IFD2303code.txt


library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;


entity LED_Driver is port
(
	
	clk:		in	std_logic;			-- Clock input
	por:		in	std_logic; 			-- Power-On Reset
	a_bus:		in	std_logic_vector(3 downto 0);	-- 4-Bit Address Bus
	d_bus:		inout	std_logic_vector(7 downto 0); 	-- 8-Bit Data Bus	
	led_out:	out	std_logic); 			-- Output to Red LED
	
	
end LED_Driver;

architecture arch_LED_Driver of LED_Driver is

	signal	Count:  std_logic_vector(15 downto 0); 	-- Internal 16-Counter
	signal 	LedCtl: std_logic; 			-- LED Control
	signal	LedMux:	std_logic_vector(3 downto 0); 	-- Led Mode MUX Control
	signal	LedOut:	std_logic; 			-- Internal signal for Combitorial Logic
	
begin
counter:
process (clk, por)
begin
   if por = '0' then 				--If POR event 
	 Count <= "0000000000000000"; 		-- reset counter
	elsif clk='1' and clk'event then 	--If clk changed and is rising edge
       Count <= Count + 1; 			-- increment counter	 	 
	end if;
end process counter;

indicate_select:
process (LedMux,Count,LedOut,LedCtl)
begin
	if(LedCtl='1') then

		case LedMux is
		-- Governing equation for pulse width at 50% duty cycle
		-- PW = 0.5 * (2^n) * (1/f)
		-- Where n = Counter Bit used to drive LED, f = Clock Frequency
		
			when "0000" =>
				led_out <= LedOut and Count(0);
			
			when "0001" =>	
				led_out <= LedOut and Count(1);
			
			when "0010" =>
				led_out <= LedOut and Count(2);
				
			when "0011" =>
				led_out <= LedOut and Count(3);
				
			when "0100" =>
				led_out <= LedOut and Count(4);
				
			when "0101" =>
				led_out <= LedOut and Count(5);
			
			when "0110" =>
				led_out <= LedOut and Count(6);
			
			when "0111" =>
				led_out <= LedOut and Count(7);
			
			when "1000" =>
				led_out <= LedOut and Count(8);
			
			when "1001" =>
				led_out <= LedOut and Count(9);
			
			when "1010" =>	
				led_out <= LedOut and Count(10);
			
			when "1011" =>
				led_out <= LedOut and Count(11);
			
			when "1100" =>
				led_out <= LedOut and Count(12);
			
			when "1101" =>
				led_out <= LedOut and Count(13);
			
			when "1110" =>
				led_out <= LedOut and Count(14);
			
			when "1111" =>
				led_out <= LedOut and Count(15);
	
			when others =>
					led_out <= '0'; --OFF

		end case;
	else
		led_out <= '0';   --OFF
	end if;

end process indicate_select;

write_bus:
process(a_bus, por, d_bus)

	begin
			if (por = '0') then
				LedMux			<= "0000";	
				LedOut			<= '0';
				LedCtl 			<= '0';			
			
			else
			
				case a_bus is				
					
					when "0001" =>
						LedCtl		<= d_bus(5);
						LedOut		<= d_bus(4);
						LedMux(3)	<= d_bus(3);
						LedMux(2)	<= d_bus(2);
						LedMux(1)	<= d_bus(1);
						LedMux(0)	<= d_bus(0);
					
					when others =>
					null;
					
				end case;
				
			end if;

end process write_bus;

end arch_LED_Driver;