請問倒數00就停怎寫?

ssejack1 · 發表於 2008-12-26 09:37:54

Key function
按鍵開關第一次 on時，開始計時。
第二次 on時，停止計時。
第三次 on時，開始計時。
未 synthesis,請自行 debug........

LIBRARY ieee;
USE ieee.std_logic_1164.all;
USE ieee.std_logic_unsigned.all;
ENTITY KeyFunction IS
      PORT(CLK,
               PB,
               RSTn       : IN  STD_LOGIC;
               START_COUNT,
               PAUSE
                       : OUT  STD_LOGIC
            );
END KeyFunction;
ARCHITECTURE arc OF debounce_v IS
SIGNAL  currently_state : STD_LOGIC_VECTOR(2 downto 0);
signal    pb_reg,debounce_counting,debounce_end : std_logic;
signal debounce_counter : STD_LOGIC_VECTOR(15 downto 0);

constant  debounce_time : STD_LOGIC_VECTOR(15 downto 0):= "0000000000000000";
BEGIN

--============================================================
-- get key push state. ( active high)
--============================================================
  PROCESS (CLK,RSTn,PB,pb_reg,debounce_counting,debounce_end)
BEGIN
if( RSTn = '0') then
         pb_reg <= 1;
elsif( CLK 'event and CLK ='1')then
      if( PB='1' and pb_reg ='0')then
           debounce_counting <= '1';
      elsif( debounce_end = '1')then
        debounce_counting <= '0';
      else
        debounce_counting <= debounce_counting;
      end if;
      pb_reg <= PB;
end if;

ssejack1 · 發表於 2008-12-26 09:38:06

--============================================================
-- key debounce timer
--============================================================
  PROCESS (CLK,RSTn,PB,pb_reg,debounce_counting,debounce_end)
BEGIN
if( RSTn = '0') then
      debounce_end <= '0';
         debounce_counter <= debounce_time;
elsif( CLK 'event and CLK ='1')then
      if( debounce_counting  ='1')then
        if( debounce_count = "1111111111111111")then
        debounce_end <= '1';
        debounce_counter <= debounce_time;
        else
        debounce_end <= '0';
           debounce_count = debounce_count+1 ;
           end if;
      end if;
end if;

--============================================================
-- key function control
-- PAUSE -(key push)-> START_COUNT -(key push)-> PAUSE -(key push)-> START_COUNT
--============================================================
  PROCESS (CLK,RSTn,pb_reg,debounce_end)
BEGIN
if( RSTn = '0') then
      currently_state <= "10"; -- pause
elsif( CLK 'event and CLK ='1')then
      if( debounce_end  ='1' and pb_reg ='1')then
        currently_state <= currently_state(0)& currently_state(1);
      end if;
end if;
               START_COUNT <= currently_state(0);
               PAUSE <= currently_state(1);

END PROCESS ;
END arc;

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[問題求助] 請問倒數00就停怎寫?