Led Control with One Button

[vitruvius]

Hi all. I'm a begginer at VHDL and Fpga and i have Spartan-3E Starter Kit. I tried to do led control with using only one button. I wanted that when i press the button, next led will be logic 1. The problem is; leds don't be logic 1 in the right order.

My Vhdl Code:

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;

entity btn_state_de is
    Port ( btn : in  STD_LOGIC;
           clk : in  STD_LOGIC;
           rst : in  STD_LOGIC;
           led : out  STD_LOGIC_VECTOR (7 downto 0));
end btn_state_de;

architecture Behavioral of btn_state_de is

type state_type is (s0,s1,s2,s3,s4,s5,s6,s7,s8);
signal state : state_type;

begin

	process (clk,rst)
	begin
		if (rst='1') then
		state <= s0;		
			elsif (clk'event and clk='1') then			
				case state is
					when s0 =>
						if btn='1' then							
							state <= s1;
						else
						state <= s0;
						end if;
					when s1 =>
						if btn='1' then							
							state <= s2;					
						else
						state <= s1;
						end if;
					when s2 =>
						if btn='1' then							
							state <= s3;
						else
						state <= s2;
						end if;
					when s3 =>
						if btn='1' then							
							state <= s4;
						else
						state <= s3;
						end if;
					when s4 =>
						if btn='1' then							
							state <= s5;
						else
						state <= s4;
						end if;
					when s5 =>
						if btn='1' then							
							state <= s6;
						else
						state <= s5;
						end if;
					when s6 =>
						if btn='1' then							
							state <= s7;
						else
						state <= s6;
						end if;
					when s7 =>
						if btn='1' then							
							state <= s8;
						else
						state <= s7;
						end if;
					when s8 =>
						if btn='1' then							
							state <= s0;
						else
						state <= s8;
						end if;
				end case;
		end if;
	end process;
	
	process (state)
		begin
			case state is
				when s0 =>led<="00000000";
				when s1 =>led<="10000000";
				when s2 =>led<="01000000";
				when s3 =>led<="00100000";
				when s4 =>led<="00010000";
				when s5 =>led<="00001000";
				when s6 =>led<="00000100";
				when s7 =>led<="00000010";
				when s8 =>led<="00000001";
			end case;
		end process;
		


end Behavioral;

Thank you for your answers.

 

[alexan_e]

I think the problem is that you are using a very fast clock so each time you press the button you execute a few thousand steps and this gives you the impression of random steps.
Use a counter to change states once per second or something.

Alex