	if rst='1' then
		cnt4<=(others=>'0');
	elsif level='1' and level'event then
		cnt4<=cnt4+1;
	end if;
end process;
process(rst,clk)
begin
	if rst='1' then 
		speed<=(others=>'0');
	elsif clk'event and clk='1' then
		case cnt4 is 
		  WHEN "00" =>  speed <= "0011" ; 
          WHEN "01" =>  speed <= "0100" ; 
          WHEN "10" =>  speed <= "0101" ; 
          WHEN "11" =>  speed <= "0111" ; 
          WHEN OTHERS =>  NULL ;
        END CASE ;
	end if;
END PROCESS;
--數字比較器模塊
process(clk,rst)
begin
	if rst='1' then
		agb<='0';
	elsif clk'event and clk='1' then
	if cnt16>speed then
		agb<='1';
	else 
		agb<='0'; 
	end if;
	end if;
end process;
--鋸齒波發生器
process(rst,clk)
begin
	if rst='1' then
		cnt16<=(others=>'0');
	elsif clk='1' and clk'event then
		cnt16<=cnt16+1 ;
	end if;
end process;
--旋轉方向控制模塊
process(rst,clk)
begin
	if rst='1' then
		z<='0';
	    f<='0';
	elsif clk'event and clk='1' then
	if z_f='1' then
	   z<=agb;
	   f<='0';
	else 
	   z<='0';
	   f<=agb;
	end if;
	end if;
end process;
level_display0 <= cnt4(0);
level_display1 <= cnt4(1);
end ;