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jlechner |
-----------------------------------------------------------------------
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-- This file is part of SCARTS.
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--
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-- SCARTS is free software: you can redistribute it and/or modify
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-- it under the terms of the GNU General Public License as published by
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-- the Free Software Foundation, either version 3 of the License, or
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-- (at your option) any later version.
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--
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-- SCARTS is distributed in the hope that it will be useful,
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-- but WITHOUT ANY WARRANTY; without even the implied warranty of
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-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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-- GNU General Public License for more details.
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--
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-- You should have received a copy of the GNU General Public License
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-- along with SCARTS. If not, see <http://www.gnu.org/licenses/>.
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-----------------------------------------------------------------------
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library ieee;
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use ieee.std_logic_1164.all;
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use ieee.numeric_std.all;
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architecture beh of debounce_fsm is
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constant CLK_PERIOD : time := 1E9 / CLK_FREQ * 1 ns;
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constant CNT_MAX : integer := TIMEOUT / CLK_PERIOD;
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type DEBOUNCE_FSM_STATE_TYPE is
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(REINIT0, REINIT1, IDLE0, TIMEOUT0, IDLE1, TIMEOUT1);
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signal debounce_fsm_state, debounce_fsm_state_next : DEBOUNCE_FSM_STATE_TYPE;
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signal cnt, cnt_next : integer range 0 to CNT_MAX;
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begin
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next_state : process(debounce_fsm_state, i, reinit, reinit_value, cnt)
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begin
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debounce_fsm_state_next <= debounce_fsm_state;
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case debounce_fsm_state is
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when REINIT0 =>
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debounce_fsm_state_next <= TIMEOUT0;
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when REINIT1 =>
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debounce_fsm_state_next <= TIMEOUT1;
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when IDLE0 =>
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if reinit = '1' and reinit_value = '0' then
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debounce_fsm_state_next <= REINIT0;
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elsif reinit = '1' and reinit_value = '1' then
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debounce_fsm_state_next <= REINIT1;
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elsif i = '1' then
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debounce_fsm_state_next <= TIMEOUT0;
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end if;
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when TIMEOUT0 =>
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if reinit = '1' and reinit_value = '0' then
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debounce_fsm_state_next <= REINIT0;
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elsif reinit = '1' and reinit_value = '1' then
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debounce_fsm_state_next <= REINIT1;
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elsif i = '0' then
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debounce_fsm_state_next <= IDLE0;
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elsif cnt = CNT_MAX - 1 then
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debounce_fsm_state_next <= IDLE1;
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end if;
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when IDLE1 =>
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if reinit = '1' and reinit_value = '0' then
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debounce_fsm_state_next <= REINIT0;
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elsif reinit = '1' and reinit_value = '1' then
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debounce_fsm_state_next <= REINIT1;
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elsif i = '0' then
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debounce_fsm_state_next <= TIMEOUT1;
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end if;
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when TIMEOUT1 =>
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if reinit = '1' and reinit_value = '0' then
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debounce_fsm_state_next <= REINIT0;
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elsif reinit = '1' and reinit_value = '1' then
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debounce_fsm_state_next <= REINIT1;
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elsif i = '1' then
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debounce_fsm_state_next <= IDLE1;
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elsif cnt = CNT_MAX - 1 then
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debounce_fsm_state_next <= IDLE0;
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end if;
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end case;
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end process next_state;
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output : process(debounce_fsm_state, cnt)
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begin
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o <= RESET_VALUE;
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cnt_next <= 0;
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case debounce_fsm_state is
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when REINIT0 =>
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o <= '0';
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when REINIT1 =>
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o <= '1';
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when IDLE0 =>
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o <= '0';
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when TIMEOUT0 =>
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o <= '0';
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cnt_next <= cnt + 1;
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when IDLE1 =>
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o <= '1';
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when TIMEOUT1 =>
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o <= '1';
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cnt_next <= cnt + 1;
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end case;
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end process output;
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assert RESET_VALUE = '0' or RESET_VALUE = '1' report
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"RESET_VALUE may only be 0 or 1!" severity failure;
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sync : process(sys_clk, sys_res_n)
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begin
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if sys_res_n = '0' then
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if RESET_VALUE = '0' then
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debounce_fsm_state <= IDLE0;
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else
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debounce_fsm_state <= IDLE1;
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end if;
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cnt <= 0;
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elsif rising_edge(sys_clk) then
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debounce_fsm_state <= debounce_fsm_state_next;
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cnt <= cnt_next;
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end if;
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end process sync;
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end architecture beh;
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