Finite State Machine working in simulation, but not working on actual FPGA board

[goodpranoy]

debouncing removes the 0/1/0/1 toggling you get when you move a switch, so the idea is after debouncing you get a single clean 0 -> 1 transition.

after the debouncing i get a constant value right.

i got this code from the net for debouncing.

how can i get a single clean transition from this code?

LIBRARY ieee;
USE ieee.std_logic_1164.all;
USE ieee.std_logic_unsigned.all;

ENTITY debounce IS
  GENERIC(
    counter_size  :  INTEGER := 19); --counter size (19 bits gives 10.5ms with 50MHz clock)
  PORT(
    clk     : IN  STD_LOGIC;  --input clock
    button  : IN  STD_LOGIC;  --input signal to be debounced
    result  : OUT STD_LOGIC); --debounced signal
END debounce;

ARCHITECTURE logic OF debounce IS
  SIGNAL flipflops   : STD_LOGIC_VECTOR(1 DOWNTO 0); --input flip flops
  SIGNAL counter_set : STD_LOGIC;                    --sync reset to zero
  SIGNAL counter_out : STD_LOGIC_VECTOR(counter_size DOWNTO 0) := (OTHERS => '0'); --counter output
BEGIN

  counter_set <= flipflops(0) xor flipflops(1);   --determine when to start/reset counter
  
  PROCESS(clk)
  BEGIN
    IF(clk'EVENT and clk = '1') THEN
      flipflops(0) <= button;
      flipflops(1) <= flipflops(0);
      If(counter_set = '1') THEN                  --reset counter because input is changing
        counter_out <= (OTHERS => '0');
      ELSIF(counter_out(counter_size) = '0') THEN --stable input time is not yet met
        counter_out <= counter_out + 1;
      ELSE                                        --stable input time is met
        result <= flipflops(1);
      END IF;    
    END IF;
  END PROCESS;
END logic;

 

[TrickyDicky]

You could use this code on your code. It works by looking for an initial transition on the switch, but then wont let the result through for 10.5ms, to allow the change to stabilize.

 

[goodpranoy]

so if i route the enter signal to the input of the debouncer module and take the output of this as the enter for my FSM
will my problems be solved??

 

[TrickyDicky]

give it a go.....

 

[goodpranoy]

give it a go.....

i gave it a go. :smile:

It is working but there is a small problem.

before the program is executed, we should give an additional enter( so to input a data we now need 2 rising edges of enter instead of 1).