Blinking LED

[Altera_Forum]

Hi, 

 I am trying to make a design that makes the LED blink 4 times when iKEY is pressed. Right now it blinks non stop when iKEY is pressed and stops blinking when iKEY is pressed again. What changes should I make to make that happen ?   library ieee; use ieee.std_logic_1164.all; use ieee.std_logic_arith.all; use ieee.numeric_std.all; use ieee.std_logic_unsigned.all;  entity pract is  port (  iCLK_50 : in std_logic;  iKEY : in std_logic_vector(0 downto 0);  oLEDG: out std_logic_vector(2 downto 0) ); end entity pract;  architecture behav of pract is    signal sel : std_logic_vector(0 downto 0) := "0";  signal newCLK : std_logic_vector (0 downto 0) := "1";  signal counting: integer := 0;  signal cycles : integer :=0 ;  type state_type is (idle, s0, s1, s2, s3);  signal current_state, next_state : state_type;  --signal   begin   ------------------------------------------------------- -----------clk code------------------------------------  clocking : process(iCLK_50, iKEY)  begin     if(rising_edge(iCLK_50)) then  counting <= counting + 1;  if (counting >= 100000000) then  counting <= 0;  end if;  end if;    end process;    newclocking: process(counting)  begin    if(counting <= 50000000) then  newCLK <= "0";  else   newCLK <= "1";  end if;  end process; -------------end clk code------------------------------ -------------------------------------------------------    p1 : process(iKEY) begin  if(rising_edge(iKEY(0))) then  sel <= sel + "1"; end if;  end process;   p2 : process(sel)  begin  case sel is  when "1"=>  -- go to s0  case newCLK is   when "0" =>  oLEDG <= "000";  when "1" =>  oLEDG <= "111";  end case; when "0"=>  oLEDG <= "000"; -- restart the counter or something end case;  end process;  end behav;  Thanks

[Altera_Forum]

First as said previously in your other thread, never use use ieee.numeric_std.all and ieee.std_logic_unsigned.all at the same time, you'll run into problems. and while you are at it, forget about the non standard ieee.std_logic_unsigned, just use ieee.numeric_std.all and its signed and unsigned types. 

Then you shouldn't use the key signal as a clock. You will run into synchronization problems and will be very sensitive to glitches problems if the key isn't debounced. You should use your iclk50 as clock, and for example compare the KEY signal to its previous value to detect a key press. For the rest, create an additional signal that will be a counter, set it to 4 when the key is pressed, decrease it by 1 each time you make the LED blink and stop when you reach 0.