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;